A Guide to UCSD Anesthesiology for Residents

3rd edition
Leon Chang, MD
Clinical Director
Associate Clinical Professor

1st edition, 2007

2nd edition, 2011

3rd edition, 2012

Chief editors: Geoffrey Langham, MD; Sonia Nhieu, MD

Assistant editors: Blake Fowler, MD; Nathalie Hernandez, MD; Jason Meeks, MD
Table of Contents

Chapter 1. Introduction to the UCSD Anesthesiology Clinical Curriculum, 4

Chapter 1A. Rotations at UCSD Anesthesiology, 5
Chapter 1B. A Typical Day in the Main OR, 5
Chapter 1C. The First Four Weeks, 7
Chapter 1D. Call Duties, 9
Chapter 1E. A Basic OR Setup, 13
Chapter 1F. The Code Pager, the Code Bags, and the Emergency OR Setups, 14
Chapter 1G. The Pre-operative Evaluation: General Comments, 19
Chapter 1H. The Pre-operative Evaluation: Section-By-Section, 22
Chapter 1I. Presenting Pre-Ops to Attendings, 28
Chapter 2. Anesthesia Equipment and Pharmacology, 31
Chapter 2A. Anesthesia Equipment, 31
Chapter 2B. Anesthesia Monitors, 40
Chapter 2C. Medications Used in Anesthesia, 47
Chapter 2D. Neuromuscular Blockade, 63
Chapter 3. Anesthesia for Specific Surgeries, 70
Chapter 3A. Anesthesia for General Surgery, 70
Chapter 3A-1. Anesthesia for Neck, Trunk, and Breast Surgery, 70
Chapter 3A-2. Anesthesia for Intraabdominal Surgery, 72
Chapter 3B. Anesthesia for Urologic and Gynecologic Surgery, 75
Chapter 3C. Anesthesia for Orthopedic Surgery, 78
Chapter 3C-1. Anesthesia for Spine Surgery, 79
Chapter 3C-2. Anesthesia for Lower Extremity Orthopedic Surgery, 82
Chapter 3C-3. Anesthesia for Upper Extremity Orthopedic Surgery, 83
Chapter 3C-4. Anesthesia for Debridement and Skin Grafting, 84
Chapter 3D. Anesthesia for Vascular Surgery, 84
Chapter 3E. Anesthesia for Ophthalmic and Head & Neck Surgery, 88
Chapter 3E-1. Anesthesia for Ophthalmic Surgery, 89
Chapter 3E-2. Anesthesia for Head & Neck Surgery, 91
Chapter 3F. Anesthesia for Interventional Pulmonology, 93
Chapter 3G. Anesthesia for Transplant Surgery, 94
Chapter 3G-1. Anesthesia for Kidney Transplantation, 95
Chapter 3G-2. Anesthesia for Liver Transplantation, 96
Chapter 3G-3. Anesthesia for Organ Procurement, 99
Chapter 3H. Anesthesia for Trauma and Burn Surgery, 100
Chapter 3H-1. Anesthesia for OR Resuscitation, 100
Chapter 3H-2. Anesthesia for Burn Surgery, 102
Chapter 4. Obstetric Anesthesia, 106
Chapter 4A. OB Anesthesia Rotation, 106
Chapter 4B. Physiologic Changes of Pregnancy, 107
Chapter 4C. Physiology of Uterine Blood Flow, 109
Chapter 4D. Placental Drug Transfer, 111
Chapter 4E. Stages of Labor, 112
Chapter 4F. Placement and Management of Epidural, Spinal, or CSE Anesthesia & Analgesia, 113
Chapter 4G. Anesthesia for Cesarean Section, 116
Chapter 4H. Anesthesia for Placenta Accreta/Increta/Percreta, 119

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 Chapter 4I. Anesthesia for Other Obstetric Procedures, 120
Chapter 4J. Anesthesia for Non-obstetric Surgery in the Parturient, 121
Chapter 4K. Special Topics in OB Anesthesia, 121
Chapter 5. Cardiothoracic Anesthesia Rotation and Cardiovascular Physiology, 126
Chapter 5A. Cardiothoracic Anesthesia Rotation, 126
Chapter 5B. Coronary Anatomy and Circulation, 127
Chapter 5C. Anesthetic Goals in Cardiac Disease States, 128
Chapter 5D. One-lung Ventilation: Anesthesia and Physiology, 133
Chapter 5E. Other Topics in Cardiothoracic Anesthesia, 136
Chapter 6. Anesthesia for Cardiothoracic Surgery, 139
Chapter 6A. Basics of Cardiopulmonary Bypass, 139
Chapter 6B. The Pre-Bypass, On-Bypass, and Post-Bypass Periods, 141
Chapter 6C. Anesthesia for Specific Cardiothoracic Surgeries, 143
Chapter 7. Neuroanesthesia Rotation and Neurophysiology, 152
Chapter 7A. Neuroanesthesia Rotation, 152
Chapter 7B. Neurophysiology and Anesthesia, 152
Chapter 7C. Intracranial Pressure, 155
Chapter 7D. Effect of Anesthetic Agents on CBF, CMRO 2, and ICP, 157
Chapter 7E. Neuroprotective Techniques, 159
Chapter 7F. Strategies to Reduce ICP, 158
Chapter 7G. Anesthetics and Evoked Potentials, 159
Chapter 8. Anesthesia for Neurosurgery, 161
Chapter 8A. Anesthesia for Intracranial Vascular Surgery, 161
Chapter 8B. Anesthesia for Emergent Craniotomy, 163
Chapter 8C. Anesthesia for Craniotomy for Mass Lesion, 164
Chapter 8D. Anesthesia for Posterior Fossa Surgery, 165
Chapter 8E. Anesthesia for Minor Neurosurgery, Including Stereotactic Surgery, 166
Chapter 9. Overview of the SICU, Pain, Regional, Pediatrics, and Pre-op Rotations, 168
Chapter 9A. SICU Rotation, 168
Chapter 9B. Pain Medicine Rotation, 169
Chapter 9C. Regional Anesthesia Rotation, 170
Chapter 9D. Pediatric Anesthesia Rotation, 172
Chapter 9E. Pre-op Clinic and Radiation Therapy, 174

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Chapter 1. Introduction to the UCSD Anesthesiology Clinical Curriculum

Welcome to the UCSD Department of Anesthesiology. This guide has three goals: to provide an
insiders look or a residents perspective on our daily lives at UCSD, to describe common approaches
to common surgeries we do at UCSD, and to describe physiology and pathophysiology pertinent to those
surgeries. It provides basic information on the various general and subspecialty clinical rotations and
other aspects of the anesthesiology residency. As such, it is intended to serve as a reference for
incoming and current residents. This guide is not intended to replace existing syllabi for the various
rotations and it does not describe anesthetic physiology or pharmacology in any great depth. Rather, it
will provide the kind of help that one resident wants from another when he or she asks, Hey, what can I
expect out of this month, rotation, case, or situation?

Our Philosophy

In many ways, the residents here make this program what it is. We pride ourselves on being a tight
program with great camaraderie and significant autonomy. Hopefully you knew this already and it was
part of why you decided to join UCSD. If the work gets done and things run smoothly during the day,
99.9% of the time its because the residents did their jobs, and did them well. This is not a place where
your hand will be held and things will be done for you. Often you will have to take the initiative and
responsibility yourself to see that things are done right. The reward for all of this is that our graduates
are tremendously skilled, fully independent anesthesiologists, and recognized as such around the
country.

Your fellow residents are there to help you, and with time you will be there to help them. We routinely
help each other out by doing pre-ops, helping with case starts, giving breaks, and so on. Possibly the
best example of this occurs during call. Often the senior resident will be supervising or helping the junior
resident, while the whole team continues setting up rooms for each other, pre-opping the next patient,
etc. If you are ready and willing to lend a hand to your colleagues, that kindness will be visited back to
you tenfold in the future. Likewise, if you shirk responsibility, or leave others to fend for themselves, it
will be noticed.

Its important to remember that were all in this together. A stressful, intense case, workweek, or call
will get balanced out by the more laid-back rotations and the fact that youre in a friendly work
environment. A week where you are late pre-call and have to do a keyword presentation is a tough one,
but there will be days when you are sent home at 1100 prior to a 1500 start call. It all works out in the
end, and if things are ever too much to handle on your own theres always a friend ready to lend a hand.

The theme which will be repeated throughout your residency is that of resident responsibility. There is
tremendous autonomy in this program, which inevitably can be accompanied by periods of stress.
Throughout the various rotations and experiences here at UCSD you will hear emphasized time and time
again: Its your case. The work is up to you. Its your responsibility.

This is a resident-driven program, and to remain so, it depends on residents taking the initiative in
patient care and getting the work done. There will be many times where going the extra mile will
make someones day easier or someones anesthetic safer. This effort will be rewarded. Conversely,
laziness can only hurt you and your fellow residents, and will be noticed.

The beauty of this program is that the responsibility we are given enhances our education and our ability
to function independently. By treating our duty with the utmost respect this tradition will continue.

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Chapter 1A. Rotations at UCSD Anesthesiology

Each year at UCSD is comprised of thirteen 4-week blocks. Of these blocks, nearly all are required
rotations. The required rotations are:

Main OR (MOR), including night float

VA (a main OR rotation)
Obstetric anesthesia (2 months)
Neuroanesthesia (2 months)
Cardiothoracic anesthesia (2 months; a 3rd month is optional)
Pediatric anesthesia (2 months; done at Rady Childrens Hospital San Diego)
Airway management
Regional anesthesia (2 months)
Pain medicine
ICU (3 months, this is in addition to any ICU experience taken during the PGY-1 year)
Pre-op clinic and PACU ( month each)

Two months of electives are taken in the CA-3 year. Available electives include:

Transesophageal echocardiography
OR management
Research
Advanced regional anesthesia
Benumofs Lessons Learned book
NICU
CA-3 pediatrics (1 month at Rady Childrens Hospital San Diego)
CA-3 pediatrics (2 months at LA Childrens Hospital)
Away rotation

Detailed descriptions of each rotation and the expectations are provided in the individual chapters. The
exact timing of when you will do specific rotations varies among residents, but in general the years
break down as follows:

CA-1 year: MOR and VA provide a solid base and exposure to daily OR anesthesia. Most residents
will complete at least one advanced rotation, e.g. OB or cardiac anesthesia, during this year. ICU,
pre-op clinic, and PACU rotations complete the year.
CA-2 year: Primarily subspecialty rotations (OB, Neuro, Cardiac, Regional, Pain, Peds, ICU, Airway),
interspersed with MOR and the VA.
CA-3 year: Primarily MOR, with the 2nd of 2 months each of Neuro, Peds, and OB; 2 months of
electives.

Chapter 1B. A Typical Day in the Main OR

The following is what a typical day in the main OR is like. There are individual variations between
Hillcrest, Thornton, and the VA; these will be discussed as applicable.

You should always plan on having your room set up by 0640 to be at morning conference promptly at
0640. Wednesday is the exception; QI conference (a.k.a., M&M) starts at 0630. Allow yourself ample

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time to gather everything you need. Depending on the case, this can be simple or quite time-consuming.
Setup activities can include preparing drugs, airway equipment, drips, special monitors, and so on.
Residents vary in how fast they can do this, so you should always allow yourself plenty of time. The
responsibility to get things properly set up is yours and yours alone. For new residents, allow around 40
minutes for a basic case. As you get your style down, setup for an uncomplicated GA case may take as
little as 10-15 minutes.

Often the anesthesia technicians (a.k.a., anesthesia monitoring) can provide invaluable assistance to
your setup. However, dont count on this. They are busy, spread thin, and have their own morning
responsibilities. They are most helpful if you need a special item like pressure transducers or a fiberoptic
bronchoscope, or if youve discovered an equipment problem during your routine check. Learn from
them as much as you can, so that you know where equipment is located and youll be able to grab it
when you need it on call at 0200, for example.

Morning conference occurs between 0640 and 0700. After conference, you will meet your patient,
review the plan with him or her, confirm NPO status and morning medications taken, and confirm a
functioning IV. (At Hillcrest and Thornton, the pre-op nurses place the IVs; at the VA this is your
responsibility). Your goal is to have the patient in the OR by 0720 at Hillcrest and Thornton, and by 0730
at the VA. However, to do this, the surgical H+P must be done, consent signed, surgical site marked,
surgeons available, blood products available, pertinent pre-op labs available, surgical equipment
available, circulator and scrub tech available, etc., etc. Its amazing how many times these things arent
ready to go, and it is rare that the anesthesiology team is the rate-limiting step here. However, your goal
is to never be the rate-limiting step. So, before you roll the patient back to the OR, check with the
circulating nurse for your room, who will have the best idea if everything else is ready to go. If you are
aware of any time-sensitive issues with your patient (blood bank needs another blood sample for
type+screen, patient needs po premedication), see your patient and start this process prior to 0640.

After youve started your case, your day is underway. You can generally expect a morning break, no
more than 15 minutes long. The timing of this might vary depending on how busy things are throughout
the OR, availability of CRNAs or your attending, and whether or not youve displeased the powers that
be.

You should prepare drugs and equipment for your next case (as much as feasible and safe) during your
current case, and enter your patients post-op orders. After you finish a case, typically you will drop off
your patient in the PACU, although patients who will remain intubated post-op will go straight to the
ICU. Once youve tucked away your patient and given report to whoever will assume care (typically,
PACU nurse), you should see your next patient, set up for the next case, and so on. This process will
depend on housekeeping and anesthesia monitoring staff to clean and prepare the room as well as the
availability of surgical equipment. So, if youve prepared during your last case and youre fast, you can
often get 5-15 minutes or more between cases to relax.

As a new CA-1, you are expected to page your attending when planning to start and finish all OR cases.
Your supervision for this will be extremely close during the initial stages of residency, and will likely be
trimmed back as you mature. As well, you are expected to contact your attending with any significant
intraoperative events throughout your residency, e.g., The surgeon has just lost 800ml blood and we
are going to transfuse 2 units. This is not only for the patients benefit, but for your medico-legal
protection as well.

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Your caseload will typically flow as originally scheduled, but cases and personnel do get moved around
quite a bit, and emergencies happen. So dont be surprised to get moved to another room, or to
suddenly have to do an emergency or interesting case that just came in. Flexibility and a positive
attitude are the goals when this happens.

Lunch breaks are no more than 30 minutes. Lunch is provided by the department every weekday and it
is typically delivered around 1100. If you are industrious, you may well have time to squeeze in a quick
lunch between cases and still be offered your 30 minute break later in the day. Breaks in the afternoon,
no more than 15 minutes, do happen but are more variable due to cases winding down and staff
availability. Your typical, non-call, non-late day will end around 1600-1700. This is by no means written
in stone, and there are regular days that go until 2100 and late days that end at 1500. Again, this is
residency, and having a positive attitude and being part of the team are key. Always keep in mind that
hard work is rewarded, while complaining or laziness are remembered for a long time.

When your room is done, ask the attending running the floor if theres any more work for you. Often the
attending will find you or let you know as youre wheeling your last patient to the PACU. Never, ever
leave without being told you can, even if it seems all the work is done. There might be a case pending
that you simply didnt hear about. You might need to take over another room.

Once youre free of clinical duty, you still must consult tomorrows schedule and find the pre-ops for
those patients, so that you can call your attending in the evening to discuss the plan. This could mean
photocopying a completed pre-op, tracking down five inpatients and pre-opping them all, or contacting
a resident at another location to email or text you the pre-ops. See the pre-op section for more
information.

Dont forget to do something fun with what remains of your day. Residency, especially the early parts of
anesthesiology residency, are tiring. Its hard and stressful at first to do the clinical work, prepare for the
next day, and read, but will get better.

Chapter 1C. The First Four Weeks

or, Im going to be doing this on my own in a month?

The transition from the clinical base year to the CA-1 year is probably the most striking and jarring
moment many of us have faced in our medical careers. In plain English, you go from a confident intern
to a completely green anesthesiology resident in a matter of days. Skills which were carefully honed
during the intern year, such as writing good notes, rounding in an efficient manner, and learning how to
do discharge paperwork, largely fall by the wayside and become irrelevant. All of a sudden you are
surrounded by equipment that you dont know how to use, drugs that you dont know how to give, and
physiology of such an acute and dynamic nature that you can easily think you never went to medical
school. Hopefully, these challenges which are largely unique to anesthesia are what drew most of us to
the field in the first place.

Here at UCSD we know that peoples exposure to anesthesiology and what it entails vary greatly. Some
will have had extensive shadowing experience while others may have had as few as 2 weeks of clerkship
time during medical school. The department knows all of this and expects no prior knowledge or ability,
save a good fundamental grounding in medicine itself. However, we do expect that you know and
appreciate one piece of information prior to embarking on your anesthesiology career. It is so
important, and so vastly different from any prior experience any doctor has had that it bears special
mention. If you never forget this fact, it will serve you well. Here it is:

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 In anesthesia, you have the potential to kill patients on a daily basis.

Lets take a hypothetical example to make this more clear. As a surgery or medicine resident, you
prescribe the wrong medication to Mr. X. For Mr. X to actually receive this lethal medication, the
following has to happen:

1. You write the wrong order, and

2. Your senior resident or attending misses the fact this is a wrong order, and
3. The pharmacist misses the fact that this is a wrong order, and
4. The nurse misses the fact this is a wrong order, and
5. The nurse physically goes to the medication dispenser, and administers it to the patient.

Here is the equivalent example for an anesthesiologist:

1. In the OR, you decide Mr. X needs a drug, and

2. You draw up the medication, with no one to confirm youre doing it correctly, and
3. You give the drug to Mr. X, who cant object to what youre giving, and
4. You dont know you did up anything wrong until the HR is 250 or the etCO2 is zero.

There are many, many other potential sources for error or harm. You could flick a switch, turning a
machine or monitor off without even knowing you flicked it. You could let air into your IV tubing. You
could commit a drug swap. Any of the myriad procedures we perform on patients can have catastrophic
outcomes. The bottom line is, as an anesthesiologist, you have a unique responsibility to the patient.

In light of all this, we have a system to transition people from interns to fledgling anesthesiologists
within the first month. This system is steeped in tradition and has withstood the test of time. It is
designed both to maximize learning and independence and to give new trainees a support structure
during this intense transition phase.

The First Two Weeks

During the first two weeks, each new CA-1 is paired up with a CA-3. The pair is assigned daily cases in
the OR. The CA-3 is expected to supervise the CA-1 with all aspects of work during the day and to start
teaching the basics of anesthesia. In this way, the CA-1 can start learning in a supervised yet informal
environment and begin meeting other fellow residents. Each day the pair is assigned to work with
different attendings to allow the faculty and new residents to get to know one another.

The CA-3 is the primary resource for the CA-1 during these two weeks. The basics of setting up an OR,
checking the anesthesia machine, finding and preparing equipment, preparing drugs, and innumerable
other pieces of information will all be covered during this time. The vast majority of CA-3s will allow the
CA-1s to do things on their own once they show they understand, in order to immediately facilitate
the independence which is a hallmark of UCSD.

The CA-1 is responsible for calling the attending to discuss the cases for the next day. However, during
the first 2 weeks, the CA-3 will be instrumental in preparing for this discussion by going over and
formulating a coherent anesthetic plan with the CA-1.

By the end of the first two weeks the CA-1 should have a small knowledge base from which to build,
some level of comfort in the OR, and some familiarity with his fellow residents and attendings. The

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groundwork for hands-on, routine anesthesia care, plus a general approach to intraoperative
emergencies or issues, will be laid during these first 2 weeks.

The Second Two Weeks

At this point, the CA-1 is paired one-on-one with a faculty member. The resident and attending work
together every day for the next two weeks. This allows the faculty to intensely train the resident and to
build off of prior knowledge and topics. Its worth noting that the attendings who do this one-on-one
training have volunteered to do so and are doing it out of their interest in resident development and
education; they are some of the departments finest educators. Typically the resident is allowed more
responsibility and independence during these second two weeks, but, as always, the attending must be
called every night to discuss the next days cases.

During this whole month the new CA-1s have a daily lecture at 1500. These lectures are designed to
provide the nuts and bolts of anesthesiology. These lectures are mandatory, and the CA-3s and faculty
know you must attend them. Therefore, you will always be released in time to make the lectures. In
general, CA-1s are not required to come back to the OR after lecture is finished, although this is always
up to the attending running the floor. Of course, the day concludes with getting the next days pre-ops
and calling the attending.

At the conclusion of these first four weeks, the CA-1 is ready to join the crew as a functioning,
independent resident. Starting from this point, for the rest of your resident career, you will be the sole
resident in any given case. In addition, you will join the overnight call pool and start taking in-house call.
While all this may seem daunting and more than you can handle after a mere four weeks of anesthesia
training, rest assured that you can handle it. Generations of anesthesiology residents have come before
you and flourished under this system. Furthermore, there are multiple support systems in place for you
to lean on: your classmates, fellow residents, and the faculty. Remember, weve been there before and
are always willing to lend a hand.

Chapter 1D. Call Duties

MOR Call

This is the first type of call a resident takes, and it is also the least predictable and the most likely to
cause anxiety. You are eligible to take this call right at the beginning of August after your 1st four weeks
of one-on-one training. You may not feel ready for it nobody does, at first but remember there are
senior residents and your attending ready to help you out.

For weekday calls, the day will typically start at either 0600 with a first-case-start OR case, or at 1445. If
the call starts at 1445, you must be immediately available on your pager to come in as needed. A call
that starts around 0900 in pre-op clinic in the 1st floor of Hillcrest is also a possibility, depending on
staffing needs; see the section on pre-op clinic. In general, the attending making the schedule makes
every attempt possible to avoid a 0600 start for the call resident, or at least to relieve you early to rest.
This in order to maximize your learning:work ratio, but this is not always possible.

Again, flexibility and a positive attitude are the name of the game here. Hard work is noticed and
rewarded, whereas complaining is noticed and, ultimately, can be punished. Residents are by no means
entitled to or default to a 1445 start, but they should always trust that the attendings who make the
schedule and run the floor are looking out for their well-being.

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On your pre-call night, always check for updated schedules. Things change. Checking your email should
be the last thing you do before you go to bed and the first thing you do when you wake up. Its a good
idea to have your pager nearby on your precall night, so if things change, and the front desk decides to
page you, youll know.

Call duties include your OR clinical work, completing any inpatient pre-ops for the next day (in
conjunction with the ICU resident), and sending inpatient and outpatient pre-ops to those residents who
need them for the next day. Obviously, these duties may be in conflict with each other; you cant email
pre-ops when youre sitting in a 6-hour finger reimplantation. However, by coordinating with your
attending and those residents who may be contacting you for pre-ops, and by using your time wisely,
you can achieve most or all of the above duties, help your colleagues, and become a resident known for
hard work, industry, and helping others out thats the UCSD way.

As the MOR call resident, you have different types of backup depending on the time of day. Currently
there is a CRNA who works 1030-1900, another who works 1500-2300, and the night float resident who
works 1900-0700. Depending on the quality and quantity of case load, you may have a call where you
are in an OR from 0700 to 0700 the next day (with appropriate breaks), or you may wrap up your cases
by 1800 and have no remaining work to do. The best way to not be disappointed is to have low
expectations, so that youre not surprised when you finish every case on the board by 0300 and still get
paged for a lap appy at 0500. The best part of an anesthesia call is that once 0700 rolls around you will
be relieved.

Weekend MOR call is a little different from weekday call. There are two residents on call: MOR1, and
MOR2. The call officially starts at 0700 and lasts 24 hours. However, nearly every weekend day, there
are elective cases scheduled, and if there is a first-case-start scheduled, you may need to be in-house
earlier than 0700 to set up.

You should treat elective cases on the weekend the same way you would a weekday: you pre-op the
patient or obtain the pre-ops, you call your attending to discuss the cases, and youre ready to be in the
OR with the patient at 0720. If there is just one OR scheduled to be running, the MOR1 resident is
responsible for pre-ops and calling the attending. If its scheduled for 2 concurrent ORs to be running,
the MOR1 and MOR2 resident will decide amongst themselves which cases theyd like to do, and call the
attending with their respective pre-ops. The brunt of the work during call falls on the MOR1,
independent of seniority. But again, in an atmosphere of cooperation, the MOR2 must always be there
to give breaks, start cases, or alternate cases with the MOR1 resident should there be many cases
scheduled to run back-to-back in a single OR.

Finding out if there are weekend cases scheduled is easy enough via PCIS in the hospital or from home
or by calling the OR front desk. A bright spot of weekend call is that the attending on call traditionally
buys the whole call team dinner from some nearby restaurant, and the call team usually coordinates to
send someone out for lunch takeout as well.

Weekend MOR Pager Call

Every weekend there is one resident assigned to backup pager call for the Hillcrest MOR. It is relatively
uncommon for the pager-call resident to be called in, however, if you are this resident you should have
your pager nearby starting the night before so that youll be prepared if youre needed at 0700 the next
day. If you look on PCIS or talk with the MOR call residents and see that there are two ORs already
scheduled to be running, be prepared and available to come in. You must be able to be in scrubs and in

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the OR within 1 hour of being paged in on this pager call. A perk here is that this call counts as a work
weekend whether you are called in or not.

MOR, Thornton, and VA Late

The late resident is the second-to-last resident to leave the hospital, before the call resident. You are
frequently scheduled to be in an OR that is expected to run late, and you will likely also take over ORs
from CRNAs or precall or senior residents, at the discretion of the floor attending. A late day may end
as early as 1500 or as late as 2200. As such, a late day is not a good day to schedule a fancy dinner at
1900 with your significant other! One implication of being the late resident on Friday is that you are
typically presenting a keyword that morning as well. Lastly, be aware that the floor attending is not
always 100% aware of who the late resident is, and if you are this person and are sent home while
multiple non-call, non-residents are still in ORs, you are effectively doing your colleagues an injustice.
So, be aware.

Thornton Call (1500 start)

This is a Monday-Friday, 1500-start shift where the resident comes in by 1445 and is ready to physically
go into an OR no later than 1500. The resident stays in-house until all the cases are done, and is then
free to go home on pager call until 0700. Breaks and dinner are arranged with the call attending. The
exact time when the cases are all finished can be quite variable at Thornton. Having your pager on
during the day, before you shift actually starts, is encouraged, because very infrequently you get called
in earlier than 1500 (e.g., an add-on emergency case that there is no one else available for). The floor
attendings will respect the 10 hour rule, such that, if you are in a room until 0700, you will not be
expected to be back at Thornton until 1700.

VA Call

On weekdays, this call starts at 1000. Call duties include completing inpatient and add-on pre-ops,
seeing inpatient post-op evaluations (QA/QI sheets, a.k.a. blue sheets), carrying the code pager and
responding to codes/airways/IVs. At the floor attendings discretion, you may be asked to help in the
ASU (the VAs pre-op clinic) or to give breaks. Your in-OR duties, i.e., starting or finishing cases, typically
do not start before 1700, but you should certainly be prepared to do so if asked. If your duties are
complete, its always welcome to lend a hand with a tough case start, observe or help out with a
regional block, or go over the TEE with the cardiac anesthesia attending.

One critical difference between VA and MOR call is that at the VA, when all the cases in the OR are done,
the call attending will leave the building. This means that for any codes or overnight airway
emergencies, the resident is on his or her own. For any OR case that is added on and at the VA, these
are typically true emergencies you must notify the call attending as soon as possible to allow them
travel time to the hospital. The resident does not do OR cases on their own. The same applies for airway
urgencies if you do not feel comfortable with an intubation that you are asked to do, you are
certainly advised to call in the attending.

Weekends at the VA start at 0700, and are typically very light. The same call duties as during the week
apply, with a few additions. Scheduled cases are rare, which means the attending will not routinely
come in. After taking over for the outgoing resident, call duties include seeing inpatient pre-ops (added
on to the main OR board), blue sheets, holding the code pager. You are also responsible for regional
anesthesia follow-ups as well as any new pain medicine consults or follow-ups over the weekend. There

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is a pain attending on call who will be able to help you with this.

The specifics of the VA, including the computer system, how to write a note, where to get food on
weekends, etc., will all be explained to you when you get there. You are advised to bring plenty to keep
you busy and to make arrangements for lunch the cafeteria is not open, and as of June 2012, only
breakfast and dinner are delivered to room 5095 at 0600 and 1800.

OB Call

Details about the duties on OB will be discussed further in the OB section. During the week, OB call
starts with MOR duties: either at 0700 for first-start MOR cases, or at 1445 where you help with
finishing up MOR cases at the discretion of the floor attending. When the MOR duties are completed,
you relieve the day OB resident.

Once you have taken over the OB pager, you become responsible for any OB issues that may arise.
Epidurals and C-sections are foremost, but difficult IV access, resuscitations, or D+E of retained placenta
in a patient in hemorrhagic shock may come along as well. The OB anesthesia attending is the person
you answer to, and you should notify him or her if you are doing anything. The MOR attending is always
a helpful resource as well. Typically, the OB call resident is one of the more senior residents in house and
thus may be called upon to hold the code pager, to supervise a junior resident in the MOR, or to help
out in any number of ways.

On weekends the procedure is fairly simple: come in at 0700 and take over for the outgoing resident.
Often times the OB call resident will help out with MOR duties (case starts, lots of pre-ops) with the
other residents, since there is usually some downtime during the day when on OB call. That said, its not
advised to expect the OB call resident to have done any pre-ops; its just a nice bonus if it happens.

Lastly, the OB day and OB call residents have been given the informal responsibility of keeping our
lounge clean.

SICU Call

This will be described in detail in the SICU section. Your duties to the anesthesiology department include
helping with inpatient pre-ops; often the ICU call resident is the only one available to do so during the
day. Also, you will hold and respond to the code/airway pager, make sure the two code bags are stocked
and ready, make sure the emergency rooms (OR7 and OR11) are stocked and ready, and respond to any
emergency OR resuscitations.

Night Float

After your cardiac and OB anesthesia rotations are complete, you become eligible for night float. This is
a 2-week, 1900-0700, Monday-Friday rotation. The night float resident is available to do OR cases, help
with the MOR duties (pre-ops, breaks, code pager, case starts), etc., at the discretion of the MOR and OB
attendings. The night float resident is also the primary liver transplant resident during the week.

The role of the night float resident is different from that of the MOR call resident. The night float
resident is preferentially kept out of the OR, while the MOR call resident is preferentially put in the OR
this is because the night float resident will be back at 1900 the next day while the MOR call resident is
resting at home. This role assisting, but not primarily responsible for, MOR duties are independent of

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the seniority of the residents who are respectively on MOR and night float. Occasionally a CA-3 on MOR
call will be up all night doing cases or holding the code pager while a CA-2 night float resident is in their
call room resting.

Although the shift is from 1900 to 0700, the responsibility for liver transplants that start at, say, 1800 or
0500, has never been clearly defined. Some attendings will attempt to use available day personnel to do
a daytime transplant, but sometimes lack of available people does not allow this. The best solution is to
have your pager with you at all times in case you get called. If you happen to work during the day you
will be given the night off, no exceptions, but this event is exceedingly rare.

CA-1 Heart Call

This is a pager call that primarily pertains to nighttime, add-on, and weekend cardiac and thoracic cases.
Typically the resident on their first month of the cardiac anesthesia is on call a majority of the weekdays.
This means if there are cardiac cases running late, or a case gets taken back to the OR after hours they
do the case. This can make for a tiring month, but in general our attendings will try to relieve you if you
get called in at night. Sometimes elective heart cases are scheduled on the weekend. The CA-1 heart call
resident will do these cases, and be expected to fulfill all the usual duties: pre-opping the patient,
setting up the room, calling the attending, etc.

Pediatric (Diamond) Call at Rady Childrens Hospital, Pain Call, and Regional Anesthesia Call

The details of these calls are described in the section giving an overview of these rotations, and will also
be explained to you at the relevant rotations. They are considered outside rotations with their own
responsibilities. You will not be called in for another duty such as MOR when you are on these rotations.

Chapter 1E. A Basic OR Setup

There are certain basics that will apply to every OR setup you do before a case. The room setup
becomes modified as the case requires, but all of have a checklist that we do not deviate from. Having,
and sticking to, your checklist will obviate embarrassment or, worse still, potential compromise of
patient safety. There are many mnemonics for a basic room setup; one example is MOM SAID. Briefly:

M: machine
O: oxygen
M: monitors
S: suction
A: airway
I: IV
D: drugs

Machine:

Perform a machine check and adjust ventilator settings, etc., as desired. This includes case-specific
equipment, e.g., appropriate sized mask, circuit extension for a case with the head away from the
anesthesia machine, etc.

Oxygen:

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Verify that you have a backup E-cylinder of oxygen in the OR, and that at least 1000 psi remains. The
tank has a bag full of simple O2 facemasks and Mapleson circuits, which you must verify. This is your way
to save your patient in the event of catastrophic machine failure. Its important.

Monitors:

Ensure that the standard ASA monitors: BP cuff, EKG leads, pulse oximeter probe, and temperature
probe are ready to go. A twitch monitor should be ready as needed for your case. If you will use special
monitors (e.g., arterial line, EEG), set up or get the necessary equipment.

Suction:

Verify that the suction is on and readily available. If you are going to place an OG or NG tube, now is a
good time to get that out.

Airway:

Prepare your Plan A airway equipment for your case, whether it is a laryngoscope, ET tube, LMA, or
other. Ensure that oral and nasal airways are available in the cart, that a Bougie is attached to the
anesthesia machine, and that there are backup LMAs in the anesthesia machine drawer. This ensures
that you have not only Plan A but B, C, and possibly D in the event of an emergent, cannot
ventilate/cannot intubate situation.

IV:

Prepare extra IV fluids or IV start equipment as needed for your case.

Drugs:

Prepare appropriate drugs for the case. The basic drugs most of us have drawn up for a general
endotracheal anesthetic are fentanyl, midazolam, propofol, lidocaine, succinylcholine, rocuronium or
vecuronium, phenylephrine, and ephedrine. Depending on the case, you may want many other drugs
ready to go. Prepare any special drips the case requires.

Chapter 1F. The Code Pager, the Code Bags, and the Emergency OR Setups

Part of anesthesiology resident duties include carrying the Code Blue/airway pager, ensuring that the
code bags are always set up, and that there are ORs set up for an emergency craniotomy and an
emergency OR trauma resuscitation. Both these duties will be described in detail.

The Code Pager

There are four basic scenarios for which the code pager will be paged:

1. A true cardiac arrest (Code Blue)

2. An airway or respiratory emergency or urgency
3. An inbound trauma or burn patient that might require airway management
4. Other: usually a request for help with a central or arterial line or difficult peripheral IV. These are
usually less urgent. Occasionally the ER, ortho, or trauma will request procedural sedation for a

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 short, painful procedure (dislocated shoulder); we typically do not involve ourselves in direct patient
care in these situations, but its wise to bring these concerns to your attendings attention.

The person holding the code pager varies on a daily basis and during the day. During the day, typically
one of the anesthesiology residents on the SICU team will have the pager. If there is someone on call in
the SICU, they will hold it for the rest of the day and night. If there is no SICU resident on call that night,
the person with the pager will distribute it to either the MOR or OB call person at the end of their duties,
or, rarely, to an attending if none of the above is available. Later at night, the MOR person generally has
the pager since the OB person is often occupied with OB work, but it may pass to either the night float
resident or MOR or OB attending, as circumstances dictate.

Theres no need to ever go find the code pager; it will find you if youre the person who should be
holding it. When these people are in-house, the order of priority of the code pager is:

SICU resident > MOR call > night float > OB call > MOR attending > OB attending

The Code Bags

It is our responsibility to ensure that the code bags at Hillcrest and at the VA are fully stocked and ready
to use. As the airway experts of the hospital, we are first and foremost responsible for that aspect of
patient care during a code, or during urgent/emergent airway management consults. The code bag
contents reflect this, with a large part of the equipment being devoted towards airway management.
However, the anesthesia provider is often the most experienced or senior physician present, not to
mention the most level-headed. Thus, while ostensibly we are only responsible for airway management
during a code, often times we find ourselves assisting with other aspects of the resuscitation, or even
running the code itself. The bag is therefore stocked with other useful pieces of equipment such as
drugs and IV lines.

At Thornton, we are not responsible for either stocking code bags or for responding to codes. However,
there are times when we might be called for an urgent intubation. Typically the floor attending at
Thornton will be notified of this.

So, who specifically stocks the code bags? Whoever is currently holding the code pager is responsible for
the contents of the bags. It must be noted that the code pager will change hands multiple times a day;
see above. So, an attending who is holding the pager for 10 minutes while all his residents are in ORs
cannot really be expected to check and stock the bags. So, at handoff of the pager, the recipient must
ask, Are the bags good to go? If you are handing off the pager, it is your responsibility to verify that
they are, both from a patient care and a personal-pride standpoint.

The fact that they truly are stocked and ready depends on mutual trust between donor and recipient of
the pager, and if you have the pager for any amount of time (MOR call, SICU resident, night float, OB
call, not in an OR for hours at a time) it is upon you to make sure the bags are good to go by going
through both of them and stocking as necessary.

Any time you use the code bag, you must immediately and completely restock all used items. This
ensures the legitimacy of the mutual trust that happens with the pager handoff.

At the VA, the person responsible for stocking the code bags is the call resident from 1000-0700.
Typically the resident on regional anesthesia or a CRNA will be holding the pager between 0700 and

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1000.

At Hillcrest, the bags are stored in the anesthesia workroom, first shelf as you enter, bottom row. They
are large and danger orange in color.

Specific things to be stocked in the bags will be described to you in more detail later, but include:

Drugs: these come in a premade pharmacy kit that is located on right side zippered compartment. It
is sealed until use. After it is opened, it is returned to the Pyxis and a new sealed bag removed from
the Pyxis. It contains etomidate 2mg/ml, propofol 10mg/ml, rocuronium 10mg/ml, succinylcholine
20mg/ml, phenylephrine 100mcg/ml, ephedrine 5mg/ml, vasopressin, and Abbojects of code
doses of epinephrine, lidocaine, calcium, atropine, and sodium bicarbonate.
Airway: this is the large roll-up package in the main code bag compartment. It must include a short
and long laryngoscope handle, and a variety of blades (MIL2, MIL3, MAC3, MAC4). Styletted and
with 10ml syringe attached are a 6, 7, and 8 regular ETT, and a 6, 7, and 8 silver-impregnated ETT.
Tongue blades, nasal airways, oral airways, lube, Magill forceps, tape, twill ties, Bougie, and
Yankauer suction are included.
Airway rescue devices: a size 3.5 and 4.5 Cookgas LMA, a Combitube, and Fastrach LMA, and a
variety of nasal RAE tubes are located in the compartment that forms the lid of the code bag.
A Cook Airway Exchange Catheter is located in the main compartment, below the airway pouch.
Mapleson circuit with at least one each of size 4, 5, and 6 masks is located on the left side zippered
compartment.
Airway confirmation devices: in the main compartment must be a colorimetric an end-tidal CO2
detector (EZ-Cap) and an esophageal detector bulb device.
Miscellaneous: IV equipment, arterial line equipment, gloves, and billing/documentation paperwork
are located on the front and back compartments of the bag.

Remember to restock the bags with whatever you have used. This this will save a lot of headache and
possibly a life later.

The airway rescue devices for cannot ventilate, cannot intubate situations are numerous, and this is
not intended to be definitive instruction on how to use them. Most of us consider the LMA the essential
and the first line option in the situation. You may ask, Why do we need several types of LMAs in the
code bag? Any properly placed LMA will allow you to ventilate and oxygenate in nearly all CV/CI
situations, but there are differences between the various types. Briefly,

The standard LMA (Classic) is usually the one we are most familiar with, and thus will probably be
easiest to place in a crisis. However, it is difficult to intubate the trachea through a standard LMA
(requiring either a nasal RAE or a bronchoscope and specific training) and it is nearly impossible to
remove a standard LMA over an ETT if one is placed.
The Fastrach LMA is intended to facilitate blind tracheal intubation in a crisis, and readily
accommodates its specific ETT and can be used with a bronchoscope.
The Cookgas LMA is designed to facilitate bronchoscope-assisted tracheal intubation.

You will learn how to use these devices in time. Do not fear.

A word on the tracheal intubation confirmation devices: we use the EZ-Cap CO2 detector and the
esophageal detector bulb device.

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 The EZ-Cap is placed on the endotracheal tube adaptor and detects expired CO2. A successful
intubation will be confirmed with a color change on the cap which roughly correlates with the
amount of expired CO2. Ventilating a tube in the esophagus will not result in sustained expired CO2
and EZ-Cap color change. However, in a situation where the patient has no cardiac output (e.g.,
cardiac arrest with ineffective chest compressions) the EZ-Cap will not change color. In these
circumstances the esophageal detector device is warranted.
The esophageal detector device is also attached to the adaptor of the ETT after intubation. When
deflated, attached to the ETT, and allowed to reinflate, it creates suction on the tube and whatever
lumen the tube is sitting in. If in the esophagus, this suction will cause the pliable folds of tissue to
collapse on the tube and the bulb will not reinflate. If in the trachea, the bulb will rapidly reinflate
since the trachea walls are rigid and will not collapse.

Both these devices are needed to cover all situations where one needs objective confirmation of tube
placement. The gold standard is, arguably, visualizing seeing the ETT passing between the vocal cords,
but this can be nearly impossible during chest compressions. Fiberoptic bronchoscopy is an excellent
option, but requires both time and equipment, which may not be available. Breath sounds and chest rise
are notoriously inaccurate measures. Although the trend of priorities in ACLS is toward Circulation (i.e.,
early chest compressions) and away from tracheal intubation, Airway and Breathing are still high
priorities, and a missed esophageal intubation is quite frankly unacceptable.

Responding to the Code Pager

Until about 6 months into your CA-1 year, you must call your attending if youre going to a code or other
emergency. After that, its on a case-by-case basis, depending on the clinical situation, the attending,
and your own comfort level. There is never any shame in asking for help from a senior resident or letting
the attending know whats going on. In general, as a CA-1, you should never go to a code or intubation
without someone else from our department. It is a good thing to have multiple people from our
department present and cooperating, both for patient safety and so that multiple residents can learn
from whatever situation comes along. We are a team and we help each other out; an extra set of
helping hands is always welcome. All senior residents can recall multiple times when they were glad an
attending was with them for what at first seemed like a routine intubation.

Most calls for airway management are semi-elective or merely urgent. If you are called for such, talk to
the primary doctor about the clinical situation and get a current set of vitals including height and weight,
so you can plan to bring the most appropriate equipment (Glidescope, bronchoscope, extra help, etc.).
Emergency calls are usually clear, e.g., Code blue, 10 East, room 1021, but might simply say,
anesthesia stat to 10E or even worse, just a number and a frantic nurse on the other end. If it seems
urgent, you should just go see whats going on for yourself and ask questions later.

This syllabus is not meant to teach ACLS or the myriad skills needed in a code/emergency. That being
said, here are some tips:

1. Try to size up the situation when you first walk in. This can be difficult, especially when there are 20
people in the room, most of which whom are running around like chickens with their heads cut off.
Is it a true code? Is the patient responsive? Is the patient ventilating? Is anyone clearly in charge?
Are any monitors on the patient?
2. If you need to get to the patient, be assertive. Theres likely to be a whole bunch of people of
dubious utility around the patient. Calmly but forcefully let people know you are present and your

17
 intentions, e.g., Im the anesthesia resident, I need to get to the head of the bed, please move.
3. If a code situation, establish early who is running it, and identify yourself to that person. All
commands should come from that person and ideally there should be little other talking. Sometimes
that person will be you, especially when no one else volunteers to run the code.
4. Be calm. Its amazing how often a composed, competent demeanor sets the whole situation at ease.
5. Prepare the appropriate equipment according to your mnemonic, MOM SAID or MSDAMIT, etc.
6. Prepare as much as you can before you do something. For example, if you go to an semi-urgent
intubation and have some time, get everything youll need out and organized beforehand so youre
not struggling to find it later. This might mean an LMA, the EZ-Cap, drugs, suction, etc., all within
easy reach or with someone you can trust prepared to hand them to you.
7. ABC! So much of what we do comes back to that. If you constantly think ABCs during most
emergencies you will be fine. Since A is first, if the patient needs an airway all other peoples
activities become secondary and yours become of the utmost importance.
8. If someone is truly in cardiac arrest, you dont need to give any drugs before laryngoscopy and
intubation.
9. After youve secured the airway, see how else you can make yourself useful. This might involve
assisting with the code, starting an arterial line, or obtaining (better) IV access. Many times the code
leader or primary team may ask for your help, or may be resistant to additional monitors or access.
Often, if you think the patient will need something, youre right, even if the primary team feels
differently. So make your case forcefully but politely; this might avoid a situation where you are sent
away only to be called back 5 minutes later to assist with an urgent arterial line.
10. Before you leave a code, you must ask the code leader if youre needed anymore.

The Emergency OR Setups: OR7 and OR11

This information applies only to Hillcrest. At the VA and Thornton, we do not have preset rooms for
emergencies due to the low volume of trauma and emergency cases. The responsibility of ensuring
these rooms is shared by no more than two people: the person holding the code pager (typically, the
SICU resident) and the MOR call resident. Whoever has the time and opportunity to check or set up
these rooms must do so; sometimes this is not the MOR call resident or the SICU resident, but rather the
night float, OB call, or MOR2 resident. Communicate with each other to make sure that the rooms get
set up.

OR7, Emergency Craniotomy Room:

One OR is traditionally reserved for emergency craniotomies after main OR hours. This is almost
always OR7, but sometimes cases from the day run late in OR7, necessitating another room to be
designated as the crani room. Check with the OR front desk staff when in doubt. The room is set up
with the goal of emergently inducing anesthesia so that the surgeons can open the cranium and dura.
Standard room setup applies with the following additions:

The bed is turned 180 so that the head is already away from the anesthesia machine. This is the
natural position of most craniotomies and will allow a truly emergent crani to be positioned without
having to turn the table. The yellow donut foam pillow for head position should be at the far end,
where the head will be.
Because the head is away from you, a Mayo stand with all relevant airway equipment must be in the
OR. This tray lives in OR7. It must include EVERYTHING you might need on the stand for intubation
and ventilation: masks, oral/nasal airways, blades and handles, various ETTs, tape, etc.

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 Because the head is away from you, you must have a long circuit extension available in the room or
attached to the circuit so the circuit can physically reach the patients head. It is very embarrassing
to intubate a patient and then not be able to connect your circuit because its too short.
Have mannitol and several 100ml bottles of propofol in the room.
Arterial and venous pressure transducers, pre-zeroed, must always be in the room.
Equipment to rapidly start an arterial line and central line must always be in the room.
Have at least one IV ready, prespiked and attached to a fluid warmer, for immediate hookup to
whatever IV access you have or place.

OR11, Emergency Trauma (OR Resus) Room

This room should be set up at all times for an emergency surgical/trauma resuscitation. This room is
where life-threatening penetrating and blunt trauma cases will be brought emergently by EMS. The only
time it will not be set up is when it is either currently in use or has just been used and is being cleaned.
The standard OR setup again applies, with the following additions:

Airway equipment, e.g. blades, tubes, oral/nasal airways, and circuit, prepared as it would be in the
crani room or the code bag, must always be ready.
Two IVs pre-spiked and attached to fluid warmers.
Emergency resuscitation drugs are drawn up and available. The cart has a standard drug tray plus
code drugs like epinephrine, atropine, and bicarbonate Abbojects.
Arterial and venous pressure transducers, pre-zeroed, must always be in the room.
Equipment to rapidly start an arterial line and central line must always be in the room. This means
the actual kits, as well as sterile gowns and gloves, must always be ready.

Chapter 1G. The Pre-Operative Evaluation: General Comments

A safe and high-quality anesthetic begins with proper pre-operative evaluation of the patient. Nothing
can better illustrate the interaction between a patients comorbidities and their anesthetic implications
than a thorough pre-operative evaluation. There will be times during your anesthetic career where
conditions preclude a full pre-operative workup (e.g., emergency situations, non-verbal patient) but in
general every case demands a full pre-op evaluation.

The difference between a good pre-op and a poor one is like night and day. A well done pre-op conveys
precisely the information you want and need to deliver a high-quality anesthetic. A poor one can often
leave you scratching your head or hunting for more information. At worst, a poor pre-op can
compromise patient safety. All of us have experienced the phenomenon of the poorly-done pre-op and
in fact most anesthesiologists can guess the level of a persons experience by the quality of their pre-
ops. The following questions are common when first starting anesthesiology residency:

When will I be doing pre-ops?

The following are the typical scenarios in which residents will do a pre-op.

1. The Pre-op Clinic at Hillcrest, Thornton or the VA:

The dedicated pre-op clinic experience at Thornton is described above in the call duties section.
Briefly, scheduled patients come in throughout the day, usually on a day anywhere from 1-14 days prior

19
to their elective surgery, when they are also seeing their surgeon and having pre-op testing done.

At the VA, the call resident is infrequently asked to seeing patients in the VA pre-op clinic (referred to as
ASU). There are multiple full-time CRNAs assigned to ASU, who typically shoulder the pre-op burden.

2. Inpatient Pre-ops

At Hillcrest, a substantial percentage of all surgical cases are for inpatients with acute or subacute
issues, including ICU patients and ortho/trauma patients. These patients clearly cannot go to our pre-op
clinic and thus must be seen on their ward. Ultimately, it is the responsibility of the resident who will be
doing the case to pre-op his or her own patient. That said, in the spirit of mutual assistance and
camaraderie, you may find that your resident colleagues will have your inpatient pre-ops completed,
especially if you are at a different site the day prior, which is very common. Generally the SICU resident,
in conjunction with the MOR call and OB call residents, will have the opportunity to pre-op these
patients, and in the case where a SICU resident pre-ops a SICU patient, they may know the patient quite
well. This is worked out on a case-by-case basis, but in general we all try to help each other out and get
each others inpatient pre-ops done. CA-1s should be doing their own inpatient pre-ops for the first six
months, independent of the prior days assignment or schedule, to help them gain more experience.

Occasionally, a CRNA will be assigned to an OR with inpatient for the next day. When this happens,
typically the resident helping with the other residents pre-ops will be responsible for these as well. Life
goes on.

The call resident at the VA does all the inpatient pre-ops for that location. The list of patients who need
pre-ops will be provided when you arrive on call at 1000. Usually, several cases are added on during the
day as well. Thus, a major difference between Hillcrest and the VA is that the call resident is technically
responsible for any inpatient pre-ops you may need at the VA for the next day.

However, at Hillcrest you could finish up in the OR only to find three inpatients waiting for you to be
seen. Again, every resident has been in this situation, it is not common, and the best tack is to complete
the work efficiently and move on.

3. Pre-ops On the Fly

All that happens in the OR is not scheduled or predictable. For truly emergent, or very urgent, cases, the
patient is not likely to have a pre-op already done, e.g., a patient with mesenteric ischemia in septic
shock who requires an emergent exploratory laparotomy. Time is of the essence, and the most you may
be able to obtain is a quick history asking about major cardiopulmonary issues, medications, allergies, an
airway examination, and pertinent lab results. Similar situations often arise in OB anesthesia, in which
there is a rapid turnover of patients, some of whom need our services immediately on arriving to the
hospital. Always be as thorough as the situation allows, which is very different, depending on if you have
2 minutes or 20 minutes.

Some elective cases are for patients who were not scheduled or did not show up to our pre-op clinic.
You may find out about this patient just a few minutes before you take them back to the OR. Your
attending will typically assist with this endeavor (particularly if you two have a previous case running).
No one will expect you to have been able to do a thorough pre-op beforehand, but you have the
opportunity to do one at that point, immediately pre-op.

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What does a basic pre-op entail?

Philosophically, the pre-op serves several functions. First, it provides a brief history and physical,
describing the patient, their current health status, and their chronic comorbidities, especially those that
pertain to anesthesia. Secondly, it provides a framework and plan for the actual delivery of anesthesia.
Clearly, as ones experience with pre-ops and anesthesia grows, it becomes significantly easier to
identify which information is pertinent and which is superfluous. The goal is to provide a brief, concise,
and relevant summary of the patient and their medical problems. A pre-op which is agonizingly
thorough but is twenty pages long is of no use to anyone.

It is impossible to list here every condition and situation which may have anesthetic relevance. Indeed,
mastery of such implies mastery of both medicine in general and anesthesia in particular, an unlikely
combination for any resident. That being said, the following will help guide you through each section of
the pre-op, pinpoint areas to focus on, and give the rationale behind why an anesthesiologist would
want this information. Refer to the blank pre-op templates (one for Hillcrest and Thornton, another
similar one for the VA). The templates are intended to be easy to read and follow and to minimize
writing hence, the checkboxes. This also serves as a primer so that certain key questions are unlikely
to be missed.

Who can I turn to for questions about pre-ops, or whether a patient needs further evaluation?

Any faculty or senior resident will be happy to assist you. Often, your own peers are your best resource.
When in doubt, ask. Theres no such thing as a stupid question.

Of note, all pre-ops done in any of the pre-op clinics need to be signed off on by an attending. This is an
assigned, daily duty for the attendings and will usually be the late attending at Hillcrest and the floor
attending at Thornton and the VA.

If I feel a patient needs further workup, another test, etc., who orders it?

This is an important question. In general, the primary service should be the ones ordering any additional
workup. This may be the surgery service or the surgeons office (for elective patients) or whichever
primary team an inpatient is on. Since the surgical team follows the patient pre- and post-operatively,
they are in the best position to both order a test and initiate any necessary follow-up. Additionally, there
is a medico-legal perspective which we are lucky in anesthesiology to be largely shielded from namely,
if you order a test and find an abnormal result, you are obligated to do something about it. For example,
if you order a chest X-ray on a patient and a mass is found, it becomes your responsibility as the
requesting physician to make sure this doesnt fall through the cracks. If no one else follows up with the
patient, and an issue arises in the future from said mass, you can be held responsible. Thus, in general,
you dont want to be ordering tests yourself.

The best way to go about obtaining further workup is to contact the surgical team, office, or attending,
and tell them what you feel is necessary. They can then go about obtaining this information. Sometimes
the information you want is broad, e.g., please evaluate this patient for coronary disease. There are
several ways to test this and the political thing to do is to leave this at the discretion of the service
performing the test. In this example the surgical service would consult cardiology, who can then choose
one of several ways to evaluate the patient. Other times the information you will want will be quite
specific, and then you can ask for it, e.g., please obtain flexion/extension x-rays of the neck to evaluate
for atlanto-occipital instability. This fulfills our role as perioperative consultants and frees us from

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having to do much of the leg work ourselves.

Chapter 1H. The Pre-operative Evaluation: Section-By-Section

1. Age, Weight, Vital Signs, PO Status, Proposed surgery, and Diagnosis

This section is mostly self-explanatory. Age and sex can have profound implications on anesthetic
technique and sequelae. Less obviously, the weight and height of the patient can dictate the airway
management plan, drug dosing, the size of an endotracheal tube, and sometimes the whole anesthetic.

Elective patients must be NPO for solid foods for at least 8 hours prior to undergoing anesthesia. Solid
food includes any food with fat or protein, to differentiate it from a light meal as below. This applies
to all anesthetics, including non-general anesthetics, such as neuraxial techniques and MAC. There is
always the potential to convert to a general anesthetic as Plan B, e.g., failed spinal, or patient who
becomes uncooperative under MAC. Small amounts of clear liquids may be taken as recently as 2 hours
prior to induction of anesthesia. A light meal, i.e., one that doesnt contain fat or protein, or milk
alone, can be taken as recently as 6 hours prior to anesthesia. The recommendations for children are
different: 2 hours for clear liquids, 4 hours for breast milk, and 6 hours for formula or solids.

The proposed procedure and diagnosis will determine the anesthetic technique. As obvious as it sounds,
it is not uncommon to find yourself preparing to perform one type of anesthetic, only to have to switch
at the last minute because the procedure you were ready for (on the pre-op) is different from the one
the surgeon actually intends to do. Accuracy is important.

2. The Cardiovascular System

There are several checkboxes here pertaining to HTN, CAD, CHF, arrhythmias, etc. Certain items, if
positive, deserve more clarification. For example, if the patient has a hx of MI it should be stated that
the patient has CAD, when the MI occurred, what interventions were done, current management, etc.
Similarly, if the patient has heart failure, is it compensated? What is their EF? What is their diastolic
function? What are the patients symptoms? In general, use your best judgment about when to provide
more information.

The question of exercise tolerance is perhaps the most useful and important of the entire pre-op. By
assessing the patients ability to tolerate physical activity or exercise, and using the threshold of 4 METs,
we can risk-stratify them and determine if further cardiac workup is necessary. Four METs is roughly the
activity of climbing a single flight of stairs, walking a few blocks at 4mph, doing light housework like
dusting or washing dishes, or running a short distance. One MET is, very simply, your resting metabolic
rate, i.e., your metabolic rate while sitting quietly.

The ACC/AHA 2007 Guidelines on Perioperative Cardiovascular Evaluation and Care for Noncardiac
Surgery are the reference for decision-making in this area, and we apply these guidelines on a daily
basis. The short version is that if the patient can perform 4 METs of activity without symptoms of chest
pain or shortness of breath, or if the case is an emergency, you should proceed with the appropriate
anesthetic plan. If neither of those is true, then depending on the patients medical conditions and the
type of surgery, further testing or therapy may be indicated. In short,

If the surgery is emergent

Go to the OR, monitor as appropriate

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 If the patient can perform 4 METs without symptoms
Go to the OR
If not emergent, and the patient has active cardiac conditions e.g. acute coronary syndrome,
decompensated heart failure, uncontrolled arrhythmia, or untreated valvular disorder
Delay going to the OR, evaluate and treat conditions as appropriate
If not emergent, and the surgery is low-risk
Go to the OR
If not emergent, and the surgery is moderate- or high-risk and the patient cannot do 4 METs
Consider additional testing or -blockade depending on the type of surgery and the patients
Clinical Risk Factors (see below)

Generally speaking, the guidelines are crystal-clear for the vast majority of planned surgeries. However,
the most common situation in which the AHA/ACC Guidelines need to be applied and decisions made
about further testing or perioperative -blockade is the 5th bullet point, where patients with 0, 1, 2, or 3
Clinical Risk Factors along with either moderate- or high-risk surgery may or may not need additional
testing or perioperative -blockade. The five Clinical Risk Factors are CAD, heart failure, DM, CKD, or
cerebrovascular disease. This decision-making tree is easiest to understand visually, and so the
algorithm follows below.

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Note that:

Low-risk surgery: endoscopy, skin surgery, cataract surgery, breast surgery, ambulatory surgery
Moderate-risk surgery: anything intraabdominal or intrathoracic, carotid endarterectomy, head &
neck surgery, orthopedic surgery, prostate surgery
High-risk surgery: aortic vascular surgery or peripheral vascular surgery

The bottom line is that when you are doing a pre-op, there should be certain red flags that you are
listening for. Any of the active cardiac conditions or multiple clinical risk factors along with a planned
moderate- or high-risk surgery should certainly grab your attention. In practice, surgeons, who generally
do not want to have their cases cancelled on the day of surgery, are not shy of ordering stress tests
(whether nuclear or echocardiography-based) or consulting cardiology. So, in many instances, the
appropriate tests have already been done, and/or the patient may have been started on -blockers.
Nonetheless, vigilance is the name of the game here, so take a detailed history and review the medical
record carefully.

Coronary Stents

Patients with prior coronary stents demand special attention. Current guidelines are designed to
minimize the risk of perioperative stent thrombosis and perioperative MI, which carries a mortality rate
of around 50%. A few items you must know about your patients coronary stents:

When they were placed

What type of stent (drug-eluting vs. bare-metal)
Which vessels they are in
The type of antiplatelet therapy and the intended duration of dual antiplatelet therapy

Timing of placement influences the timing of the dual antiplatelet therapy regimen, which is typically
aspirin and clopidogrel. Generally speaking, a patient should not be taken off clopidogrel for at least 12
months following DES and for at least 6 weeks following BMS. And since almost no surgeon will perform
surgery on a patient taking clopidogrel, this effectively means that elective surgery should not happen
for at least 12 months following DES and 6 weeks following BMS.

Where the stents are located influences your choice and placement of ECG leads. A patient with a BMS
placed in the LAD 8 weeks ago, off clopidogrel for an elective surgery, will certainly benefit from
monitoring of lead V4 or V5.

Ultimately, decisions about timing of elective surgery following coronary stenting and management of
antiplatelet agents are made mutually by the patients cardiologist, surgeon, and anesthesiologist. Be
sure to contact an attending with any questions regarding coronary stents and medication management.

Pacemakers and Automated Implantable Cardioverter-Defibrillators (AICD)

These devices represent another unique challenge to the anesthesiologist. Current guidelines are
designed to allow safe management during the entire perioperative period, as well as assessment of the
device itself. The old days of simply placing a magnet on the device during surgery have gone by the
wayside. In short, these devices are very time-consuming and managing them can be quite complex. The
guidelines for this topic are available from the ACC/AHA website. A few items you must know about

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your patients implanted device:

Where it physically is (right/left) and how many leads it has

Model and manufacturer of the device (e.g, Medtronic, Boston Scientific)
If a pacer,
o Indication for its placement (heart block vs. sick sinus/tachy-brady)
o Pacing settings (DDD? VVI? AAI?)
o What happens when a magnet is applied? I.e., what is the magnet mode?
o Single-chamber, dual-chamber, or biventricular?
If an AICD,
o Indication for its placement (actual VT/VF vs. low-EF heart failure)
o What the magnet does when applied (it usually disables antitachycardia therapy)
o Backup pacing function
Phone number for the device representative

Depending on the location on the patients body of the surgery, the need for electrocautery, the
patients position, and device characteristics, the device may need no special management
perioperatively, or it may require the representative to come to the hospital to reprogram the device
pre-op and then to re-reprogram and interrogate the device post-op. Add in the challenge that most, if
not all, patients have little to none of the above information. So, obtain everything you can, and write it
down on the pre-op form. Calling the device representative ahead of time and/or scheduling a day-of-
surgery visit is the most important. All the major manufacturers have national phone numbers and local
representatives on call 24/7/365. Most patients at least have this phone number on them.

You will learn much more about these devices throughout your residency and especially during the
cardiac rotations. The above simply represents the minimum information which should be gathered
during a pre-operative visit.

3. Respiratory System

COPD (emphysema and chronic bronchitis) and asthma are conditions that need further description,
primarily in delineating the severity of the condition and any recent changes in symptoms. For both
COPD and asthma, you must know the patients current medication regimen, and any previous
hospitalizations or intubations for their condition. A patient who has exercise-induced asthma and uses
albuterol once a week is very different from a COPDer who wears 3L oxygen 24 hours a day and uses
daily inhaled steroids and long-acting bronchodilators. What are their usual symptoms, and have these
changed in the prior days or weeks? Many patients with COPD, or even just those suspected of having
COPD, will have pre-operative pulmonary function tests done. Note the absolute values and the ratio of
FEV1 and FVC.

Previous significant instrumentation or changes to the airway bear further explanation. Examples of
these might include history or presence of a tracheostomy, significant radiation to the head and neck, or
prior surgeries in these same areas. Clearly an ongoing, active issue with the patients airway warrants
further investigation and explanation.

Obstructive sleep apnea has profound implications in the perioperative period. The Practice Guidelines
for the Perioperative Management of Patients with Obstructive Sleep Apnea, published by the ASA in
2006, is an excellent reference. Dr. Benumof has been an instrumental member of the taskforce that

25
created these guidelines. At the minimum, the presence or suspicion of OSA must be noted on the pre-
op form. Changes in anesthetic technique, planned postoperative monitoring, discharge requirements,
and even whether to proceed with surgery can occur in the presence of OSA. At UCSD, generally
speaking, patients with known OSA who have undergone GA will be monitored in the hospital overnight
with continuous pulse oximetry, to monitor for life-threatening hypoxemia. However, there are
exceptions. Refer to the guidelines for specific recommendations.

4. Neurologic System

History of cerebrovascular disease is important to note, in that patients may have neurologic deficits or
significant vascular disease as described above. Patients with seizure disorder should always maintain
their medication regimen throughout the perioperative period. It is essential to carefully document
preexisting neurologic dysfunction or deficits, because perioperative neurologic dysfunction makes up a
substantial amount of claims brought against anesthesiologists, whether theoretically due to
positioning-related neuropathies or manipulation of the cervical spine.

5. Hepatic and Renal Systems

Preexisting hepatic and renal disease can profoundly influence the choice of individual anesthetics and
timing of surgery. Patients with advanced disease in either of these organ systems will have decreased
metabolism and/or elimination of drugs, in addition the effects on other organ systems. If the patient is
on peritoneal or hemo-dialysis, note the normal schedule of dialysis and when the patients pre-
operative dialysis will be.

6. GI, Hematologic, Endocrine, and Musculoskeletal Systems

If the patient has GERD or symptoms of heartburn, be sure and clarify the situation. Are the symptoms
more indicative of simple heartburn, or that of true GERD (worse when supine, acidic taste in the mouth
or throat). Additionally, note if the symptoms are controlled on any medications or not.

Dysfunction of the hematologic system is important to note, especially preoperative anemia or

coagulopathy and any known causes or treatment regimens.

Diseases of the endocrine system, particularly diabetes mellitus and thyroid disorders, can have
profound implications in the perioperative period. At minimum, note the type of diabetes (1 vs. 2) and
whether a type 2 diabetic is insulin-dependent. Hypo- or hyperthyroidism is typically controlled with
medication to an asymptomatic state prior to elective surgery. Here, you can also note any comments
about morbid obesity, or pheochromocytoma.

Preexisting musculoskeletal problems can also be noted here. Be sure to clarify between osteoarthritis
and rheumatoid arthritis, as these have very different implications for anesthesia.

6. Cancer, Infectious Diseases, History of Postoperative Nausea and Vomiting (PONV), Smoking,
Alcohol, and Other Drug Abuse

Indicate as appropriate. Pay special attention to cancers of the head and neck, cancers that have been
irradiated, or exposure to bleomycin or adriamycin (hydroxydaunorubicin) as they may have profound
implications for anesthetic management.

26
If a patient uses recreational drugs, note if they are an active user. Patients who have abused tobacco,
ethanol, cocaine, or methamphetamines and have only recently stopped may still have altered
physiology from substance abuse.

8. Family History of Problems with Anesthesia

This section is asking for a history of malignant hyperthermia or pseudocholinesterase deficiency. Often
patients will know this themselves, and can also be asked about a history of high temperatures or
bad reactions anesthesia. A positive answer warrants further investigation and planning; see the
malignant hyperthermia section.

9. Previous Surgeries, Medications, Allergies

Indicate as appropriate. Certain medications must have their doses noted. An occasional vicodin 5/500
as needed is different than someone taking 8 tabs of percocet 10/325 a day. The same goes for
antihypertensives lisinopril 5mg daily vs. 40mg daily, for example. Some which will alter the anesthetic
(e.g., narcotics, antiepileptics). Certain herbal medications bear mentioning. If applicable, try and
describe the allergic reaction a patient has.

10. Physical Exam

Brief and focused should be the goal. Note the presence of any indwelling catheters or instrumentation.
General inspection and auscultation of heart and lung sounds is the minimum here.

11. Airway Examination

Note the Mallampati class, hyomental disease, neck and head range of motion, quality and quantity of
dentition, and the ability to prognath the jaw. There is room to provide further description if necessary:
does the patient have a profound overbite? A thick neck? Scarred submandibular tissue due to prior
radiation? If the patient has an endotracheal tube or tracheostomy, you must note the size and type of
airway tube. Any available information about past intubation attempts and/or their success must be
noted. The importance of a good airway exam cannot be overemphasized.

12. Labs and Other Studies

Note chemistry, hematology, coagulation, and blood gas studies as applicable. Some patients will have
had substantial workup prior to their pre-op visit. Men over the age of 40 and women over 50 need a
baseline EKG. Note the results of a chest X-ray if available and pertinent.

13. Assessment and Plan

Here is where you indicate a one-line summary of the patient, a pertinent problem list or items in the
medical history, and a description of the anesthetic plan. A quick example might be:

42 y/o F with cholelithiasis s/f lap chole. PMH: morbid obesity, DM2, HTN. Plan: NPO > 8h, routine
monitors, GA with ETT.

In general, it is good to be broad with the anesthetic plan and it is not necessary to define specifics (e.g.,
propofol for induction). For one, plans change. Secondly, anesthesia providers change, and for

27
medico-legal reasons you dont want to create potential problems by being too specific on the pre-op
evaluation form. For example, if use of an arterial line for the case at hand would be a judgment call of
the anesthesiologist on the day of surgery, you might indicate Routine monitors arterial line.

Be sure to the ASA Physical Status Classification (ASA class). The ASA class attempts to assign a
numeric value to the overall health status of the patient and has been shown to correlate with
perioperative outcomes. Billing and reimbursement have historically been adjusted for ASA status, in
recognition of increased complexity of the patient, but this is always changing. The following definitions
are the strict definitions taken from the ASA, with our own examples in bulleted below:

ASA 1: A normal healthy patient

ASA 2: A patient with mild systemic disease
o controlled HTN, controlled hypothyroidism
ASA 3: A patient with severe systemic disease
o CAD with stents, morbid obesity, advanced COPD
ASA 4: A patient with severe systemic disease that is a constant threat to life
o end-stage heart failure with AICD; an ICU patient intubated with ARDS
ASA 5: A moribund patient who is not expected to survive without the operation
o A patient with mesenteric ischemia in septic shock; a patient with an expanding base-of-
tongue mass that could occlude the airway
ASA 6: A brain-dead donor whose organs are being removed for donation purposes

Any of the above can have an E added to them, e.g. ASA 2E, to identify surgeries that are emergent.
For example, if a patient has just eaten a meal and the surgeon says We cannot wait 8 hours to do the
surgery, you would do well to indicate an E status in this case.

The VA Pre-op

The pre-op form at the VA is essentially the same as the one used at Hillcrest and Thornton. Notably, the
VA administration insists that the question of TB yes or no must be answered, so check the
appropriate box.

The pre-op must also be reviewed and signed off by an attending, without exception. For practical
purposes, this means all pre-ops must be signed before they are scanned, including pre-ops done on
inpatients after the attendings have left the building.

Lastly, the pre-ops at the VA are scanned into the electronic system when completed. You will be shown
how to do this when you rotate through the VA. So, if you see an inpatient after all the attendings have
left for the day, dont scan it in until after an attending has read and signed off on it.

Chapter 1I. Presenting Pre-Ops to Attendings

One ritual which you will grow intimately familiar with as a resident is calling attendings, typically in the
evening between 1700-2000, to discuss the next days cases. This is done around the country at virtually
every anesthesiology residency, so take heart in the fact that you are not alone. The case presentations
are an opportunity for the resident to formulate a plan and iron out any potential issues before they
arise, as well as to learn about the case in general. They are also an opportunity for the attending to
know what they will be doing the next day, to teach, and to make sure that they are on the same page

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as the resident.

Usually the resident photocopies the pre-op and takes it home to call the attending in the evening.
However, depending on your work schedule, you may just call with it from the hospital, physically talk to
the attending if he or she is in-house, have the pre-op photo-texted or photo-emailed to you by an on-
call or otherwise friendly resident if the pre-op is at a different hospital than you are, or, as a last resort,
examine the patients medical record and clinic notes on EPIC from home.

The number of attendings styles is almost as varied as the attendings themselves. Some attendings
expect a thorough understanding of the physiology and pathophysiology of whichever medical
condition(s) your patient has, or an intricately detailed anesthetic plan. Others are more laid back and
might expect a 30 second presentation, to which they might respond OK, see you tomorrow.
Experience will help you determine who falls into which camp, but as a junior resident, you should
always be prepared for the former (intense) rather than the latter (laid-back), both in the interest of
your education and in the interest of not embarrassing yourself. Furthermore, the attendings as a whole
tend to instruct or grill the junior residents more than the seniors during the presentations. In many
ways this is only natural; it is natural to assume that the junior resident knows less, has less (or no)
experience with the case at hand, and is in more need of teaching. So, treat this as the learning
opportunity that it is.

Presenting a case is an art form. Done poorly, they can expose gaps in knowledge, waste time and create
frustration for both resident and attending. Done well, they can be a great learning opportunity in a very
brief space of time. With experience the ease and quality of presenting a case improves dramatically.

Thus, there is a good general format for presenting to attendings. Again, the goal is brevity and clarity.
Certain additional pieces of information may be useful from time to time, but in general most attendings
do not want to hear a 45 minute description of the patient. For example, it is usually not necessary to go
into an exhaustive list of medications and doses during your case presentation. Below are a few
examples of case presentations, varying with the complexity of the hypothetical patient.

Hello Dr. X, this is resident Y. I am calling to discuss tomorrows cases with you. Our first case is

Case 1: A 45 year old man having a left inguinal hernia repair. He is otherwise healthy and the airway
exam is normal. My plan is general anesthesia versus neuraxial versus MAC/local and standard monitors,
depending on the size of the hernia and the patients preference.

Case 2: A 50 year old woman having a laparoscopic cholecystectomy. She has a significant history of
asthma, for which she takes albuterol and steroid inhalers daily. She has never been hospitalized or
intubated for her asthma. Otherwise she has no medical problems. Airway exam and pre-op labs are
normal. Recent PFTs show a mild obstructive defect consistent with her asthma. My plan is general
anesthesia with an ET tube, standard monitors, and to have her use her inhalers immediately pre-op.

Case 3: A 66 year old man having a right carotid endarterectomy. He has 90% stenosis of his right
carotid and recently had a stroke that left him with residual left sided weakness. He also has 50-69%
stenosis of his left carotid. His past medical history is significant for HTN, DM2 and peripheral vascular
disease. He does not exercise but a recent AMIBI showed no evidence of CAD and good ventricular
function. Airway examination and pre-op labs are all normal. My plan is general anesthesia with an ET
tube, standard monitors with an arterial line, and EEG. I will be maintaining with desflurane and nitrous
oxide along with remifentanil infusion, with the goal being a quick wakeup so the surgeons can perform

29
a neuro exam. Ill keep the patients blood pressure at normal-to-slightly-elevated to maintain cerebral
perfusion, especially during carotid clamping. Hopefully the EEG will allow us to monitor for possible
ischemic episodes. Lastly, I will administer a longer acting narcotic like fentanyl at the end of the case to
bridge the patient from remifentanil.

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Chapter 2. Anesthesia Equipment and Pharmacology

Chapter 2A. Anesthesia Equipment

I. Medical Gases
A. Oxygen
Stored as a compressed gas at room temperature or refrigerated as a liquid.
Oxygen stored in the hospital central supply is at high pressure (2000psi); this cylinder pressure
is reduced by valves to line pressure (~55psig).
A standard E-cylinder of oxygen is green and contains 650L of gas when full at a pressure of
2200psig.
Cylinder pressure falls in direct proportion to content; thus, a half-full E-cylinder contains 325L
of oxygen, at a pressure of 1100psig.
Most anesthesia machines have 1 or 2 backup E-cylinders attached; standard practice at UCSD
is also to have a separate E-cylinder in the room, with a Mapleson circuit for positive-pressure
ventilation. All post-anesthesia patients are transported with oxygen to PACU.
B. Nitrous Oxide
Can be liquefied at room temperature by storing under pressure.
A full E-cylinder contains 1590L of gas (liquefied) at a pressure of 745psig and is blue.
The cylinder pressure does not fall as nitrous oxide is consumed until the cylinder reaches below
400L. This is because nitrous oxide will vaporize at the same rate it is used and will thus exert a
constant pressure (745psig). Only below 400L ( empty) will the cylinder pressure fall.
Thus, the only way to determine the volume of nitrous oxide in a cylinder is to weigh it.
C. Air
Stored as a gas in yellow E-cylinders.
A standard E-cylinder of air shares the same characteristics as oxygen with respect to capacity
and pressure.

The Pin Index Safety System is designed to prevent incorrect cylinder attachments to the anesthesia
machine. Each type of cylinder has holes that lock with pins in the anesthesia machine. The spacing and
position of pins/holes is unique for each type of gas, which generally prevents erroneous connections.

II. Delivery of Anesthetic Gases to the Patient (Breathing Systems)

A. Insufflation
Gases are blown across a patients face; no direct contact is made between the circuit and the
patient.
Potentially useful in children who may resist a face mask touching them.
Can also be used in situations where the patients head and neck are draped to avoid carbon
dioxide buildup under the drape.
Limitations: cannot control ventilation, entrainment of room air, and unpredictable delivery of
gases.
B. Mapleson circuits (semiopen system)
Comprised of a breathing tube, a fresh gas inlet, an adjustable pressure limiting valve and a
reservoir bag.
The positioning of these components determines the type of Mapleson circuit and how it
performs.

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 The efficiency of the circuit is determined by how much fresh gas flow is necessary to prevent
rebreathing; there is usually some rebreathing in any Mapleson system.
The APL valve should be completely open during spontaneous ventilation but must be partially
closed to allow positive pressure during controlled ventilation.
The longer the breathing tube, the larger the dead space in the system. Longer circuits increase
the difference between volume delivered to the circuit and volume actually delivered to the
patient during controlled ventilation. This is because the circuit has some inherent compliance
and expands during positive pressure ventilation.
Advantages: low resistance, low dead space, small and portable, little equipment and thus room
for error.
Disadvantages: constant loss of heat and humidity, need high flows to prevent rebreathing,
difficult to scavenge waste gases.
Best systems for spontaneous ventilation: A, D, C, B (A Dog Can Bite).
Best systems for controlled ventilation: D, B, C, A (Dog Bites Can Ache).
See the diagram below for characteristics of the various Mapleson systems under both
controlled and spontaneous ventilation.

C. Circle systems (semi-closed)

The anesthesia machine is a semiclosed system; the addition of unidirectional valves and a
carbon dioxide absorber convert a semiopen to a semiclosed system.
These additions allow better conservation of heat and humidity (due to rebreathing of alveolar
gas) and scavenging; however, there is more resistance during spontaneous ventilation, more
dead space and more components, making the system both larger and more prone to
malfunction.
Unlike Mapleson circuits, the length of the circuit has essentially no impact on dead space.
Longer circuits still increase the difference between delivered circuit volume and actual
delivered volume to the patient; see above in the Mapleson section.
CO2 absorbers: exhaled carbon dioxide reacts with water to form carbonic acid. This acid is

32
 neutralized by hydroxide salts (CO2 absorbent), forming water, calcium carbonate, and heat.
Soda lime is the most common absorbent; barium hydroxide lime is also seen but both forms
come with an indicator dye that changes color with pH (as the lime becomes more exhausted,
the dye will change color). Ethyl violet, the most common, is white when fresh and purple when
exhausted. Be aware there are other types of dye with different colors. Further, exhausted lime
that is allowed to rest can revert back to its original color. It is recommended the lime be
changed when it is more than 50% exhausted. The anesthesia monitoring technicians typically
will replace the lime daily, ensuring a fresh supply, or it can be replaced when the inspired CO2
exceeds 5mmHg.
Drier lime has a propensity to absorb and degrade volatile anesthetics. Absorbed volatile agent
can delay induction and emergence. Degradation products include sevoflurane to compound A
(seen only with fresh gas flows < 1L/min) and desflurane to carbon monoxide (barium lime only);
see the section on volatile anesthetics. High flows running through an unused anesthesia
machine increase the likelihood of dry lime. The so-called Monday morning effect comes from
a hypothetical anesthesia machine that someone has inadvertently left with high flows going on
a Friday afternoon. If the OR is unused the whole weekend, by Monday, the soda lime can be
highly desiccated.
The patients tidal volume should not exceed the volume between the granules, as this could
result in rebreathing of carbon dioxide.
Unidirectional valves: the inspiratory and expiratory valves should open only during the
corresponding phase of the ventilatory cycle. Warped or cracked valves, or mis-seating of the
valves can lead to incompetence and rebreathing of CO2. Malfunction of either valve can result
in rebreathing.

Note the diagram of a circle system above. The fresh gas inlet should be between the absorber
and the inspiratory valve. Were the FGI to be distal to the inspiratory valve, during exhalation
fresh gas would be vented out and wasted. If the FGI came before the absorber, it would dilute
with expired gas, and would be partially absorbed by the soda lime.
Placing the pop-off valve immediately before the absorber conserves the absorber (exhaled gas
vents before passing through the lime) and minimizes the venting of fresh gas.
The reservoir bag should be in the expiratory limb. This reduces resistance to exhalation during
spontaneous ventilation, and tends to vent exhaled gas through the popoff valve.

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 With low flow rates, the difference between fresh gas concentrations and actual inspired gas
concentrations can be markedly different. This is because the actual inspired gas is a mixture of
fresh gas and the exhaled gas that has passed through the absorber. For example, take a fresh
gas flow with a concentration of 100 units of gas X and exhaled gas with a concentration of 0
units. If the fresh gas flow and exhaled gas flow are both 1L/min, then the mixed (inspired) gas
will contain (100 + 0)/2 = 50 units of gas X. However, if the FGF is 4L/min, then the concentration
of gas X in the mixed gas will be (100 + 100 + 100 + 100 + 0)/5 = 80 units of gas. Thus, higher
fresh gas flow rates will cause the inspired gas to more closely reflect the fresh gas itself, as well
as speeding induction and emergence. High flows can also compensate for leaks in the system.
D. Closed systems
Primarily of historical interest now.
In a closed system, all gas except CO2 is rebreathed; no gas is evacuated through a popoff valve.
The amount replaced by fresh gas flow is nearly equal to that taken up by the patient.
By contrast, open systems have a fresh gas flow that exceeds minute ventilation (no
rebreathing). Semiopen and semiclosed systems feature partial rebreathing, where the gas
supplied exceeds that taken up by the patient, but is still less than total minute ventilation.
Technique: the predicted oxygen consumption, minute ventilation and anesthetic uptake are
calculated and then the exact flows are delivered to achieve this delivery. The goal is an
unchanging circuit volume.
Advantages: excellent conservation of heat and humidity, cheap, little or no waste gas to
scavenge.
Disadvantages: the amount and concentration of gas supplied must be precisely calculated;
tedious, difficult and potentially dangerous; cannot rapidly change anesthetic concentration.
E. Nasal cannula, Simple Face Masks, Non-rebreathing Masks
Nasal cannula: this is a low-flow system. Each additional liter of O2 increases FiO2 by 4-5%, to a
max of 6L/min or about 45% FiO2. Significant entrainment of room air occurs, further diluting the
oxygen in the nasopharynx. Peak flow rates during tidal breathing are around 40L/min, far
exceeding that delivered by the nasal prongs. Thus, the actual FiO2 which the lungs see is
much lower than the maximum deliverable by NC.
Face masks: deliver approximately 50% FiO2 at flows of 6-10L/min.
Non-rebreathing masks: have a reservoir bag, and can achieve > 80% FiO2 at flows of 10-
15L/min.
None of these systems allows for positive pressure ventilation.

III. The Anesthesia Machine

The anesthesia machine is perhaps the most complex piece of equipment that we use on a daily basis. In
fact, it is probably inaccurate to think of the machine as a single piece of equipment, as it is comprised of
a multitude of components and serves simultaneously to deliver anesthetic gases to the patient and as
multiple monitors.

One can literally finish an entire residency in anesthesia and still only have a basic understanding of the
machine and its components. The complete description of the machine and its function is beyond the
scope of this text. Rather, the following pages will serve to describe the essential features of the
machines and detail the basic elements of a machine check. There are three machines currently in use
at UCSD: the Datex-Ohmeda Aestiva 3000, which is the most common machine in use at Hillcrest,
Thornton, and the VA; the newer Datex-Ohmeda Avance, in select ORs at Hillcrest and the Sulpizio

34
Cardiovascular Center; and the Draeger Apollo at Thornton. The newer Datex-Ohmeda Avance is a
digital anesthesia machine and is the same machine that is used at Radys Childrens Hospital. Subtle
differences between the machines will be described here.

A. Gas Supply
All machines receive the supply of O2, N2O and air from two sources: the central hospital
pipeline and the E-cylinders physically attached to the machine. Depending on the machine,
there may be a fourth pipeline connection for helium/oxygen, or rarely, CO2. Some machines do
not have an air E-cylinder. The E-cylinders should be considered as backups to the primary
source, the pipeline.
The E-cylinders attach to the machine via the Pin Index Safety System (PISS) described above.
Similarly, the anesthesia machine receives pipeline input via color-coded connecting hoses using
the Diameter Index Safety System (DISS), whereby each pipeline connection has a specific and
unique diameter of locking pins to prevent incorrect attachment.
Before gas from the E-cylinders reach the flow valves, a pressure regulator reduces gas pressure
to ~45psig for safety. The pressure is usually lower than pipeline pressure, so that if an E-
cylinder is inadvertently left open, gas will still be preferentially drawn from the pipeline.
B. Flow valves and safety
Before reaching the flow control valves, all gases except oxygen must first pass through a safety
device. These devices will only allow the gases to be delivered if there is sufficient oxygen
pressure, thereby reducing the chance of delivering a hypoxic mixture to the patient.
Proportioning safety devices reduce the flow of other gases as the flow of oxygen falls. This is
also to ensure against delivery of a hypoxic mixture. If you have both N 2O and O2 flowing and
suddenly reduce the flow of O2, the flow of N2O will automatically be reduced as well once the
FiO2 reaches the preset critically low value.
A low oxygen-pressure alarm is also present which sounds whenever oxygen inlet pressure falls
below a preset value.
The flow valves are specifically designed and arranged to maximize safety and minimize the
chance of delivering a hypoxic mixture in the event of a leak. For the non-digital machines, there
are knobs for each gas, and the knob for the O2 valve is always furthest to the right
(downstream), is larger and protrudes more than the other knobs, and has ridges that can be
felt even when not looking at the knob.
The flow meters on the older machines are glass tubes in series (Thorpe tubes). The indicator
ball or bobbin float rises as the flow of gas creates pressure underneath. Thorpe tubes get
progressively wider near the top (variable orifice) so that as the float rises higher, more gas is
allowed to escape around the sides of the float. The tubes are specifically calibrated for each
gas.
Typical board question: the rate of flow depends on the gass viscosity at low, laminar flow and
its density at high, turbulent flow.
The oxygen flow valve delivers a mandatory minimum flow of 150ml/min as long as the machine
is turned on, ensuring some oxygen is present even if the anesthesiologist forgets to turn the
oxygen on.
C. Vaporizers
Each vaporizer has an lockout device that prevents more than one vaporizer being on at a
time.
Each vaporizer is calibrated to a specific agent, and is designed to deliver a consistent
concentration regardless of temperature or flow changes. Each vaporizer must only be filled

35
 with the intended anesthetic, and specific ports and caps for filling are designed to prevent
incorrect attachment of the wrong agent to vaporizer.
Basic mechanism: a certain portion of gas flow is diverted through a chamber containing liquid
volatile anesthetic. This gas becomes saturated with anesthetic vapor, and the combined gas
flow leaves the chamber where it dilutes with the rest of the unchanged (bypassed) gas flow.
The vaporizers are therefore variable bypass vaporizers.
The amount of gas + vapor diluted with the gas flow determines the concentration of
anesthetic delivered to the patient.
Desflurane vaporizer: desflurane has a very high vapor pressure, and a low potency. This creates
two problems, both of which are addressed by the vaporizer. Due to the high level of
vaporization, there is a tremendous cooling effect, because vaporization of the liquid agent
requires heat which cools the vaporizer housing. This cooling must be compensated for by direct
warming by the vaporizer, which is why the desflurane vaporizer is warm to the touch. Also,
because of such high levels of vaporization, the amount of fresh gas flow needed to dilute the
carrier gas would be excessive. Thus, small amounts of pure desflurane vapor are added to the
fresh gas flow, which does NOT enter the vaporizer chamber itself. The desflurane vaporizer is
therefore not a variable-bypass vaporizer. Lastly, the vaporizer cannot compensate for changes
in elevation (ambient pressure). Elevation does not decrease the amount of anesthetic
delivered, but it does decrease the partial pressure of the agent. Thus, at high altitude, a higher
concentration must be delivered manually by the anesthesiologist.
D. High-flow oxygen flush valve
Provides high flow (30-55L/min) of oxygen directly to the common gas outlet, bypassing the
vaporizers and flowmeters.
Is useful for rapidly refilling or flushing the circuit.
Risk of barotrauma: the oxygen is supplied at line pressure; use the flush valve cautiously when
attached to the patient. When the ventilator is off, ensure the popoff is completely open, or
when the ventilator is on, ensure that the bellows are not on an inspiratory cycle.
The button is recessed in the machine, making it more difficult to inadvertently trigger the flush
valve.
E. Oxygen analyzer
Mandatory; turns on when the machine is turned on.
Should be placed in the inspiratory or expiratory limb of the circuit, but not the fresh gas line.
F. Pressure sensor
Mandatory; placed somewhere in the circuit (varies by machine); generally reflects airway
pressure.
The closer to the Y-connector the sensor is, the more closely it reflects airway pressures.
Changes in airway pressure may reflect obstructions, disconnections or changes in compliance
and must be investigated.
G. Adjustable pressure-limiting (APL, popoff) valve
Should be fully opened during spontaneous ventilation; however, closing it slightly can be used
to add CPAP to the circuit.
Designed to have an upper limit (~70cmH2O) so that the valve can never be truly closed,
limiting the risk of inadvertent barotrauma.

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H. Humidity
Delivered gases are room temperature and low in humidity, which can cause drying of the
patients airways and loss of heat both from warming of the gas itself and from vaporizing water
to increase humidity (heat of vaporization, the more important phenomenon with respect to
heat loss).
This heat loss represents ~10% of total intraoperative heat loss and is more significant with
longer procedures (> 1hr).
Passive humidifiers can be added to the circuit; they function by trapping exhaled water vapor.
They are cheap and simple to use but can increase circuit resistance and rarely can become
plugged when excessively saturated.
Active humidifiers add both water and heat to inhaled gases; they are quicker than passive
humidifiers but also bulkier and more expensive. Downsides include the possibility of thermal
inhalational injury, infection, increased chance of circuit disconnection, and increased dead
space. These are typically used only in pediatrics, where airway heat losses can contribute
significantly to overall heat flux.
I. Ventilator
In Volume-Controlled Ventilation, the machine aims to deliver a set volume with each breath.
High pressure limits will automatically cut off the breath if excessively high peak pressures are
encountered. The machines also have the ability to deliver Pressure-Controlled Ventilation.

37
 Here, a set pressure will be delivered for a certain length of time, depending on the set rate and
the I:E ratio. The tidal volume delivered will vary with inspiratory time as above and with the
patients pulmonary/thoracic mechanics.
The newer digital Datex-Ohmeda Avance has a new mode of ventilation called Pressure Control
Ventilation-Volume Guarantee (PCV-VG). This mode combines the advantage of pressure-
controlled ventilation (the ability to limit peak airway pressures) with the ability to deliver a
guaranteed tidal volume. A goal tidal volume is set and the machine will use only the minimal
amount of pressure needed to deliver that tidal volume.
I:E ratio: this determines the amount of time the vent will spend in each phase of ventilation. A
typical ratio is 1:2. Increasing the I:E ratio (e.g. to 1:1) means there will be more time spent in
inspiration and less in exhalation. Increasing the I:E ratio during volume control will typically
lower the peak inspiratory pressures. Increasing the ratio during pressure control will result in a
smaller volume delivered. Decreasing the I:E ratio (e.g. to 1:3) is a commonly-cited strategy to
facilitate expiration in obstructive lung disorders such as COPD or asthma. Here, allowing more
time for exhalation can overcome intrinsic expiratory gas-trapping.
All machines have a switch to change from bag to mechanical ventilation; on the Drager,
confirmation of your selection is confirmed by pressing the dial a second time.
In ventilator mode, the popoff valve and reservoir bag are excluded from the circuit.
Ventilator bellows: pneumatically driven (typically by oxygen, sometimes by air). During an
inspiratory cycle the driving gas will fill the plastic chamber outside the bellows themselves,
compressing the bellows and delivering a breath to the patient. If the chamber housing is
cracked or incorrectly seated, pressure will be unable to build and the bellows will not drive.
Similarly, if there is a leak in the bellows itself, high pressure gas normally used to drive the
bellows can be transmitted to the patient.
Phenomenon of ventilator/fresh gas flow coupling: during an inspiratory cycle, the ventilator
will deliver both the preset tidal volume, and a certain percentage of the fresh gas flow itself.
This additional amount is dependent on the number of breaths/min the vent is delivering, the
time spent in the inspiratory phase, and the fresh gas flow itself. The equation for calculating
this is:

Extra volume delivered = (FGF) x (% of time in inspiration)/(respiratory rate)

Thus, if the FGF is 5L/min, the I:E ratio is 1:3 (25% of time in inspiration), and the machine is
delivering 10 breaths/min, the extra volume delivered is (5) x (0.25)/10 = 0.125L, or 125ml extra
per breath.
High fresh gas flows increase the magnitude of this phenomenon, as is typical during
emergence, when we often turn the oxygen flow very high to wash out the anesthetic agent
while the vent is still on, and actual delivered volumes can exceed the set volume.
Potential reasons for discrepancies between set and delivered tidal volumes include leaks in the
circuit, breathing circuit compliance (less with stiffer circuits), compressive gas losses, gas
sampling from the capnograph, and ventilator/fresh gas flow coupling.
J. Scavenging systems
Remove gases that vent from the popoff valve (when the machine is set to bag) or the spill
valve (when the vent is on).
Closed scavenging systems empty into a reservoir bag, which has a positive pressure relief
valve (prevents excessive buildup of pressure if the scavenging line is occluded) and a negative
pressure relief valve (prevents excess negative pressure from the wall suction system to be

38
 transmitted to the patient).
Open scavenging systems empty into a canister with vents, which prevents positive pressure
or negative pressure being applied to the patient due to scavenger occlusion, but which can
send scavenged gas into the OR.

A Quick Anesthesia Machine Check Out

The full machine checkout list is available from the FDA or our anesthesia monitoring technicians. In
reality, it is not practical for most of us to perform a full machine check every time we are about to use
an anesthesia machine. Thus, most practitioners have a truncated list that hits the most important
points in a machine checkout. This list can be further abbreviated for subsequent cases during the day
(after a more thorough check has been done earlier).

1. Check appropriate alarms turn on when the machine is turned on.

2. Check high pressure system: physically disconnect the oxygen pipeline from the wall. Line pressure
should drop to zero, and a low oxygen pressure alarm should sound. Now open the E-cylinder of
oxygen and verify both that the alarm goes away, and that the cylinder pressure is adequate. Close
the E-cylinder and reattach the pipeline.
3. Check the low pressure system: occlude the end of the Y-connector, close the popoff valve, and
ensure gas flows are off. Flush the high flow oxygen system to build a pressure of at least 30cmH2O.
The circuit, if leak free, should hold this pressure. Opening the popoff while keeping the Y-piece
occluded should release the pressure, verifying that the popoff valve opens and closes
appropriately.
4. Check the valves: there are different ways to accomplish this. One way is to place the reservoir bag
at the end of the Y-piece, and turn the ventilator and fresh gas flow on, and observe for a few
breaths. The valves should move with inspiration and expiration. This also checks your ventilator.

Tips for the Anesthesia Machine

1. Extra circuit tubing and breathing bags are in a drawer in the anesthesia machine. Whenever our
anesthesia monitoring technicians are not available to turn the machine over for another case
(e.g., weekends) you must change the circuit tubing and breathing bag yourself. (You also have to
clean the machine and monitors.)
2. Circuit disconnections are very common. Typically your first clue will be the ventilator alarming and
the bellows not refilling, accompanied by a loss of etCO2 on the capnograph. Common places for
disconnections are: where the circuit meets the machine, between pieces of the circuit (if using an
extension), at the CO2 sampling port, and at the ETT or LMA connector to the circuit.
3. Common sources of leak: the bag, the circuit tubing, the CO2 canisters (improperly seated) or at any
of the connection sites. Others include the bellows cover or the endotracheal tube itself (leak
around an underfilled or ruptured cuff). Leaks within the machine itself are very uncommon. When
in doubt, think of places where the equipment is often changed or disconnected/reconnected (e.g.,
where the circuit tubing meets the machine).
4. Make room for yourself prior to starting a case. The anesthesia machine can be pushed back or to
the side if necessary to allow better access to the patient.
5. If the anesthesia machine is malfunctioning or there is a problem you just cant figure out, you can
connect the patients airway (ETT, LMA, etc.) to a Mapleson circuit and backup E-cylinder oxygen
tank and hand-ventilate. This will serve to exclude the machine entirely as a potential source of the
problem.

39
6. Sudden collapse of the bellows and inability to ventilate just after placing an NG or OG tube likely
indicates placement of the OG/NG tube in the trachea.
7. Avoid plugging accessories into the outlets in the back of the machine. This includes many items in
the OR such as the warmer for heating blankets, fluid warmers or forced-air blankets,
electrocautery, etc. A short or overload is possible, potentially leading to malfunction of the
machine.
8. The color-coded caps that connect the volatile anesthetic bottles to their vaporizers are reusable.
Do NOT throw them away!

Chapter 2B. Anesthesia Monitors

Vigilance is one of the most defining characteristics of an anesthesiologist, and is in fact the motto of the
American Society of Anesthesiologists. There is no better reflection of our constant attention to detail
and to the patients status than in our use of monitors. Indeed, an outsider with little experience inside
an OR would probably identify an anesthesiologist as the person who is constantly watching the screen
and listening to the beeps. In fact, our duty to the patient demands that we be constantly vigilant of
our monitors and the information they provide. Anesthesia profoundly impacts the patients physiology
while rendering the patient incapable of telling us if something is wrong. Vigilance is thus the essence
of preventing, detecting, and treating adverse events.

The following section will discuss the basic monitors as outlined by the ASA, as well as other more
advanced monitoring equipment. The basic science or engineering concepts behind the monitors will
not be discussed. For more complete information, consult a textbook or manufacturers guide.

The ASA standards for basic monitoring stipulate certain expectations for patients undergoing
anesthesia. As standards, they are intended to be universal among anesthesia practice. By definition,
standards are what we are all expected to do or employ, and deviation from them requires unusual and
extenuating circumstances. The ASA does recognize this fact and several times in their standards
mention that requirements may be waived in unusual circumstances, or that sometimes it is not
possible to hold to these standards. That being said, the following are the expectations which we
attempt to uphold with every anesthetic:

1. A qualified anesthesia provider will be continuously present for all anesthetics. Continuous is
defined as prolonged without any interruption at any time. The wording does allow for absences
in extenuating or emergency circumstances, at the providers discretion.
2. Oxygenation, ventilation, circulation and temperature shall be continually measured. Continually is
defined as repeated regularly and frequently in steady rapid succession.
A. Oxygenation
FiO2 is measured and a low oxygen alarm is employed during general anesthesia.
A quantitative measure of blood oxygenation such as pulse oximetry is used.
B. Ventilation
Adequacy of ventilation must be measured. Capnography should be used unless
circumstances do not allow it.
If intubation or LMA placement occurs, correct position must be verified by capnography,
and end-tidal CO2 must be continually monitored.
Ventilation by a machine must have an audible disconnection alarm.
C. Circulation
EKG must be employed throughout the anesthetic.

40
 Blood pressure and heart rate should be ascertained at least every 5 minutes.
Every patient receiving general anesthesia must have an additional continual measure of
circulation such as pulse oximetry, auscultation, or palpation of a pulse.
D. Temperature
Temperature must be measured whenever clinically relevant changes are expected or
suspected.

I. The Non-invasive Blood Pressure Cuff

The NIBP cuff is the most commonly employed device to measure blood pressure during anesthesia. For
most cases, the cuff is the sole measure of blood pressure. BP cuffs can be placed at a variety of
locations, including the upper and lower portions of the arms or legs.

The BP cuff can be set to automatically inflate and measure pressures at various time intervals. The cuff
typically inflates to suprasystolic pressures and then deflates in small increments, measuring oscillations
in cuff pressure caused by arterial pulsation. These oscillations increase markedly at systolic pressure,
are maximal at MAP, and decrease sharply below diastolic pressure. The NIBP measures the pressure at
which these oscillatory changes occur and using a proprietary algorithm is able to calculate MAP, systolic
and diastolic BP.

Sizing a NIBP cuff is important. Cuffs that are too small tend to overestimate SBP (more pressure is
needed to occlude an artery) while cuffs that are too large will underestimate pressure. The cuff itself
should be 20-50% wider than the width of the extremity being measured.

A word to the wise: make sure the cuff is placed to your satisfaction and that things are functioning
properly before draping is done and surgery begins. It is a major headache to troubleshoot a BP cuff
after the drapes are on and surgery has begun. Some patient factors may preclude placement of a BP on
a particular extremity, such as presence of an AV fistula or a history of lymph node dissection on that
side (which is controversial). Clearly, placing a cuff on an extremity that will be operated on is not ideal.

II. Pulse Oximetry

A pulse oximeter actually employs two scientific principles in its function: oximetry and
plethysmography. Oximetry measures the ratio of red and infrared light absorption in blood. Specifically,
deoxygenated blood tends to absorb red light more than oxygenated blood, which absorbs more
infrared light. The ratio of oxygenated to deoxygenated blood will produce characteristic amounts of
light absorption. Using standardized computations, the pulse oximeter can measure the spectrum of
light absorption and calculate the percent oxygen saturation of hemoglobin. The oximeter is linked to an
audible tone that rises and falls with saturation, giving us a way to know the saturation or detect
changes without even having to see the monitor.

The plethysmographic component identifies arterial pulsations, which help differentiate absorption
from tissue and non-pulsatile venous blood. Functionally this is displayed on our monitor as a wave
corresponding to arterial pulsation. When the signal is clean, one can readily make out features of an
arterial pulse on the plethysmography, sometimes including the dicrotic notch. Conversely, when the
signal is distorted or poor, the tracing is poor. Not surprisingly, the reported saturation during these
times can be erroneous due to poor signal.

Many different types of sat probe exist, including preshaped plastic finger probes, stickers, and

41
smaller probes which can be placed on the earlobe, forehead, or tongue. Picking the right kind of probe
is a function of the patient and type of surgery (e.g., pediatric patient, severe peripheral
vasoconstriction).

Two common types of artifactual readings from other hemoglobin species commonly show up on the
boards. Carboxyhemoglobin absorbs red light to the same extent as oxyhemoglobin, which can produce
falsely high SpO2 readings. Patients with carboxyhemoglobin poisoning will typically show a high S pO2
but low oxyhemoglobin saturation on ABG/co-oximetry. Methemoglobin has the same absorption
coefficient for both red and infrared light, which clinically produces a saturation of 85%. Classic
questions usually involve some trigger for methemoglobinemia (e.g., benzocaine) and a SpO2 of 85%.

Common sources of error in SpO2 readings are motion, ambient light, hypoperfusion (arterial
hypotension or peripheral vasoconstriction) or poor placement of the sensor. Methylene blue dye also
causes a transient, artifactual drop in SpO2. As with the NIBP cuff, make sure the probe is functioning
after final positioning and before surgery starts. All of us can remember long cases constantly being
worried low saturation that was only artifact due to a poorly positioned but inaccessible probe. Surgical
personnel leaning on or compressing the probe or movement of the cable can also cause errors in
measurement.

III. Capnography

The capnographs we employ are diverting capnographs; that is, they continuously aspirate small
samples of gas from the breathing circuit, drawing about 100-200ml/min sample gas into the machine
for analysis. By analyzing the infrared light absorption of aspirated gas, the capnograph can determine
not only CO2 concentration but also the concentration of inhaled anesthetics and oxygen in the sample.
The gas lost to sampling is not usually clinically significant.

Confirmation of sustained end-tidal CO2 following intubation is the gold standard for confirming correct
placement of an endotracheal tube or LMA. Furthermore, patterns and changes in the sampled gas
provide invaluable information throughout the anesthetic. For example, sudden drops in pulmonary
perfusion (e.g., pulmonary embolism or drop in cardiac output) will be reflected as a drop in etCO2.
Given below are some very common examples of intraoperative problems and their presentation on the
capnograph. (Images of waveforms and explanations from Millers Anesthesia, 6th ed.)

The capnograph has an audible alarm that will sound for a whole host of situations, such as apnea,
abnormally low or high etCO2, or high inspired agent. It is imperative that these alarms not be disabled.
Because gas is actively aspirated, the tubing or sample chamber can become saturated with water vapor
or even occluded which can produce false measurements. In these situations it might be necessary to
change the tubing, chamber or both. This equipment can be found in the top drawer of our anesthesia
machines.

At times alternate methods of oxygenation are employed, such as a face mask or nasal cannula. Our
nasal cannulas have a second channel that can be plugged into the sampling chamber of the
capnograph. For face-mask oxygen, it is common to connect the sampling line to a 16g angiocath that
has been cut short and inserted through one of the holes in the face mask. These measures will be more
qualitative than quantitative due to entrainment of room air or a mouth-breathing patient with a nasal
cannula.

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Examples of capnograph waves. A, Normal spontaneous breathing. B, Normal mechanical ventilation. C, Prolonged exhalation
during spontaneous breathing. As CO2 diffuses from the mixed venous blood into the alveoli, its concentration progressively
rises. D, Increased slope of phase III in a mechanically ventilated patient with emphysema. E, Added dead space during
spontaneous ventilation. F, Dual plateau (i.e. tails-up pattern) caused by a leak in the sample line. The alveolar plateau is
artifactually low because of dilution of exhaled gas with air leaking inward. During each mechanical breath, the leak is reduced
because of higher pressure within the airway and tubing, explaining the rise in the CO2 concentration at the end of the alveolar
plateau. This pattern is not seen during spontaneous ventilation because the required increase in airway pressure is absent. G,
Exhausted CO2 absorbent produces an inhaled CO2 concentration greater than zero. H, Double peak for a patient with a single
lung transplant. The first peak represents CO2 from the transplanted (normal) lung. CO2 exhalation from the remaining
(obstructed) lung is delayed, producing the second peak. I, Inspiratory valve stuck open during spontaneous breathing. Some
backflow into the inspired limb of the circuit causes a rise in the level of inspired CO 2. J, Inspiratory valve stuck open during
mechanical ventilation. The "slurred" downslope during inspiration represents a small amount of inspired CO2 in the inspired
limb of the circuit. K and L, Expiratory valve stuck open during spontaneous breathing or mechanical ventilation. Inhalation of
exhaled gas causes an increase in inspired CO2. M, Cardiogenic oscillations are commonly seen with patients who have had
their pericardial sac surgically opened in the past, or may occur with sidestream capnographs for spontaneously breathing
patients at the end of each exhalation. Cardiac action causes to-and-fro movement of the interface between exhaled and fresh
gas. N, Electrical noise resulting from a malfunctioning component. The seemingly random nature of the signal perturbations
(about three per second) implies a nonbiologic cause.

IV. Temperature Monitoring

Most temperature probes we employ are disposable. Temperature can be measured in a variety of
places, the most common being the esophagus, nasopharynx, axilla, tympanic membrane, bladder,
rectum and blood. Skin temperatures are prone to inaccuracy and often do not reflect a patients core
body temp. Likewise, rectal temperatures are often slow to reflect changes in core temp (insulating
effect of feces). Esophageal probes are most commonly employed for routine cases. The probe can

43
double as an esophageal stethoscope by connecting the end of a cheap stethoscope to the proximal part
of the probe.

Hypothermia is a very common problem during surgery. Part of this is due to the cold environment and
nature of the OR. Compounding these effects, during general anesthesia, compensatory mechanisms
such as vasoconstriction and shivering are ablated by anesthetic inhibition of the hypothalamus.
Regional anesthetics also contribute to heat loss by peripheral vasodilation and altered temperature
sensation in blocked dermatomes. Thus, anesthetized patients cannot actively warm themselves and
compensate for hypothermia. Problems associated with hypothermia include surgical site infection,
coagulopathy leading to blood loss, decreased drug metabolism, prolonged PACU stay, adverse cardiac
events, and postoperative shivering and its associated increased oxygen consumption (up to 5x
baseline).

Techniques used to maintain body temperature include warming the OR, forced-air warming blankets
(Bair Huggers), warming and humidifying inspired gases, warming IV fluids and surgical irrigation
fluids, and minimizing exposure of the patients body surface area. Conservation of heat in general is
much more efficacious at keeping a patient warm than trying to replace lost heat, which can take
much longer. Try to keep patients warm from the start of a procedure.

V. Electrocardiography

Typically, a three-lead or five-lead EKG is employed in the OR. A three-lead EKG consists of a R arm
(white), L arm (black) and a L leg (red) lead. This allows us to monitor the electrical axis of lead II, which
is the best lead to observe the basic rhythm and P waves of the heart. Using a five-lead adds a R leg
(green) and precordial V (brown), and adds the ability to monitor lead V lead V3, V4, or V5, any of which
are more sensitive in detecting left ventricular ischemia than lead II.

One helpful mnemonic to remember where the leads are placed is: white on the right, black is opposite
from white (left), snow over grass (white over green), smoke over fire (black over red).

The EKG leads are very prone to artifact from motion or electrocautery. Furthermore, the monitor
displays HR by counting QRS complexes, which it sees as the highest voltage during a cardiac cycle.
Abnormally tall T waves, sometimes due to incorrect lead placement, can give an erroneous heart rate,
a.k.a. double counting. The EKG pads can be a potential area for burns if the electrocautery ground
pad is dysfunctional.

VI. Arterial Pressure Monitoring

Arterial lines provide beat-to-beat information about a patients blood pressure. Indications for placing
an invasive arterial monitor include anticipated wide swings in blood pressure, need for precise beat-to-
beat knowledge of pressure (e.g., heart disease, intracranial aneurysm), arterial blood sampling,
repeated blood sampling, failure of the NIBP cuff, or precise titration of blood pressure (vasopressor use
or deliberate hypotension).

The transducers for an arterial line are found in our workroom and often are paired with a transducer
for central venous pressure. Some rooms will often have a transducer already hooked up to the machine
and zeroed thanks to our anesthesia monitoring technicians. One end of the transducer tubing is
connected to a heparinized saline flush bag, and the other end should be connected to the arterial (or
central) line. The transducer must also be plugged into monitoring cable of the machine (color coded).

44
After the cable is plugged in, a colored waveform line should appear on the screen, indicating the
monitor is online. It now must be zeroed. To zero a transducer, the cap should be taken off the
transducer and the stopcock closed to the patient. Hit the zero button and do not move the transducer.
The monitor will beep twice to indicate that zeroing is complete.

After a transducer is zeroed, moving its height in relation to the patient will produce artifacts in
pressure. A transducer that is too high will produce a pressure that is artifactually low. Conversely, a
transducer that is too low with produce an erroneously high pressure. The transducer should be placed
at the height of the organ whose perfusion is most relevant to the case; this may be the heart, or it may
be the brain, depending on positioning and the surgery.

There are many different ways to place an arterial line. Techniques to place a radial A-line will be
discussed here. The most important principle to remember is that adequate preparation is essential for
success with any procedure. You will encounter situations where an A-line is needed emergently and
preparation is minimal, but these situations are few and far between.

To begin, ensure that the patients wrist is extended and secured. This can be facilitated with an
armboard or a rolled towel. In an awake patient, infiltrate the area liberally with local anesthetic to
make the procedure more tolerable and reduce the possibility of vasospasm. The lidocaine we are
usually supplied with is 2% and tends to burn; experiment with dilution to 1% or alkalinization. The
method below describes placement with a 20g angiocatheter, the most commonly used catheters in the
OR. Arrow catheters with a built-in wire are also available. The basic technique for cannulating the
artery is similar with these two devices, but most people in our department prefer the 20g pink BD
brand angiocatheters due to longer length and ergonomics.

To directly cannulate the artery, palpate the artery with your fingertips and advance the needle at
approximately a 30-45 angle directly in line with the palpated path of the artery. Avoid the distal wrist if
possiblethe artery tends to be torturous and it may be difficult to thread the catheter. After getting a
flash of blood, drop the angle of the needle and advance 1-2mm more to get both the tip of the catheter
and the needle within the vessel lumen. This is very important; most blown IVs and arterial lines occur
after a flash of blood is obtained, but attempts are made to thread the catheter before it is within the
vessel. Blood flow should still be evident at this stage. Gently attempt to thread the catheter off,
possibly with a twirling motion; it should go easily and blood should come up inside the catheter. If it
does not advance easily, stop. Either do a new stick or attempt to salvage it with the wire-guided
technique below.

An alternative method is to use a guidewire to thread the catheter, known as the transfixation or
through-and-through technique. If direct cannulation has failed, you can advance the whole needle
another 3-5mm, also going through the back wall of the artery. This can also be the technique intended
from the beginning of the procedure, by getting a flash of blood and then initially advancing the needle
through the vessel without trying to thread the catheter. The needle is then removed with the catheter
in place. Slowly backing up the catheter should now result in arterial blood flow when the tip of the
catheter resides in the vessel lumen (the tip has backed up into the vessel). At this point a sterile
guidewire can be placed through the catheter, and the catheter can then slide over the wire into the
artery. This guidewire should pass easily. If it does not, dont force it the wire will not end up in the
vessel.

Arterial lines can be very challenging, especially in certain patients (obese, edematous, vasculopathic).

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Often multiple practitioners can spend a lot of time trying to obtain an A-line with no success.
Remember this rule: dont force it. If the guidewire or catheter doesnt go in easily, the line wont work
or be in the right place. Its probably better to simply restick and try again. And again, it is best to have
all position and equipment optimized for your first attempt; your first shot is your best shot.

VII. Central Venous Catheters

Central lines are indicated for monitoring central venous pressure, to infuse certain medications (TPN,
hypertonic saline, potassium), to provide large-bore venous access, to provide access for placement of
other monitors or tools (e.g., pulmonary artery catheter or transvenous pacing leads), to aspirate
venous air emboli, or when peripheral access is not possible.

VIII. Pulmonary Artery Catheters

Our first major exposure to these catheters often comes during our cardiac anesthesia rotation. The
indications for placing a pulmonary artery catheter include precise measurements of cardiac output,
right heart pressures, or mixed-venous oxygen saturation.

IX. Peripheral Nerve Stimulators

These are more fully discussed in the section on neuromuscular blockers. They are found in the drawers
in our anesthesia machines.

X. EEG

For specific cases we periodically employ either true (16 lead) EEGs or processed EEG devices such as
the BIS monitor or SEDline. Use of any of these devices is not routine here at UCSD. You will most often
encounter the EEG during carotid endarterectomy, where it is employed to monitor electrical activity
and detect possible ischemic events in the brain. The BIS and SEDline are sometimes used to measure
depth of anesthesia, although the data they provide is of controversial value. One common place where
the BIS or SEDline is used is in the heart room, when sometimes low levels of anesthetic and increased
possibility of patient awareness are a recognized phenomenon. The anesthesia monitoring technicians
are invaluable in helping us set up and use these monitors.

XI. Urine Output

A Foley catheter is often placed by the circulating nurse or surgical personnel for cases where it is
needed for surgical exposure (e.g. C-section) or cases longer than about 2hrs. Monitoring urine output is
also useful any time major fluid shifts are expected, end-organ perfusion measurement is desired,
keeping in mind the many factors that affect intraoperative urine output. Some Foleys also have
temperature sensors included.

XII. Transesophageal Echocardiography (TEE)

TEE is used routinely for every cardiac surgery and most liver transplants at UCSD, and occasionally for
less major surgeries when major hemodynamic disturbances are expected or occurring. An example
would be an open AAA repair or a patient who develops myocardial ischemia and/or shock
intraoperatively. All of our cardiac anesthesia attendings are experts at TEE and many of our non-cardiac
attendings are skilled with it also. TEE is a powerful and useful monitor that you will gain experience

46
with during your cardiac anesthesia months.

XIII. Cardiac Output Monitors

Several non-invasive or minimally-invasive cardiac output monitors exist, including those based on
esophageal Doppler, thoracic impedance, transpulmonary thermodilution, and arterial pulse contour
analysis; TEE can also be used, but is considered invasive. At UCSD, we most commonly use the
Edwards Vigileo-Flotrac system. This device analyzes the shape of the A-line waveform and uses patient
data to calculate stroke volume; this is then used to calculate cardiac output. This monitor needs an A-
line, a special proprietary transducer, and another display monitor. Since it is somewhat expensive, it is
typically reserved for cases with expected large fluid shifts, where monitors in addition to a standard A-
line and/or CVP may be needed.

Chapter 2C. Medications Used in Anesthesia

The following is a list of the drugs we commonly use in anesthesia. It is by no means all-inclusive or
meant to replace definitive texts or manufacturers guidelines. I offer the list as a quick reference for
99% of the drugs we encounter and administer on a daily basis.

I. Vasopressors
A. Ephedrine
Uses: hypotension, especially with slower HRs.
Mechanism of action: indirect adrenergic agonist, causes release of endogenous
catecholamines. Mild increases in BP, HR, and contractility. Affects both and receptors.
Duration of action: minutes if given IV, up to 1hr IM.
Usual dose: 5mg bolus IV, 25-50mg IM. Can also be given SC or PO (not common).
Notes: considered first line agent for hypotension in pregnancy as it theoretically spares uterine
blood flow. Tachyphylaxis develops with repeated administration. Avoid with MAO inhibitors
(risk of malignant hypertension due to too much endogenous catecholamines). Potentially
ineffective in catecholamine-depleted states (i.e. chronic methamphetamine or cocaine use).
B. Phenylephrine
Uses: hypotension, especially from low SVR state with a higher HR.
Mechanism of action: direct 1 agonist, causing marked vasoconstriction, rise in BP and SVR.
May cause reflex bradycardia.
Duration of action: minutes.
Usual dose: 50-100mcg IV bolus, or run as an infusion 10-200mcg/min.
Notes: must be diluted from its packaged concentration which is 10mg/ml. Most of mix 10mg in
a 100ml bag of saline to make 100mcg/ml concentration. Safe in pregnancy.
C. Epinephrine
Uses: cardiac arrest, anaphylaxis, bronchospasm, cardiogenic shock, refractory hypotension,
reduced CO.
Mechanism of action: direct agonist at 1, 1, and 2 receptors, depending on dose. Increased
HR, SVR, BP, contractility and bronchodilation.
Duration of action: minutes.
Usual dose: 10mcg/kg SC, 0.03-0.2mcg/kg IV bolus, 0.01-1 or more mcg/kg/min infusion, 0.5-
1mg IV bolus for cardiac arrest.
Notes: can cause tissue necrosis if extravasates from IV; cardiac arrest doses can cause profound

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 hypertension; if given via ETT, give 2-3x IV dose, diluted to > 5ml.
D. Vasopressin
Uses: alternative to epinephrine in cardiac arrest, catecholamine-resistant hypotension.
Mechanism of action: activates V1 receptors, causing direct peripheral vasoconstriction and
raising SVR independent of adrenergic receptors.
Duration of action: minutes.
Usual dose: 40units IV bolus for cardiac arrest, 1-2units IV boluses for hypotension, can also be
given as infusion, typically 1-4units/hr. Can also be given via endotracheal tube.
Notes: very potent. Can cause splanchnic hypoperfusion, lactic acidosis, or myocardial ischemia
(especially with infusions). Causes unpleasant symptoms in awake patients.
E. Dopamine
Uses: hypotension, primarily due to low CO state.
Mechanism of action: has mixed effects depending on dose. At low dose (1- 3mcg/kg/min), has
primarily DA receptor effects, at 3-10mcg/kg/min 1 effects predominate, and > 10mcg/kg/min
primarily 1 effects are seen.
Duration of action: minutes.
Usual dose: IV infusion, 1-20mcg/kg/min.
Notes: preferred 1st line agent for coming off cardiopulmonary bypass by our CT surgeons; low
renal doses may improve renal perfusion and will cause diuresis. Must be diluted. Drip is
usually 400mg in 250ml.

II. Antihypertensives
A. Nitroprusside
Mechanism of action: converted to nitric oxide, a potent vasodilator. Nitric oxide activates
guanylyl cyclase, increases cGMP, decreases intracellular calcium, and thus produces smooth
muscle relaxation.
Properties: causes arterial > venous dilation, reducing BP by reduction in afterload > preload.
Duration of action: quick onset and offset, allowing precise titration.
Usual dose: 0.5-10mcg/kg/min infusion, or small (10-20mcg) boluses.
Notes: Can cause coronary steal (dilation of normal coronaries, stealing flow away from
stenotic, maximally-dilated areas). Reduces PVR. Increases cerebral blood flow which can be
attenuated by hyperventilation.
Metabolism: this is a commonly tested question on the boards. Nitroprusside is essentially an
iron atom bound to nitroso and cyanide moieties. It oxidizes hemoglobin in RBCs, producing
methemoglobin and cyanide ions. Cyanide ions do one of three things:
1. Bind to methemoglobin, forming cyanomethemoglobin
2. Combine with thiosulfate to form thiocyanate
3. Bind to cytochrome oxidase, interfering with oxygen utilization
Signs of cyanide toxicity include metabolic acidosis, increased mixed venous O2 (less O2 is used),
arrhythmias and tachyphylaxis. Cyanide toxicity is unusual in durations less than 2 days and
cumulative doses less than 0.5mg/kg/hr. Supportive treatment of toxicity includes stopping the
drug, oxygen, thiosulfate and sodium nitrate. Thiosulfate will divert cyanide ions and produce
thiocyanate (above). Sodium nitrite converts hemoglobin to methemoglobin, which can then
react with cyanide ion.
Excess thiocyanate can also produce toxicity, characterized by weakness, hypoxia, thyroid
dysfunction and agitation. This risk is increased in renal failure because thiocyanate is cleared by
the kidney. Lastly, methemoglobinemia can be treated with methylene blue, which reduces

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 methemoglobin back to hemoglobin.
B. Nitroglycerin
Mechanism of action: donates NO, like nitroprusside.
Properties: primarily venodilation, reducing preload and BP.
Duration of action: quick onset and offset, allowing precise titration.
Usual dose: 0.5-10mcg/kg/min, or as small boluses 10-40mcg IV. Can also be given sublingually
or transdermally.
Notes: Relieves coronary vasospasm and does not possess the steal properties nitroprusside
does. Reduces preload and myocardial oxygen demand while increasing supply. Pulmonary and
cerebral vasodilation, can cause headaches. Also used for uterine relaxation in OB procedures.
Metabolism: metabolized to nitrites, which can cause methemoglobinemia (see above).
C. Hydralazine
Uses: hypertension, especially on OB for pregnancy-induced hypertension.
Mechanism of action: causes direct arteriolar vasodilation.
Usual dose: 5-20mg IV. Onset is within 5-20min and duration is 2-6hrs, making it difficult to
titrate.

III. Neuromuscular Blockers and Reversal Agents

A. Vecuronium
Mechanism of action: competitive antagonism at ACh receptors in the neuromuscular junction
Duration of action: 45-90min for intubating dose
Usual dose: 0.1mg/kg IV for intubation, 0.01mg/kg IV boluses for maintenance
Notes: hemodynamically unremarkable, cheap. Primarily excreted in bile, 25% by kidneys. May
have prolonged block in patients with renal failure. When given as a long-term infusion, can see
prolonged blockade lasting for days, possibly due to a polyneuropathy. Forms a precipitate with
thiopental (avoid giving concomitantly in same line).
B. Rocuronium
Mechanism of action: competitive antagonism at ACh receptors in the neuromuscular junction.
Duration of action: 20-60min for lower doses, up to 2hrs for 4x ED95 rapid sequence dose.
Usual dose: 0.6mg/kg for intubation, 1.2mg/kg for RSI.
Notes: quick (1min) onset when given in rapid sequence doses. Rapid (20min) offset when given
at lower doses. Used as an alternative to succinylcholine for RSI. Anecdotally, is more resistant
to reversal, especially after large doses or redosing.
C. Cisatracurium
Mechanism of action: competitive antagonism at ACh receptors in the neuromuscular junction.
Duration of action: 30-60min for intubating dose.
Usual dose: 0.2mg/kg for intubation, 0.02mg/kg for maintenance.
Notes: eliminated via Hoffman degradation, an organ-independent process, thus is useful in
liver/renal failure patients. Unlike atracurium, there is no significant histamine release.
Laudanosine is a potentially toxic metabolite (causes CNS excitation, less laudanosine than seen
with atracurium, probably clinically insignificant).
D. Pancuronium
Mechanism of action: competitive antagonism at ACh receptors in the neuromuscular junction.
Duration of action: 60-120min for intubating dose.
Usual dose: 0.1mg/kg IV for intubation, 0.01mg/kg IV boluses for maintenance.
Notes: can cause tachycardia due to vagolytic effects and sympathetic stimulation. Long acting.
Excreted primarily by kidney leading to prolonged action in renal failure. May inhibit

49
 pseudocholinesterase, resulting in a prolonged block from succinylcholine or mivacurium.
E. Succinylcholine
Mechanism of action: ACh receptor agonist. Causes depolarization of the muscle-end plate, then
prevents end-plate repolarization, blocking further depolarization.
Duration of action: 5-10min. Onset is within 30 seconds.
Usual dose: 1-1.5mg/kg IV. Boluses of 0.1mg/kg IV for maintenance, or 2-15mg/min infusion.
Can be given IM (4-5mg/kg).
Notes: the only depolarizing muscle relaxant in use today. Metabolized by
psuedocholinesterase. Most rapid onset and offset of all muscle relaxants. Repeated doses may
cause prolonged phase II block or arrhythmias (often bradycardia, more pronounced in
children). May cause hyperkalemia, raise intragastric and intraocular pressure, masseter muscle
rigidity, can trigger malignant hyperthermia. Can be used in renal failure provided no baseline
hyperkalemia. Causes fasciculations which may lead to myalgias (can pretreat with a small
amount of nondepolarizing muscle relaxant).

F. Neostigmine
Use: to reverse non-depolarizing neuromuscular blockade and treatment of myasthenia gravis.
Mechanism of action: an acetylcholinesterase inhibitor, neostigmine increases the
concentration of ACh available in the neuromuscular junction.
Duration of action: more than 1hr. Peak effect is within 5-10min.
Usual dose: 0.05-0.07mg/kg, to a max of 5mg. Ggiving more could result in paradoxical
weakness.
Notes: lipid-insoluble so cannot cross the blood-brain barrier. Administer with an antimuscarinic

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 to block cholinergic side effects (usually glycopyrrolate, since onset is similar). Paradoxical
potentiation of neuromuscular blockade occurs when excessive doses are used. Side effects
include those of muscarinic stimulation: bradycardia, bronchospasm, secretions, CNS excitation,
bowel spasm/defecation, urination, miosis. Can result in a prolonged block with succinylcholine
due to decreased activity of psuedocholinesterase.
G. Edrophonium
Use: reversal of neuromuscular blockade, diagnosis of myasthenia gravis (Tensilon test).
Mechanism of action: same as neostigmine (see above).
Duration of action: Quick onset, within 1-2min but lasts shorter than neostigmine, about 15min.
Up to 1 hr with higher doses.
Usual dose: 0.5-1mg/kg.
Notes: does not cross blood-brain barrier. Similar side effect profile as neostigmine. Muscarinic
effects are less pronounced, requiring half the amount of anticholinergic as an equipotent dose
of neostigmine. Atropine should probably be used as the anticholinergic, since its quick onset
will parallel that of edrophonium.
H. Physostigmine
Use: penetrates the blood-brain barrier, making it useful to counter anticholinergic toxicity (e.g.,
scopolamine). Not used to reverse neuromuscular blockade, and thus not usually given with an
anticholinergic.
Mechanism of action: similar to neostigmine.
Usual dose: 0.01-0.03mg/kg.
Notes: the only available cholinesterase inhibitor that crosses the blood-brain barrier.
I. Atropine
Use: treatment of bradyarrhythmias, slow PEA, block muscarinic side effects of
acetylcholinesterase inhibitors.
Mechanism of action: antimuscarinic, blocks the ACh receptor.
Duration of action: rapid onset, lasts up to 30min.
Usual dose: 0.01-0.02mg/kg. Can also be given IM or via ETT.
Notes: most potent and quickest-acting anticholinergic for serious bradycardia. Crosses the
blood-brain barrier but CNS effects are usually minimal. Also causes bronchodilation. Avoid in
narrow-angle glaucoma, bladder neck obstructions or prostatic hypertrophy.
J. Glycopyrrolate
Use: decrease airway secretions, block cholinergic side effects of acetylcholinesterase inhibitors,
treatment of mild bradycardia.
Mechanism of action: same as atropine.
Duration of action: up to 2hrs, slower onset that atropine.
Usual dose: 0.005-0.01mg/kg.
Notes: does not cross the BBB, thus OK to use in narrow angle glaucoma.
K. Scopolamine
Use: premedication because of the sedative effect, decreases airway secretions, good for
motion sickness or PONV prophylaxis.
Mechanism of action: same as atropine.
Usual dose: same as atropine. Usually given IM. Available as transdermal patch.
Notes: used to be widely used as a premedication. More sedating than atropine or
glycopyrrolate. Pronounced ocular effects; avoid in narrow angle glaucoma. Occasionally used
for trauma patients when volatile or IV anesthetic is contraindicated due to hypovolemia.
L. Sugammadex

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 Use: reversal of neuromuscular blockade from rocuronium.
Mechanism of action: a cyclodextrin, it encapsulates and binds rocuronium molecule, rendering
it unavailable to bind to acetylcholine receptors in the neuromuscular junction.
Duration of action: onset within 5-15min.
Usual dose: 2mg/kg.
Notes: Only available in Europe. Lower affinity for vecuronium. Does not need to be
administered with antimuscarinic agents. When insufficient doses are administered, risk of
agent wearing off because neuromuscular blocker is incompletely cleared.

IV. Inhalational Anesthetics

General Considerations
Blood:gas partition coefficient reflects the blood solubility of an agent. The more insoluble an
agent is, the less it is taken up by the bloodstream, the faster it raises the partial pressure, and
the faster the induction time. Conversely, the higher the blood:gas partition coefficient, the
more soluble the agent is.
The Fa/Fi ratio is an expression of how much an agent is taken up by the bloodstream. As gas fills
the alveolar space it is taken away by pulmonary blood flow. Thus, the Fa is less than the Fi.
More soluble agents are taken up more avidly, so the F a/Fi ratio is less than for a relatively
insoluble agent. Conversely, the Fa/Fi ratio is greater for more insoluble agents. The Fa
determines the partial pressure of anesthetic in the alveoli, and ultimately the brain. Thus, more
insoluble anesthetics will have higher Fa/Fi ratio and faster induction times.
Low cardiac output states speed induction because less anesthetic will be taken up by the
bloodstream and the Fa/Fi ratio rises rapidly. This effect is less pronounced for insoluble
anesthetics since minimal amounts are taken up anyway.

A right-to-left intracardiac shunt will slow induction, because a portion of blood flow will bypass
the lungs, not become saturated with anesthetic, and lower the arterial partial pressure.
Similarly, a mainstem intubation will also slow induction, since half of pulmonary blood flow will
go to a non-ventilated lung.MAC, or minimum alveolar concentration, is an expression of an
agents potency. 1 MAC has been defined as the concentration to which 50% of patients will not
move to surgical incision. At 1.3 MAC, 95% of patients will not move to that same stimulus.

52
 Lastly, 0.3 MAC is considered MACawake (awakening from anesthesia). It is important to
remember that MAC is additive, and that other agents may decrease MAC requirements (e.g.,
opioids, propofol). MAC decreases by 6% for each decade of life.
The agents available at Hillcrest and Thornton are sevoflurane, isoflurane and nitrous oxide. The
VA has all of the above plus desflurane. There is also a desflurane vaporizer in OR7 at Hillcrest.
Halothane is not used at any of the three locations, although you may encounter halothane
ontrips to under-served areas, e.g., Mexico.
A. Desflurane
General: very fast onset and offset, nearly as fast as nitrous oxide. Requires a special vaporizer
because of its high vapor pressure; see the anesthesia equipment section. MAC is 6%; not
potent, and relatively expensive.
Cardiovascular: minimal cardiac depression, but does cause decrease in SVR and MAP. May
cause a significant increase in HR if its concentration is rapidly raised above 6%, not mediated by
airway irritation.
Pulmonary: decreases hypoxic respiratory drive and increases apneic threshold. Very pungent,
so not ideal for inhalation induction. Induction and awakening can be associated with coughing,
bronchospasm, or laryngospasm.
Neurologic: increases CBF but decreases CMRO2. Uncouples cerebral autoregulation,
rendering CBF proportional to MAP.
Other: degraded by dry CO2 absorbent (especially barium hydroxide) to carbon monoxide,
classically in the Monday morning scenario described above. Trigger for malignant
hyperthermia.
B. Sevoflurane
General: fairly rapid onset and offset (second to desflurane). MAC is 2%.
Cardiovascular: minimal cardiac depression, but does cause decrease in SVR and MAP. Dilates
coronary arteries.
Pulmonary: decreases hypoxic respiratory drive and increases apneic threshold. Is a very potent
bronchodilator. Nonpungent, suitable for inhalational inductions.
Neurologic: increases CBF but decreases CMRO2. Uncouples cerebral autoregulation,
rendering CBF proportional to MAP.
Renal/hepatic: decreases blood flow to both systems.
Other: can be degraded by dry barium hydroxide or soda lime to compound A, a potentially
nephrotoxic compound. This risk is increased with low flows (<1L/min), or high concentrations
of sevoflurane; the recommendation is to run 2L/min or higher if more than 2 MAC-hours are
used. Trigger for malignant hyperthermia.
C. Isoflurane
General: slow onset and offset (compared to desflurane and sevoflurane). MAC is 1.1%.
Inexpensive.
Cardiovascular: minimal cardiac depression, but does cause decrease in SVR and MAP.
Associated with tachycardia, which tends to maintain cardiac output in the face of decreased
SVR. Dilates coronary arteries.
Pulmonary: decreases hypoxic respiratory drive and increases apneic threshold. Pungent, so not
suitable for inhalational induction.
Neurologic: increases CBF but decreases CMRO2. Uncouples cerebral autoregulation,
rendering CBF proportional to MAP.
Renal/hepatic: decreases blood flow to both systems.
Other: partially metabolized to triflouroacetic acid by the liver (metabolism inhibited by

53
 disulfiram), which is potentially nephrotoxic but probably not clinically relevant. Trigger for
malignant hyperthermia.
D. Halothane
General: inexpensive. MAC is 0.7%.
Cardiovascular: causes direct myocardial depression. Dilates coronary arteries. Blunts
baroreceptor response to hypotension. Can sensitize the myocardium to catecholamines and
predispose to arrhythmias.
Pulmonary: decreases hypoxic respiratory drive and increases apneic threshold. Suitable for
inhalational inductions.
Neurologic: increases CBF but decreases CMRO2. Uncouples cerebral autoregulation,
rendering CBF proportional to MAP.
Renal/hepatic: decreases blood flow to both systems.
Other: partially metabolized to triflouroacetic acid by the liver (metabolism inhibited by
disulfiram), which is potentially nephrotoxic but probably not clinically relevant. Halothane
hepatitis is extremely rare (1:30000 cases) and is associated with multiple halothane exposures,
obese women, and family history. The lesion is centrilobular necrosis and is also associated with
hypoxia. Halothane does not seem to worsen preexisting liver dysfunction. Trigger for malignant
hyperthermia.
E. Nitrous Oxide
General: colorless and odorless. Supports combustion. MAC is 105% (greater than 1 atmosphere
needed to produce 1 MAC).
Cardiovascular: weakly stimulates the sympathetic nervous system. Increases pulmonary
vascular resistance.
Pulmonary: decreases hypoxic drive.
Neurologic: mildly increases cerebral blood flow and CMRO2.
Renal/hepatic: decreases blood flow to both systems
Other: inhibits methionine synthase, a B12-dependent enzyme, which is necessary for DNA
synthesis. Prolonged or repeated exposure can result in B12 deficiency with megaloblastic
anemia and peripheral neuropathy. Possible teratogen; avoid in pregnancy. Will rapidly fill air-
filled cavities, potentially creating hazardous increases in pressure or volume- examples include
pneumothorax, air embolism, bowel gas, or intraocular air bubbles. Can cause PONV.

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V. Hypnotics
A. Barbiturates
Mechanism of action: potentiates GABA at the GABAA receptor.
Route of administration: typically IV. Thiopental and methohexital can be given PR, and
pentobarbital and secobarbital can be given IM.
Pharmacokinetics: rapid onset when given IV. Rapid offset due to redistribution. Elimination
half-life is actually on the order of hours; repeated doses can saturate peripheral compartments,
making recovery dependent on metabolism (and thus much slower).
Cardiovascular: decreases BP and CO, mostly due to peripheral vasodilation, pooling of blood
and decreased preload, reflex tachycardia with thiopental.
Pulmonary: causes respiratory depression and apnea. May not fully depress airway reflexes,
resulting in bronchospasm or laryngospasm in light patients.
Neurologic: profound decreases in CMRO2 and CBF. Considered good agents in the setting of
increased ICP. Can be used to induce electrical silence on EEG which may offer cerebral
protection from ischemia. Also used as antiepileptic.
Other: induces cytochrome P450 enzymes which may speed metabolism of some drugs. Can
stimulate the formation of porphyrin; avoid in patients with acute intermittent porphyria.
B. Benzodiazepines
Midazolam will be discussed since it is the benzodiazepine most commonly used by
anesthesiologists.
Mechanism of action: enhances activity of GABA receptor.
Route of administration: PO, IM or IV. Only IV is suitable for inducing general anesthesia.
Pharmacokinetics: rapid onset when given IV. Elimination half-life is 2hrs. Large doses can have
prolonged effects resulting in slower wakeups.
Cardiovascular: minimal effects when given alone. Often combined with an opioid to induce
general anesthesia in tenuous (e.g., cardiac) patients.
Pulmonary: can cause respiratory depression. Usually not significant when given alone, however
when combined with another agent such as an opioid the effect is synergistic.
Neurologic: decreases CMRO2 and CBF. Causes anterograde amnesia.
Other: useful premedication due to anterograde amnesia and useful in children who cannot
tolerate an IV.
C. Etomidate
Mechanism of action: enhances activity of GABAA receptor.
Route of administration: IV.
Pharmacokinetics: rapid onset. Rapid offset as well, due to redistribution.
Cardiovascular: maintains cardiac output, contractility and SVR, almost unique amongst
induction agents. Does not blunt response to intubation.
Pulmonary: typically does not cause apnea when given alone. If given in conjunction with other
agents, can cause profound respiratory depression.
Neurologic: decreases CBF and CMRO2. Can activate epileptic foci.
Other: can cause adrenal suppression with even a single dose, but this is more of a concern
when given as an infusion or to those who are critically ill. Significant incidence of myoclonus,
which can be disturbing. May cause nausea/vomiting. Burns on injection.
D. Propofol
Mechanism of action: enhances activity of GABAA receptor.
Route of administration: IV.
Pharmacokinetics: rapid onset. Rapid offset as well, due to redistribution.

55
 Cardiovascular: decreases MAP by decreasing SVR, causing venodilation, and reducing cardiac
contractility.
Pulmonary: causes respiratory depression all the way to complete apnea depending on dose.
Neurologic: decreases CBF and CMRO2. Considered one of the best agents to reduce ICP or brain
size, or as the anesthetic for craniotomies. Antiepileptic.
Other: Antiemetic. Long term infusions can cause propofol infusion syndrome: cardiac failure,
renal failure, rhabdomyolysis, lactic acidosis. Lipid emulsion is also a good growth medium for
bacteria, use strict aseptic technique and within 6hrs of opening. Burns on injection. Contains
soy and lecithin; found in egg yolks, not egg white. Most people with egg allergies are probably
allergic to the albumin found in egg whites, not lecithin.
E. Ketamine
Mechanism of action: antagonizes NMDA (glutamate) receptors.
Route of administration: IV or IM.
Pharmacokinetics: rapid onset. Rapid offset as well, due to redistribution.
Cardiovascular: is a sympathomimetic and thus typically maintains SVR, CO and BP. Also
increases HR. However, is actually a negative inotrope in vivo, and thus in patients who are
already maximally sympathetically driven or have depleted catecholamine stores (e.g., end-
stage shock), there may be profound myocardial depression.
Pulmonary: does not affect respiratory drive when given alone and works well as a
bronchodilator. Increases secretions.
Neurologic: increases CMRO2 and CBF. The dogma is to avoid ketamine any time increased ICP is
an issue. May cause delirium or illusions, less if pretreated with a benzodiazepine. Can cause
myoclonus and nystagmus.
Other: is a dissociative anesthetic, in that patients may appear awake but do not respond to
sensory input. Also has weak opioid activity, and can be a profound analgesic, or used as an
infusion to augment analgesia or reduce post-op opioid requirement. Small doses can be useful
for sedation/analgesia in various settings.

VI. Opioids

Opioids are excellent analgesics and mild sedatives. They do not reliably produce amnesia. Although
there are many different opioids, only the most commonly used ones will be discussed here: morphine,
fentanyl, alfentanil, sufentanil, remifentanil, hydromorphone, and meperidine. Opioids have a very wide
therapeutic index and dosing can vary tremendously based on tolerance, general state of the patient,
and other medications that may be coadministered. Thus, it is difficult to provide standard doses.

Morphine is the prototypical drug against which the other IV opioids are measured. The relative
potencies of the various drugs in relation to morphine are:

Hydromorphone: 5-7x more potent than morphine

Meperidine: 1/10 as potent as morphine
Fentanyl: 100x as potent as morphine
Alfentanil: 1/5 as potent as fentanyl (20x morphine)
Sufentanil: 10x as potent as fentanyl (1000x morphine)
Remifentanil: 2x as potent as fentanyl (200x morphine)

Comparison of doses between the opioids generally reflect these relative potencies. For example, you

56
might consider giving 5mg morphine, 50mcg fentanyl, or 0.8mg hydromorphone to the same patient for
postoperative pain.

A. Morphine
Dose: 0.05-2mg/kg IM, 0.03-0.5mg/kg IV.
Route of administration: IV, PO, intrathecal, epidural.
Pharmacokinetics: longer onset and duration of action due to low lipid solubility. Onset typically
within 5-15min, peak plasma levels within 60min, duration of action around 4hrs.
Cardiovascular: by blocking sympathetic output, may cause decrease in BP and HR. Reduces SVR
secondary to histamine release; can be profound. Minimal changes when given slowly or in
small doses.
Pulmonary: causes respiratory depression, depression of hypoxic drive and increases apneic
threshold.
Neurologic: may decrease CMRO2 and CBF to small extent, although associated respiratory
acidosis may outweigh this. Can cause nausea, vomiting and pruritus. At equianalgesic doses,
tends to be more sedating than other opioids.
Other: slows GI motility and gastric emptying. Is the equivalent against which other opioids
are measured (morphine equivalents). Primary products of metabolism are morphine 3- and
6-glucuronide which are active metabolites; these metabolites and morphine itself can
accumulate in renal failure patients, causing prolonged respiratory depression.
B. Fentanyl
Dose: varies depending on tolerance and state of patient; a typical IV dose to block sympathetic
response to intubation is 2-5mcg/kg. Doses can be up to 50mcg/kg for cardiac anesthesia.
Route of administration: IV, intrathecal, epidural, intranasal via a spray, transdermal via a patch,
or transmucosal via a lollipop.

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 Pharmacokinetics: highly lipophilic, crosses the blood-brain barrier easily. Rapid onset within 1-
3min, peak plasma levels 3-5min, short duration of action due to redistribution (30min-1hr),
longer duration with larger doses.
Cardiovascular: less histamine release than morphine.
Pulmonary: similar to morphine, can also cause chestwall rigidity when given in large doses,
which may compromise ventilation.
Neurologic: similar to morphine.
Other: slows GI motility and gastric emptying. Repeated doses or infusions can cause saturation
of peripheral redistribution sites, increasing the time to offset (context-sensitive half-time).
Chestwall rigidity can be managed with neuromuscular blockers.
C. Alfentanil
Dose: 10-50mcg/kg, varies depending on length of procedure.
Route of administration: IV.
Pharmacokinetics: Although less lipid soluble than fentanyl, onset/offset is more rapid due to
low pKa. Thus, most of alfentanil exists in non-ionized, lipophilic form. Onset within 1-2min,
duration of action varies depending on dose given but typically 10-30min.
Cardiovascular: less histamine release than morphine.
Pulmonary: similar to morphine, can also cause chestwall rigidity with large doses.
Neurologic: similar to morphine.
Other: slows GI motility and gastric emptying. Repeated doses or infusions can cause saturation
of peripheral redistribution sites, increasing the time to offset (context-sensitive half-time),
although the effect is less pronounced than with fentanyl. Chestwall rigidity can be managed
with neuromuscular blockers. Excellent for situations requiring intense, short-lived analgesia
(e.g. rigid bronchoscopy).
D. Sufentanil
Dose: given in doses typically 1/10 that of fentanyl; intubation dose 0.2-0.5mcg/kg.
Route of administration: IV, intrathecal, epidural (in some countries, only indicated for epidural
use); a transdermal sufentanil patch is in clinical trials.
Pharmacokinetics: when given IV, onset within 1-3min, duration of action around 3hrs.
Cardiovascular: less histamine release than morphine.
Pulmonary: similar to morphine, can also cause chestwall rigidity with large doses.
Neurologic: similar to morphine.
Other: slows GI motility and gastric emptying. Repeated doses or infusions can cause saturation
of peripheral redistribution sites, increasing the time to offset (context-sensitive half-time), but
less than either fentanyl or alfentanil over an 8-hour infusion. Chestwall rigidity can be managed
with neuromuscular blockers.
E. Remifentanil
Dose: induction dose 1-3mcg/kg followed by 0.1-0.5mcg/kg/min infusion for GA, 0.02-
0.2mcg/kg/min for MAC.
Route of administration: reconstituted from powder form and given IV.
Pharmacokinetics: onset within 1min and duration of action of 5-10min. Metabolized by red
blood cell and nonspecific esterases. This unique mode of metabolism makes the
pharmacokinetics very predictable and titratable. Furthermore, the context-sensitive half-time
(3-7min) for remifentanil does not change for long infusions.
Cardiovascular: less histamine release than morphine; very high incidence of bradycardia due to
vagal potentiation.
Pulmonary: similar to morphine, can also cause chestwall rigidity with large doses.

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 Neurologic: similar to morphine.
Other: excellent for cases that are very stimulating and have intense analgesic requirements, yet
also need precise titration of opioids. Does not have a tail, so all analgesic effects will be gone
within 10-20 minutes of stopping the drug. Thus, another longer-acting opioid must be used to
avoid postoperative pain. Can cause opioid-induced hyperalgesia, possibly due to its intense
agonism of opioid receptors.

Context-sensitive half-time: the time required for 50% reduction in the plasma concentration of a drug on termination of a
constant infusion. This time is determined by both elimination and redistribution, and it varies considerably as a function of
infusion duration.

F. Hydromorphone
Dose: 7x more potent than morphine; typical doses 0.2-2mg.
Route of administration: IV, PO, SC/IM, PR.
Pharmacokinetics: when given IV, onset in 5-10min, peak effect in 15-30min, duration of
action around 4hrs.
Cardiovascular: less histamine release than morphine.
Pulmonary: causes respiratory depression, depression of hypoxic drive and increases apneic
threshold.
Neurologic: similar to morphine.
Other: has largely supplanted morphine due to less histamine-related side effects and faster
onset.
G. Meperidine
Dose: 0.2-0.5mg/kg IV for post-op analgesia or shivering.
Route of administration: IV, IM.
Cardiovascular: often causes tachycardia due to structural similarity to atropine. Can also
depress cardiac contractility.
Pulmonary: causes respiratory depression, depression of hypoxic drive and increases apneic
threshold.
Neurologic: The active metabolite, normeperidine, can cause CNS stimulation, myoclonus
and seizures. This risk is increased in renal failure patients.
Other: uniquely effective among opioids at decreasing shivering via receptors. Also has
weak local anesthetic properties. Contraindicated in patients taking MAO inhibitors because

59
 combination can lead to serotonin toxicity, hyperthermia, and death.

VII. Local Anesthetics

Local anesthetics function by blocking sodium channels, preventing depolarization and action potentials.
The non-ionized form must cross the lipophilic cell membrane and the ionized form must bind the
channels on the inside of cellular membranes to achieve their action.

Local anesthetics are weak bases, have a pKa above 7.4, and tend to be positively charged at physiologic
pH. They are classified as either esters or amides based on the intermediate chain. You can differentiate
between an ester or amide by knowing this simple rule: amide anesthetics all have an I in the
beginning of their name (excluding the I in caine). Therefore, lidocaine is an amide, while
chloroprocaine is an ester.

True allergies to local anesthetics are rare. Esters tend to be more allergenic because they are
derivatives of PABA, which can be an allergen. Some amides are packaged with methylparaben, which is
structurally similar to PABA and may also be allergenic. Amides are metabolized by the liver. Esters are
metabolized by pseudocholinesterase, and therefore tend to have a shorter duration of action
compared to the amide local anesthetics. Their activity is prolonged in patients with abnormal
pseudocholinesterase; see the neuromuscular blocker section.

The pharmacokinetics of local anesthetics depend on the pKa (the pH at which 50% of the drug
molecules are ionized), the lipid solubility, the degree of protein binding, and the concentration of drug.
A lower pKa means that more drug exists in non-ionized form at physiologic pH and more molecules
cross the plasma membrane, making onset faster. More lipid-soluble agents like bupivacaine tend to be
more potent and more protein-bound, thus having a longer duration of action. Higher concentration of
drug typically creates a denser and faster block. A typical example of this is 3% chloroprocaine.
Chloroprocaine has a high pKa, which should confer a slower onset, but the amount administered results
in a higher concentration and therefore, a quick onset.

Nerves are affected differently according to size and myelination; this is known as differential
blockade. Smaller fibers and nonmyelinated fibers tend to be blocked earlier. The order of onset for
any group of nerves is autonomic, pain, temperature, touch, proprioception, and motor. Level of block
for a spinal or epidural tends to be 1-2 levels higher for the more sensitive nerves than the motor block.
So, a T6 motor block may correspond with a T4 sensory block, and a T2 autonomic block.

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Epinephrine is often used as an adjunct with local anesthetics. By causing local vasoconstriction,
epinephrine decreases systemic absorption of the local anesthetic, prolonging duration and potentially
decreasing toxicity. It should be noted that bupivacaine and ropivacaine are not affected, and their long
duration of action is a result of high protein binding. Epinephrine can also warn of possible intravascular
injection, signaled by tachycardia. It should be avoided in blocks of the distal extremity (e.g., digital
blocks, ankle blocks) to avoid excessive vasoconstriction in end-arterial areas.

Acidic environments (e.g., local infection) antagonize block and slow its onset. Premixed solutions of
local anesthetic containing epinephrine have a pH around 5, which is needed to maintain epinephrine
stability. Adding epinephrine manually to local anesthetics rather than using premixed solutions may
speed onset. Similarly, using small amounts of sodium bicarbonate to alkalinize the solution can greatly
speed onset of certain local anesthetics. Bicarbonate is not used with bupivacaine since it precipitates
above a pH of 6.8.

Toxicity to local anesthetics is a frequently tested topic. Typical reactions are CNS excitation
(restlessness, agitation, perioral tingling, dizziness) and depression (drowsiness, slurred speech,
unconsciousness) progressing to full-blown seizures. Cardiac complications are the most feared reaction,
and include heart block, arrhythmias including ventricular tachycardia, ventricular fibrillation, and
cardiac arrest. In general, the excitatory phenomena precede the depressive phenomena, which in turn
precede cardiovascular toxicity. The exception to this is bupivacaine, the most toxic local anesthetic,
which has a lower CNS-to-cardiovascular effect ratio, and can present with cardiac reactions as the first
sign of intravascular injection. Cardiotoxicity from bupivacaine is notoriously difficult to resuscitate
owing to its intense binding to cardiac tissue. Lipid emulsion infusion (Intralipid) or cardiopulmonary
bypass may be needed; lipids seem to absorb the bupivacaine. The treatment of all types of local
anesthetic systemic toxicity is supportive: reassure the patient, support airway and breathing, support
circulation, inhibit seizure activity, and provide ACLS as necessary. Esters seem to be less toxic than
amides due to their rapid breakdown in plasma.

The most commonly used local anesthetics, as well as those with specific, board-tested issues will be
discussed below.

1. Benzocaine (Hurricaine)
Uses: topical anesthesia, usually used as a mucosal spray (e.g., airway anesthesia).
Duration of action: 1hr.
Other: Does not exist in a charged form, so it probably acts by an alternate mechanism; can
cause methemoglobinemia via its metabolite O-toluidine, the treatment for which is methylene
blue.

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2. Procaine
Uses: spinal, local, regional block.
Duration of action: 30min-1hr; maximum safe dose: 12mg/kg (like chloroprocaine).
Other: first synthetic local anesthetic.
3. 2-Chloroprocaine
Uses: epidural, caudal, local, regional blocks.
Duration of action: 30min-1hr; maximum safe dose: 12mg/kg.
Other: when used epidurally, may decrease the efficacy and duration of action of bupivacaine,
fentanyl, and morphine; associated with neurologic damage when used in intrathecal space,
which may be due to an old preservative, sodium bisulfate.
4. Tetracaine
Uses: spinal, topical (common for airway anesthesia by pulmonologists).
Duration of action: 2-6hrs; maximum safe dose: 3mg/kg.
Other: derivative of procaine; associated with cauda equina syndrome when given intrathecally.
5. Prilocaine
Uses: dental procedures, topical (EMLA cream).
Duration of action: 30min-1hr; maximum safe dose: 8mg/kg.
Other: Can cause methemoglobinemia.
6. Lidocaine (Xylocaine)
Uses: spinal, epidural, local, regional, airway topicalization, IV regional anesthesia (Bier block),
antiarrhythmic, can be given via ETT.
Duration of action: 1-2hrs (greater with epinephrine); maximum safe dose: 5mg/kg alone,
7mg/kg with epinephrine.
Other: thought to be neurotoxic in high concentrations. As such, 5% lidocaine given through
small-bore infusion catheters is associated with cauda equina syndrome and permanent
neurologic damage. Associated with transient neurologic symptoms (TNS) when given
intrathecally. TNS includes burning, pain, and aching of the lower extremities, lower back, and
buttocks without motor symptoms or signs. It is associated with lidocaine > bupivacaine >
tetracaine, the lithotomy position, outpatient surgery, and obesity. Onset of TNS is within 12-24
hours and symptoms typically resolve within 1 week.
Lidocaine formulations are used for topical anesthesia to the airway for awake FOB intubation.
5% paste is useful for the oropharynx and hypopharynx, and atomized 4% solution is useful for
the hypopharynx and trachea.
7. Mepivacaine (Polocaine)
Uses: epidural, local, regional block.
Duration of action: 1-2hrs; maximum safe dose: 5mg/kg, 7mg/kg with epinephrine.
Other: often employed in regional blockade for quick onset. We typically dose our continuous
peripheral nerve catheters with mepivacaine for surgical anesthesia, and switch postoperatively
to a less dense, more sensory-specific local anesthetic such as ropivacaine for postoperative
analgesia.
8. Bupivacaine (Marcaine)
Uses: spinal, epidural, local, regional blocks.
Duration of action: depends on dose and site. Locally, 2-4hrs, epidurally 2-4hrs, spinal 1.5-
2.5hrs, peripheral nerve block 8-24hrs. Maximum safe dose: 3mg/kg.
Other: highly potent; cardiotoxicity is cumulative as described above, unique in that it is very
difficult to treat. Proven safety in spinal and epidural anesthesia.
9. Ropivacaine (Naropin)

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 Uses: same as bupivacaine. Chemical analogue of bupivacaine with similar potency, onset,
duration (more predictable), and toxic doses.
Duration of action: as for bupivacaine; maximum safe dose: 3mg/kg.
Other: Thought to be less cardiotoxic than bupivacaine. Tends to have preferential sensory
blockade over motor, making it ideal for postoperative catheters and analgesia.

VIII. Herbal Medications

Herbal medication use is increasingly common in the general patient population. As a rule, herbal
medications have not been thoroughly studied and their long-term effects on the human body are
unknown. Further complicating matters is the fact that many of these medications are not regulated in
any way with regards to dosing or even purported content of the medications themselves.

There is a small amount of data to suggest certain herbal medications can have unwanted effects in the
perioperative period. The following is a brief list of common herbal medications, their effects, and
perioperative recommendations. For more information, consult a more detailed reference.

Herbal Agent Purported Benefits Effects Recommendations

Valerian Root Decreases anxiety May decrease MAC via GABA Taper weeks before surgery if
possible
Echinacea Stimulates immune Allergic reaction; Hepatotoxicity; d/c before surgery
system Interferes with immunosuppressive
therapy

Ephedra Weight loss Sympathetic stimulation similar to d/c before surgery, avoid use
Boosts energy ephedrine; Increased HR, BP, and with MAOIs
arrthymias
Garlic Reduces BP and Irreversible inhibition of platelet d/c 7 days before surgery
cholesterol aggregation
Ginkgo Improves cognition Inhibits PAF d/c 2 days before surgery
and circulation
Ginseng Protects against Hypoglycemia; Inhibition of platelets d/c 7 days before surgery
stress and clotting cascade
Kava Decreases anxiety May decrease MAC via GABA d/c 24hrs before surgery

St. Johns Wort Antidepressant Inhibits reuptake of NE, dopamine, d/c 5 days before surgery
serotonin; Induces cytochrome P450
(increased drug metabolism)

The G herbal medications (garlic, ginseng, ginkgo) all inhibit the clotting cascade and/or platelet
aggregation. Despite this, the American Society of Regional Anesthesia feels herbal medications do not
pose an increased risk of bleeding in the setting of neuraxial blockade.

Chapter 2D. Neuromuscular Blockade

Neuromuscular blockers, or paralytics, are commonly used in anesthesia. Besides preventing movement
and facilitating intubation, paralytics can often provide optimal operating conditions for the surgeon.
That being said, neuromuscular blockade must be carefully monitored, and the thoughtless use of NMBs
can be problematic for anesthesiologists and patients alike. Never forget that NMBs are not
anesthetics; they provide no analgesia, amnesia, or hypnosis.

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The following is a brief description of the usage, reversal, and monitoring of neuromuscular blockade.
Pearls of wisdom concerning NMBs will also be covered. For specific details of each drug, see the section
on anesthetic drugs.

The Neuromuscular Junction

The neuromuscular junction is composed of the terminal end of a motor neuron and the muscle cell
separated by the synaptic cleft. When an action potential depolarizes the terminal end of the neuron,
ACh is released, which diffuses across the synaptic cleft. This ACh binds to receptors on the muscle
(motor endplate), causing depolarization (endplate potentials). When enough endplate potentials are
generated, the whole membrane will depolarize via opening of sodium channels, which subsequently
release calcium from the sarcoplasmic reticulum, causing muscle contraction. Termination of the action
potential is caused by rapid hydrolysis of ACh by acetylcholinesterase.

Depolarizing vs. Nondepolarizing Blockade

Depolarizing NMBs (succinylcholine) very closely resemble ACh and therefore readily bind to ACh
receptors and cause conformational changes in the ACh receptor, bringing about ion channel opening
and ultimately, prolonged depolarization of the muscle endplate. Thus, succinylcholine is an ACh
receptor agonist. By contrast, nondepolarizing NMBs are competitive antagonists at the ACh receptor,
binding it but not inducing the conformational changes necessary for ion channel opening.

Succinylcholines offset is dependent on diffusion away from the neuromuscular junction and
subsequent hydrolysis by pseudocholinesterase, also known as plasma cholinesterase. In contrast,
nondepolarizing NMBs must be metabolized and eliminated. They can be outcompeted by additional
amounts of ACh, as occurs when we clinically reverse neuromuscular blockade.

Succinylcholine

No other NMB is as rapid in onset (within 30 seconds) and offset (usually 5-10min) as succinylcholine.
The classic short blockade caused by succinylcholine is termed a phase I block. After repeated
administration, a phase II block may occur; this resembles the block of nondepolarizing NMBs in
duration and response to nerve stimulation; see below.

People who possess abnormal genes for pseudocholinesterase may exhibit a prolonged block from
succinylcholine. This is a frequently tested topic on the boards. Heterozygotes (one abnormal, one
normal gene; 1:50 people) may experience blockade up to 30 minutes. Homozygotes (1:2500 people)
may have a profoundly long blockade, on the order of 8 hours. The dibucaine number is proportional
to the level of normal pseudocholinesterase activity. Normal pseudocholinesterase is 80% inhibited by
dibucaine (a local anesthetic), while abnormal pseudocholinesterase is only 20% inhibited. Thus, a
normal dibucaine number is 80, while a homozygote for atypical pseudocholinesterase would have a
dibucaine number of 20. Heterozygotes fall in the 40-60 range. Beware using succinylcholine in patients
with known or family history of atypical pseudocholinesterase, and keep in mind that patients
experiencing a prolonged block will need mechanical ventilation and sedation until muscle function
returns to normal.

Cholinesterase inhibitors prolong succinylcholine blockade by inhibiting pseudocholinesterase and by

providing more ACh at the neuromuscular junction, thereby intensifying depolarization. Other drugs
which inhibit pseudocholinesterase include pancuronium, esmolol, metoclopramide, cyclophosphamide,

64
phenelzine, and organophosphates.

Lithium and magnesium both prolong the onset and duration of succinylcholine. Similarly, quinidine,
calcium channel blockers, and certain antibiotics (mycins other than erythromycin, aminoglycosides)
can prolong blockade. Small doses of nondepolarizing NMB tend to antagonize succinylcholine blockade,
i.e., they prevent depolarization.

Succinylcholine is relatively contraindicated for routine use in young children because these patients
may have undiagnosed myopathies. It is also contraindicated in patients with a preexisting condition
associated with succinylcholine-induced hyperkalemia (examples include, but not limited to, old burns,
spinal cord injury, myopathies, etc.) and in patients with a history of malignant hyperthermia. For more
info, see the drug section.

Nondepolarizing Neuromuscular Blockers

Two classes of nondepolarizing NMBs exist: benzylisoquinolones and steroids. All function via the same
mechanism, that being competitive antagonism at the ACh receptor. As such, they can be
outcompeted by ACh, which is the mechanism of action of NMB reversal agents. However, for reversal
of neuromuscular blockade to be effective, some recovery from the NMB must already be present.
Recovery depends on metabolism and elimination of the NMB in question.

Typically, 1-2x the ED95 dose of a NMB is used for an intubating dose, while 0.1x the ED95 dose is used for
maintenance relaxation. Higher doses may afford slightly quicker onset of blockade but can also greatly
prolong the block.

Certain NMBs, particularly some benzylisoquinolones such as mivacurium and atracurium, can cause
histamine release. Histamine release can manifest itself as flushing, bronchospasm, and hypotension.
Pretreatment with antihistamines and giving the drug slowly seem to attenuate these effects.

Hypothermia prolongs blockade by decreasing activity of the enzymes that metabolize the drug.
Similarly, hypoventilation and respiratory acidosis prolong blockade. Electrolyte imbalances such as
hypocalcemia, hypokalemia, or hypermagnesemia will result in abnormally long paralysis. Obviously,
hepatic or renal disease or dysfunction can also prolong blockade depending on the particular route of
metabolism and excretion of the NMB in question. Other drugs that can prolong nondepolarizing
blockade are the same antibiotics that can prolong succinylcholine: (mycins other than erythromycin
and aminoglycosides), quinidine and calcium channel blockers, dantrolene, and inhalational anesthetics.
Drugs that induce enzyme metabolism, such as antiepileptics, can greatly shorten the duration of NMB
metabolized by the liver (vecuronium and pancuronium). Mivacurium and cisatracurium are not affected
due to their liver enzyme-independent metabolism.

Different muscle groups are more sensitive to neuromuscular blockade than others. The orbicularis
oculi, diaphragm, and laryngeal muscles all relatively more resistant than the adductor pollicis or the
muscles innervated by the posterior tibial nerve. However, these resistant muscle groups are also highly
perfused, and a relatively larger proportion of a bolus of NMB is delivered to these muscles. This
explains the phenomenon that the pharyngeal and laryngeal muscles are the first to be blocked but also
the first to recover, whereas the less-resistant peripheral muscles are blocked more slowly but recover
more slowly. In general, the orbicularis oculi corresponds best with the level of paralysis of the
diaphragm and larynx, the two muscle groups we are often most concerned about.

65
Certain disease states and the changes in response to NMB are often tested on the boards.
Myasthenia gravis patients are ultrasensitive to nondepolarizing NMBs, but are often resistant to
succinylcholine due to their fewer ACh receptors. (MG patients may have profound weakness with
volatile anesthetics alone). Use of either type of NMBs is unpredictable and must be monitored closely.
Burn and chronic denervation injury patients have increased extrajunctional ACh receptors, making
them resistant to nondepolarizing blockade.

Monitoring Neuromuscular Blockade with Peripheral Nerve Stimulation

Any patient who is given a NMB should have the state of that blockade monitored. The most common
way we do this is with a peripheral nerve stimulator. Briefly, the nerve stimulator leads are placed over a
peripheral nerve, which, when stimulated, elicits contraction of a muscle group. The three most
commonly monitored nerves are the ulnar nerve, the facial nerve, and the posterior tibial nerve. As
previously discussed, the facial nerve most closely approximates the diaphragm and laryngeal muscles.

As neuromuscular blockade ensues, the response to peripheral nerve stimulation exhibits a

characteristic pattern depending on the agent used. Three types of stimulation are discussed here: train-
of-four, single twitch, and tetany. A twitch is a single pulse of 0.2ms in duration. Train-of-four is a
series of four twitches delivered at a frequency of 2Hz (2 twitches per second). Tetany delivers a
sustained stimulus of 50-100Hz usually lasting 5 seconds. The twitch height is a quantitative measure
of the level of muscle response to stimulation.

As nondepolarizing muscle blockade is intensified, each successive twitch in a train-of-four will show
fade, a gradual decrease in the height of each successive twitch. As blockade increases, twitches fade
altogether from last to first. Disappearance of the 4th twitch corresponds to ~75% blockade while the
disappearance of the 2nd corresponds to a 90% blockade. Thus, if a patient has one twitch present during
a train-of-four stimulation, 90% of ACh receptors at the neuromuscular junction are blocked. Fade will
also occur during tetanic stimulation in the setting of residual NMB.

Train-of-four response to
nondepolarizing blockade.
Arrow ( ) represents NMB
administration.
progressive fade, with
eventual loss of twitch number

After a tetanic stimulus is applied, a subsequent train-of-four will show supramaximal response. This
phenomenon is known as post-tetanic facilitation. Facilitation can even be seen when a patient has no
response to train-of-four (no twitches) and no response to tetany. If a tetanic stimulation is applied
and then a train-of-four is checked, it may be possible to see twitches due to this phenomenon. Post-
tetanic facilitation is thought to be due to briefly increased levels of ACh in the neuromuscular junction
due to repeated stimulation, thereby allowing out-competition of the neuromuscular blocker. The

66
junction is flooded with ACh by the tetanic stimulus, but the fade remains.

Clinically, five seconds of sustained tetany (no fade), the ability of a patient to be able to lift their head
up for 5 seconds, or a strong bite on a bite block or tongue depressor correlates with at least 50% of
receptors being unblocked. These are the best clinical tests we have to assess recovery from
neuromuscular blockade, and represent a train-of-four ratio of no higher than 0.8-0.9, which most
would consider a bare minimum threshold for recovery. Inadequate recovery from NMBs poses various
risks, including hypoventilation and psychological distress in the case of an obviously-weak patient, and
microaspiration in the case of a subclinically-weak patient.

Reversal of neuromuscular blockade is guided by the response to peripheral nerve stimulation. Reversal
should not proceed until at least one twitch is present. This is because without twitches, the level of
neuromuscular blockade present is unknown, and the response to a reversal dose will be unpredictable.
The patient could be 5 minutes or 60 minutes from recovery of the blockade, but all we can see clinically
is that the patient has no twitches. Reversal at this stage will provide some recovery, but will either
result in a patient with incomplete recovery, or worse, a patient who briefly regains strength but
becomes weak or paralyzed an hour later due to excessive amounts of paralytic. In general, it is a good
idea to keep patients no more paralyzed than one twitch so that they are always reversible, should
the case end unexpectedly. As in all of anesthesia, the goal is to carefully titrate medications and to give
only what is necessary. All of us have been burned at some stage in our careers by giving too much
muscle relaxant, only to have the surgery end five minutes later and be stuck with a completely
paralyzed, non-reversible patient. The lesson here is: if you have no twitches and the case is over, wait.
Dont reverse the patient. Even though it is embarrassing and time consuming, it is the safest way to
proceed. The patient should not be put at risk for your impatience.

As previously mentioned, the best evidence of recovery from neuromuscular blockade is 5 seconds of
sustained tetany, 5 seconds of sustained head lift, or a strong bite on a bite block. Return of train-of-
four without fade is necessary but not adequate, because humans are insensitive detectors of fade,
with up to 70% of receptors still blocked in this case. Anesthesiologists do not have a better test in
clinical practice, so great care must be taken when assessing recovery from neuromuscular blockade.

Blockade with succinylcholine exhibits a different response to stimulation than nondepolarizers. Twitch
height during train-of-four and tetany is equally decreased at all stages. There is no fade and no post-
tetanic facilitation. However, be aware that a phase II block of succinylcholine will respond like a
nondepolarizer to stimuli.

Train-of-four response to
depolarizing blockade.
Arrow () represents depolarizing
NMB administration.
Note the lack of fade, although
twitch height is
decreased.

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Myasthenia Gravis

This disorder is due to autoimmune destruction of postsynaptic ACh receptors, resulting in skeletal
muscle weakness and easy fatigability. Antibodies (IgG) against nicotinic ACh receptors are found in 85-
90% of patients with MG. Muscle strength characteristically improves with rest but rapidly deteriorates
with exertion. The ocular, laryngeal, and pharyngeal muscles (bulbar muscles) can all be involved, as well
as respiratory and proximal skeletal muscles. 10-15% of patients with MG develop a thymoma and 65%
have thymic hyperplasia. It is more common in women than men; female incidence is highest during
their third decade, while male patients typically present in their sixth or seventh decade.

Anticholinesterase drugs are the usual treatment and work by increasing available ACh in the
neuromuscular junction. Pyridostigmine is the most commonly used anticholinesterase. Other
treatments for more advanced disease include plasmapheresis, IV immunoglobulin infusions, and
steroids. Excision of the thymoma or the hyperplastic thymus greatly alleviates symptoms and is often
curative.

Anesthetic considerations include the propensity for these patients to develop postoperative respiratory
dysfunction, aspiration (due to weakness of bulbar muscles), and sensitivity to neuromuscular blockade
and the relaxing effects of volatile anesthetics. Predictors of the need for postoperative mechanical
ventilation include disease duration > 6 years, concomitant pulmonary disease, a vital capacity < 4ml/kg,
and pyridostigmine dose > 750mg daily.

The preoperative goals should be to optimize medical therapy. Preoperative respiratory or bulbar
weakness should be treated with IV immunoglobulin or plasmapheresis. A classic boards topic is
differentiation of myasthenic crisis (acutely decompensated MG) from cholinergic crisis (due to excess
anticholinesterase). Patients in cholinergic crises are also weak, but exhibit signs of muscarinic excess
such as salivation, lacrimation, miosis, bradycardia, and diarrhea. Edrophonium is short-acting and can
be used to differentiate cholinergic crisis from myasthenic crisis. Following a dose of edrophonium,
worsening of the symptoms implies cholinergic crisis, while improvement suggests issues arising from
myasthenia.

For patients with MG, the response to succinylcholine is very unpredictable. Patients can have
prolonged or shortened effects, or a phase II block. Sensitivity to nondepolarizers is profound. These
patients need to be closely monitored and reduced doses of NMBs should be used or even entirely
avoided.

Lambert-Eaton Myasthenic Syndrome

This disease involves autoimmune antibodies to presynaptic calcium receptors, reducing ACh release
from the motor endplate. It is characterized by proximal muscle weakness that typically begins in the
lower extremities, but may spread to involve upper limb, bulbar, and respiratory muscles. It is
associated with paraneoplastic syndromes, classically small cell cancer of the lung. In contrast to MG,
muscle weakness improves with repeated effort. Immunosuppression or plasmapharesis helps improve
symptoms to a certain degree, but anticholinesterases have less dramatic effects when compared to
treating patients with MG. These patients are very sensitive to both succinylcholine and nondepolarizing
NMBs.

Final Thoughts

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There is a very common pattern to the use of NMBs as one progresses through training. At first,
residents tend to use too much NMB, either because of inexperience with the length of surgery or a fear
of the patient moving and upsetting the surgeon. This results in slow wakeups, over-paralyzed
patients who cannot be reversed, or those who become weak and need reintubation in the PACU. Later,
a resident may greatly curtail the use of NMBs, tailoring his anesthetic to a quick wakeup and not
worrying about surgical concerns. As experience with NMBs grows, we learn the right times and the
right doses to give to patients.

Surgeons often ask for paralysis but sometimes do not understand why they need it or if the patient is
paralyzed at all. All of us have had surgeons ask for more relaxation when the patient is already
maximally blocked with no twitches. Often, the request for more relaxation represents inadequacy of
surgical technique. That being said, the challenge for us becomes how to accommodate the surgeon and
maintain a good working relationship, while at the same time being responsible and safe for the patient.
If the surgeon asks for more relaxation and you know that it is a) not necessary because the patient is
already paralyzed, or b) that they will end soon, use your best judgment. Remember, you can always call
your attending with questions.

With the above in mind, there are certain cases where NMB is critical. These include craniotomies, most
abdominal surgeries, cardiothoracic surgery, or any procedure where patient movement could be
catastrophic. A quick way to check is to ask yourself: If my patient coughed or moved right now, would
it be harmless (but annoying) or would it be potentially catastrophic? Interestingly, the better surgeons
seem to be the ones who least often ask for paralysis, whereas surgeons who are constantly struggling
with exposure or the size of their incision consistently ask for more relaxation. With time, you will
learn which are which.

Troublesome spots for us include cases where intense paralysis is desired but the case itself is short,
e.g., direct laryngoscopies by the head & neck surgeons. Here, the challenge becomes providing intense
blockade (recall that the laryngeal muscles are some of the last to become blocked) in cases that are
typically quick. Succinylcholine, with small repeat doses, can often be handy here, but you must watch
out for phase II block and bradycardia.

Lastly, be aware when a case might end very quickly and unexpectedly. A typical example of this is an
exploratory laparotomy to evaluate a malignancy. Sometimes, the surgeons will open the belly only to
find an inoperable tumor or conditions which otherwise preclude surgery. In these cases, they will
simply close the patient up and the case is over. This is the so-called peek and shriek. Be aware of this
possibility. If you stick to the general rule of giving enough drug to get the job done, but no more, things
should turn out just fine.

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Chapter 3. Anesthesia for Specific Surgeries

The chapters, and the chapters that follow, are not intended to provide an encyclopedic index of
anesthetic management for every type of surgery. Rather, the surgeries included are those that are
common at UCSD, anesthetically interesting, or frequently tested on board exams.

Chapter 3A. Anesthesia for General Surgery

General surgery encompasses many different types of cases, each with its own anesthetic
considerations. Examples include thyroid and parathyroid surgery, soft tissue surgery on the trunk and
back, and the gamut of hernia repairs. Intraabdominal surgery is the classic general surgery case.
Fittingly, the prevailing anesthetic option for general surgery tends to be general anesthesia, although at
times other options may exist.

Chapter 3A-1. Anesthesia for Neck, Trunk, and Breast Surgery

Thyroid and Parathyroid Surgery

Technique: general. Monitors: standard. IV access: one IV (must reliably draw back for parathyroid
cases). Duration: 2-3hrs. EBL: < 100ml. Position: supine. Special equipment: usually, a NIM (Nerve
Integrity Monitoring) ET tube. Special considerations: as below.

The usual indications for either type of surgery are neoplasms or hypersecretory glands. For elective
thyroid surgery, the patients thyroid state must be normalized preoperatively so that the patient is
clinically euthyroid; this is typically done by the surgeon or the patients endocrinologist. Surgery is
withheld until the patient is medically stabilized; there is no such thing as emergency thyroid surgery. A
patient in a hyper- or hypothyroid state is managed with methimazole or levothyroxine, respectively.

General surgeons usually perform thyroid and parathyroid surgeries without turning the OR table 180,
in contrast to head & neck surgeons. Because the procedure takes place close to the airway, ensure that
the airway is secure. The operation carries the risk of damage to surrounding structures, including
laryngeal nerves. Damage to these nerves can manifest themselves in a variety of ways, including
postoperative hoarseness and complete vocal cord immobility.

The surgeon will almost always ask for a NIM tube to be placed. This tube has a short monitoring strip,
approximately 3cm long and a few centimeters above the cuff, that is capable of detecting vocal cord
spasm in the event that the surgeon dissects near or stimulates the recurrent laryngeal nerve. It is very
important that the strip be placed precisely at the vocal cords; excellent laryngoscopy conditions or even
a Glidescope are needed to confirm this. The tube has several leads which are connected to a special
monitor, which is set up by the surgeon.

Because this monitoring technique depends on vocal cord movement, neuromuscular blockade is
forbidden during the surgery. Typically, succinylcholine is used for laryngoscopy, but paralytics can be
avoided altogether (propofol 2-3mg/kg with alfentanil 30-40mcg/kg or remifentanil 1-3mcg/kg), or a
very low dose of nondepolarizer can be used.

The NIM tube is different from a standard ETT in several other ways. It is quite thick, such that the
outside diameter of a given size corresponds to that of a standard ETT one size larger; e.g., a 6.0 NIM is
as large as a 7.0 standard. The adapter that connects to the circuit is NOT removable, so this tube cannot

70
pass through a LMA. The NIM tube is also quite floppy and requires a stylet for placement.

All neck surgeries carry a risk of postoperative hematoma formation, which can potentially lead to
airway compromise. In this event, the airway must be supported while the surgeons are notified.

During parathyroid surgery, we are routinely asked to draw blood to check parathyroid hormone levels
prior to excision and at least once after the glands are removed. An IV that draws back reliably is
needed, which may necessitate a 2nd IV; phlebotomy might suffice. Removal of all hypersecretory glands
reliably causes a reduction in PTH levels within 10 minutes, while sustained high levels of PTH will
prompt the surgeon to explore further.

Superficial Surgery on the Trunk and Back

These are usually for lipoma excisions or similar soft tissue masses. Anal exams under anesthesia
fistulotomies are also included. The surgeries are typically short.

Technique: general or local/MAC. Hyperbaric neuraxial techniques (saddle block) work well for anal
surgery. Monitors: standard. IV access: one IV. Duration: 30min-1hr. EBL: minimal. Position: supine,
prone, or prone jackknife depending on operative site. Special equipment: prone mask or cushion if
indicated. Special considerations: none.

Esophageal Surgery

These are rare procedures but can be quite long and quite challenging, combining the considerations of
thoracic surgery, one-lung ventilation, and a large open abdominal operation. Refer to a textbook for
additional information.

Technique: general thoracic epidural. Monitors: standard, plus arterial line. IV access: at least 1 large
IV central line. Duration: 2-8hrs. EBL: 200-1000ml or more. Position: supine, or lateral decubitus, or
thoracoabdominal (operative side slightly propped up with the arm airplaned across the body and spine
extended). Special equipment: equipment for one-lung ventilation. Special considerations: Although
this is a long and involved operation, blood loss is typically small. Proximity to large vessels makes
significant bleeding a rare, but real, possibility.

Breast Surgery

These cases range from needle-localized biopsies, to simple lumpectomies, to bilateral mastectomies
with abdominal flaps, to major reconstructions or breast reductions (usually in conjunction with plastic
surgeons). The extent of the surgery dictates the duration and sequelae of the case.

Technique: general paravertebral block. Rarely, minor cases can be done under local/MAC. Monitors:
standard, rarely an arterial line, urine output. IV access: one IV. Duration: anywhere from 30min for
simple cases to 8hrs for major reconstruction. EBL: minimal to 500ml; most cases are on the low side.
Position: supine. Many breast cases require the patient to be sat up at times to check alignment and
symmetry of the breasts. Special equipment: none. Special considerations: as below.

Position changes may dictate the choice of airway device. For breast reductions or reconstructions, the
patient is sat up to 45-60 at times, so an ETT may be indicated. Additionally, the surgeon may have
specific requests about neuromuscular blockers: either to use them to provide tissue laxity or not to use

71
them as a form of nerve-monitoring technique for dissection near the axillary and long thoracic nerves.

Even for long breast cases, the blood loss is typically small, due to the relative avascularity of the tissues.
If axillary lymph node dissection is planned, avoid placing IV lines or monitors on the side of the affected
extremity. The surgeon may ask that you not use pressors like phenylephrine because of the thought
that it may decrease blood flow to a flap.

After wound closure, there is usually an extensive bra-type dressing that is applied.

Chapter 3A-2. Anesthesia for Intraabdominal Surgery

There are three major categories of intraabdominal surgery: major open, minor open, and
laparoscopic/robot-assisted.

Major Open Surgery

These types of surgeries are generally lengthy, with the potential for large fluid shifts and blood loss.
Large abdominal incisions and exposed bowel cause extensive evaporative and heat losses for the
patient. Examples of this type of surgery include:

Pancreatic, gastric or esophageal resection, including Whipple procedure

HIPEC
Partial hepatectomy
Major bowel resection
Intraabdominal mass resection
Major abdominal explorations or lymph node dissection
Open gastric bypass
Splenectomy

Technique: general epidural, depending on the incision location, extensiveness of the surgery, and
potential for postoperative coagulopathy. Monitors: standard, urine output, usually arterial line. CVP
can be helpful. IV access: at least two large IVs central line. Duration: 3-8hrs. EBL: 500ml-2L or more.
Position: supine. Special equipment: fluid warmers, forced-air warming blankets. Special
considerations: as below.

Insensible fluid losses from exposed bowel during these cases can be extensive. Historically, these losses
have been replaced with crystalloid at a rate > 10ml/kg/hr. The overall trend is toward fluid restriction
and the use of more colloids and fluid boluses; some advocate as little at 4ml/kg/hr as the insensible
replacement rate. Note that this rate is just for insensible losses and does not begin to take into
account volume lost from bleeding.

Patients undergoing bowel surgery usually have a bowel prep before surgery which can leave them
significantly volume depleted or with electrolyte disturbances. Take this into consideration prior to
induction.

Be aware of cases with the possibility of a peek and shriek, where the surgeons open the belly and
find inoperable conditions, and quickly close. Dont go overboard on NMBs at the beginning of the case.

Partial hepatectomy cases share the anesthetic considerations above, with the added potential for huge

72
and rapid blood loss. Central venous access is standard, not only for large-bore access but also for CVP
monitoring. Surgeons typically ask us to minimize fluids, with the reasoning that a low CVP causes a low
venous back-pressure to the portion of the liver in question and limits blood loss. Have nitroglycerin
available for the rare possibility that the surgeon asks for prompt and dramatic CVP reduction to reduce
bleeding.

HIPEC

HIPEC stands for Hyperthermic Intraperitoneal Chemotherapy. This procedure is relatively rare outside
of UCSD, which is a leading referral center for this surgery. The procedure is used to treat advanced
abdominal malignancies, usually peritoneal-based. The patients are typically age 30-50, previously
healthy, and relatively free of comorbidities. The surgery involves a large midline abdominal incision,
tumor debulking, and heated chemotherapy infusion. The initial stage is identification and resection of
as much tumor and tumor-affected organs as possible (cytoreduction). Then, the surgeon places
perfusion cannulas and temporarily closes the abdomen. The chemotherapeutic solution (mitomycin C)
is infused at > 40C throughout the peritoneal cavity for up to 90 minutes. This is called shake and
bake because the surgeon or assistant will gently shake the abdomen while the chemotherapy drug is
infusing. The chemotherapy portion is intended to kill any remaining cancer cells once all visible disease
is removed. The chemotherapy solution is then removed, and the incision is closed.

Technique: General with thoracic epidural. Monitors: Standard, arterial line, urine output, CVP. IV
access: Two large bore IVs usually suffice; difficult access or expected blood loss may require a central
line. Duration: 6-10hrs. EBL: 300-2000ml. Position: Supine. Special equipment: fluid warmers and
forced-air warming blankets. Special considerations: derangements specific to HIPEC are discussed
below.

During the pre-chemotherapy portion of the surgery, fluid warmers and warming blankets are left off
and the patient is allowed to passively become hypothermic. This is due to the expected whole-body
heating effect that will come later.

During the heated chemotherapy infusion, patients typically develop a sepsis-like hyperdynamic
circulatory state that is characterized by a steady increase in oxygen consumption, etCO2, heart rate,
and cardiac output, with a decrease in SVR. Electrolyte abnormalities and fluid shifts become a challenge
during the heated perfusion, so frequent blood gases should be monitored during this time. Fluid
requirements, already high for this type of abdominal surgery, become profound; it is common for total
ins to be on the order of 4-5L of crystalloid and 3-4L of colloid and blood products.

Mitomycin C is nephrotoxic. A steady urinary output is required to flush the agent and avoid renal
injury, so close monitoring of urine output is key. The surgeon may ask for diuretics to improve urine
flow if it is inadequate otherwise.

This surgery is exquisitely painful due to the large incision and peritoneal irritation that accompanies the
chemotherapy. Thoracic epidural analgesia is the rule for these patients. However, balancing the dosing
of the epidural for adequate coverage of the incision without causing hypotension (with fluid shifts
ongoing) can be challenging. A good starting dose is 0.0625% bupivacaine at 10ml/hr with patient
demand dose of 4ml q30min. The opioid is intentionally left out and the patients are given IV opioid
PCAs.

Minor Open Surgery

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There is quite a bit of overlap between minor and major abdominal surgery. A simple bowel resection or
colectomy tends to be a minor affair, but depending on surgical skill and patient characteristics, it can
quickly develop into a major, extensive case. There is still the potential for substantial insensible fluid
losses. Examples of minor procedures include:

Open cholecystectomy
Small bowel resection
Colectomy, sigmoidectomy
Biopsy
Hernia repair
Appendectomy

Technique: general. Inguinal hernias may be repaired under a variety of techniques, including general,
regional, neuraxial, and local/MAC. Patients with mid- and lower-abdominal hernia repairs may have a
TAP (transversus abdominis plane) block done for post-op analgesia. Monitors: standard, rarely an
arterial line. IV access: one large IV should suffice for the vast majority of cases. Duration: 1-4hrs. EBL: <
500ml. Position: supine. Special equipment: warmers. Special considerations: The same comments
about keeping patients warm, replacing fluid losses and bowel prep for major procedures apply.

Laparoscopic and Robotic-assisted Surgery

Many traditionally open procedures are now being performed laparoscopically. A variant of laparoscopic
surgery is robotically-assisted surgery. Laparoscopic procedures often reduce the physiologic insult of
the surgery as well as fluid shifts and blood loss. However, this is highly dependent on surgical skill, and
the procedure can take a very long time.

Robot-assisted surgery is intended to combine the minimally-invasive nature of laparoscopic surgery

with a device (robot) that translates the imprecise movements of the surgeons hands to smooth
mechanical motions and allow instrument manipulations that are not possible with manually-operated
instruments. It is absolutely key to remember that the OR table cannot be moved while the robot is
docked, since the robotic arms will not move with the patient and can cause serious injury.

Currently, very few general surgery cases are done with robotic assistance. Examples of laparoscopic
surgeries include:

Cholecystectomy
Hernia repair
Appendectomy
Colectomy, APR, LAR
Gastric bypass, banding, or Nissen fundoplication

Management for urologic and gynecologic surgery using laparoscopy with or without robotic assistance
are discussed in the pertinent section.

Technique: general. Monitors: standard, rarely an arterial line, urine output for longer procedures. IV
access: one IV. Duration: 1-8hrs depending on the procedure. Use of a robot typically slows down a
case. EBL: usually minimal. Position: supine. Significant Trendelenburg or reverse Trendelenburg may be
needed, and may be needed for long durations. Special equipment: none. Special considerations: as

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below.

Steep T-burg or reverse T-burg for long periods of time can have significant impacts on circulatory and
respiratory physiology. In short, in T-burg, ventilation and oxygenation are impaired but venous return is
high; in reverse T-burg, ventilation and oxygenation are improved but venous return is very low. There
have been many cases where steep T-burg position for many hours has resulted in such severe facial
edema that the patient had to be kept intubated at the end of the case. Additionally, some laparoscopic
surgeries have to be aborted or converted to open due to patient intolerance of the needed position,
with prohibitively high peak airway pressures or inadequate oxygenation in steep T-burg.

Insufflation of the abdomen with CO2 creates unique issues for the anesthesiologist. In no particular
order, they are: increased CO2 load, decreased venous return, increased afterload, difficulty with
ventilation, possibility of CO2 embolism, subcutaneous deposition of CO2, pneumothorax, and
pneumomediastinum. Additionally, the anesthesiologist must be vigilant at the time of initial trocar
placement, as life-threatening vascular injuries have occurred at that time. From the outset, most of us
decrease tidal volumes and increase respiratory rate when the abdomen is insufflated to keep peak
airway pressures low and blow off the excess CO2. In general, minute ventilation will have to be
increased by about 1/3 of baseline. Intravascular injection of CO2 is usually benign but the surgeon
should be notified. Typically you would see a sharp rise in etCO2 on the capnograph beginning with
insufflation. Pneumothorax or pneumomediastinum should be treated as needed.

Laparoscopic procedures always have the potential of being converted to an open procedure if
circumstances dictate.

Patients presenting for gastric bypass or banding are, by definition, morbidly obese and with the usual
assortment of physiologic derangements that obesity causes. These include the possibility of a difficult
airway, full stomach, increased oxygen consumption, decreased FRC, restrictive-pattern lung disease,
rapid desaturation during apnea, hypertension, difficult vascular access, and difficult
positioning/padding. The surgeon may repeatedly perform upper endoscopy to place a Bougie or
investigate suture lines; this creates a risk of ETT dislodgement for which you must be vigilant.

Chapter 3B. Anesthesia for Urologic and Gynecologic Surgery

Urologic, gynecologic, and urogynecologic surgery comprise a significant percentage of cases performed
at UCSD. Although these are distinct surgical specialties, they will both be covered here due to many
intraoperative similarities. While many of the cases are simple, outpatient surgeries, many more
complex and invasive procedures are also performed. There is significant overlap between many of
these cases and those done by general surgeons, such as laparoscopic/robotic procedures and major
pelvic dissections, so for further information, see the general surgery section.

A common position for urologic and gynecologic surgery is the lithotomy position. In this position, the
patients legs are raised and flexed at the hip and knee. The legs are either allowed to hang freely from
soft straps or are placed in padded holders. This position has the potential for many different
peripheral nerve injuries. Medial compression of the thigh and knee can injure the saphenous nerve,
which clinically will present as anesthesia over the medial calf. Lateral compression of the lower leg can
result in common peroneal nerve injury and foot drop. Hyperflexion of the thigh can also produce
sciatic, femoral and obturator nerve injuries. Usually the surgeons are quite attentive to this, but we are
also responsible to ensure that all areas are properly padded and supported.

75
The lithotomy position increases intraabdominal pressure, leading to reduction of FRC and poor
pulmonary compliance. Many of these procedures also employ steep Trendelenburg position, which
further increases these problems. In extreme cases, difficulty with ventilation and oxygenation may
cause the case to be aborted. Venous return tends to be high.

The intraoperative use of indigo carmine is common in many of these procedures; methylene blue is
used rarely. When given intravenously, these dyes are excreted in the urine. They allow the surgeon to
see damage or holes in the ureter when the dye extravasates. As discussed in the monitoring section,
indigo carmine has a vasopressor effect while creating a transient, mild artifactual desaturation on S pO2.
Methylene blue has a milder vasopressor effect due to NO scavenging; the artifactual desaturation it can
cause is transient but may be as low as 60-70% on SpO2.

The TURP syndrome is a common boards topic and something every anesthesiologist needs to be aware
of. It classically is seen during a true TURP, where large volumes of hypotonic irrigating solutions can be
absorbed through the prostates dorsal venous plexus. This syndrome can also happen in any other case
when large amounts of irrigating solutions are used. Absorption of the irrigating fluid leads to
hypoosmolality, hyponatremia, solute toxicity, and intravascular fluid overload. The amount of
absorption is determined by the pressure (i.e., height) of the irrigation fluid, opening of vascular
structures, and the length of the procedure. Absorption is reported to occur at ~20ml/min of irrigation.
The problems described above manifest themselves as confusion, agitation, hypotension, and
arrhythmias all the way to dyspnea, coma and death. Clearly, most of the signs of TURP syndrome are
masked by general anesthesia, and for this reason many of us feel neuraxial blockade is safer any time
it is a possibility.

Because polar electrolyte solutions such as NS disperse monopolar cautery and render it useless for
TURP, other solutions containing glycine, sorbitol and mannitol are classically used. Each of these solutes
can become toxic when significant amounts are absorbed. Glycine toxicity is associated with transient
blindness, hyperammonemia, hypotension and neuroexcitatory phenomenon. Sorbitol solutions can
lead to hyperglycemia, and mannitol can lead to volume overload. Pure water is generally avoided
except in bladder procedures due its marked hypotonicity.

Recently, bipolar cautery for TURP has become more prevalent, which allows the use of NS as an
irrigant, and thus avoids the problems of hypotonicity and solute toxicity. However, the risk of
intravascular volume overload remains.

The treatment of TURP syndrome is supportive. Usually, cessation of irrigation, volume restriction, and
diuresis are sufficient. Severe neurologic manifestations such as seizures or coma should be treated with
hypertonic saline according to standard guidelines. Antiepileptic medication is useful for managing
seizures, and the airway should be protected as needed.

Coagulopathy during a TURP procedure is another commonly tested board topic. It is thought to result
from two etiologies: one is a dilutional coagulopathy from massive blood loss with crystalloid and
irrigant in the intravascular space, and the other is systemic fibrinolysis due to prostate tissue release
into the circulation.

Urologic and gynecologic procedures can be classified as minor, moderate, and major.

Minor Surgery

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Examples of this include TURP, cystoscopy with TURBT, cystoscopy with ureteroscopy stenting,
hysteroscopy, dilatation and curettage/evacuation, extracorporeal shock wave lithotripsy, and minor
laparoscopic or diagnostic procedures.

Technique: general or neuraxial. Monitors: standard. IV access: one IV. Duration: 30min-2hrs. EBL: <
100ml for all but D+C and D+E, which are still < 500ml. Position: lithotomy, supine, Trendenlenburg.
Special equipment: none. Special considerations: as below.

ESWL employs high frequency acoustic shocks which can damage or reset pacemakers; these minimally
painful, short procedures can be done with an opioid-only spinal. Discuss with an attending on how to
proceed. Many of these surgeries are short and outpatient procedures and the anesthetic should be
tailored accordingly.

D+Es and less commonly D+Cs have the potential for fair amounts of bleeding due to the highly vascular
nature of the pregnant uterus and placenta. The gynecologists will generally inform you if this happens,
and additional interventions may become necessary. The gynecologists may sometimes ask for specific
agents to aid in uterine contraction, e.g., oxytocin or methylergonovine. These agents and anesthetic
implications for the parturient are discussed in the OB section.

Moderate Surgery

Examples include open hysterectomy/oophorectomy, vaginal vault reconstruction, surgery for

incontinence or organ prolapse, and laparoscopic/robotic procedures such as laparoscopic
prostatectomy and laparoscopic hysterectomy/oophorectomy.

Technique: general. Monitors: standard, arterial line for long cases, urine output. IV access: typically
one IV will suffice. Duration: 2-8hrs. Robotic prostatectomies were notorious in the past for taking 8
hours or longer, but they are typically in the range of 4-5 hours now. EBL: 100-500ml, rarely more.
Position: supine or lithotomy steep Trendelenburg. Special equipment: fluid warmers and forced-air
warming blankets. Special considerations: as below.

IV dye such as indigo carmine or methylene blue may be requested; see above.

Urologic, gynecologic, and urogynecologic surgery with laparoscopy and/or robotic assistance are
common procedures. These procedures necessitate attention to careful positioning and padding given
the steep T-burg and rotational positions that are usually required. Since the arms are usually tucked
securely at the sides, it is crucial to verify all lines and monitors function appropriately prior to prepping
and draping. Difficulties with oxygenation and ventilation are not uncommon, and your ability to non-
invasively investigate these problems is limited. Use of FOB to verify ETT placement or suction secretions
is not unheard of. The long duration of the case, fluid shifts, lack of access to the BP cuff in the event of
malfunction, plus the potential for intraabdominal vascular injury usually require an arterial line. Facial
and/or laryngeal edema resulting from prolonged steep T-burg may preclude extubation. Lastly, it is
absolutely key to remember that the OR table cannot be moved while the robot is docked, since the
robotic arms will not move with the patient and can cause serious injury.

Many urologists will ask that the patient be run dry for the initial stages of a laparoscopic
prostatectomy. The rationale behind this is not fully clear but likely involves their desire for minimal
urine output and thus bladder distension during resection of the prostate. While it is true that blood and
insensible losses in laparoscopic procedures tend to be small, remember that the patient still has

77
maintenance fluid requirements. Objective data such as BP, ABGs and other trends are the best guide to
therapy, not the surgeons random opinion. Furthermore, these initial stages may take anywhere from
2-6 hours depending on the surgeon. When in doubt, be political and defer to your attending, but keep
in mind your duty is first and foremost to the patient.

Major Procedures

Examples include major pelvic dissection, nephrectomy, open prostatectomy, cystectomy, pelvic lymph
node dissection, and typically any surgery for gynecologic or urologic cancer. Many of these are done (or
just started) as laparoscopic cases.

Technique: general epidural. A paravertebral block also may be done for post-op analgesia for lateral
abdominal wall incisions. Monitors: standard, arterial line, urine output, CVP. IV access: at least 2 large
IVs; Cordis placement is common. Duration: 4-12hrs. EBL: 500ml-3L, possibly more. Position: any
position other than prone may be used: supine, lithotomy, lateral, etc., often with Trendelenburg.
Special equipment: fluid warmers, warming blankets. Special considerations: see below.

These cases should be treated like major abdominal cases as outlined in the general surgery section in
regard to blood loss, fluid management, and physiologic consequences. Blood loss can be insidious and
should be closely monitored. The potential for major vascular injury, diaphragmatic injury, hepatic
injury, or pneumothorax is always present. Several patients have suffered IVC or aorta injuries,
particularly during laparoscopic and open nephrectomy cases. Be vigilant, and prepare with monitors
and IV access appropriately.

Renal tumors are often in close proximity to major vessels including the IVC and may have associated
thrombus. Compression or retraction of the tumor and kidney can decrease venous return and cause
hypotension. Associated thrombus may be just in the renal vein or extend all the way into the IVC or
right atrium. In certain situations, cardiopulmonary bypass and a joint procedure with the cardiothoracic
surgeons is indicated. Clearly, the anesthetic management of these cases is profoundly different. These
cases are thankfully rare.

Open prostatectomy, now a rare procedure, is included as a major case given its association with large
blood losses, classically on the order of 1-2L. Reduction of blood loss is one way in which robot-assisted
laparoscopic prostatectomy has likely improved patient outcomes.

Chapter 3C. Anesthesia for Orthopedic Surgery

Orthopedic procedures comprise a significant percentage of cases at our three hospitals. The patient
population is very broad, ranging from the moribund elderly patient with many medical problems
coming for a fractured hip to a young athlete with a torn ACL. Typical scenarios for orthopedic cases
range from scheduled, elective surgery to urgent or emergent repairs for open fractures. Orthopedic
procedures make up a large part of add-on or late-night cases. The orthopedic surgeons are likewise
heterogeneous in terms of personality and ability. With time and experience you will discover who is
who, and what to expect intraoperatively. This guide will hopefully ease the learning process.

Regional anesthesia, or peripheral nerve blocks, will be a viable option for many orthopedic procedures
on the extremities. You will gain tremendous exposure to regional techniques throughout your
residency, especially so during your CA-2 and CA-3 regional rotations. The relevant and commonly-done
blocks will be indicated in each section.

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Many orthopedic procedures are ambulatory or same-day surgeries. The anesthetic technique for
these patients can be challenging and is geared towards quick wakeups, quick room turnovers, and good
control of pain and nausea. Any of these components could keep a patient in the PACU for an extended
period of time. Be mindful of these short procedures and tailor the anesthetic to the patients needs and
discharge goals.

Many orthopedic procedures involve use of a tourniquet. The tourniquet is intended to reduce blood
flow, reduce blood loss, and improve surgical visualization of the field. You may occasionally encounter a
surgeon who asks for controlled hypotension as well, with the idea that a normal or high BP can increase
flow past the tourniquet and cause bleeding. As always, weigh the risks and benefits to the patient, be
political, and consult with your attending.

Risks of tourniquet use include pain (increases with duration of use, especially with tourniquet times
>1hr) and the reperfusion syndrome that occurs when the tourniquet is released, due to washout of
metabolic waste products and relief of pain. These waste products typically lead to a transient rise in
CO2 levels, potassium, and lactic acid, with a drop in preload and core temperature. Tourniquet pain is
also notoriously difficult to treat. Tourniquet use on the lower extremity is associated with a higher
incidence of DVT. Lastly, the ischemia produced by a tourniquet makes it a relative contraindication in
patients with sickle cell disease.

DVT is a feared and common complication of orthopedic procedures, particularly on the knee and hip.
Prophylactic anticoagulation is often given, and compression stockings are the rule. Subcutaneous doses
of heparin are not a contraindication to regional anesthesia; see the ASRA guidelines in the section on
regional anesthesia. Regional anesthesia may lower the risk of DVT by improving regional blood flow via
vasodilation and the reduction of inflammatory mediators. However, the routine use of postoperative
anticoagulation can make the placement, use, and removal of an indwelling epidural catheter tricky.

Procedures on fractured long bones carry the risk of emboli, particularly fat emboli. This acute insult to
the right side of the heart may manifest as a sudden drop in etCO2, a drop in arterial blood pressure, and
hypoxemia. Other classic signs include mental status changes and petechiae, which typically appear 1-3
days post-op. The surgeons must be notified if this occurs; treatment is supportive.

Joint replacements involve the use of methylmethacrylate to as bone cement to hold the artificial joint
in place. This cement can cause a variety of intraoperative problems, including hypotension,
arrhythmias, increased pulmonary vascular resistance, hypoxia, and debris/fat embolization (the cement
itself expands within bone). The cement itself liberates heat via an exothermic reaction, which can burn
tissues. Treatment is supportive. The odor of the cement is distinctive; you will know when the surgeons
are applying it.

Chapter 3C-1. Anesthesia for Spine Surgery

Spine surgeries can be broadly placed into one of two categories: those with significant blood loss, and
those without. The anesthetic management is largely governed by the expected blood loss or fluid shifts.
Spine surgeries with the potential for significant blood loss include:

Instrumented fusion (anterior or posterior), especially multilevel

Spinal tumor resection
A combined anterior and posterior surgery

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 Corpectomy and fusion, especially multilevel
Redo surgery

Spine procedures with typically little blood loss include:

Discectomy
Laminectomy (without instrumentation/fusion)
Single-level surgery
Cervical spine surgery
Isolated minimally invasive spine surgery like XLIF or TLIF

Patients coming for spine surgery, particularly those having redo or major staged operations,
frequently have severe opioid-dependent pain and may be on staggering doses of narcotics. Many
of these patients will have been to our preoperative pain clinic. At UCSD, it is common to use a low-
dose intraoperative ketamine infusion (around 0.3-0.6mg/kg/h) which the literature supports as a
way to reduce post-op opioid requirements in these patients.

The Prone Position

A consideration of virtually every spine procedure is the necessity of placing the patient in the prone
position. This position demands special padding to protect the eyes, face, chest, breasts, arms, genitals,
and feet. The surgeons will attempt to properly pad and position the patient, but it is also our
responsibility to the patient that these things are done correctly. Padding of the face and protection of
the eyes, ears, and nose are primarily our responsibility. There is a very small but finite incidence of
postoperative visual loss following prone surgery. There are various causes including retinal artery or
vein occlusion and the much-feared posterior ischemic optic neuropathy (PION). The exact cause of
PION is unknown but is associated with long prone surgeries, blood loss, anemia, and hypotension. The
retinal vessel-related injuries are more associated with direct pressure on the eyes. At UCSD, most
practitioners use the Prone View head support which has a headrest, a foam cushion with cutouts for
the nose and eyes, and a mirrored base, to allow direct observation of the face. As a general rule, for
long surgeries in the prone position, we try to keep the patients BP within 20% of their baseline, the
hematocrit above 30%, the slightly above the level of the heart, and the saturation as high as possible.
Many cases that would otherwise be very lengthy are done in multiple stages across several days. An
arterial line is very useful in prone spine cases and is almost always indicated.

The prone position has implications for airway management and management of all our monitors and
lines. The airway must be carefully secured prior to turning to the prone position; if it is lost in this
position, it would be next to impossible to resecure it. One cardinal rule of prone cases is that the
patients gurney must be readily available after the patient is turned prone, in case of an emergent need
to flip them supine again (e.g., for reintubation). Similarly, every one of our monitors and IVs has the
potential to snag, kink or otherwise stop working after flipping the patient to the prone position. Extra
efforts must be made to ensure everything is secure, for the same reasons that the airway must be
secure.

One approach many of us take prior to flipping a patient prone is to disconnect every extraneous line
and monitor and then reconnect them after the flip. This minimizes the chance for tangle and snags and
allows the anesthesiologist to focus on the airway and proper placement of the eyes/head. The patient
is almost always stable enough to go unmonitored for 30 seconds. A typical sequence for this would be:

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 Induce anesthesia with the patient supine on their gurney.
Disconnect and cap off all but one IV line.
Ventilate with 100% O2.
When all team members are ready, disconnect the BP cuff, EKG leads, arterial line, and hang up
neatly for immediate reconnection.
Disconnect pulse oximeter and breathing circuit.
Flip patient.
Reconnect circuit and confirm ventilation/etCO2 while verifying face and eyes are free.
Reconnect pulse oximeter, then all other monitors and IV lines.

Spine Surgery with Significant Blood Loss

Technique: general. Monitors: standard, arterial line, urine output CVP.IV access: At minimum, 2 large
IVs. Often, 1 large IV plus a Cordis. Duration: anywhere from 1-16hrs, depending on the surgeon and the
case. EBL: several hundred ml to many liters. Position: usually prone; supine for anterior cases. Special
equipment: prone headrest, fluid warmers, forced-air warming blankets. One-lung ventilation may be
needed for anterior thoracic spine procedures. Special considerations: as below.

Blood loss and resuscitation is the key factor here. Stay on top of blood loss, and give fluids and/or
pressors liberally to maintain normal blood pressures. Invasive monitoring, urine output and frequent
ABGs can help guide therapy. Our surgeons typically use blood scavenging (cell-saver) to reduce need
for transfusion. Pay attention to all the potential negative sequelae of massive transfusion, which
includes coagulopathy, hypothermia, immune reactions, and electrolyte disturbances.

A surgeon might request an intraoperative wakeup test, which is exactly what it sounds like, and is
thankfully rare. This plan would be made known to you far in advance, because it requires specific
planning to allow timely and smooth patient emergence in the prone position. Monitoring of evoked
potentials has supplanted this technique to some degree.

More commonly, the surgeons will employ neurophysiologic monitoring (evoked potentials) to monitor
for impending neurologic damage. The choice of evoked potentials (sensory, motor or both) influences
the type and amount of anesthetic agent we can use. For example, motor evoked potentials are a
contraindication to neuromuscular blockers and a relative contraindication to higher levels of volatile
anesthetics, whereas sensory evoked potentials are a relative contraindication to nitrous oxide.
Typically, the neurophysiology team, a neurologist and a physiologist, will consult with us beforehand
and let us know which of our anesthetics they would like us to avoid. For more information, see the
neurophysiology section.

Some spine procedures will have an anterior component. The approach to the anterior thoracic and
lumbar spine is generally done by a non-orthopedic surgical team such as trauma surgery. If the
procedure has both anterior and posterior elements during the same surgical session, there is the
potential for multiple positioning flips during the case. As such, it is doubly important to make sure all
of our equipment is secure as outlined above. Thoracic anterior spine procedures are a relative
indication for one-lung ventilation, which allows the surgeons to have excellent access to the spine. The
techniques of one-lung ventilation will be discussed later. Anticipate if there will be a need for one-lung
ventilation and choose an appropriate ETT at the start of the case.

Spine Surgery without Significant Blood Loss

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Technique: general. Monitors: standard arterial line. IV access: usually one IV. Duration: 1-8hrs. EBL:
usually less than 500ml. Position: prone; supine for anterior cases. Special equipment: prone face mask.
Special considerations: as below.

In general, there is a low possibility of significant bleeding with these cases and thus, most of the
requirements for extensive spine surgeries do not exist. An arterial line may still be prudent depending
on the duration of the case and patient comorbidities because the same risk of blindness exists.

Anterior cervical procedures are done supine. Additionally, cervical procedures may be done for
impending or preexisting neurologic damage. These cases might involve evoked potentials and the same
considerations as above apply. Securing the airway in a patient with an unstable or compromised
cervical spine can present challenges. Awake intubation techniques to document stability of neurologic
function prior to induction of general anesthesia may be indicated.

Newer minimally invasive spinal fusions such as XLIF and TLIF are gaining popularity. Many of these
involve multiple smaller incisions and complicated retractor systems, and are done with the patient in a
lateral position. They may utilize a modified EMG-sensing instrument that the surgeon uses to detect
nerve roots; if so, neuromuscular blockers are contraindicated. Sometimes these low-blood-loss
procedures are used as one component of a multi-level fusion case that overall does have the potential
for major blood loss; be aware.

Chapter 3C-2. Anesthesia for Lower Extremity Orthopedic Surgery

As previously stated, most lower extremity procedures can be carried out under regional or neuraxial
anesthesia as alternatives to general. Notable exceptions include when there is long bone fracture and
the possibility of compartment syndrome (e.g., tibial fractures). In these cases we do not place blocks to
avoid compromising the surgeons ability to monitor for compartment syndrome. We routinely place
peripheral nerve blocks in certain types of elective, scheduled cases for post-op pain control and to aid
in the rehabilitation process. In these cases, the regional anesthesia team almost always does the block.

Hip Surgery

Technique: general, neuraxial, or both. The routine for elective total hip arthoplasty is general with
ETT and pre-op epidural, which is then removed early on post-op day 1. Some hip cases can be done
under spinal, epidural, or CSE, depending on the duration of surgery, patient factors, and surgeon
factors. Monitors: standard arterial line, urine output. IV access: one large IV. Duration: 2-3hrs for
first-time operations, potentially double for redo or complicated hip cases. EBL: usually < 1000ml,
although significant blood loss can go unnoticed within the joint and surrounding structures. Redo
operations can involve much more blood loss. Position: lateral or supine. Special equipment: none.
Special considerations: as below.

Hip fractures make movement painful for the patient and may preclude easy positioning prior to
induction of anesthesia. It may be easier to induce general anesthesia on the patients stretcher prior to
moving the patient to the OR table. Alternatively, if a neuraxial block is to be used, the block can be
placed with the patient already in the lateral position on their stretcher, and then moved after analgesia
has occurred.

There are a wide variety of hip surgeries, ranging from the purely elective total hip arthoplasty, to
various procedures for fractures, including percutaneous pinning, intramedullary nailing,

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hemiarthroplasty, or total arthroplasty. The blood loss usually varies with the invasiveness of the
procedure as well as the status of the bones involved: intact vs. completely shattered, younger patient
with OA vs. elderly patient with osteoporosis.

Total Knee Arthroplasty

Technique: general or neuraxial. The routine for elective TKA is GETA with femoral nerve
block/catheter a single-shot sciatic block. Monitors: standard, urine output. IV access: one large IV.
Duration: 3-4hrs, longer for redo or repeat procedures. EBL: < 200ml; a thigh tourniquet is almost
always employed. Position: supine. Special equipment: none. Special considerations: Risks of reaction
to cement, use of a tourniquet, and risk of DVT. The surgeons mobilize the leg and make a lot of noise
during the surgery, which may bother an awake or lightly-sedated patient. Neuraxial can be done per
patient request or patient need. Post-op pain is very significant. The above peripheral nerve blocks are
almost always done, and can significantly lower intraoperative anesthetic requirements.

Other Lower Extremity Surgery

Examples include knee arthroscopy, fracture repair (ORIF), amputation, and all types of foot surgery.

Many of these surgeries have the potential to be outpatient procedures and the anesthetic technique
should be tailored accordingly. For example, we avoid peripheral nerve blocks in patients undergoing
knee arthroscopy because they are discharged quickly, and would be unable to bear weight safely on a
blocked leg. A tourniquet is often employed; see above.

Technique: general, neuraxial, or regional. Sciatic, popliteal, femoral, or ankle blocks as applicable.
Monitors: standard. IV access: one IV will generally suffice. Duration: 1-4hrs. EBL: < 200ml for almost
every case. Position: usually supine. Certain cases such as talar reconstructions (posterior foot) may be
prone or lateral. Special equipment: none. Special considerations: tourniquet, possible outpatient
status.

Chapter 3C-3. Anesthesia for Upper Extremity Orthopedic Surgery

Shoulder Replacement or Reconstruction

Technique: General interscalene block for post-op analgesia. Monitors: standard. IV access: one large
IV. Duration: 3-4hrs. EBL: usually < 500ml. Position: beach chair (sitting), sometimes lateral with the arm
specially positioned. Special equipment: none. Special considerations: The beach chair position is
commonly employed. Here, the whole OR table is repositioned to place the patient in a sitting position,
as if in a chair. Attention must be paid to securing the patients thorax and head to the table well,
placing appropriate padding, and doubly-securing the airway. Perfusion to the brain is compromised in
the head-up position, so BP measurements on the arm or leg may need significant correction to
accurately reflect cerebral perfusion pressure.

Clavicle Surgery

Technique: general. Blocks usually do not apply due to the highly proximal nature of surgery. Monitors:
standard. IV access: one large IV. Duration: 3-4hrs. EBL: usually < 500ml. Position: supine. Special
equipment and considerations: none.

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Other Upper Extremity Procedures

Examples include:

Humerus fracture repair

Elbow surgery
Radius and ulna surgery
Nerve transposition
Hand surgery: from minor to extensive

Technique: general or regional to include interscalene, infraclavicular, axillary or more distal blocks as
applicable, continuous catheter for longer post-op analgesia. We tend to avoid regional anesthetics if
there is a possibility of nerve injury to avoid complicating the picture (e.g., nerve transpositions). Minor
hand procedures such as carpal tunnel release or Dupuytrens contracture release can often be done
under IV regional anesthesia (Bier block). Monitors: standard. Duration: 30min-4hrs. EBL: usually <
100ml; tourniquet is often used. Position: supine. The arm may be individually positioned. Special
equipment and considerations: tourniquet, outpatient status.

Chapter 3C-4. Anesthesia for Debridement and Skin Grafting

Incision & drainage or debridement of infected bone or soft tissue are common surgeries at UCSD, and
share some features with minor burn surgery, described below. Patients with osteomyelitis, sacral
pressure ulcers, or post-traumatic soft tissue defects often return for multiple surgeries; they may have
comorbidities related or unrelated to the surgery. Two examples are a morbidly obese ICU patient who
is intubated and on pressors, with a sacral pressure ulcer, or a previously healthy young patient with a
leg injury following an MVA. Often, these cases will also employ wound vacuums or skin grafting from
another site. In general, the procedures themselves are minor, but some may involve extensive blood
loss.

Technique: general or regional. Skin grafting from another site may make regional anesthesia either
desirable or undesirable. Monitors: standard. Duration: 30min-4hrs. EBL: minimal to < 500ml. Position:
highly dependent on the position of the lesion. Special equipment and considerations: possible
tourniquet.

Chapter 3D. Anesthesia for Vascular Surgery

Vascular surgery patients are some of the most ill patients we regularly take care of. Often, the vascular
disease co-exists with multiple other serious disorders and comorbidities, such as coronary artery
disease, systolic or diastolic cardiac dysfunction, cerebrovascular disease, diabetes, hypertension, kidney
disease, COPD, and a long history of smoking, to name a few. A careful and detailed preoperative
workup is necessary. These patients should be, and usually are, in their best medical state when they
present for surgery.

Common intraoperative issues seen with vasculopaths include the tendency for very labile BPs due to
their poorly-compliant vascular tree. Essential hypertension and vascular disease may mask
hypovolemia. Before induction, they may be normotensive, but upon induction, they may become
radically hypotensive, only to then become profoundly hypertensive and after intubation or surgical
stimulation. These wild BP swings can be difficult to manage and often occur despite our best efforts.

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Another issue is difficulty in obtaining IV access and invasive monitors. The same disease process which
necessitates the surgery often affects peripheral veins, making these patients notoriously tough sticks.
Compounding this problem is that these patients often have frequent blood draws or hemodialysis
access grafts/fistulas, all of which make securing IV access even more difficult. Similarly, the arteries can
be quite calcified or have had prior instrumentation and are challenging to cannulate. Unfortunately, it
is precisely this class of patients who most need an arterial line.

Minor Vascular Surgery

These will be considered as a group and include creation or revision of AV fistulas or AV grafts, I+Ds,
angiograms, and amputations.

Technique: most AV fistulas and angiograms are done under local/MAC or peripheral nerve block with
MAC, either of which is well-tolerated by the patient. GA or neuraxial are other options. Monitors:
standard usually suffices. IV access: one IV. Duration: 1-2hrs. EBL: minimal-300ml. Position: supine.
Special equipment: none. Special considerations: I+Ds and amputations are also discussed in the
orthopedics section.

Patients in renal failure needing a fistula are typically on the verge of needing dialysis, or have an
indwelling dialysis catheter. Ensure medical optimization prior to surgery. With that said, creation of an
AV fistula is a minor procedure, and most anesthesiologists feel perfectly comfortable taking a patient to
the OR with a potassium < 5.5-6.0 and no EKG changes. Recent trends in the patients potassium can be
helpful in deciding how to manage any hyperkalemia present.

If an indwelling catheter is to be used, you must be aware that these contain concentrated heparin to
keep the catheter from clotting off. The dialysis catheters should be avoided altogether because of the
risk of infection and compromising the line, so only use this line in absolutely dire circumstances. If it is
used, the heparin must first be withdrawn and discarded. Aspirating from the catheter until undiluted
blood appears, at least 2 times the dead space in the catheter, is the best way to accomplish this.
Similarly, when finished using the catheter, it must be reflushed with concentrated heparin. Consult with
your attending, a nephrologist, or the vascular surgeon.

Angiograms are often done on a special table which can move significantly in all horizontal planes. The
design is meant to allow the surgeon to track dye in the patients blood vessels by moving the table.
Often apnea or the patient holding their breath during these stages is required. Thus, either GA with
controlled ventilation or the alternative (a completely responsive, awake patient) is required. It is
extremely important to ensure that all lines and monitors be untangled and have significant length, with
extensions as necessary, to allow free motion of operating table and avoid snags. Generally, the entire
range of motion of the table is tested prior to starting the procedure to ensure that there is enough
length on our lines and no obstruction to table movement. Extensions may be necessary.

Moderate Vascular Surgery

These include peripheral bypass (e.g., femoral-popliteal bypass), thrombectomy, endovascular AAA
repair, and carotid endarterectomy (CEA). The unique requirements of CEA and endovascular AAA repair
will be explored further in the special considerations section.

Technique: almost always general. Some peripheral bypasses can be done under neuraxial techniques or
blocks, but often the length of the procedure and concomitant administration of heparin precludes

85
them. Similarly, endovascular AAA and CEA can both be done under local/MAC, but possibility of
catastrophic rupture and need for emergency GA makes this a poor choice. In addition, our surgeons
have very little experience with local/MAC or cervical plexus block/MAC for CEA; see more below.
Monitors: standard. Usually an arterial line for bypasses, always for CEAs and endovascular AAA repairs.
Urine output, EEG for CEAs. Possibly a central venous line for endovascular AAA repair. IV access: at
least one large IV. Blood loss is usually small, but surgery on large arteries always has the possibility of
rapid and significant blood loss. Duration: 3-6hrs. EBL: typically < 100ml, as vessels and bleeding are
rapidly identified and clamped. Vessel damage can generate much larger volumes of blood loss.
Position: supine. Special equipment: EEG for CEAs. Equipment to check ACT for heparin monitoring.
Fluid warmers. Special considerations: as below.

1. Endovascular AAA Repair

In endovascular AAA repair, the surgeon attempts to place a stent within the diseased portion of the
aorta, preventing further growth and/or rupture of the aneurysm. This procedure employs the movable
angiography table. This procedure is intended to be minimally invasive and generally does not cause
much physical perturbation to the patient. However, the possibility of rupture of the aneurysm during
the procedure is a feared complication. Thus, GA and an arterial line are usually employed, allowing for
the procedure to transition rapidly to an open one in the case of a catastrophic event. To this end, some
people also place a large central line (Cordis) or multiple large peripheral IVs for use in case of rupture.
This is usually not necessary. Open AAA repair is a much different procedure and is briefly described
below.

2. Carotid Endarterectomy

There are three basic goals in our anesthetic management of CEA: keeping the patients blood pressure
normal or supranormal (as during carotid clamping), monitoring for neurologic ischemia, and tailoring
the anesthetic for a quick wakeup to allow for rapid neurologic assessments. Maintaining the BP at the
patients baseline is important because the presence of carotid disease also implies generalized
atherosclerotic disease within the cerebral and coronary vessels. Cross-clamping of the operative carotid
makes the distribution of the ACA and MCA on that side dependent on a back pressure from collateral
flow through the circle of Willis. This back pressure depends entirely on MAP. To this end, most
anesthesiologists employ a phenylephrine or norepinephrine infusion from the outset of the case to
allow rapid titration and adjustment of BP. A nitroprusside infusion may rarely be needed to rapidly
lower a dangerously high BP. Minute-to-minute monitoring and adjustments clearly necessitate an
arterial line.

There are several ways to monitor for cerebral ischemia. The first and perhaps best way is to keep the
patient awake, so that they can then act as their own monitor for neurologic insult. Unfortunately, our
surgeons are not as comfortable with this technique and generally do not employ it. The EEG allows us
to monitor electrical activity as a surrogate for cerebral perfusion. For more definitive information,
consult an appropriate text. The monitor itself will be set up by our anesthesia monitoring technicians.
Large reductions in electrical activity from a baseline EEG obtained during a stable depth of anesthesia,
especially unilateral on the operative side during carotid clamping, are worrisome for ischemia and the
surgeon must be notified. At times, the EEG is not employed, depending on the surgeon and/or
anesthesiologist. Other methods to maintain or monitor cerebral perfusion employed by the surgeon
are creation of a temporary common-carotid-to-distal-internal-carotid shunt to bypass the operative site
and maintain flow, or the measurement of stump pressures after carotid clamping. The stump

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pressure is the pressure in the internal carotid distal to the clamped section, and theoretically reflects
the back pressure via collateral flow as described above.

A quick, smooth wakeup is a goal for several reasons. The surgeons desire serial neurologic checks as
soon as possible. A cough- and buck-free wake up reduces the risk of trauma or hypertension to the
freshly-incised artery. To this end, many of us employ techniques that allow for this. One common
method is to use a nitrous oxide-inhalational anesthetic, preferably desflurane combined with a fast
opioid technique, often remifentanil. All of these agents can be discontinued immediately before
surgery ends with a predictably fast recovery. Finding a balance between two conceptsthis surgical
incision is only mildly painful, but at the same time an agitated, thrashing, hypertensive emergence must
be avoidedmust be done to allow quick and pain-free awakening.

Monitoring of BP is key in the post-op period; excessive hypertension must be avoided, and many
patients are started on antihypertensives post-op. Patients who have had bilateral CEA are prone to the
effects of denervated carotid bodies, namely hypertension due to the lack of baroreceptor reflex and
loss of hypoxemic respiratory drive. The loss of hypoxemic drive could be particularly devastating in the
context of baseline COPD.

Major Vascular Surgery

Examples include open AAA repair and aortic, iliac, or mesenteric bypass. They are separated from the
surgeries above because the anesthetic management can be very different.

Technique: general. Thoracic epidural is often employed for postoperative pain, which can be severe.
Monitors: standard, arterial line, CVP, often a PA catheter, TEE. Urine output. IV access: at least two
large IVs, and usually a Cordis. Duration: 4-8hrs. EBL: 500ml to possibly many liters depending on
duration and intraoperative events. Position: supine. Potentially thoracoabdominal approach for higher
aneurysms. Special equipment: Warmers are mandatory as blood transfusions are exceedingly likely.
Equipment to check ABGs and ACT. Rarely, a spinal drain to remove CSF. Double-lumen ET tube for one-
lung ventilation may be necessary if a thoracic approach is to be taken. Special considerations: as
below.

Open AAA repair is one of the most labor-intensive and difficult cases we do. In the age of endovascular
AAA repair, it is also exceedingly rare, but continues to be a commonly-tested boards topic. Areas of
interest include:

The physiologic derangements brought on by aortic cross-clamping and unclamping

Cardiopulmonary comorbidities such as CAD, CHF, and COPD
Epidural analgesia in the context of systemic anticoagulation
Thoracoabdominal aortic aneurysms and the implications for lung isolation
Organ dysfunction brought on by aortic cross-clamping including renal injury, mesenteric ischemia,
and spinal cord ischemia

Given the infrequency of this surgery, a full discussion is outside the scope of this guide. Consult a
definitive reference for more details on this demanding case.

Aortic or iliac bypasses typically involve less blood loss and postoperative sequelae than a frank AAA
repair, and share many considerations with moderate vascular surgery described above.

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Chapter 3E. Anesthesia for Ophthalmic and Head & Neck Surgery

These surgeries are grouped together for one reason: they occur in close proximity to the airway,
making close communication between the surgeon and anesthesiologist absolutely essential. Few other
types of surgeries combine the unique demands and challenges presented by these cases. Other unique
issues are also discussed below.

It is common during these surgeries for the surgeon to be closer to the airway than the anesthesiologist.
The OR table is usually turned 90 or 180 away from the anesthesia machine, creating a twofold
problem: airway issues are both harder to detect and more difficult to correct. Further compounding the
problem is that the airway is often in the surgical field, covered under drapes, or under constant
manipulation by the surgeon. All of these create the need for effective communication with the surgeon
and the need to doubly-secure the airway from the outset to reduce the chance for complications. A
circuit extension is often necessary to reach from the anesthesia machine to the patient, and securing
any airway tubes (ETT, LMA, tracheostomy) is done with great care.

Many head & neck surgeries involve advanced cancer or other obstructive lesions in or near the airway,
which may make ventilation and intubation difficult or impossible. A thorough preoperative airway
exam and a careful plan, often after discussion with the surgeon, are needed. Awake intubation or
tracheostomy may be indicated. In the situation of a potentially difficult airway where GA is to be
induced, the surgeon should be present and equipped to perform an emergency tracheostomy.

Oral or dental surgery necessitates an airway that does not occupy the mouth. A nasal RAE (Right Angle
Endotracheal) tube is typically used for this purpose. The nasal RAE is designed to enter the glottis and
trachea, exit via a nostril, and take a 90 cephalad bend at the nostril toward the forehead, where it is
typically taped. In this way, the circuit can be placed away from the operative field. It is a long ETT, and
the distance from tracheal tip to 90 bend is proportional to the ETT diameter. Nasal RAEs can be placed
awake after topicalization, or after a standard induction. Usually, the RAE is soaked in warm water to
soften the PVC and avoid trauma to the nasal passages, and generous lubrication is used. If placed under
direct laryngoscopy, the RAE is advanced blindly into the oropharynx and then advanced past the vocal
cords using Magill forceps, or by forming a bend in the tube and guiding the tube towards the trachea.
Trauma or bleeding in the oropharynx may make intubation difficult and require an awake technique.

An oral RAE is generally used for nasal surgery. Like the nasal RAE, it is designed to curve caudad away
from the operative field via a nearly-180 bend that is meant to reside at the lower incisors. Also like the
nasal RAE, the distance from tip to this bend is proportional to the ETT diameter. Oral RAEs can be
placed in all the same ways as a standard ETT, with the caveat that the preformed bend may require a
rigid stylet to straighten the tube for placement.

Occasionally an MLT (Micro-Laryngeal-Tracheal) tube is used for vocal cord surgery and endoscopic
surgeries. This tube is designed to be smaller in diameter and allow the surgeon to work around the
tube and vocal cords. The other design components are intended to overcome the traditional
disadvantages of smaller standard ETTs. Thus, an MLT tube is longer (will reach the trachea in full sized
adults) and is stiffer.

Armored or reinforced ETTs have a metal framework in them that resists kinking or obstruction from
external pressure. They are not the same thing as a laser tube; see below.

Airway Fire

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Head & neck surgery routinely employs the use of a laser. Specific issues arise with laser use, the most
devastating being an airway fire. The smoke and vaporized gas must be appropriately scavenged by the
surgeon as it represents a biohazard, and eye protection is mandatory for personnel and the patient. To
prevent an airway fire, the following maneuvers are employed:

FiO2 as low as the patient can tolerate, preferably 21%.

Nitrous oxide must be avoided, as it supports combustion.
Standard tubes (PVC) are highly combustible. A metal laser tube is designed to reflect and disperse
laser light and is non-combustible.
Cuffs should be filled with saline with dye (e.g., methylene blue) to signal rupture from the laser and
decrease combustion.
Saline-soaked gauze should be used to pack all other parts of the airway.
Water should be immediately available to extinguish fires.

In the event of an airway fire, take the following steps:

Stop ventilation.
Remove the ET tube.
Turn off oxygen.
Extinguish the flames.
Ventilate and reintubate the patient.
Evaluate damage to the airway; chest X-ray, bronchoscopy, ABG, or lavage may be needed.

Surrounding structures are also at risk of fire, including the drapes around the patients head.
Insufflation of oxygen (nasal cannula, oxygen mask, blow-by oxygen) can combust these drapes if
cautery is being used near that oxygen.

Coughing and bucking can raise venous, intraocular, nasal and inner ear pressures; cause bleeding and
disruption of suture lines; and even dislodge surgically placed grafts or artificial membranes. Likewise,
hypertensive episodes can exacerbate these problems. These problems are most often encountered
during induction, intubation, and emergence. Therefore, many ENT and ophthalmic surgeons ask for
deep extubations. The flipside to this coin is that many ENT procedures produce significant blood,
secretions or edema in close proximity to the airway, placing the patient at risk for aspiration or
postoperative obstruction. When these surgeons ask for a deep extubation what they really want is a
smooth emergence devoid of coughing or hypertensive episodes. Deep extubations may be suitable for
some patients, while for others the anesthetic technique is geared towards a smooth but fully awake
extubation (e.g., with narcotics).

In sum, these surgeries can test even the most even-keeled persons patience. It can be difficult to
maintain good humor after a day of sharing the airway, constant circuit disconnections by the surgeon,
and repeated requests for deep extubations in patients with significant aspiration risk. Remember that
our duty is to the patient, and that you can always defer to your attending.

3E-1. Anesthesia for Ophthalmic Surgery

In general, most eye procedures are relatively noninvasive. Postoperative pain is minimal. However,
PONV is a significant problem. Most patients should receive some form of PONV prophylaxis. The issues
of keeping intraocular pressure to a minimum are discussed above. The following common anesthetic

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situations raise intraocular pressure:

Coughing and bucking via increased venous pressure

Increased systemic arterial pressure (modest effect)
Succinylcholine (modest effect)
Hypercapnia
Topical anticholinergics, which decrease aqueous drainage from the eye, thereby increasing
pressure; IV anticholinergics seem to have little to no effect

Ophthalmologists sometimes place a bubble of gas (usually sulfur hexafluoride) in the eye to assist with
healing and immobility of intraocular structures, like a detached retina. These gas bubbles will avidly
take up nitrous oxide, potentially leading to disastrous increases in intraocular pressure. Therefore,
nitrous is to be avoided before placement of a gas bubble and for up to 2 weeks afterwards. After this
point, the bubble has been absorbed into the systemic circulation and those risks do not apply.

Many eye surgeries are performed as outpatient procedures. Quick emergence and discharge times are
desirable.

The oculocardiac reflex can result from pressure or traction on the eye or the extraocular muscles. The
reflex involves trigeminal nerve afferents and vagal efferents. Bradycardia is the most commonly seen
arrhythmia, but ectopy or even asystole can occur. The reflex is usually mild and is controlled in the
following ways:

Tell surgeon to stop whatever traction or pressure is being applied.

Atropine or glycopyrrolate as necessary.
Deepening anesthesia.
If persistent, retrobulbar blocks can be done to block the afferent limb of the reflex.

Minor Eye Surgery

Examples include cataract removal, vitrectomy, and blepharoplasty.

Technique: usually topical anesthesia or local/MAC. Some patients may require general anesthesia.
Retrobulbar or facial nerve blocks are also a possibility, and are usually performed by the
ophthalmologist. Monitors: standard. IV access: one IV. Duration: 30min-2hrs. EBL: minimal. Position:
supine, head away from anesthesiologist. Special equipment: none. Special considerations:
oculocardiac reflex, lack of access to the airway, ambulatory surgery.

Major Eye Surgery

Examples include retinal detachment repair, strabismus surgery, ruptured globe repair.

Technique: usually general. These surgeries are more invasive, longer in duration, and often require a
completely still surgical field. Retrobulbar or facial nerve blocks are also a possibility, and are usually
performed by the ophthalmologist. Monitors: standard. IV access: one IV. Duration: 1-4hrs. EBL:
minimal-100ml. Position: supine, head away from anesthesiologist. Special equipment: none. Special
considerations: oculocardiac reflex, lack of access to the airway, PONV.

Ruptured globes are open-eye injuries and the goal is to avoid elevations of intraocular pressure,

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especially during intubation and emergence. Succinylcholine should probably be avoided, and deep
anesthesia and paralysis should be achieved before intubation. On the other hand, emergency surgery
necessitates rapid control of the airway and minimization of aspiration risk, for which succinylcholine is
ideal. Deep extubation is more controversial; see above. Avoiding PONV and its associated increases in
intraocular pressure is important.

Chapter 3E-2. Anesthesia for Head & Neck Surgery

Head & neck surgeries can be broadly classified as endoscopy, minor surgery, and major surgery.

Endoscopy

Examples include laryngoscopy, bronchoscopy, and esophagoscopy, or any combination thereof.

Technique: general with profound muscle relaxation. Monitors: standard. IV access: one IV. Duration:
30min-1hr. EBL: minimal. Position: supine, typically with aggressive neck and head extension, head away
from anesthesiologist. Special equipment: as needed, laser ETT, MLT tube, oral RAE, armored ETT.
Special considerations: Use of a laser, sharing the airway with the surgeon, instrumentation near the
endotracheal tube.

Some of these cases are done with a non-sealed airway via oxygen insufflation and spontaneous
ventilation, precluding the use of volatile anesthetics, control of the exact FiO2, and positive-pressure
ventilation. Many patients have masses or distorted anatomy of the upper airway which may cause
difficult ventilation or intubation. A thorough airway exam and plan is needed. Typically, the surgeon has
done at least an abbreviated examination, e.g., nasopharyngoscopy with topical anesthetic, in the office.
Postoperative airway issues can arise from surgical instrumentation and manipulation, edema, or
secretions.

Profound paralysis may be needed to ensure a motionless surgical field. Repeated small doses or an
infusion of succinylcholine is an option, bearing in mind the possibility of cholinergic effects or a phase II
block; see the neuromuscular blockade section. Alternatively, non-depolarizing blockade can be used,
keeping in mind the short nature of most of these procedures.

These procedures can be profoundly stimulating, but typically cause minimal postoperative pain. Short-
acting analgesia, deep anesthesia, and muscle relaxation are key to avoid wide swings in BP.

Minor Head & Neck Surgery

Examples include nasal surgery, ear surgery, oral and maxillofacial surgery, and thyroid/parathyroid
surgery. Tracheostomy itself is a relatively benign procedure, but is often performed on patients with
significant comorbidities.

Technique: general. Monitors: standard. IV access: one IV. Duration: 1-4hrs. EBL: generally < 300ml.
Position: supine, head away from anesthesiologist. Special equipment: laser ETT, oral RAE for nasal
procedures, nasal RAE for oral/mandibular procedures, armored ETT, circuit extension for airway.
Special considerations: PONV due to blood flowing into stomach, need for smooth emergence for neck
incisions, lack of access to the airway. Preexisting airway issues may make ventilation or intubation
difficult, e.g., nasal obstruction from polyps, blood in oropharynx from mandibular fracture, limited
mouth opening.

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Head & neck surgeons will often ask for hypotension to decrease intraoperative bleeding. This must be
considered on a case-by-case basis as the patients physiology allows. The need to be political and
maintain a good relationship with the surgeon should be stressed. The surgeons often place cocaine-
soaked pledgets in the nose to cause vasoconstriction, decrease bleeding and provide some anesthesia;
seeing the effects of systemic absorption (hypertension, tachycardia, and arrhythmias) is not
uncommon.

During many of these procedures significant amounts of blood and secretions can collect near the
airway and in the stomach. This can contribute to PONV and risk of aspiration. The stomach should be
suctioned prior to emergence. Oropharyngeal throat packs are often employed to soak up debris.
These fluids are the primary reason that deep extubation is often unsafe, and can also contribute to
laryngospasm and bronchospasm.

Procedures on the ear (e.g., tympanoplasty) create situations where closed air spaces can form, creating
a hazardous situation with nitrous oxide. Normally, the Eustachian tubes provide a vent for nitrous oxide
buildup; however, these are typically obstructed in many patients with chronic ear problems. Nitrous is
best avoided in this situation.

Patients with mandibular fractures must be suspected of having a basilar skull fracture, which is an
absolute contraindication to placing a nasal ETT. Recognize this possibility, review appropriate imaging,
and confer with the surgeon as needed.

Tracheostomy in a patient with an indwelling ETT merits discussion here. Always ensure that the
tracheostomy tube cuff has been tested by the surgeons, just as you would for an ETT you are going to
place. The surgeons proceed with dissection until they are quite close to making incision into the
trachea itself. At this point, the FiO2 is reduced as low as possible, ideally < 30-50%, to decrease the risk
of airway fire. The cuff of the ETT is deflated to avoid puncture by the surgeons, and the tape securing
the ETT in place to the face is loosened. From this point on, ventilation may be difficult or impossible
due to large leaks. The surgeons enter the trachea, and will ask you to pull the ETT back until it is just
above the incision. The surgeons then place the tracheostomy tube with a flexible airway connector, and
will hand off this connector to you, who will then confirm ventilation and etCO2. The ETT can then be
removed. Depending on the speed of the surgeon and the patients oxygenation status, significant
desaturation can occur. If necessary, the surgery can be stopped, tracheostomy removed, and the ETT
moved distal to the incision and cuff reinflated for further ventilation and oxygenation.

Major Head & Neck Surgery

These cases include extensive maxillofacial reconstruction, oral/lingual/pharyngeal/laryngeal tumor

resection, laryngectomy, pharyngectomy, radical neck or face dissections, with or without free flap from
the chest or other location. They are sometimes done in conjunction with plastic surgeons.

Technique: general. Monitors: standard arterial line, urine output; CVP may be useful. IV access: at
least two IVs. Duration: 4-12hrs. EBL: 500ml-2L depending on extent of surgery. Position: supine.
Special equipment: facial nerve monitors often employed; see below. RAE or armored tubes as needed.
Awake tracheostomy under local anesthesia may precede general anesthesia and the surgery itself. Fluid
warmers. Circuit extension. Special considerations: lack of access to the airway, potential difficulty
securing the airway due to preexisting disease.

These surgeries in general are lengthy and extensive dissections with the potential for significant blood

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loss. Keeping the patient warm and adequately resuscitated is important. Often, because of the
proximity of disease and surgery to the airway, the patient will remain intubated or have an
intraoperative tracheostomy performed; see above.

If a free flap will be used, the surgeons will often request that no vasopressor be given due to concerns
over graft ischemia. Clearly, maintaining the patients BP is important, and the effect of small amounts
of vasopressor on graft circulation is questionable, but within these parameters, it is probably best to
avoid pressors such as phenylephrine or epinephrine. Volume resuscitation and keeping the patient
warm will improve graft circulation.

Depending on the location of the surgery, the surgeons may monitor the facial nerve to avoid damage
from dissection. They will request that no neuromuscular blockers be used in this situation.

Dissection around the carotid sinus can cause bradycardia, other arrhythmias, or wild swings in BP.
Treatment consists of cessation of surgical manipulation, supportive treatment, or infiltration of local
anesthetic around the carotid sinus. Bilateral neck surgery, including dissections and endarterectomy,
can result in denervated carotid bodies, causing loss of hypoxemic ventilatory drive and baroreceptor
regulation of BP.

Chapter 3F. Anesthesia for Interventional Pulmonology

The pulmonology department at UCSD is particularly active and their cases constitute a significant
portion of the anesthesia services provided in and out of the OR. While pulmonologists typically perform
simple flexible bronchoscopy with topical anesthesia and light sedation (without anesthesiologists), the
more invasive procedures described below warrant both the provision of general anesthesia and the
expertise of an anesthesiologist.

Rigid Bronchoscopy with or without Tracheal/Bronchial Stenting, Lasering, or Dilation

Many patients who have had a tracheostomy go on to develop subglottic strictures, obstructive scar
tissue, or tracheomalacia. UCSD is a referral center for many patients with chronic periglottic and
subglottic airway disorders in this setting. These patients often have rigid bronchoscopy and
intervention serially over many months or years, have comorbid pulmonary disease such as COPD or
interstitial lung disease, have a tracheostomy or tracheal/bronchial stents in place, or are dependent on
home O2. This is a sick class of patients with tenuous respiratory function undergoing an intensely-
stimulating procedure with a shared airway.

Technique: general. Monitors: standard. IV access: one IV. Duration: 10min-2hrs. EBL: minimal.
Position: supine with full head extension. Special equipment: Bain circuit (provided by the anesthesia
technicians), IV infusion pumps, methylprednisolone. Special considerations: as below.

Despite their advanced respiratory disorders, many of these patients do not go to pre-op clinic since
they have been anesthetized at UCSD before and, in all truth, the anesthetic would not be postponed for
medical optimization; these patients need the procedure.

The anesthetic most typically employed is TIVA with propofol, lidocaine, alfentanil, and
succinylcholine/nondepolarizer. The reasoning follows. Since the airway will be entered with a rigid
bronchoscope that is capable of ventilating but that is not sealed, a volatile anesthetic cannot be used.
Aggressive instrumentation of the airway also requires profound muscle relaxation to avoid coughing

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and patient movement during crucial maneuvers in the trachea. However, many of these procedures are
short (< 15min), and require very short-acting agents. For longer procedures, a nondepolarizing NMB
can be used; the pulmonogists will let you know if this is the case.

The typical approach is as follows: preoxygenation, IV induction with propofol and alfentanil,
establishment of a mask airway, placement of the rigid bronchoscope by the pulmonologist, and
continuation of the propofol infusion. Oxygenation is done by connecting the circuit to the ventilating
port of the bronchoscope and bagging manually, sometimes furiously, and often with the high-flow O2
flush valve since the airway is not sealed. Often, minimal or no etCO2 is detected but you may be able to
see airway distension and fogging via the bronchoscope screen. Alfentanil and succinylcholine are
redosed, with attention to bradycardia with succinylcholine. Methylprednisolone is given to reduce
airway inflammation and edema. The propofol infusion is terminated as soon as is practical to allow
rapid awakening. Emergence is done with a mask airway, and is often stormy given the intense pro-
tussive effect of the procedure. Humidified O2 is the rule in PACU given the airway irritation that occurs.

Endobronchial Ultrasound (EBUS)

Another common pulmonology procedure we are asked to provide anesthesia for is EBUS. The
procedure involves ultrasound-guided biopsy of suspicious lymph nodes via flexible FOB. Often we are
asked to place a CookGas intubating LMA instead of an ETT, with the idea that this supraglottic airway
allows access to the entire trachea and has a shorter and large-diameter airway tube to facilitate the
FOB. However, an ETT may be indicated depending on patient characteristics. We may also be asked to
keep the patient spontaneously ventilating in order to reduce the risk of pneumothorax. The
pulmonologists are quite good at clearly communicating these preferences. After induction of general
anesthesia, the pulmonologists will provide topical anesthesia to the tracheobronchial mucosa.

Technique: general. A TIVA is preferred given the frequency with which the airway seal is broken to
place/remove the FOB. Monitors: standard. IV access: one IV. Duration: 30min-2hrs. EBL: minimal.
Position: supine. Special equipment: CookGas LMA. Special considerations: as above.

Chapter 3G. Anesthesia for Transplant Surgery

The most commonly performed organ transplantations at UCSD are kidney and liver transplants.
Pancreas transplantation is uncommon at UCSD, but shares many considerations with kidney
transplantation. Anesthesia for organ procurement will follow at the end of this section. Lung
transplantation will be addressed in the chapter on anesthesia for cardiothoracic surgery. Heart
transplantation is usually done by our CT anesthesia fellows, and will not be discussed in this guide.

The most important factors to consider in transplant surgery are the physiologic derangements
imparted by the patients organ failure. In the case of kidney transplantation, the most obvious is renal
failure, which predisposes the patient to volume overload, volume sensitivity, electrolyte abnormalities,
acidosis, hypertension and anemia. Elimination of many drugs may be impaired. Patients should be
medically optimized prior to surgery. Depending on the timing of dialysis, they may be relatively volume
overloaded or underloaded, with their electrolyte and acid/base status under varying degrees of control.

End-stage liver patients are some of the most ill patients anesthesiologists care for, and a liver
transplantation is one of the largest, most labor-intensive cases that we do. To begin, the patients liver
dysfunction can cause, or co-exist with, dysfunction of the neurologic, cardiac, pulmonary, GI, renal, and
hematologic systems. Poor or non-existent liver function predisposes patients to coagulopathy, anemia,

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hypoalbuminemia, ascites, and a high-cardiac-output, low-SVR state. Metabolism of drugs and hepatic
synthetic function are deranged. There may be hepatorenal syndrome, hepatopulmonary syndrome, or
portopulmonary hypertension. Furthermore, the case itself involves significant and rapid blood loss,
fluid shifts, and major physiologic perturbations, which will be considered in the section below.

Associated disease, such as diabetes or hepatitis C, may be the cause or a result of the organ failure, and
further complicates these cases. For cadaveric transplants of any organ, there is a limited window of
viability. Transplants occurring after this window have a marked reduction in organ function and
survival. For the liver, the window is generally 12hrs, and for the kidney, the window is generally within
24hrs (the sooner the better). Thus, there is usually an urgency placed upon transplants and they should
proceed in a timely manner. They are not purely elective cases, with the exception of schedule, elective
living-related kidney donations and transplantation.

Chapter 3G-1. Anesthesia for Kidney Transplantation

Kidney Transplant Recipient (Living-Related or Cadaveric)

Technique: general. Monitors: standard, urine output, rarely arterial line, rarely central line for CVP
measurement. IV: one large IV should suffice. If the surgeon requests thymoglobulin to be given, a
separate dedicated IV line will be needed. Duration: 3-4hrs. EBL: < 500ml. Position: supine. Special
equipment: mannitol, furosemide, methylprednisolone or other immunosuppressive agents; the
surgeon will ask for this. Heparin and protamine. Special considerations: Fluid management must be
judicious, with the conflicting factors of increased insensible losses from an open abdominal case being
balanced against oliguria or anuria and poor tolerance of volume shifts.

Prior to anastomosis of the kidney to the iliac vessels, heparin will be asked for. Depending on the
duration of anticoagulation, protamine may be needed. See the cardiothoracic section for more
information about protamine.

Before reperfusion of the kidney, the surgeons will often ask for mannitol (0.5-1g/kg) to be given to
create osmotic diuresis of the new graft. If urine output is not brisk following graft reperfusion,
furosemide may be requested. A tinge of blood in the new urine flow is common; overt blood should be
brought to the surgeons attention. Methylprednisolone will be asked for by the surgeons at the
appropriate time; fast administration has been associated with arrhythmias.

While these patients are typically ill, the case itself is not terribly complicated and usually does not
require invasive monitoring. They generally go quite smoothly.

Living-Related Kidney Donation

Technique: general. Monitors: standard. IV: one IV. Duration: 2-4hrs. EBL: < 500ml. Position: supine, or
in a 45-90 lateral position for laparoscopic procurement. Special equipment: mannitol, heparin,
protamine. Special considerations: Living-related kidney donors are typically otherwise healthy patients
and the donor operation is not a major cause for concern. The case can be done either laparoscopically
or open. Typically, these cases are timed simultaneously with the recipient, with the goal being the
donor kidney being harvested just before the recipient is ready for implantation. This requires two OR
teams.

Mannitol will be requested by the surgeon prior to harvest of the kidney to promote diuresis. Heparin

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will also be asked for prior to clamping of the renal vessels and may be reversed with protamine.

Chapter 3G-2. Anesthesia for Liver Transplantation

Technique: general. Monitors: standard, arterial line, usually a femoral A-line, urine output, CVP, PAC,
TEE. IV access: as much as possible. Routine lines for a liver transplant include one peripheral IV, a
Cordis (a 9Fr sheath/introducer), and a triple-lumen Edwards catheter (central line with 3 large bore
components). Rapid infusion catheters can also be used (essentially a mini-Cordis in a peripheral vein).
Duration: 4-12hrs. EBL: Varies depending on surgeon but can be large. There is no maximum. 100+ unit
transfusions were not uncommon in the past, but low blood loss/transfusion cases are becoming more
common. Position: supine. Special equipment: TEE, warming blankets, fluid warmers to warm IV lines,
TEG, perfusionist to aid with massive transfusion. Special considerations: as below.

Liver patients should be regarded as full stomachs due to compression from ascites, the urgent nature
of the case, and/or recent GI bleeding. Thus, they should have a rapid-sequence induction with cricoid
pressure.

Due to peripheral vasodilation throughout the case, caused by both the patients baseline disease and
acidosis and hypocalcemia at critical portions, a radial arterial line may not accurately reflect the
patients central BP. For this reason, a femoral arterial line is often placed after induction.

The goal of a liver transplantation is to keep everything as normal as possible. Frequent ABGs and TEGs
are checked, often q30min or more frequently depending on the stage of the case. Acidosis, anemia,
coagulopathy, and electrolyte abnormalities are aggressively treated with an attempt at normalization.
Similarly, we attempt to maintain all vital signs within the normal range whenever possible.

Thromboelastography (TEG)

A thromboelastogram is a technique of monitoring coagulation that has proven invaluable for

intraoperative monitoring and treatment. TEG requires a special machine, is run by the hematology lab,
and requires at least 1 hour notification prior to use. For this reason, it is typically employed by us only
for liver transplantations and for on-pump cardiac surgery. A blood sample (3ml) is sent to the lab and
placed in a special cuvette. A small pin is placed in the blood and rotates to and fro. As the blood clots,
its viscosity and clot strength influence the rotation of the pin, and the forces detected and recorded by
the machine. Many variables are provided, but the ones we are most interested in are:

1. R value: this is the time to first clot formation, generally reflects the initial stages of clot formation
(factor-dependent) and also reflects overall clot formation. Low R values are generally treated with
FFP.
2. Angle (): reflects the rapidity of clot amplification (cross-linking) once formation begins. Low values
reflect inadequacy in fibrinogen, and are generally treated with FFP or cryoprecipitate.
3. Maximum amplitude (MA): reflective of platelet presence and function, and overall clot strength.
Defects may be related to either of the above, or to platelet deficiency/dysfunction.

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Each of the parameters on the TEG diagram above has a normal range, and the sample TEG is compared
to those normals. These values are evaluated at 30min and 1hr of incubation. Therefore, TEG
information is at least 30 minutes old and cannot be used to titrate minute-to-minute therapy. However,
every attempt is still made to normalize abnormalities seen on the TEG. Frequent TEGs present a more
linear, continuous picture.

The perfusionist is invaluable in assisting us with meeting transfusion and volume requirements. The
perfusion machine is capable of delivering very high flows of crystalloid, colloid, RBCs, or FFP. Typically,
we provide the perfusionist with two of our large lines, generally the two smaller lumens of the triple-
lumen Edwards catheter. In this way, the perfusionist can maintain high flows without preferential flow
through one line. Working with the perfusionist requires close communication; the perfusionist
generally will not give anything we do not ask for. Common instructions to the perfusionist are to
continuously give blood products in a variety of ratios (e.g. 1:1 pRBC:FFP) or flow rates (e.g. 50ml/min),
titrating to CVP or PA pressures, or simply at intermittent intervals based on patient needs. It is
generally advisable to leave all blood product infusions to the perfusionist, freeing our remaining lines
for drips, boluses of drugs, and platelets.

Cell-saver (blood salvaging) is also employed unless the patient has a carcinoma or infection. The
perfusionist or our anesthesia monitoring technicians usually handle the processing and washing of RBCs
before giving the blood back to us to be infused. It should be noted that the bag of Cell-saver blood has
air in it. Unlike a bag of PRBCs, a bag of Cell-saver cannot be pressurized due to risk of venous air
embolism.

The presence of renal failure, with or without hepatorenal syndrome, often means that continuous
veno-veno-hemodialysis (CVVHD) will be employed. The nephrology team will be present in the OR
throughout CVVHD, and another central venous line will be needed, often femoral. The CVVHD machine
can help with maintaining the patients pH and electrolytes (notably potassium) at normal levels,
depending on the dialysate used. The nephrology team can also run the patient hypo-, hyper-, or
euvolemic depending on our joint plan and patient needs at that time. Clearly, precise communication
with the CVVHD team is also needed. Fluid management and acid/base status can be very complicated
with surgical losses and the anesthesia, perfusion, and CVVHD teams all contributing to changes in
patient status. Citrate is used as an anticoagulant, which contributes to hypocalcemia; see below.

The two most common and most important electrolyte abnormalities seen are hypocalcemia and
hyperkalemia. Hyperkalemia results from massive transfusion, acidosis, potassium washout of the

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transplanted organ, and/or concomitant renal failure. It should be aggressively managed and is most
relevant during reperfusion of the new liver as below, but deaths have occurred from hyperkalemia
even hours after the neohepatic phase. Frequent monitoring is thus mandatory and is done via serial
ABGs. The perfusionist has an ABG machine in the OR with us, and can run nearly-real-time ABGs when
we provide the sample.

Hypocalcemia also results from several mechanisms. End-stage liver patients are frequently
hypoalbuminemic at baseline. Massive transfusion and CVVHD impart a high citrate load, which binds
calcium. The diseased liver also has severely decreased metabolism of citrate, and during the anhepatic
phase, there is no liver whatsoever to metabolize citrate. Frequent ABGs also help us monitor this
situation. Massive calcium requirements, over 10g of calcium chloride, are not uncommon. A continuous
calcium infusion is often employed.

A liver transplant has three distinct phases:

1. Pre-anhepatic: from induction of anesthesia until clamping of all hepatic vessels. The old liver is
dissected out, and there may be massive blood loss if there is extensive perihepatic scarring. By the
end of this phase, the liver remains connected only via the IVC, portal vein, hepatic artery, and
common bile duct. Normalization of all abnormalities proceeds. Volume loading, so that the patient
can tolerate the preload reduction that follows, is done.
2. Anhepatic: from clamping of the hepatic artery, suprahepatic IVC, infrahepatic IVC, and portal vein
until these vessels are fully anastamosed and their clamps are removed (reperfusion). The IVC is
typically completely clamped at this stage, with a dramatic reduction in venous return and potential
for hypotension. Moreover, venous congestion typically causes engorgement of veins distal to the
clamp, resulting in increased bleeding and possibly ischemia of the bowel. Veno-veno bypass is
considered at this stage if the patient cannot tolerate complete or partial IVC clamping, and may use
any right-sided central lines we have. Thus, the PA catheter and triple lumen Edwards is better
placed on the left side. Veno-veno bypass does not require heparin but does carry a high risk of air
embolism. During this period, there is zero metabolism of lactate and citrate leading to acidosis and
hypocalcemia with possible hyperkalemia. Aggressive resuscitation continues, and typically a
buffer of mild hypercalcemia, mild hypokalemia, and mild alkalosis is induced prior to reperfusion.
3. Neohepatic: from reperfusion to closure of the abdomen. This is the most dramatic phase of the
case. The vessels to the new liver are unclamped, reperfusion of the organ commences, and a
cholecystectomy is performed. The reperfusion of the liver and unclamping of vessels creates severe
physiologic perturbations, not unlike unclamping of the aorta (see the section on open AAA repair).
Washout and reperfusion of the new liver and previously ischemic organs introduces high
concentrations of acid, high potassium, CO2, lactate, adenosine, etc. The preservative solution is also
washed out, and it (and the liver) were ice-cold until the start of the anhepatic phase. Taken
together, acidosis, hyperkalemia, volume, and hypothermia constitute a massive insult to the right
side of the heart, and cause profound hemodynamic changes. Acidosis and metabolic waste
products cause a massive drop in SVR, a decrease in cardiac contractility, and arrhythmias.
Hyperkalemia exacerbates this situation and can cause arrest on its own. The serum potassium
concentration generally rises 1-2mEq/L during this phase. Therefore, we typically take the following
steps prior to reperfusion of the new liver, always done in conjunction with the surgeons, who are
well aware of the dangers of reperfusion:

Everything is normalized as much as possible prior to unclamping.

Some practitioners routinely start a dopamine, epinephrine, or norepinephrine infusion prior to

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 unclamping for positive inotropic/pressor effects.
Slight hypercapnia is allowed during the anhepatic phase, but just prior to reperfusion, a
respiratory alkalosis is induced. This will help with combating acidosis and drives excess
potassium intracellularly.
All anesthetics are d/cd and the patient is ventilated with 100% O2. Midazolam is useful here.
Several ampules of sodium bicarbonate and calcium are placed in line, as well as bolus syringes
of vasopressor. Of note, bicarbonate and calcium should not be given at the same time through
the same IV because calcium carbonate (chalk) will precipitate.
These ampules are usually given immediately before or after unclamping, knowing that
hyperkalemia and acidosis are inevitable. We do not draw labs at this point, as the clinical
situation changes literally on a second-to-second basis. Titration to BP and normalizing EKG
changes (if any) are the goals.

After the new liver has been reperfused, it will typically start metabolizing waste products as well as
synthesizing proteins and factors within the hour. Typically is the key word here; sometimes the
previous coagulopathy and hypocalcemia persist, depending on graft function and health. It is still
important for us to maintain homeostasis and check labs frequently. A slight coagulopathy is typically
tolerated at this point. The goal is to avoid thrombosis of vessels of the new liver and return of
endogenous synthetic function. Air embolism is also a possibility after reperfusion as air can enter the
donor liver during harvesting. Thorough flushing by the surgeons decreases this risk.

Due to the massive transfusions, fluid shifts, and length of the case, these patients are usually kept
intubated post-op and allowed to recover in the ICU. However, with shorter cases with minimal
transfusion requirements and good liver function, extubation in the OR may be considered.

The presence of hepatitis B will necessitate the use of hepatitis B immune globulin (HBIg). This is
started during the anhepatic phase at the direction of the surgeon.

Similar to kidney transplants, an immunosuppressive such as methylprednisolone is given at induction

and after the new organ is implanted; this will be specifically requested by the surgeon.

Chapter 3G-3. Anesthesia for Organ Procurement

Technique: general. Monitors: standard. These patients often have additional monitors that have been
placed during their hospital course. IV access: one IV. Duration: 1-4hrs. EBL: n/a, but < 500ml for our
portion of the procedure. Position: supine. Special equipment: none. Special considerations: see below.

The most common type of organ donor is a brain-dead, ASA6 donor. These donors have met all criteria
for brain death, with no cortical or brainstem function, and in this sense are not actually patients.
Organs that can be procured include the heart, lungs, pancreas, small bowel, kidneys, and liver. Our
involvement consists of transporting the donor from the ICU to the OR and maintaining homeostasis
throughout the warm phase of procurement, until the surgeons ask for systemic heparinization and
perform circulatory arrest by cross-clamping the aorta and cooling the organs as rapidly as possible.
These donors are frequently on multiple hemodynamic drips including levothyroxine and vasopressors,
which should be continued as the clinical situation dictates. Although no intact cortically- or brainstem-
mediated pain pathways exist, spinal cord-mediated reflexes may still be active, producing hypertension
(or even movement of the extremities) upon surgical stimulation. This can be treated with opioids if
necessary.

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The surgeons will make an incision from sternal notch to the pubic symphysis, do as much inspection
and dissection as possible, prompt us for a full heparin dose (on the order of 30,000 units), clamp the
aorta, and vent the IVC. The surgeons will notify us that we are no longer needed, the ventilator can be
shut off, and the circuit can be detached from the airway. Our involvement generally ends here.

Another type of organ donation is Donation after Cardiac Death, or DCD. DCD donors have suffered an
irreversible neurologic injury, but still preserve some element of cortical or brainstem function, and thus
are still alive, i.e. they do not meet criteria for brain death. Nonetheless, patients selected for DCD are
expected to have circulatory arrest within minutes of d/c of circulatory and ventilatory support. These
situations are quite different than with brain-dead donors, and are exceedingly rare at UCSD. A full
discussion is outside the scope of this guide.

Chapter 3H. Anesthesia for Trauma and Burn Surgery

UCSD is both a Level 1 trauma center and the only burn center for the entire county of San Diego. As
such, we have our fair share of OR Resuscitations and surgeries for severely burned patients. Burn
patients in particular often need extensive debridement and prolonged care requiring multiple trips to
the OR.

Chapter 3H-1. Anesthesia for OR Resuscitation

Some trauma patients require immediate surgery to have any chance at survival. Our role as
anesthesiologists is often focused on primary resuscitation. Broadly, traumatic insults break down into
one of two categories: blunt or penetrating. Examples of blunt trauma include MVA or falls, while stab
or gunshot wounds are prototypical examples of penetrating injury. OR Resuscitation is the term used
at UCSD for emergency trauma surgery for patients with life-threatening injuries. They occur exclusively
in OR11 at Hillcrest; the setup for OR11 is described in the Emergency OR Setups section. On average,
we get about 1-2 OR Resuscitations per week.

UCSDs trauma program uses a complex algorithm to determine which patients need OR Resus and
which do not. Patients who are true candidates for an OR Resus are generally brought straight from the
field by EMS personnel. Typically, these are patients with known or suspected trauma in the field and
unstable or no vital signs. Because resuscitation is begun in the field by the first responders, these
patients will often arrive intubated and with IV access already established. Many times, the report from
the field (e.g., properly placed ETT) can be quite different from reality.

The primary survey of the trauma patient can be remembered by the acronym ABCDE, for Airway,
Breathing, Circulation, Disability, and Exposure. Often these elements happen concurrently, but it is
useful to remember the order of importance. The typical scenario of an OR Resus is as follows:

The trauma surgery team, anesthesiology team, and OR staff are informed of an inbound trauma
resuscitation. There is generally a brief report from the field regarding vitals, history, relevant lines
and tubes, and ETA.
The patient arrives in OR11. EMS personnel continue with their report while the patient is
transferred to the OR table and connected to monitors. This situation is often quite chaotic and
loud, with many people excited, talking loudly, and all pushing to do their jobs. It is vital to remain
calm and focused in this setting, and often helpful to try and calm others down and keep the noise
level low.

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 ABCDE follows. Assess the patients airway and adequacy of ventilation.
Indications for an advanced airway are myriad but include persistent obstruction, apnea,
unconsciousness, facial or neck trauma, and chest or head injury. Burns involving the upper airway
are particularly dangerous, as rapid swelling and edema can lead to life-threatening obstruction,
even if the initial presentation is benign. Consider early intubation in these patients. Depending on
the area of trauma, securing an airway via conventional laryngoscopy may be impossible. Options
include tracheostomy or awake intubation. If the patient is already intubated, you must confirm
proper placement via etCO2 or an esophageal bulb detector.
Intubating a trauma patient can present many challenges. These patients are full stomachs with
potential cervical spine injury. Thus, rapid sequence induction with manual inline cervical
stabilization and cricoid pressure must be performed. The inability to properly position these
patients combined with the stress of the situation may make intubation difficult. Furthermore,
blood, secretions or regurgitated gastric contents make visualization even more difficult. Ventilate
with 100% O2 until the clinical situation allows.
Assessment of circulation by other members of the team is often concurrent with airway and
breathing. Connect all monitors and/or manually check pulse, blood pressure, and heart rate. ACLS
should be initiated whenever indicated. Definitive surgical control of hemorrhage is the first priority.
Replacement of intravascular volume is often necessary but does not supersede the above.
Surgical control of bleeding should proceed as rapidly as possible while intravascular volume is
replaced. If there is cardiac arrest before or after arrival to the hospital in the setting of chest or
abdominal trauma, the surgeons typically perform an emergency thoracotomy. This allows control
of bleeding, potentially via aortic cross-clamp, repair of cardiac injuries (if any), and buys time to
control the situation.
Replacement fluids include blood products along with crystalloids and colloids. The current trend in
resuscitation and trauma surgery is to use blood products as the primary fluid therapy, and in ratios
approaching whole blood. A sample ratio of RBC:FFP:PLT may be 6:6:2 or 4:4:1. There is continual
debate over the superiority of crystalloids/colloids with no good answer.
Fluids of all varieties must be warmed.
Type O negative (trauma blood) can be given while definitive type and crossmatch is performed.
Often there is a SICU nurse assigned to run the Level 1 Rapid Infuser in the OR, which pressurizes
and rapidly delivers fluid.
An early priority is to establish an arterial line for accurate measurement of blood pressure and to
allow blood draws. Large venous access is a priority as well. Large peripheral IVs may suffice. Central
access is desirable but should not delay the case. Establishing a central line carries increased risk to
the patient, but may be necessary if peripheral access is impossible.
Disability is a rapid assessment of the patients neurologic status, and Exposure involves removing
the patients clothes to allow assessment for injury. Typically these are done while other aspects of
the primary survey commence.
Appropriate labs (e.g., ABG) should be sent as soon as possible.

Other special considerations for an OR resuscitation follow.

Giving amnestic doses of anesthetics is often a secondary priority. Anesthesia can be given only as
tolerated, but the first goal is resuscitation of the patient. Trauma victims are often so unstable that
they cannot tolerate any volatile anesthetic. Your anesthetic may be muscle relaxant small doses of
midazolam or scopolamine, until circulatory stability is achieved.

Multiple injuries often produce multiple, potentially conflicting anesthetic goals. For example, a patient

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with both head and traumatic chest injury needs rapid control of the airway and resuscitation, but care
must also be taken to minimize increases in ICP and prevent brain injury. When in doubt, always come
back to ABCDE as the first priorities. Specific injuries should be managed as the clinical situation allows
(e.g., hyperventilation in the setting of suspected increased ICP).

Constantly reassess the situation and the patient. The patients vital signs and labs will guide therapy. Do
not hesitate to initiate ACLS if needed. You must avoid the lethal triad of hypothermia,
coagulopathy, and acidosis. To this end, make sure to keep the patient warm by monitoring
temperature, warming the room, warming all fluids, etc.

The more hands available, the better. Typically this will not be a problem, since the OR Resus is truly an
all hands on deck situation. There will always be an attending present and often another resident if
free. Help is invaluable in ensuring the resuscitation proceeds smoothly and expeditiously. Also,
remember that an OR Resus demands a team approach, and will usually be performed concurrently with
the surgeons playing a very active role such as recognizing the need for ACLS and initiating therapy,
requesting specific blood products, etc.

Finally, because it bears repeating: try to remain calm and focused on the task at hand. This may be
difficult at first as the gravity and stress of the situation can be overwhelming. Remember that at the
most basic level an OR Resuscitation is actually a simplistic case. The priorities are simply A, B, and C.

Chapter 3H-2. Anesthesia for Burn Surgery

As previously discussed, UCSD is a major burn center and the only center in the greater San Diego area.
Surgery for burn victims encompasses the realms of plastic and trauma as well as true burn surgery.
Because there is often need for extensive, continual debridement and skin grafting, many burn patients
make repeated trips to the OR. Furthermore, the healing and reconstructive process can take months or
even years. Patients may be discharged home following resolution of their initial, perhaps life
threatening injury, only to return to the operating room months later for another procedure (e.g.,
release of contractures) and be otherwise healthy. Thus, burn surgeries break down into roughly two
categories: surgery for major or acute burn injuries, and surgery for minor or chronic injuries. The
former are critically ill and will be discussed in detail.

Major Burn Surgery

Prototypical examples include excisional debridement, skin grafting, and placement of Wound-Vacs.

Technique: general. Rarely, a regional technique may be employed depending on the location of the
burn, but possible preexisting or evolving nerve damage may make this choice impractical. Monitors:
standard, urine output, almost always an arterial line; CVP may be useful.IV access: large. May be
difficult in extensively burned patients. Duration: up to 8hrs, depending on the extent of the injury and
complexity of the case. EBL: 100ml to several liters depending on the extent of injury. Position: typically
supine or prone. Special equipment: transport monitor, needle electrodes for EKG, warm room, fluid
warmers and warming blankets. Special considerations: as below.

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As discussed in the trauma section, the airway of a burn victim with inhalation injury must be treated
with respect. Thermal injury or inhalation insults (e.g., smoke, ash) can cause rapid, life threatening
edema in these patients and loss of the airway. Signs of inhalation injury include hoarseness, stridor,
singed nasal or facial hair, facial burns, soot near the airway or mouth, and respiratory compromise. If
there is any doubt of impending airway compromise, these patients are prophylactically intubated. Signs
of airway obstruction necessitate an awake fiberoptic intubation. In general, most of these patients are
intubated or have a tracheostomy in place before they come to the OR. At times, we may be called to
assist with an acute burn that does not yet possess an airway. Also, because many of these patients will
be in the Burn ICU already intubated and ventilated, the anesthesiologist must go and physically pick the
patient up in the ICU for transport and monitoring on the trip to the OR: the so-called anesthesia
transport. This will be addressed further below.

The extent of body surface area involved in the burn correlates

with the severity of the injury and likelihood of survival. The rule
of 9s can be used to estimate the BSA affected. Each arm, the
head, and the anterior and posterior aspect of the thorax,
abdomen, and legs each represent roughly 9% of TBSA. The
perineum is the remaining 1%. In children, the head comprises
double the TBSA than in the adult.

Derangement of the pulmonary system is a hallmark of burn

injuries. Obviously, direct inhalational injury can compromise lung
function. Carbon monoxide inhalation causes a left-shift of the
oxyhemoglobin dissociation curve; carboxyhemoglobin is read by
pulse oximeters as oxyhemoglobin, so the pulse oximeter reading
will be artifactually high. Burns cause an increase in capillary
permeability throughout the entire body, predisposing to
pulmonary edema and ARDS. Long periods of intubation and
ventilation predispose these patients to ventilator-associated pneumonia. Secretions can be profuse and
thick. Adequate ventilation and oxygenation can be quite difficult. These patients are often in a
profound hypermetabolic state, with increased O2 consumption and increased CO2 production, both of
which place additional demands on the respiratory system.

The increase in capillary permeability mentioned above affects the entire body in burn patients. Large
amounts of fluid shift from the intravascular to the interstitial space, resulting in massive edema and
relative intravascular depletion. Incredible amounts of fluid resuscitation may be necessary to restore
intravascular volume. Typically this is initially carried out with crystalloid according to the Parkland
formula. After 48 hours post-burn, capillary integrity begins to be restored, and colloid will remain in the
intravascular space. For this reason, our burn surgeons prefer us to use blood products or albumin for
routine volume replacement, with sparing of crystalloid. Loss of skin integrity allows substantial
evaporative losses which must be replaced. The maintenance fluid requirements of a burn patient are
often on par with that of a large, open abdominal case.

Loss of skin integrity creates three additional problems: predisposition to infection, evaporative heat
loss, and difficulty with monitor placement. Because of the tremendous potential for heat loss, special
measures must be taken. The room is warmed to the point of being uncomfortable. This measure is a
major downside of being in the burn room. All fluids should be warmed, the circuit should be
humidified, and warming blankets should be placed wherever possible. In regards to monitors, there

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may be little or no skin to place EKG pads on. In these cases, needle electrodes can be used; the
anesthesia monitoring techs can assist with this. Finding an appropriate site to place a pulse oximeter
and BP cuff can likewise prove challenging; many patients have an arterial line for this reason.

Excision of burned tissue is essentially shaving the tissue until viable tissue bleeds profusely. While this
surgical bleeding is often overt, the magnitude of bleeding may be hard to appreciate at first. Frequent
administration of blood products is often necessary. Serial ABGs and hematocrits help guide therapy.
For this reason, and because of the inherent critically ill nature of most of these patients, an arterial line
is mandatory. In fact, there will often be a preexisting arterial line that has been placed by the burn
service. As appropriate sites for an arterial line may be limited due to the burn injury itself, it is not
uncommon to find the line in an unusual location like the femoral or dorsalis pedis arteries. The large
fluid and blood requirements also mandate large venous access. Large TBSA burns can severely limit
sites for peripheral access. Furthermore, CVP can be useful for ongoing fluid management. For these
reasons, a central line is often indicated and is usually present, courtesy of the burn service.

After about 24 hours, burn patients begin to develop immature, extrajunctional nicotinic ACh receptors
on their muscle cells. As a result, dangerous hyperkalemia could follow the administration of
succinylcholine, so this drug is contraindicated in patients with burns older than 24 hours.

Because these patients return to the OR frequently, it is quite possible a recent pre-op has been done
and the record is available in EPIC. This can save a tremendous amount of time and provide valuable
information about prior anesthetics.

Anesthesia transport refers to those patients who we physically bring from their ICU to the OR, with
continuous monitoring, ventilation, and treatment of the patient. This can be time-consuming and
physically demanding. Do not be afraid to ask for help pushing the bed, IV poles or other equipment,
either from the circulating nurse, the ICU nurse, surgery personnel, or anesthesia technician. Mechanical
ventilation means we must either bring an E-cylinder of oxygen and a Mapleson circuit, or have a
respiratory therapist accompany the patient with a transport ventilator. The latter frees up our hands
but is bulky and cumbersome. A transport monitor is mandatory, and can either be supplied by our
workroom or the BICU. Required items also include airway equipment (mask, ET tube, laryngoscope,
LMA), emergency and anesthesia drugs, and an IV bag with Y-tubing for rapid infusion if necessary.
These patients often have multiple infusions, delivered through a towering assembly of infusion pumps
and a bewildering tangle of lines. For these reasons, it is usually helpful to call the ICU nurse about 15
minutes before you anticipate arriving to pick up the patient. Generally speaking, all non-essential
infusions, IV piggyback bags, CVP monitoring lines, etc., should be disconnected, which will make your
life easier. Advance coordination with the ICU nurse and the RT can make an anesthesia transport much
smoother. Always ask the RT about recent secretions and suctioning needs and do in-line tracheal
suctioning yourself. Make sure to preoxygenate with 100% oxygen via the ventilator before
disconnecting; most RTs forget to do this.

Minor Burn Surgery

Examples include dressing changes, surgery to minimal areas of injury, or surgery in a now healthy
patient.

Technique: general or regional. Monitors: standard, arterial line if present. Duration: 30min-several
hours. IV access: one IV should suffice. EBL: < 500ml. Position: generally supine or prone. Special
equipment: warming measures may still be necessary. Special considerations: By definition, most of the

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considerations above for major burn surgery do not apply. These patients are typically healthier with
little to none of the whole-body derangements seen with major burns. If a patient has major burn
injuries, but is coming for a minor procedure, they should be treated as a major burn patient. Typically
these patients are on the burn ward (as opposed to the ICU) or are outpatients returning for
reconstructive surgery.

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Chapter 4. Obstetric Anesthesia

The Obstetrics service at UCSD has a high volume of procedures and deliveries. In addition, a significant
percentage of its patients are high-risk. Because of UCSDs proximity to Mexico and because UCSD
performs many of the functions of a county hospital, a large portion of our patients do not speak
English, have received little prenatal care, or both. These factors combined with the high-risk nature of
the patients make OB anesthesia particularly challenging. This section will address the structure of the
OB anesthesia rotation, uterine and labor physiology, and the physiologic changes of pregnancy that set
parturients in a class by themselves. Specific anesthetic techniques then follow, including anesthesia for
non-obstetric surgery in an obstetric patient.

Chapter 4A. OB Anesthesia Rotation

Residents begin the rotation midway through their CA-1 year. Each month, a new resident will come
onto the OB service until every resident in each class has become OB trained. This means that about
half of any given class will be OB trained by the end of the CA-1 year, with the remaining people finishing
the training during the CA-2 year. No prior knowledge of OB anesthesia is anticipated, although it is
expected that some basic fundamentals in anesthesia will have already been ingrained. Indeed, the
timing of the rotation is specifically designed this way, so that the resident learning OB anesthesia at
least has a firm general skill set from which to draw upon (e.g., airway management, administering
general anesthesia).

For the entirety of the rotation, the resident works with an attending that is solely dedicated to OB and
does not have any rooms in the MOR to attend to. The OB day attending takes over at 0700 and is there
until 1900, at which time the OB call attending comes in. At the end of the second week, overnight call
begins, at which point the resident should have a firm grounding in OB anesthesia. There are generally
4-5 overnight calls in the month.

The usual day on OB begins at 0640 with morning conference or at 0630 on Wednesdays for M+M. After
conference, the OB day resident receives signout from the outgoing OB call resident. There are usually
several scheduled procedures throughout the day that will demand our services. These can be found on
the main OB board, which is discussed below. Other than scheduled procedures, the OB day resident is
responsible for any labor epidural requests and unscheduled procedures (e.g., urgent Cesarean sections)
as well as completing post-op checks on patients that received either intrathecal or epidural morphine
for post-C-section analgesia the day before. On the weekends, the call person is responsible for
completing the post-op checks. While on the OB rotation, the day resident can expect to receive a daily
lecture at some point during the day; the OB attendings are generally quite good at this. The shift
generally ends around 1600-1700, depending on when the OB call resident for that night is available to
take over the OB duties. For more information on the OB call hours, see the section on call
responsibilities.

The Labor and Delivery suite (L+D) is comprised of 9 delivery rooms, a recovery room where pre- and
post-procedure patients are held, an additional small holding area (the OB ER) and 3 ORs (LDR rooms),
all surrounding a central area where the OB board and patient charts are kept. LDR3 is the main room
used for Cesarean sections. LDR2 is generally held in reserve for a second section or a minor procedure
(e.g., tubal ligation). LDR1 is almost never used for services that require anesthesia, but deliveries may
take place there. OB patients are also held on the 4th floor antepartum and postpartum suites, and
rarely in the SICU. We rarely have any involvement with patients prior to their arrival on L+D, but may

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sometimes be consulted on a patient on the antepartum ward on the 4th floor. Parturients also have the
option of giving birth in the birthing center on the 4th floor. This only becomes pertinent if birthing
center patients require our services (whether for a C-section or an epidural), in which case they must be
transferred down to L+D.

Because of the sometimes emergent nature of OB anesthesia, LDRs 2 and 3 must always be set up for
an emergency C-section. In this respect they are no different than OR7, OR11, and the code bags; see
the emergency OR setup section. The expectation is that the rooms will always be restored after use,
and that they will be in order when giving signout or handing over OB duties to another resident. The
basic setup and checkout of an LDR is as follows, and is essentially the same as ensuring a standard OR is
good to go with a few modifications:

Machine checked.
Suction functional.
Airway equipment is ready to go generally left on top of our anesthesia carts. Smaller ETTs and
rescue devices such as an LMA should be available. See the section on physiologic changes of
pregnancy for more information.
Standard monitors, plus an arterial and central line transducer for LDR3, where it is most likely to be
employed.
Stand-alone E-cylinder of O2 with Mapleson circuit.
The routine drugs provided to us daily by pharmacy are ephedrine, phenylephrine, etomidate,
succinylcholine, and rocuronium. Ensure that at least 20units of pitocin are present, if not drawn up.
Most residents also like to have cefazolin and antiemetics also pre-drawn given that these can be
needed urgently; see the section on C-sections.
Spinal and epidural kits.

The central OB board is the best place to find out at a glance the patients on the OB service and to learn
of any impending crises or critically ill patients. The board contains the location of each patient, brief
pertinent information such as estimated gestational age, parity and concomitant disease, type of labor
analgesia present (if any), scheduled procedures for the day, as well as pager numbers for staff on-call
for that day, including anesthesia. The OB anesthesia resident has a dedicated pager with an unchanging
number (5090), but it is our responsibility to update the OB board with the relevant name, as well as the
pager number and name of the anesthesia attending so the OB secretary knows who to call in an
emergency. Further details of the OB board will be explained during the rotation.

Chapter 4B. Physiologic Changes of Pregnancy

Pregnancy produces profound physiological changes, many of which have direct impact and implications
on anesthetic care. Only with a complete understanding of these changes can one hope to deliver a
rational and safe anesthetic to a parturient. This complex physiology will be covered in detail during the
OB rotation and comprises a major percentage of board questions.

I. Cardiovascular System

Increased maternal and fetal metabolic demands dictate an increase in cardiac output, up to a 40%
increase at term. This increase is caused by an increase in both heart rate and stroke volume. Most of
the increase occurs during the first trimester, although the greatest increase occurs during labor itself
and delivery (up to 80%).

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Blood volume is also increased by 35%. A relative increase in plasma volume (45%) to red blood cells
causes a relative, dilutional anemia of pregnancy. Typical hematocrits range from 31-35%.

Systemic blood pressure is decreased in pregnancy. The uterus can be thought of as a gigantic, low-
resistance circuit in the circulation that acts as a pressure sink. Uterine blood flow is 500 to 700
mL/min at term.

II. Pulmonary System

The increased metabolic demands and oxygen consumption of pregnancy are also met by an increase in
minute ventilation (50%). Both tidal volume (40%) and respiratory rate (10-15%) increase. A slight
chronic respiratory alkalosis develops.

FRC is markedly decreased (20%) due to larger tidal volumes and decreased expiratory reserve volume.
In addition, increased abdominal volume and compression of the diaphragm raises closing volume and
predisposes to atelectasis and shunting, especially when in the supine position. Because of increased
oxygen consumption and reduced FRC, apneic parturients rapidly desaturate.

Rate of uptake and elimination of inhaled anesthetics is increased due to increased minute ventilation
and decreased FRC.

Airway mucosal edema is often present, and even the most gentle laryngoscopy can lead to bleeding
and airway obstruction. The additional weight of many parturients can make laryngoscopy doubly
difficult, similar to an obese patient. As described above, parturients do not tolerate apnea and failed
intubation well. For this and other reasons which will be described, general anesthesia is typically
avoided in pregnant patients. Intubation should be done gently and with smaller ETTs available.

III. Neurologic System

MAC decreases throughout pregnancy, up to 50% by term. Maternal hormones, especially

progesterone, are thought to play a role. Likewise, sensitivity to local anesthetics is increased. This is
especially relevant given the large amount of regional anesthetics that are performed in OB anesthesia.
Dosing for epidural and spinal anesthesia is typically 20-30% less than for a comparable non-parturient.
Decreased epidural space due to engorged epidural veins may be responsible for the propensity for
cephalad spread of local anesthetics and the need for a decreased dose.

IV. Hematologic System

There is both a rightward shift of the oxygen-hemoglobin dissociation curve and an increase in 2,3-DPG
levels, both of which favor offloading of oxygen to tissues.

The physiologic anemia of pregnancy is discussed above in the cardiovascular section. Pregnancy is a
state of marked hypercoagulability, with major increases in various clotting factors. Remember that
pulmonary embolus is a major cause of maternal mortality and that this hypercoagulability is the root
cause.

IV. Renal, Hepatic, and GI Systems

GFR is increased by up to 50% of baseline. Think of the kidneys having to filter a solute load for both

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mother and fetus during pregnancy.

Hepatic function is maintained. Pseudocholinesterase levels are slightly decreased but do not appear to
have any clinical effect.

Pregnancy is associated with relative insulin resistance and a propensity towards diabetes. Many
patients on our service have gestational if not outright preexisting diabetes. Diabetes predisposes
patients to macrosomic fetuses with associated difficult vaginal delivery and increased rate of Cesarean
section.

Pregnant patients are always considered full stomachs and aspiration risks due to several factors. First,
there is increased intraabdominal pressure from the gravid uterus. Second, acidity is increased due to
fetal gastrin secretion, increasing the risk of pneumonitis if aspiration were to occur. Third, there is less
lower esophageal sphincter tone due to progesterone. The effect on gastric motility is controversial.
Some texts state gastric motility is decreased which would increase the likelihood of a full stomach,
while other texts state there is no change. Regardless, all pregnant patients undergoing general
anesthesia should receive a rapid sequence induction with cricoid pressure. Pharmacologic agents which
can attenuate or decrease the risk of aspiration include H2 blockers (decreased acidity, takes time to
work), sodium citrate (works immediately to neutralize stomach acid), and metoclopramide (increases
gastric emptying and lower esophageal sphincter tone).

Chapter 4C. Physiology of Uterine Blood Flow

The gravid uterus receives an enormous supply of blood, about 600ml/min or 10% of the cardiac output.
Of this, 90% goes to the placenta, while the remaining 10% perfuses the uterine myometrium. This high
amount of blood flow makes potential losses from bleeding a major concern. Indeed, the most common
morbidity associated with pregnancy is severe hemorrhage.

Many factors can decrease uterine blood flow, potentially to the detriment of the fetus. Maternal
hypotension is often the most obvious and correctable cause. Due to lack of uterine blood flow
autoregulation, flow is directly proportional to systemic pressures. Abnormal systemic vasoconstriction
(e.g., preeclampsia) can also constrict uterine vessels and decrease flow. Uterine contractions
themselves decrease flow due to both increased venous pressure and decreased uterine arterial flow.

Aortocaval compression is the phenomenon whereby the gravid uterus can compress the aorta and IVC,
compromising blood flow and venous return to the heart. This can result in severe hypotension,
especially in the supine position. Treatment for aortocaval compression is left uterine displacement.
This maneuver involves placing a roll or bump under the patients right hip/pelvis, in order to displace
the uterus to the left and off of the great vessels (especially the IVC). This is a commonly asked board
topic and should be one of the first responses to any hypotensive situation. In fact, it is recommended
that term parturients should not be allowed to lie perfectly supine but rather should have LUD instituted
as a matter of course. In extreme instances, you may see the obstetricians having the patient on their
hands and knees to completely displace the uterus.

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Summary Table of Physiological Changes of Pregnancy

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Chapter 4D. Placental Drug Transfer

Most anesthetic drugs cross the placenta. This includes inhalational agents, IV induction agents, opioids,
and benzodiazepines. Clinically, there is little uptake of inhalational agent by the fetus below
concentrations of 1 MAC. Similarly, most IV agents when given in their usual doses have little or no
effect on fetal physiology, probably due to first-pass metabolism and redistribution.

Although all opioids cross the placenta, most have little to no depressant effect on the fetus unless large
doses are used. Morphine is a notable exception and higher IV doses have been associated with
newborn respiratory depression. Epidural and intrathecally administered opioids seem to have little
effect on the fetus.

Local anesthetics vary in their ability to cross the placenta. Highly protein-bound agents such as
bupivicaine and ropivicaine are quite restricted in the ability to cross the placenta and are a safe choice
in pregnancy. Chloroprocaine does not cross the placenta to any great extent, because it is rapidly
metabolized in the maternal circulation by esterases. Lidocaine is also safe but crosses the placenta in
greater amounts than the aforementioned drugs. The phenomenon of ion trapping refers to a
potential buildup of local anesthetics in the fetal circulation during conditions of acidosis. Only the un-
ionized form of the anesthetic can cross the placenta. During ion-trapping the local anesthetic diffuses
across to the fetal circulation, and then becomes ionized by hydrogen ions and unable to cross back to
the maternal circulation. Under these conditions potentially toxic buildup of local anesthetics in the fetal
circulation is possible.

Drug (crosses placenta) Drug + H + Drug-H+ (now trapped in fetal circulation)

Notable agents which do not cross the placenta are heparin, insulin, glycopyrrolate (ionized structure),
neuromuscular blockers (highly ionized large molecules) and succinylcholine (highly ionized). These can
be remembered by the mnemonic He Is Going Nowhere Soon.

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Fetal Circulation

The fetal circulation is an

important concept to know
because of the anesthesiologists
role in the peripartum period.
Oxygen is transferred across the
placenta and into the umbilical
vein. It then bypasses the liver
through the ductus venosus and
enters the right atrium. Because
of differential of pressure, this
blood mainly travels through the
foramen ovale and into the left
atrium, where it is pumped by the
left ventricle into the systemic circulation. The blood that gets into the right ventricle is shunted away
from the lungs via the ductus arteriosus and into the aorta. Deoxygenated blood then enters the
umbilical arteries and is carried back to the placenta to be reoxygenated.

Chapter 4E. Stages of Labor

Understanding the basic progression of labor is important for anesthesiologists for several reasons. The
stage of labor influences the duration and frequency of contractions and can greatly affect our choice of
regional anesthetic, and indeed whether a regional anesthetic is even possible. Understanding the
stages of labor also helps the anesthesiologist gauge the overall time course to better plan the
anesthetic. Lastly, specific pain pathways differ for each stage of labor and are frequently tested on
exams.

The first stage of labor begins with cervical dilation and ends when dilation is complete (10cm). The
latent phase is typically from 0-4cm of dilation, where the cervix slowly becomes more effaced and
dilated (typically over 8hrs). The active phase of the first stage then begins, with more rapid cervical
dilation and more intense and frequent contractions. The entire first stage of labor generally lasts 10-
12hrs for nulliparous patients and can
be much quicker (4-8hrs) for
multiparous ones. Pain during this
stage of labor is visceral, related to
uterine contraction, and involves T10-
L1. Analgesic options other than
regional anesthesia include IV
medication and paracervical blocks.
Paracervical blocks carry a high risk of
fetal local anesthetic toxicity which
manifests as bradycardia and acidosis.
This is probably due to the close
proximity of the block to the uterine
vessels. Paracervical blocks are
infrequently employed and are
performed by the obstetrician in this institution.

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The second stage of labor starts with full cervical dilation and ends with delivery of the baby. It generally
lasts 30min to 2hrs. Pain from this stage is somatic and secondary to vaginal and cervical distension,
via S2-4 (perineal and pudendal nerves). These nerves are notoriously difficult to completely block with
epidural anesthesia due to their rostral position and thickness of the nerve roots/fibers. A pudendal (not
paracervical) block is another anesthetic option and can be performed by the obstetrician.

The third stage of labor lasts from delivery of the baby to delivery of the placenta. Typically there is
minimal discomfort associated with this stage. Occasionally we may be called upon to dose an epidural
to provide anesthesia for procedures immediately post-partum, e.g. repair of perineal laceration. This
stage generally lasts 15-30min.

Chapter 4F. Placement and Management of Epidural, Spinal, or CSE Anesthesia & Analgesia

Similar to the old saying, a picture is worth a thousand words, being shown how to do and walked
through a procedure is infinitely more instructive than any attempt to explain it through text. Thus, the
following sections will not describe how to place an epidural or spinal per se but rather offer useful tips
and advice and describe common management at UCSD.

Briefly, the layers that an epidural needle will pass through on the way to the epidural space are: skin,
subcutaneous tissue and fat, supraspinous and interspinous ligaments, and the ligamentum flavum.
Standard technique for placing a lumbar epidural is to locate the posterior iliac crests (hip bones); a
horizontal line at this point crosses through the L3-4 interspace. As the spinal cord ends at L1 in adults
and the lower nerve roots of the cauda equina are not fixed, any neuraxial block below L1 should have
no risk of spinal cord injury and little risk of nerve root injury. The interspinous spaces are palpated and
the epidural needle is advanced until the distinct resistance, toughness, or crunchiness of the
ligamentum flavum is felt. At this point, a loss-of-resistance syringe filled with saline or air is attached.
The needle is advanced millimeter by millimeter while gentle attempts at injection of the syringe are
made. The ligamentum flavum does not allow injection and will bounce back any attempts to do so
(resistance). When the epidural space is encountered, there will be a sudden loss of resistance with
easy injection of saline. At this point an epidural catheter can be placed.

Proper positioning, as with any procedure, is of paramount importance. Confirming proper positioning
of the patient can often yield success in a difficult placement. The majority of the time, if an epidural

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placement is difficult, a recheck and correction of position will save the day. The patients shoulders
should be level and the lumbar spine flexed (lordosis eliminated) so as to maximize the space between
the interspinous processes. If the patient can tolerate the position, having her sit Indian-style may
optimize the position.

By starting with your needle midline and keeping it midline, all while insisting on perfect patient
positioning, encountering bone at shallow depths is likely to due to hitting a spinous process or simply
being off midline. Hitting bone at deeper depths likely represents hitting the inferior aspect of the
superior lamina, and walking the needle caudad may help.

Loss of resistance is rarely equivocal; the majority of the time, the difference between the feel of the
needle in LF and the needle in epidural space is as different as night and day. Occasionally, a pseudo
loss of resistance is encountered, where there is a boggy and indistinct ability to inject saline, making it
unclear whether the epidural space has actually been reached. Using a small air bubble in the syringe
along with saline can help in this regard. Air in the syringe will definitely bounce back if the needle is
not within the epidural space. Usually pseudo LOR represents the needle being in subcutaneous tissue
or interspinous ligament. Using only air in the syringe is not recommended due to the possibility of
accidental intrathecal injection of air and pneumocephalus.

After loss-of-resistance is encountered, dilating the epidural space with an additional 2-4ml of saline
may help with placement of the catheter. A standard length Touhy needle is 9cm from tip to wings,
and 11cm from end to end. Be sure and note at what depth loss of resistance is encountered as it will
guide depth of catheter insertion. This is easily done by counting the remaining centimeter marks on
the Touhy needle. With experience this will become habit and second nature; however most people can
recall early experiences where an epidural catheter was placed, the needle withdrawn, and then the
dawning realization that the appropriate depth of insertion of the catheter was completely unknown.

Try to have a systematic way of preparing the epidural tray and placing the block. One good way is to
open all necessary vials, draw up all drugs and the loss-of-resistance syringe and arrange the kit before
starting so that everything is readily available. Try to anticipate special needs you might have before
putting on sterile gloves and arrange for them beforehand, such as another 3ml syringe and a long spinal
needle for a CSE.

The obstetricians typically will consult us to place a labor epidural once labor is established, generally
around 2-3cm of cervical dilation. Epidurals placed after 3-4cm of dilation do not slow progression of
labor or make Cesarean section more likely; patients or families may ask you this. In general, the later in
the first stage of labor the patient is, the more frequent and intense the contractions and the harder it is
to place an epidural.

If placing an epidural in the lateral position, the interlaminar foramen (true midline) is almost always
above what appears to be midline from visual inspection. As an example, for a patient lying on her right
side, true midline is probably slightly left of what her back may look like, due to sagging and the effects
of gravity on the soft tissues, pulling them down (towards the right side).

If you encounter a patient in excruciating pain, another option is to place a combined spinal-epidural
(a.k.a., CSE), where you achieve loss of resistance as above, then use a spinal needle to place a small
amount of local anesthetic and/or fentanyl intrathecally for immediate relief, and then place the
epidural catheter per usual routine. Be sure to use a spinal needle that is longer than the epidural
needle. Benefits of this technique include immediate relief of pain and confirmation that your epidural

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catheter is just separated from CSF by the dura. However, it runs the risk of uterine hypertonic
syndrome, caused by the sudden withdrawal of catecholamines and a subsequent loss of 2 agonism by
epinephrine. This leads to a hypertonic uterus and can cause fetal distress that, if intense enough or
lasts long enough in duration, may necessitate an emergent C-section. Diagnosis is made with palpation
of a rock-hard abdomen, tetanic contractions on the tocometer tracing, and fetal decelerations on the
fetal heart rate monitor. To avoid this, the anesthesiologist must keep the diagnosis in their differential,
and have uterine relaxants (tocolytics) ready. Some of these include terbutaline (a 2 agonist), sublingual
nitroglycerin, and calcium-channel blockers. The OB anesthesia carts located in the L&D hallways all
have sublingual nitroglycerin spray in the drug tray.

Tips for Spinal (SAB) Placement

In general, many of the same comments for epidural placement can be said about spinal placement as
well. In many respects, placing a spinal (subarachnoid block, SAB) is technically easier than an epidural
as there is no need to find the occasionally-elusive epidural space, and the endpoint for the block is
objective: CSF return. When the dura is punctured, a distinct pop is usually felt. At this point, removal
of the stylet should produce free-flowing CSF.

Before injection of the spinal anesthetic, aspirate a small volume of CSF. It should be easy and free
flowing, and will visually swirl in the syringe due to the difference in dextrose concentration. If this is
not evident, DO NOT inject; it is likely the needle tip is no longer within the subarachnoid space and the
block will fail. It is much better to simply reposition the needle or attempt the block again.

For extremely obese patients, a needle larger than the standard 25g may be needed for rigidity, or a
longer needle may be needed to reach the subarachnoid space, or both. In extreme instances, it may be
useful to use a Touhy needle as an introducer for a spinal needle for added structural stability and
stiffness.

In OB anesthesia, spinals are generally reserved for surgical procedures such as Cesarean section, tubal
ligation, or potentially a very low dose for repair of perineal laceration. Rarely, a dilute spinal may be
used as the sole anesthetic for labor, for example, if the parturient is nearly complete but in extreme
discomfort and there is not time to place an epidural. Most, however, would place a CSE in this scenario.

Please consult an appropriate textbook for more complete and thorough explanations of epidural and
spinal techniques.

Epidural Analgesia for Labor

The following describes common approaches to labor analgesia at UCSD. The primary choice of
anesthetic technique is regular epidural vs. CSE. Reasons to place a CSE are described above, and
include rapid relief for a particularly uncomfortable parturient or short-lasting relief for a particularly
late-in-labor neuraxial block placement.

The most common approach at UCSD is as follows. Typically around 3-4cm of dilation, i.e., when the OBs
have confirmed the patient is in true labor (contractions with cervical change), you will be consulted to
place a neuraxial anesthetic/analgesic. After a brief history and physical, confirmation of pertinent
coagulation studies (platelet count INR/PTT), and discussion of the risks/benefits/alternatives, the
patient is placed in the sitting position. DuraPrep is used as the antisepsis, and an epidural kit with a 17g
Tuohy and a 19g flexible single-orifice catheter is prepared. Local anesthesia with 1% lidocaine is done,

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loss of resistance is found, the catheter is advanced usually 2-5cm into the epidural space, and a test
dose of 1.5% lidocaine with 5mcg/ml epinephrine is given through the catheter to rule out IV and
intrathecal placement. You must always aspirate the epidural catheter prior to giving any medications
through it.

In the case of a negative test dose, the epidural is loaded with increments of 3-5ml at a time, to a total
of 5-10ml, of any combination of medications. Choices include 1% lidocaine for fast analgesia, 0.25%
bupivacaine for somewhat slower but excellent analgesia, the bag solution of 0.1% bupivacaine with
2mcg/ml fentanyl, or any of the above with 50-100mcg of fentanyl. The patient-controlled epidural
analgesia (PCEA) infusion is programmed and started, with settings most commonly 8-10ml/hr
continuous with 5-6ml q20-30min demand.

In the case of a CSE, at the time of loss of resistance, a 5 25g spinal needle is passed through the Tuohy
and CSF is encountered. At this time, 1-2ml of 0.25% bupivacaine, fentanyl, or a combination of the two
can be given. Then, the catheter is threaded and tested, with the caveat that intrathecal catheter
placement can no longer be ruled out with the test dose.

Rarely, a CSE is done without giving intrathecal medications; this is known as a dural-puncture
epidural. This might be done simply to confirm placement of the Tuohy in the epidural space without
confounding the test dose, or with the idea that the analgesia might be of a better quality with this
technique. Regardless, any time the dura is punctured, the risk of post-dural-puncture headache is
increased.

Approaches to troubleshooting labor pain in patients with epidural catheters will be discussed in great
depth during the OB anesthesia rotation.

Lastly, an in situ epidural catheter can be used for a semi-elective or urgent Cesarean section, as
described next.

Chapter 4G. Anesthesia for Cesarean Section

Cesarean section is the single most common operation in the United States. Indications for Cesarean
section are myriad and range from the innocuous to the emergent. A particular challenge for the OB
anesthesiologist is balancing two demands: the sometimes-frantic requests from the obstetricians to
proceed immediately with Cesarean section, and the best interests of both mother and child. In general,
the indications for Cesarean section fall into one of several broad categories:

I. Urgent or Emergent C-section

Bleeding
Risk of infection (chorioamnionitis or herpes with ruptured membranes)
Fetal distress
Maternal death
Umbilical cord prolapse
II. Abnormal fetal presentation, or failure of labor to progress
III. Unsafe labor for fetus or mother
Abruption
Placenta previa, accreta, increta or percreta
Previous uterine or vaginal surgery (including prior C-section)

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 Multiple gestations
IV. Elective (e.g., patient desires)

General Anesthesia and the Emergency C-section

Truly emergent Cesarean sections necessitate the use of general anesthesia. Even if the patient has an
indwelling epidural catheter, the time needed to dose and establish a surgical block is unacceptable
when the Cesarean section is truly emergent. This situation needs to be discussed on a case-by-case
basis with the obstetrician. Because of the risks of aspiration and failed intubation with parturients, as
well as the eight-fold higher increase in maternal mortality, it is prudent to avoid general anesthesia
unless the need is truly emergent and the benefits (speed) outweigh the risks.

General anesthesia for emergent C-section does not proceed until the obstetrical team is scrubbed and
gowned, with the patients abdomen prepped for immediate incision. During this time, standard
monitors should be placed and the patient preoxygenated. Four vital capacity breaths, although not as
effective in total body oxygenation as 5 minutes of breathing 100% O2, should suffice. An assistant
should be present to help with cricoid pressure or with a difficult airway. When all team members are
ready, general anesthesia is induced with rapid sequence induction with an ETT and cricoid pressure.
Establishment of GA must be clearly and quickly communicated to the OB team, who should make
incision as soon as the patient is unconscious and etCO2 is confirmed. The goal is to deliver the fetus as
quickly as possible from the time of induction. Typically, from the time of induction to delivery of the
fetus, a high-volatile-agent anesthetic is provided to assist with uterine relaxation. After delivery, a high-
nitrous-oxide, low-volatile-agent anesthetic is provided to prevent uterine relaxation.

The remainder of the case can proceed as in a non-emergent Cesarean section.

Anesthesia for the Non-emergent C-section

Technique: general, epidural, spinal, or CSE. Monitors: standard. Invasive monitoring is generally not
necessary unless warranted by concomitant disease (e.g., severe preeclampsia). IV access: one large IV
is generally sufficient. Duration: 45min-2hrs. EBL: 800-1200ml, may be more depending on uterine tone
or lack thereof. Position: supine with left uterine displacement. Special equipment: none. Special
considerations: as below.

The progression of a typical Cesarean section is as follows:

Regional anesthesia is induced and appropriate sensory level confirmed, patient prepped and
draped. Or, the patient is prepped and draped in preparation for general anesthesia, and GA is
induced and the airway is controlled.
Antibiotics should be given prior to surgical incision.
Skin incision is made and surgery proceeds.
Uterine incision is made. Times above 3min from uterine incision to delivery have been shown to
correlate with lower Apgar scores and fetal acidosis.
The fetus is delivered, the umbilical cord is clamped, and delivery of the placenta is started.
Management of uterine atony after delivery consists of pharmacologic and mechanical strategies.
Pharmacologic techniques include oxytocin (Pitocin), methylergonovine (Methergine), and
carboprost (Hemabate). Mechanical techniques include routine suture closure, uterine massage,
and the B-Lynch locking suture.

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 o Oxytocin is given with every C-section. The typical dose is 20 units, which is diluted in a 1L IV bag
and infused over 20-40 minutes, starting immediately after delivery. Oxytocin induces uterine
contractions and helps maintain uterine tone. It lowers SVR in a dose-dependent fashion by
relaxing vascular smooth muscle, and can induce systemic hypotension if given in large or fast
doses. The OBs may ask you to double the Pit, i.e., give 40 instead of 20 units, often before the
initial dose of 20 has had any time to have a physiologic effect. Take care with double-dosing
given the hypotensive effect of oxytocin described above.
o Methylergonovine is an ergot alkaloid which causes sustained uterine contraction. It is only
given postpartum and causes smooth muscle contraction throughout the body, potentially
resulting in hypertension and bronchoconstriction. Its major contraindication is hypertension,
whether pre-existing or pregnancy-induced. The dose is 0.2mg IM; in a patient with a neuraxial
block, give this in a leg. Side effects include nausea and vomiting.
o Carboprost is 15-methyl-prostaglandin-F2, i.e., a prostaglandin analog, which causes uterine
contractions. It is given IM, 0.25mg at a time. Its primary side effect is bronchoconstriction, and
so its major contraindication is asthma/reactive airway disease. Other side effects include
diarrhea, nausea, and vomiting.
o Manual uterine massage can also help with uterine atony, and so does surgical closure of the
uterus with sutures, which the OBs should be doing expeditiously in the setting of atonic
bleeding.
The uterus is exteriorized to aid with exposure during surgical closure. If regional anesthesia is
employed, it is common at this stage for the patient to have an uncomfortable sense of pressure
due to the peritoneal traction and unblocked vagal afferents. Additionally, the OBs tend to reach
with lap pads toward the upper abdomen (foregut) which is not blocked by a typical T4-T6 sensory
level. Reassurance with or without small doses off ketamine or fentanyl or nitrous oxide may be
helpful.
The uterus, fascia, and skin layers are closed.

Regional anesthesia is often preferred due to less risk to the mother as described above, and because it
allows the parturient to be awake and alert at the time of delivery. A T4 sensory level is necessary.
Advantages of SAB versus epidural include a more profound and reliable block, quicker onset, and
perhaps easier placement. Disadvantages include lack of titratibility, inability to re-dose in the event the
case is longer in duration than expected, and more profound hemodynamic changes.

Typical dose ranges for a SAB are 1.4-1.8ml of hyperbaric 0.75% bupivacaine. Most will add 10-25mcg of
fentanyl and 0.1-0.2mg of morphine to the mixture. This can be drawn up sterilely beforehand and given
to an assistant to inject into the spinal syringe prior to administration. Fentanyl is thought to improve
the quality of the block, although firm data are lacking on this point, and morphine provides good
analgesia for up to 24 hours. Epinephrine 200mcg is rarely used to prolong duration of the blockade.
Prior to placement of any regional block, the patient should have at least 1L of crystalloid fluid bolus,
standard monitors, O2, and the relevant history/physical/labs checked. Hypotension immediately after
SAB is common and should be aggressively treated with fluids and vasopressors. Many people often
administer nausea and vomiting prophylaxis at this time. Indeed, one of the first manifestations of the
onset of hypotension is maternal nausea and vomiting.

When epidural anesthesia is employed, it is usually because the patient has a prior labor epidural in
place and then develops an indication for Cesarean section, such as failure to progress, arrest of
descent, or fetal distress. Less commonly, it is employed as part of a CSE and as an alternative to a
spinal; CSE may be chosen if the operation is expected to take a long time. An epidural also offers

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titratability, unlike SAB, which could be beneficial in a patient with severe preeclampsia or severe aortic
stenosis.

Two options to speed the onset of epidural anesthesia include the use of 3% chloroprocaine or 2%
lidocaine with 5mcg/ml epinephrine alkalinized with NaHCO3. The mixture is prepared as 1ml NaHCO3
added to every 9ml of 2% lidocaine. The usual doses are 15-20ml of either medication, titrated in
increments of 5ml. Epidural fentanyl can also be added (50-100mcg). Chloroprocaine needs to be
redosed about every 45min, lidocaine every 1-2hr, and bupivicaine every 1.5-3hrs. Epidural morphine,
for sustained post-op analgesia, is typically given after delivery of the fetus; the dose is 2-4mg.
Occasionally, an epidural block may be incomplete or patchy (hot spot). Small doses of ketamine (10-
20mg IV at a time) or narcotics can be of great assistance during these times, with special care and
vigilance as always. Ketorolac 30mg IV should be given to all C-section patients at the end of surgery, in
whom it is not contraindicated by allergy, hemorrhage, or renal dysfunction.

If general anesthesia is employed, the patient should not be induced until the obstetrical team is ready
as described above for emergency C-section. A rapid-sequence induction with cricoid pressure is
necessary. Anesthesia can be maintained with many agents: 50% O2 and 50% N2O with 1% sevoflurane is
common in our institution. Often, nondepolarizing muscle relaxant is necessary to facilitate surgery and
to prevent interference from maternal respirations. Keep in mind the decreased MAC requirements of
the parturient. Emergence is typically uncomplicated and usually requires only increased vigilance in
regards to the airway and risk of aspiration.

A tubal ligation may be combined with the C-section in patients desiring sterilization. It is performed
after delivery of the fetus and uterine closure, and typically adds 10-15min to the procedure. A repeat C-
section, or a primary C-section in a patient with previous abdominal surgeries and scar tissue, can take
significantly longer than one in a virgin belly due to adhesions.

It is very common for spouses or family members to be present for the operation. They generally are
brought to the delivery room after the patient is prepped and draped but prior to skin incision. This lone
family member and you are advised to insist that just one person be present is often placed very
near to the anesthesiologist, sitting near the head of the bed and away from viewing the surgical field.
Allowing family to be present should always be a balance between optimal care and giving the patient
and family what they desire. The extra family member should never be allowed to distract the
anesthesiologist from his or her duties. However, there are also times when they can be of great
assistance in reassuring and calming a hysterical patient.

Rarely, the OBs may ask for sublingual nitroglycerin to be administered to aid with uterine relaxation.
This can be given safely as long as attention is paid to maternal
blood pressure.

Chapter 4H. Anesthesia for Placenta Accreta/Increta/Percreta

UCSD is privileged to be a center that performs many deliveries

for patients with placental abnormalities. There are three
types: placenta accreta is when the placenta grows into the
uterine endometrium, increta is when it grows into the
myometrium, and percreta is when it grows completely
through the uterus and may invade nearby structures such as
the bladder or bowel. Because the placenta has grown into the

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uterus abnormally, it does not separate cleanly during delivery and can cause massive bleeding. Thus,
the patient with any of these conditions cannot be allowed to labor but must instead have delivery by
Cesarean section. A hysterectomy is almost always indicated to control bleeding and allow removal of
the placenta. Other concurrent procedures may be necessary to remove the placenta from surrounding
structures.

The Cesarean hysterectomy for these cases is unique, as are the anesthetic goals. Historically, these
patients are taken to interventional radiology where uterine artery balloons are placed, and can be
inflated during the procedure to control bleeding. An epidural is generally placed by us to provide
anesthesia during interventional radiology and for the Cesarean portion of the case. Once delivery is
complete, general anesthesia is induced to provide better operative conditions and better control in
case of overt bleeding. There is usually a perfusionist on standby in case massive volume resuscitation
becomes necessary. Due to the likelihood of severe bleeding and volume resuscitation, an arterial line
and large IV access are mandatory. These are placed pre-induction since there is no time to place them
intraoperatively once the need becomes apparent.

As these patients are generally young healthy women, they tolerate blood loss and resuscitation fairly
well. These cases combine the challenges of a Cesarean section and maintaining maternal and fetal well-
being, with the complexity of a large intra-abdominal case with the potential for massive blood loss.

There are several approaches to the anesthesia for Cesarean hysterectomy, including doing the
Cesarean portion under epidural anesthesia and the rest of the procedure under general, or the entire
procedure under general without an epidural. Often a large incision is necessary to completely expose
the uterus and allow the OBs to work around the placenta. This incision is often poorly covered by an
epidural. Furthermore, a neuraxially-induced sympathectomy is undesirable in situations with
potentially large blood loss. Inducing GA in a patient with a preexisting T4 sympathectomy is potentially
dangerous. About the only advantage of using an epidural for the first portion of the procedure is that
the mother can be awake for the delivery of the baby.

As previously stated, uterine contractions and placenta separation can be catastrophic and should be
avoided at all costs. Tocolytics may be necessary, and oxytocin should be avoided at all costs. In this
regard, GA may be superior to neuraxial anesthesia in causing uterine relaxation.

Technique: general regional anesthesia. Monitors: standard, arterial line. IV access: Large. Frequently
a large central line is placed. Duration: 2-4hrs. EBL: 1L and up, potentially many liters. Position: supine
with left uterine displacement. Special equipment: perfusionist available. Fluid warmers for volume
resuscitation. Special considerations: as above.

Induction of GA for this procedure requires the usual precautions for GA in parturients, including
preparing a ramp for intubation, smaller ETTs, and rapid sequence induction with cricoid pressure.

Chapter 4I. Anesthesia for Other Obstetric Procedures

This category includes postpartum tubal ligations, cerclage placement or removal, and other minor
procedures.

Technique: regional or general, with preference again towards a neuraxial technique. Monitors:
standard. IV access: one IV. Duration: 30min-1hr. EBL: < 100ml. Position: supine or lithotomy. Special
equipment: none. Special considerations: Generally a lower sensory level is necessary due to smaller

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incisions and the lower nature of the procedures. A T6 level is more than adequate even for a
postpartum bilateral tubal ligation. Similarly, intrathecal or epidural morphine is not given, as these
patients tend to be discharged the same day.

Chapter 4J. Anesthesia for Non-obstetric Surgery in the Parturient

In general, all elective surgeries should be postponed until at least six weeks postpartum. Truly urgent,
emergent, or necessary surgery should proceed with the following items in mind.

The 3rd to 10th weeks of pregnancy are when major organogenesis occurs and when the fetus is most
susceptible to teratogens.
There is ongoing concern about the teratogenic potential of N2O and benzodiazepines, despite lack
of conclusive evidence. These agents should probably be avoided. Most of our other anesthetic
agents have been proven safe in clinical concentrations.
Most clinicians feel a parturient at 20 weeks gestation or beyond should be considered to have all
the physiologic changes of pregnancy described above. Others feel that parturients as early as 12-16
weeks should be treated with the same caution with regards to physiologic changes, airway
management, risk of aspiration, and so on.
Any surgery can induce preterm labor, but those at particular risk are lower abdominal surgeries.
Typically the OB team will monitor the fetus and uterine activity from induction of anesthesia to the
completion of the procedure. Coordination between teams is often necessary. If coordinated
uterine activity is detected, 2 agonists or magnesium may be employed as tocolytics. A plan for
delivery of the fetus should be in place should the pregnancy be threatened.
Regional anesthesia is preferred if possible, for the same reasons as described above. However, the
specific anesthetic technique is determined by the type of surgery needed.

Chapter 4K. Special Topics in OB Anesthesia

I. Hypertensive Disorders of Pregnancy

A. Gestational hypertension (Pregnancy-induced hypertension (PIH))

Hypertension in pregnancy is abnormal. As stated earlier, the normal physiology of pregnancy produces
a drop in systemic blood pressures from baseline. Hypertension in pregnancy can be preexisting, or due
to the pregnancy itself. It is defined as a systolic pressure above 140 or a diastolic pressure above 90
that develops after 20 weeks of pregnancy and resolves within 12 weeks postpartum. By definition, this
is a retrospective diagnosis because it can only be established after delivery.

B. Preeclampsia, Eclampsia and HELLP syndrome

Preclampsia is defined by hypertension and proteinuria (>300mg in a 24 hour urine collection).

Eclampsia is much rarer and includes seizures. Severe preeclampsia is defined as blood pressure over
160/110, greater than 5g/d of proteinuria, or signs of end organ damage (headache, seizures, vision
changes, hepatic tenderness or rupture, pulmonary edema, oliguria). HELLP syndrome refers to the
development of Hemolysis, Elevated Liver enzymes and Low Platelets, and is considered a variant of
severe preeclampsia.

PIH and preeclampsia is more likely in nulliparous young women and those with a previous history of

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PIH. As a rule, these women are prone to vasospasm, are intravascularly volume depleted, and are
edematous.

Treatment of PIH includes bed rest, antihypertensive therapy (hydralazine or labetalol are common),
and magnesium for seizure prophylaxis. The only definitive treatment is delivery of the fetus and
placenta. PIH behaves like an immune reaction to the fetus, with resolution after delivery.

Typically, we as anesthesiologists tend to become involved early in the management of a patient with
PIH. Often, the OB service will inform us of any patients with PIH due to their propensity to progress to
Cesarean section and their risk of thrombocytopenia. It behooves us to know of these patients so that
we can evaluate them early and potentially assist with management. Furthermore, these patients often
need invasive monitoring, which the OBs have little to no experience with, and they will consult us in
these cases as well.

Anesthesia for the patient with PIH depends on the severity of disease. Epidural anesthesia tends to be
the best choice due to titratibility and gradual onset of action. Furthermore, a decrease in
catecholamines from neuraxial blockade has been shown to improve uteroplacental perfusion.
Hypertension and relative hypovolemia should be treated as much as possible before anesthesia.
Coagulation parameters and platelet count should be checked prior to the initiation of neuraxial
blockade, with particular attention paid to the trend of these factors. In some cases, platelet transfusion
may be necessary prior to initiating a block.

Magnesium Therapy

Many parturients that we come across will be on magnesium therapy for a myriad of reasons, including
seizure prophylaxis in preeclampsia and neonatal neuroprotection for women in labor with severely
premature babies. Magnesium has many effects on the body and our anesthetics. The therapeutic range
for magnesium is 5-9 mg/dl. The patients will typically get a bolus followed by a continuous infusion.
They are followed by serial magnesium levels and clinical exam to ensure they are not exceeding toxic
levels. The first sign of magnesium toxicity is loss of deep tendon reflexes, followed by respiratory
depression, and rarely, cardiac arrest. Treatment of suspected magnesium toxicity includes
discontinuation of the infusion and administration of 1g calcium gluconate IV. If there is respiratory
compromise, ensure that ABCs are being addressed.

Magnesium potentiates neuromuscular blockade, so a patient on magnesium therapy who requires

general anesthesia requires less muscle relaxant. Administering a normal dose could potentially result in
a longer duration of paralysis. Magnesium can also cause hypotension and decrease uterine tone,
putting these patients at higher risk for uterine atony and increased bleeding during a C-section.

II. Uterine Rupture

This is a life-threatening but rare condition (1:2000 pregnancies). Predisposing factors include prolonged
labor with a large fetus, prior uterine surgery, augmented contractions (e.g., oxytocin) or external
manipulation of the uterus (e.g., version for breech presentation). It typically presents as abrupt onset
of abdominal pain with fetal distress and hypotension, and may classically include palpable fetal parts on
abdominal exam. Treatment includes resuscitation, immediate laparotomy and delivery of the fetus, and
repair of the uterus or frank hysterectomy.

This is a frequently tested topic on board exams. The possibility of uterine rupture in patients

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undergoing VBAC (vaginal birth after C-section) means that these patients should be identified and
evaluated by us as soon as possible. Epidural anesthesia generally will not mask the signs of uterine
rupture, and in fact may help in identifying it when a previously comfortable (due to the epidural),
laboring patient suddenly develops abdominal pain.

III. Placenta Previa

This complication occurs when a placenta attaches to the uterine wall and covers the internal cervical
os, either completely or partially. A placenta previa places the patient at higher risk of bleeding during
the pregnancy, and if severe enough, necessitates Cesarean section. The placenta can either be low-
lying (near the cervical opening but not covering), marginal (touching the os but not covering it), partial
(part of the placenta is covering the os) or complete (completely covering the os). Parturients with prior
C-sections are at higher risk for placenta previa, as well as placenta accreta, increta and percreta. These
patients can bleed profusely. The OB team will usually alert us if there is a parturient with placenta
previa because she will usually need a C-section.

IV. Placental Abruption

Abruption occurs when there is abnormal separation of the placenta, with bleeding into the space
between the placenta and uterine wall. Abruption tends to present as painful vaginal bleeding and can
cause severe fetal distress or demise. Diagnosis is made by ultrasound. Predisposing factors include
hypertension, multiparity, drug abuse, and an abnormal uterus.

Vaginal delivery can be undertaken with a mild abruption. However, any sign of fetal distress or large
abruption is an indication for emergency C-section. Bleeding can be substantial. Additionally, release of
thromboplastins into the maternal circulation can cause frank DIC and coagulopathy. In all these cases
general anesthesia and resuscitation must be employed.

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V. Amniotic Fluid Embolism

This is a rare (1:20,000) condition in which the mother has an acute and profound immunologic reaction
to fetal tissue, usually amniotic fluid, entering the circulation. It has a very high mortality (over 50%).
Most AFEs occur during labor (90%) but they can also occur during C-section and even postpartum. The
presentation is generally a sudden onset of tachypnea, respiratory distress, and circulatory collapse. AFE
can mimic pulmonary embolism, but also shares features of circulatory and pulmonary compromise
similar to septic shock and ARDS. DIC develops and leads to coagulopathy and massive bleeding.
Hypoxemia, shunting, and increased dead space all occur. The treatment for AFE is supportive. Delivery
of the fetus must occur for there to be any chance of effective maternal and fetal resuscitation.

VI. Apgar Scores

This is another frequently tested topic on board exams. Apgar scores range from 0-10 and are measured
at 1 and 5 minutes. The 1-minute score correlates with survival, while the 5-minute score correlates with
neurologic outcome. The five components of the Apgar score are as follows:

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125
Chapter 5. Cardiothoracic Anesthesia Rotation and Cardiovascular Physiology

Chapter 5A. Cardiothoracic Anesthesia Rotation

The cardiothoracic anesthesia rotation at UCSD is an intensive two-month exposure to cardiothoracic

physiology, anesthesia, and surgery. Beginning in the middle of the CA-1 year, one resident at a time
begins the rotation each month. Thus, by the middle of the CA-2 year, an entire class will have
completed their cardiac rotation. The first month is spent primarily at the Sulpizio Cardiovascular Center
(CVC), while the second month is at the VA. At the CVC, you will have lots of one-on-one time with the
cardiac anesthesia fellow and cardiac attending to cover the most critical information and basics of
cardiac anesthesia, especially during the first week. At the VA, your attending will always be covering
another room and there is usually no fellow, in accordance with your increased experience.

The cases encountered at Sulpizio will generally be pulmonary thromboendarterectomies (PTEs), on-
and off-pump CABGs, and valve replacements. Thoracic cases happen with some regularity but with
lower volume. PTEs are not performed at the VA, but CABGs and valve cases are common. It is
exceedingly rare for cardiothoracic cases to be done at Hillcrest. In general, the heart resident does any
cardiothoracic case available; if there are none scheduled on a given day, you will be assigned a general
OR case.

UCSD also hosts visiting anesthesiology residents from the University of New Mexico, who are in San
Diego for a month and need the cardiac volume that we have at UCSD to achieve their ACGME-
mandated minimum case requirements.

Call during the two months is also discussed in the section on call responsibilities. During the first month
you will be assigned heart call at the CVC during many days of the week. This is pager call, and you are
responsible for returning to the hospital for emergency cases (e.g., takebacks for bleeding, lung or
heart transplants). On weekends, you will be called in for the same or for elective cases. As the heart call
person, you may be asked to finish an ongoing cardiac case at the CVC after you have finished your main
OR cases for the day. This is at the discretion of the attendings. Expect to work hard during these two
months and take these things in stride.

At the VA you will be part of the regular VA call pool and assigned 4-5 in house calls for the month. You
will be given any cardiothoracic case available. Cases usually have a 0730 start time, as opposed to the
CVC, which start at 0630. There is usually a CT case every day except for Wednesday, so you will typically
be on-call on Tuesday and post-call on Wednesday. Call at the VA normally starts at 1000, but on
Tuesdays you will come in early to do the CT case for that day. While at the VA, you are not part of the
CVC heart call pool, since the resident one month behind you is covering those duties.

Cardiothoracic cases are demanding, and require that you own your patient. Accordingly, it is
expected that you will be more responsible than usual for pre-opping your patients. Many elective
cardiac patients at CVC go to our regular pre-op clinic, as do all the patients for elective cases at the VA,
so the task of pre-opping has been taken care of for you. PTE patients, however, are usually from out of
state, are admitted the day prior to surgery, and will not have gone to pre-op clinic. You will have to see
the next days patient and review the chart prior to calling your attending and heading home for the
day. So, a typical day during the first month of cardiac starts early and ends late, after youve wrapped
up your cases and seen the one for the next day. Again, expect to work hard during these two months.

You should allow at least one hour or more to set up your room when you are first starting the rotation.

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There is a lot to do and in addition you will be unfamiliar with many of the necessary steps, like making
all the drips. Also, your patient needs a good IV and an arterial line before induction. Add to this the fact
that patients at CVC should be in the OR by 0630. So, you may find yourself having to come into the
hospital at 0500 in the beginning of your cardiac month. In general, allow yourself more rather than less
time in the beginning. You can always make adjustments later as you get faster, but it looks bad when
everyone but the anesthesiologist is ready. Specifics of the room setup are covered later, but are best
addressed in the departmental cardiac rotation syllabus.

Cardiac surgeons are notorious throughout the country as being difficult to work with. In general, at
UCSD this is not true. Our CT surgeons are usually quite friendly and will make an effort to learn your
name. Keep in mind that the field of cardiac surgery is under pressure to standardize and protocolize
care to improve outcomes, so cardiac surgeons who see a new, green anesthesiology resident come on
the rotation each month can be somewhat suspicious of us. Also, cardiac surgeons understand the
patients physiology better than any other type of surgeon; just imagine a hypothetical discussion of
valvular disease with an orthopedist. This tends to create situations where the CT surgeons basically tell
you what they want you to do with your management and anesthetic. As with all things, being political
and working as a team is the best way to go. Remember you can always defer to your attending if you
are unsure. With time and greater experience you will learn what things you can let slide and which
battles are truly worth fighting.

The cardiac months will be some of the most educational during your entire time at UCSD. Most people
feel that after their heart months there is no case that is too big for them. In addition, you should have
gained a firm understanding of basic cardiovascular physiology and anesthesia. It is demanding work but
well worth it.

Chapter 5B. Coronary Anatomy and Circulation

Blood flow to the myocardium is supplied by the right and left coronary arteries. The right coronary
supplies the RA, most of the RV, and the inferior wall of the LV. It typically gives rise to the posterior
descending artery (85% of the time), which supplies the posterior interventricular septum and the
inferior wall. This is termed right-dominant circulation. The remaining 15% of the time the PDA arises
from the left coronary: left-dominant circulation. The SA node is supplied by the RCA 60% of the time.
The AV node is almost always supplied by a branch from the RCA.

The left main supplies the LA and the anterior, lateral, and septal walls of the LV. It quickly divides into
the LAD and the circumflex artery. The LAD supplies the anterior wall of the LV and most of the septum
and gives rise to diagonals, while the circumflex supplies the lateral wall and gives rise to the obtuse
marginals.

Most coronary venous return is through the coronary sinus and anterior cardiac veins into the RA,
although a small amount drains into the LA through the thebesian veins, representing a portion of
physiologic shunt.

Perfusion occurs anytime there is coronary flow, which in turn occurs anytime aortic pressure exceeds
intrachamber pressure. So, the RV (normally < 40mmHg) is perfused during both systole and diastole,
while LV perfusion occurs almost entirely during diastole. The endocardium is the area most sensitive to
ischemia because the highest transmural pressures and lowest perfusion pressures are encountered
here.

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Myocardial Oxygen Supply and Demand

Normal coronary blood flow is regulated almost entirely by constriction or dilation of coronary vessels in
response to metabolic demand. Myocardial oxygen extraction is ~60%, compared to 25% for most of the
body, so myocardium cannot compensate for increased oxygen demand by increased extraction. Flow
must increase to meet any increased demands. Pathophysiology that inhibits the coronaries to increase
supply (e.g., coronary atherosclerosis, already maximally dilated vessels in response to chronically high
demand) can lead to ischemia if metabolic demand increases. Much of cardiac anesthesia is goal-
directed therapy to improve myocardial oxygen supply/demand characteristics.

The determinants of myocardial oxygen supply are:

Coronary perfusion pressure (DBP LVEDP)

o Increasing arterial pressure, especially diastolic pressure, and reducing LV end- diastolic
pressure will increase CPP.
o The converse of the above also holds.
Coronary vessel caliber
o Reductions in vessel diameter (e.g., coronary vasospasm or atherosclerosis) reduce the
ability to delivery blood flow and oxygen.
o Similarly, measures to dilate coronary vessels (e.g., nitroglycerin) can improve flow.
Arterial oxygen content
o Determined by the hemoglobin concentration, oxygen saturation, and P aO2.
o Increases or reductions in either are directly linked to oxygen supply.
Heart rate
o The LV is perfused in diastole.
o The slower the HR, the more time for diastole.

The determinants of myocardial oxygen demand are:

Heart rate
o Each contraction consumes oxygen.
o Faster heart rates increase myocardial oxygen consumption in a linear fashion.
Wall tension
o The primary determinants of wall tension are chamber size, chamber wall thickness, and
afterload.
o Chamber size is determined by preload and inherent ventricular size.
o Chamber wall thickness is fixed at a given point in time.
o Afterload increases wall tension.
Contractility
o Increases in contractility increase oxygen consumption.

Chapter 5C. Anesthetic Goals in Cardiac Disease States

Each cardiac lesion has specific considerations for management during anesthesia. These considerations
apply to cardiac patients coming for surgery for the lesion (e.g., CAD in a patient coming for a CABG) as
well as patients having non-cardiac surgery who have one of these lesions as a comorbidity (e.g., critical
AS in a patient coming for hip fracture repair). When multiple lesions coexist and their management is
disparate, e.g. AS coexisting MR, the dominant lesion takes priority in management. The specific goals

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during anesthesia are discussed below.

Coronary Artery Disease

Patients with CAD presenting for CABG usually have disease in at least 2 of the 3 major arterial
distributions (RCA, LAD, circumflex) or left main coronary disease. In terms of clinical presentation, these
patients may have a long history of stable, exertional chest pain or shortness of breath (angina) or have
had a recent acute event that prompted investigation, e.g. NSTEMI. Preoperative evaluation may reveal
evidence of impaired systolic function with or without diastolic dysfunction and possibly coexisting
valvular disease. Most patients coming for CABG have several comorbidities including hypertension,
COPD, diabetes, or advanced kidney disease. The underlying principle in patients with CAD is to carefully
match myocardial oxygen supply and demand.

The anesthetic goals for a patient with CAD are:

Heart rate and rhythm

o Tachycardia must be avoided at all costs, since it increases myocardial oxygen demand while
impairing oxygen supply.
o Sinus rhythm is preferred but not critical.
Preload
o Should be maintained within normal limits.
o Decreases in preload that could potentially lead to tachycardia, e.g. hypovolemia, should be
avoided.
o Hypervolemia is to be avoided since an increased LVEDV increases LVEDP and myocardial
work.
Afterload
o Extremely high afterload (e.g., arterial hypertension due to pain or anxiety) is to be avoided
since it increases myocardial wall tension.
o Drastic reductions in SVR and aortic diastolic pressure impair coronary perfusion pressure
and must be avoided.
Contractility
o Should be maintained.
o Increases in contractility increase
oxygen demand and must be avoided.

Aortic Stenosis

AS is now usually due to calcific degeneration (a

process similar to atherosclerosis); congenital
defects (e.g., bicuspid valve) and rheumatic disease
were previously the most common causes. These
processes lead to gradual impairment of LV
outflow. In compensation, the LV develops
concentric hypertrophy, which serves to both
increase transvalvular flow with more squeeze
and to decrease LV wall tension. As the disease
worsens, these patients are not able to increase
cardiac output in response to demand because the

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stroke volume is maxed and heart rate increases are limited by impaired coronary flow to the thickened
myocardium. Myocardial oxygen demand is increased due to increased work of the hypertrophied
myocardium, while supply is diminished from a fixed CO. The hypertrophied LV is stiff, often with
diastolic dysfunction, which causes a decrease in the LA-to-LV diastolic pressure gradient and results in
decreased LV filling. This makes these patients very dependent on coordinated atrial contraction (atrial
kick) for diastolic filling.

The classic presenting signs of AS are exertional syncope, angina, and heart failure. Angina can be
independent of true CAD and results from functional ischemia and the inability to perfuse the
hypertrophied myocardium. Heart failure, if present, is the worst prognostic sign of the three. The
normal aortic valve area is > 2.5cm2, while < 0.6cm2 is considered critical AS. Typical surgical intervention
involves replacement of the valve; percutaneous valvuloplasty is a rare option.

The anesthetic goals for a patient with AS are:

Heart rate and rhythm

o Avoid tachycardia or excessive bradycardia. Increases in HR result in decreased ventricular
filling and increased oxygen consumption, while bradycardia can impair CO because CO is
HR-dependent.
o Sinus rhythm must be maintained. These patients are very dependent on their atrial kick
for LV filling. Intra-op atrial fibrillation should be immediately cardioverted.
Preload
o Should be maintained within normal limits.
o Decreases in preload leading to decreased BP should especially be avoided; see below.
Afterload
o A normal to high-normal afterload is absolutely essential.
o Drastic reductions in SVR and aortic diastolic pressure, such as those that accompany a
typical induction, must be avoided.
o Raising arterial blood pressure and SVR does not increase the obstruction to flow or
ventricular work in these patients, since the obstruction is fixed at the valve itself.
Contractility
o Should be maintained.

Hypotension can set off a spiral of decreased coronary perfusion, myocardial ischemia, decreased
contractility, leading to further hypotension, decreased coronary perfusion, and so forth. In a patient
with critical AS this can be impossible to recover from due to the fixed stenotic valve. For the same
reason, chest compressions are ineffective.

The choice of anesthetic agent is not as important as maintaining the above parameters. Neuraxial
anesthesia is a contraindicated in severe AS due to an unacceptable drop in blood pressure. These
patients should have an arterial line placed prior to induction, and any hypotension must be dealt with
immediately. Many practitioners choose a titratable agent such as phenylephrine and have it running
prior to induction.

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Aortic Regurgitation

AR can be acute or chronic in nature. Acute causes

include endocarditis, aortic dissection, or traumatic
injury. Chronic causes include congenital (e.g.,
bicuspid valve), rheumatic disease, syphilis, Marfan
syndrome, and other connective tissue diseases.

The pathophysiology involves LV volume overload

as a portion of the stroke volume passively returns
backwards into the LV during diastole. This reduces
effective stroke volume. In its chronic form, the LV
eccentrically dilates to accommodate the increased
volume, and the AR can present as insidious CHF or
angina. Eventually these changes to the LV become
irreversible. Ventricular dilation may also cause MR.
Aortic diastolic pressure tends to be low, and LVEDP tends to be high, so coronary perfusion pressure
can be tenuous. In the acute situation, the LV is unable to dilate, and the increased volume and pressure
are translated back to the LA and pulmonary circulation, manifesting as pulmonary edema and
hypotension.

The anesthetic goals for a patient with AR are:

Heart rate and rhythm

o High-normal rates are preferable. Increases in diastolic time allow for increased
regurgitation, so avoiding bradycardia is necessary.
o Maintaining sinus rhythm is preferable but not essential as in AS (above).
Preload
o High-normal volumes should be maintained to allow for adequate filling and forward stroke
volumes. Excessive preload should be avoided.
Afterload
o AR patients generally benefit from a reduction in afterload, which improves forward flow.
o Sudden increases in afterload increase the regurgitant volume.
o Typically these patients have a very wide pulse pressure.
Contractility
o Inotropic support may be necessary to maintain forward flow, especially in acute AR.

A good mnemonic for management of regurgitant lesions is Full, Fast, and Forward.

Mitral Stenosis

MS is almost always due to rheumatic fever and is increasingly rare in this country. The valve leaflets
and chordae tendinae thicken, fuse and become calcific, all of which contribute to impaired valvular
opening, decreased LV preload, and dilation of the LA to overcome the transvalvular pressure gradient.
Dilation of the LA can lead to arrhythmias such as A-fib. Static blood in the LA leads to formation of clot
and the potential for systemic emboli. Furthermore, increases in pressure in the LA translate back into
the pulmonary circulation, which can lead to pulmonary edema, increased PVR, and RV failure.

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The anesthetic goals for a patient with MS are:

Heart rate and rhythm

o Maintenance of sinus rhythm is
necessary to improve LV filling.
o Preexisting A-fib and/or clot are
common and may make cardioversion
unwise.
o Avoid tachycardia so as to allow
sufficient diastolic time and LV filling.
Preload
o Adequate filling pressures must be
maintained.
o Excessive volume is poorly tolerated,
does not increase LV preload, and is
readily transmitted back to the pulmonary circulation.
o Keep these patients euvolemic.
Afterload
o Should be maintained near-normal.
Contractility
o Avoid increases in CO, as the LV is poorly able to compensate and has a relatively fixed
preload.

Mitral Regurgitation

MR can either be acute or chronic. Chronic causes

include rheumatic disease or degenerative dilation
or destruction of the mitral annulus. Acute causes
include endocarditis, trauma or myocardial
ischemia (dysfunction or rupture of a papillary
muscle). MR is characterized by backflow of the LV
stroke volume into the LA, resulting in decreased
forward flow and CO. To compensate for this
increased volume, the LA dilates. Severe LA volume
overload is transmitted back to the pulmonary
circulation. Meanwhile, the LV also eccentrically
dilates and increases end-diastolic volume. This
compensatory response increases CO in the face of
decreased forward EF. Patients with acute MR, often due to ischemia, are unable to compensate in this
way, present with pulmonary edema. Under the low-SVR, low-demand state of anesthesia, MR often
appears better on TEE than it would in the awake patient.

The anesthetic goals for a patient with MR are:

Heart rate and rhythm

o Keep HR at high-normal ranges.
o Slow heart rates, and long systolic times, increase regurgitant flow.
o Maintain sinus rhythm if possible.

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 Preload
o Adequate preload must be maintained to meet increased filling requirements from the
dilated LV.
Afterload
o Reducing afterload favors forward flow and effective SV.
Contractility
o Should be maintained.

Again, the mnemonic for management of regurgitant lesions is Full, Fast, and Forward.

Right-sided Valvular Lesions

Valvular lesions on the right side of the heart are generally better tolerated by patients and only rarely
present for surgery. They may be congenital or degenerative in nature or from infective endocarditis.
Often, right heart pathology is secondary to pulmonary hypertension resulting from left heart pathology.
For further discussion of right-sided lesions, consult an appropriate text.

Hypertrophic Obstructive Cardiomyopathy

This disease entity is characterized by idiopathic hypertrophy of the myocardium, most commonly in the
LV at the interventricular septum. Diastolic dysfunction is encountered, with elevated LVEDPs reflecting
increased LV stiffness. There is outflow obstruction during systole due to narrowing of the subaortic
area by the hypertrophied myocardium. Additionally, a systolic anterior motion (SAM) component of the
anterior leaflet of the mitral valve may be present. In this phenomenon, the mitral leaflet is drawn by
the Venturi effect into the subaortic area during systole, worsening outflow obstruction.

HOCM can present insidiously as dyspnea, fatigue and syncope or near-syncope. It is the most common
cause of sudden cardiac death in young patients. Other associated findings include arrhythmias, LVH and
Q waves on ECG, and evidence of hypertrophy on echo. Treatment includes -blockers, calcium channel
blockers, and surgical myomectomy if severe. This is a rare indication for heart transplantation.
Rationale for medical therapy is below.

The anesthetic goals of a patient with HOCM are aimed at avoided factors which make the outflow
obstruction worse. Increased contractility, decreased LV volume and decreased afterload all worsen
obstruction. Therefore, adequate preload, maintenance of afterload, and avoidance of increased
sympathetic output and increased contractility are key.

Chapter 5D. One-lung Ventilation: Anesthesia and Physiology

Single-lung ventilation can be one of the most challenging maneuvers we encounter in anesthesiology.
In addition to the mechanics of placing an appropriate ET tube and physically separating the lungs,
profound changes in respiratory physiology are created with potentially deleterious consequences.

The indications for one-lung ventilation can be divided into absolute and relative, and are a favorite
topic on the boards. The only absolute indications are:

Isolate bleeding to one lung (e.g., pulmonary artery rupture)

Isolate infection to one lung (e.g., overwhelming abscess or pus confined to one lung)
True need to ventilate only one lung (e.g., bronchopleural fistula, tracheobronchial disruption,

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 bronchoalveolar lavage)

Relative indications are mostly related to the surgical procedure or technique:

Pneumonectomy, lobectomy, thoracoscopy

Anterior thoracic spine procedures
Thoracic or high abdominal aortic aneurysms
Lung transplantation
Severe unilateral lung disease with hypoxemia
Esophageal surgery

Several types of ET tubes and equipment are available to create lung separation and one-lung
ventilation, including double lumen ETTs and various types of bronchial blockers. Specific techniques for
each are covered in detail in the thoracic surgery chapter in Millers Anesthesia and during the airway
rotation. Advantages and disadvantages of each are discussed below.

Double-lumen ETT
o This is a large ETT with a bronchial lumen and a tracheal lumen. They come in either left- or
right-sided types and in sizes measured in French.
o Advantages include the ability to suction either lung, the ability to ventilate either lung,
relative stability once placed, and the ability to give oxygen and CPAP to the nonventilated
lung.
o Disadvantages include the larger size, relative difficulty of placement, and the fact that it
cannot be left in place if post-op ventilation is needed.
Univent ETT
o This is a large, single-lumen ETT with a Uniblocker-type bronchial blocker incorporated into
the ETT wall.
o Advantages include better ease of placement, the ability to leave it in place at the
conclusion of the case, and relative stability.
o Disadvantages include the inability to suction the nonventilated lung, relative difficulty in
switching ventilation between lungs, the lack of pediatric sizes, and the slow rate of lung
deflation due to the small efflux lumen.
Bronchial blocker through a standard ETT
o Examples include the Uniblocker, Arndt, Cohen, and the Fogarty embolectomy catheter.
These are similar; each is a balloon on a stick.
o Advantages include coming in many sizes and small pediatric sizes.
o Disadvantages include relatively poor stability, the inability to suction or provide oxygen to
the nonventilated lung, and the slow rate of lung deflation due to the small efflux lumen.

Regardless of the choice of tube, confirming and maintaining the ability to ventilate only one lung is
critical. After insertion, proper tube position and the ability to separate the two lungs must be
confirmed. After the patient is positioned for surgery (usually lateral), both tube position and lung
separation should be rechecked. Any movement or repositioning of the patient can result in tube
migration and the inability to separate the lungs or appropriately ventilate the patient. The following is a
complete checklist to follow after placement of a DLT, the type most commonly employed for one-lung
ventilation. Although there are many ways to confirm proper placement, this checklist is a thorough
starting point.

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Before starting, have all the appropriate equipment available. This includes the correct DLT size plus one
larger and one smaller, a firm clamp, suction catheters (included in the DLT packaging), a working
fiberoptic bronchoscope, and a stethoscope.

1. Place DLT at estimated appropriate depth.

2. Inflate both bronchial and tracheal cuffs.
3. Listen for bilateral breath sounds while ventilating through both lumens.
4. Clamp one lumen at a time and listen for absence of breath sounds on the clamped side and
continued presence on the contralateral side.
5. Place fiberoptic bronchoscope down tracheal lumen, confirm proper placement of tube and
bronchial cuff, and and adjust as necessary.
6. Secure with tape or ties.
7. Run the checklist again after positioning.

Confirming Correct Tube Placement with FOB

At UCSD, lung isolation is almost universally achieved with a left-sided DLT, the placement of which is
confirmed immediately after placement with FOB. Auscultation alone has a success rate < 80%.

When using a Univent or single lumen ETT with a bronchial blocker, confirmation of correct tube/blocker
placement is fairly straightforward. The tracheal rings will be evident on the anterior aspect of the
trachea, and the first major division into the right and left mainstem bronchi occurs at the carina. The
right mainstem can be further identified by noticing the straighter, more caudal takeoff, the fairly rapid
takeoff of the RUL, and the trifurcation where the RML, segment 6 of the RLL, and the 4 inferior
segments of the RLL take off. The left mainstem bronchus is much longer, and its first division is a
bifurcation into the LUL+lingula and the LLL.

DLTs come in either left- or right-sided types, corresponding to the direction of the bronchial lumen and
cuff. In practice, a left-sided DLT is almost always chosen as it is technically easier to place with fewer
complications and still allows separation of either lung. The main disadvantage of right-sided DLTs is that
the RUL bronchus takes off of the right mainstem bronchus very proximally, so it is easy to block with
the bronchial cuff; the margin of safety is quite low. With correct left-sided DLT placement, the
following features will be observed:

The tracheal rings should be anterior and visible when the FOB is passed down the tracheal lumen.
The bronchial lumen should extend into the left mainstem bronchus but not all the way to the
bifurcation of LUL and LLL. It is possible to measure the distance from lumen tip to bifurcation,
keeping in mind that the left mainstem is often 4-5cm long.
Seen through the tracheal lumen, the inflated blue bronchial cuff should be stably seated just below
the carina.
Again through the tracheal lumen, the right mainstem bronchus and RUL bronchus should be widely
patent.

Physiology of One-lung Ventilation

The lateral position is the most commonly employed position for surgery involving one-lung ventilation
and is partially responsible for the physiologic changes encountered. The awake, spontaneously
ventilating patient in the lateral position generally has preserved V/Q ratios. The dependent lung

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receives more perfusion due to gravity, but is better ventilated due to more efficient diaphragmatic
movement and optimal position on the alveolar compliance curve. Under general anesthesia, a
reduction in FRC and change in ventilatory patterns creates significant V/Q mismatching. The dependent
lung now continues to receive more perfusion, but becomes relatively less well ventilated, creating the
potential for large amounts of shunting and hypoxemia. Positive-pressure ventilation and one-lung
ventilation will correct or abolish many of these effects.

During positive-pressure ventilation with the nondependent lung deflated, i.e., one-lung ventilation, the
nondependent lung continues to receive some amount of pulmonary blood flow. This blood does not
become oxygenated, so this represents right-to-left shunt and can lead to hypoxemia. Fortunately,
hypoxic pulmonary vasoconstriction limits flow to the nondependent lung. This creates a situation
where most of the perfusion and all of the ventilation is delivered to the dependent, ventilated,
nonoperative lung. Factors which can decrease HPV and increase shunt include hypocapnia,
vasodilators, and inhaled anesthetics in doses > 1 MAC.

Decreasing perfusion to the dependent lung can also create shunt and worsen hypoxemia by diverting
blood to the nondependent lung. Factors which decrease perfusion include high airway pressures
(excessive PEEP, autoPEEP from inadequate expiratory times), low FiO2 causing HPV in the dependent
lung, and compression of relevant blood vessels as in surgical manipulation.

Elimination of CO2 is typically not compromised providing minute ventilation does not change. Smaller
tidal volumes, on the order of 4-8ml/kg, and faster respiratory rates are usually employed during one-
lung ventilation. Hyperventilation and hypocapnia are avoided as they inhibit HPV, and permissive
hypercapnia is an accepted technique.

Correction of Hypoxemia During One-lung Ventilation

Hypoxemia and oxygen desaturation during one-lung ventilation must be corrected, and strategies to do
so are a common boards topic. The first goal is to determine the minimum tolerable saturation for the
patient, recognizing that some amount of shunting is inevitable during one-lung ventilation. Many
practitioners use an SpO2 of 88-92% as their cutoff, although clearly this varies according to the patient
and their disease state. Its important to recognize that hypoxemia below this threshold is life-
threatening and is a legitimate reason to change surgical technique or abort surgery altogether. The
following steps can be employed to correct hypoxemia:

1. Ventilation with 100% O2. Most anesthesiologists do this anyway for the duration of one-lung
ventilation.
2. 5-10cm H2O of CPAP (with oxygen flow) to the nondependent lung. This is an effective maneuver.
This can be done with a Mapleson circuit with an in-line manometer. Beware that this can cause
reinflation of the operative lung and interfere with surgery.
3. PEEP to the ventilated lung. This can theoretically worsen hypoxemia by decreasing perfusion to the
ventilated lung. It can also correct hypoxemia if atelectasis is the etiology.
4. Periodic two-lung ventilation. This also interferes with surgery.
5. In extreme cases, the surgeon can clamp the pulmonary artery of the nonventilated lung, essentially
eliminating all shunt from that source.

Chapter 5E. Other Topics in Cardiothoracic Anesthesia

Intra-aortic Balloon Pump

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An IABP is a device designed to improve myocardial oxygen supply and reduce oxygen demand in a
failing or ischemic heart. It is often used to wean patients from CPB. The balloon is typically placed in a
femoral artery and threaded retrograde to sit in the proximal descending aorta. The balloon inflates and
deflates with the cardiac cycle. Inflation is timed to occur just after the aortic valve closes (dicrotic
notch), to improve aortic diastolic pressure and therefore coronary perfusion pressure. Deflation is
timed to occur just before LV ejection, so that aortic pressure (afterload) at that time is low and
myocardial work is reduced. The net result is afterload reduction and coronary perfusion augmentation;
which is the more important component is a matter of debate.

Properly timed inflation of the balloon is critical. Inflating the balloon too early results in increased
afterload and myocardial work and can cause aortic regurgitation. Inflating the balloon too late negates
diastolic pressure augmentation. The balloon can be set to inflate with a variety of timings, such as with
every beat (1:1), every other beat (1:2), or less (1:4, 1:8). This adjustability can be used to wean the
heart from the IABP. Timing with the heartbeat is accomplished either by sensing the QRS complex or
the arterial waveform.

If an IABP is to remain in place for more than several hours, anticoagulation becomes necessary.
Complications of the IABP include limb ischemia, mesenteric ischemia, aortic dissection or rupture,
infection, bleeding, coagulopathy (especially thrombocytopenia), gas emboli, renal failure, and spinal
cord ischemia resulting in paraplegia. Contraindications to IABP placement include AR, sepsis, and
severe vascular disease, which can cause problems with placement and raises the risk of thrombosis.

Although invasive, IABP use is becoming increasingly common. They are clearly beneficial in assisting
patients in need of LV support and are first-line agents in some centers (not UCSD).

LVAD/RVAD

Patients with heart failure refractory to medical management may require a right or left ventricular
assist device. Rarely, they may be placed to aid a patient in coming off CPB when all other measures
have failed. VADs may be temporary, used for a few months as a bridge to heart transplantation, or as
destination therapy in patients not suitable for heart transplant. Essentially, a VAD is a centrifugal pump
that takes blood from the ventricle and pumps it to the downstream artery (aorta or PA). Presence of a
VAD requires systemic anticoagulation.

CO in patients with a VAD becomes dependent on preload and VAD speed. In low-CO states, volume
administration is usually attempted first, before adjustment of the pump speed.

Patients with VADs may have nonpulsatile blood flow. Therefore, non-invasive blood pressure cuffs and
pulse oximeters may work poorly or not at all.

Heparin Resistance and Anticoagulation

Heparin resistance is generally due to antithrombin III deficiency. In normal patients, heparin binds to
ATIII, greatly enhancing its anticoagulant effects. ATIII-deficient patients cannot achieve this
anticoagulated state, so administration of FFP (which contains ATIII) or ATIII concentrate will allow
heparin to be effective for CPB.

Patients with heparin-induced thrombocytopenia can be a challenge to anticoagulate prior to CPB. In

HIT, heparin antibodies bind to platelets, causing thrombocytopenia and possibly thromboembolism. If a

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patient has a history of HIT, blood samples should be sent specifically to check for heparin antibodies. If
there are no antibodies present and the history of HIT is distant, heparin may be used for CPB. If
antibodies exist, alternative anticoagulation must be used, including hirudin, bivalirudin, and
argatroban. Plasmapheresis may be necessary to remove significant amounts of antibodies.

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Chapter 6. Anesthesia for Cardiothoracic Surgery

Much of the relevant information and physiology is covered in the preceding section on cardiovascular
physiology, and will also be addressed in depth during the rotation. This section is intended to provide a
general game plan for the CT cases encountered here at UCSD.

Chapter 6A. Basics of Cardiopulmonary Bypass (CPB)

In general, any case involving CPB can be broken down into three broad stages: the pre-bypass, on-
bypass, and post-bypass periods. Each stage has different physiologic goals and requirements. CPB is
used for any open heart procedure including valve repair and replacement, pulmonary
thromboendarterectomies (PTEs), heart and double lung transplants (usually), aortic aneurysm or
dissection repair, and many CABGs. Additionally, partial bypass may be used in other rare cases (e.g.,
extensive tumor involving the IVC). Essentially, CPB diverts blood away from the heart and lungs to the
bypass machine, which then oxygenates the blood, removes CO2, and returns the blood to a major
artery, usually the aorta.

The CPB machine is complex and its function is only briefly covered here. At UCSD, a dedicated
perfusionist is responsible for maintaining and monitoring the function of the pump at all times, as well
as making any adjustments during bypass (e.g., increasing flow, correcting electrolyte imbalances). It is
still important for anesthesiologists to understand the CPB mechanism, especially because it is a tested
topic on the boards.

The CPB has five basic components: a venous reservoir, an oxygenator, a heat exchanger, a pump, and
an arterial filter. The pump is typically primed with around 2L of isotonic solution in the venous
reservoir, and many different solutions can be added depending on surgical preference or patient needs
(e.g., mannitol, albumin, blood products). Venous blood drains from the venous cannula, in the patient,
to the reservoir by gravity. Drainage is thus proportional to the difference in height from the patient to
the reservoir and also depends on the size and resistance of the venous cannulas. Entrainment of air
into the system can result in an air lock, preventing further drainage and proper pump function, with
potentially devastating consequences.

From the reservoir, the blood passes through a thin membrane where O2 is added and CO2 is removed.
Next, the blood is brought to the desired temperature and sent to the pump. Pumps are either roller
pumps or centrifugal pumps. The former uses rollers to squeeze blood through large tubing and flow is
proportional to speed of the rollers. Increasing the number of revolutions will increase flow. This form of
flow is non-pulsatile; this non-physiologic type of flow may be partially responsible for decreased organ
perfusion during CPB. Centrifugal pumps spin, flinging the blood outward and using centrifugal force
to propel blood to the patient. The flow is proportional to the resistance encountered, and increases in
SVR require an increase in centrifugal pump speed to create the same flow. This form of pumping may
be less traumatic to the blood (no squeezing). Before returning to the patient, the blood passes through
an arterial filter, which serves to trap debris such as particulate matter and emboli. The blood then
returns via the arterial cannula.

CPB machines have many additional features. Various suction and vent lines return blood from the
field and the heart, since even on CPB the heart will still receive venous blood from the bronchial and
thebesian circulations. A separate pump is used to infuse cardioplegia solution to the heart; see below.
Additionally, inhaled anesthetic can be directly added via the oxygenator.

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Myocardial Protection

Upon initiation of CPB and aortic cross clamping, all coronary blood flow ceases. Techniques to protect
the myocardium must be initiated to prevent myocardial ischemia and cell damage.

Cardioplegia

Cardioplegia solution containing a high potassium concentration is most commonly used. Infusion of this
solution antegrade via the coronary arteries causes cardiac arrest and cessation of electrical and
mechanical activity, reducing oxygen requirements dramatically. Cardioplegia can also be delivered
retrograde, via the coronary sinus, to ensure all myocardium is reached, since arterial flow in a patient
with CAD is limited. Cardioplegia must be reinfused periodically, and washed out prior to coming off
CPB.

Distention of the heart and electrical activity both increase myocardial oxygen demand. Fibrillation is
especially energy-consuming and thus detrimental. Satisfactory conditions for myocardial preservation
are not met until the heart is both empty and asystolic.

Hypothermia

Systemic hypothermia reduces metabolic oxygen requirements by about 50% for every 10C reduction
in temperature. CPB is carried out under hypothermic conditions, with the patient typically cooled to 25-
30C. Additionally, cold slush solutions are directly applied to the heart and chest cavity to reduce
myocardial temperature and assist with cardioplegia. This hypothermia must be corrected before CPB is
removed.

Other Techniques

Other factors which may lessen myocardial damage include minimizing bypass time (over 2hrs is

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considered suboptimal); minimizing surgical manipulation of the heart; de-airing the heart and grafts
prior to termination of bypass; and the use of inhaled anesthetics, which have been shown to attenuate
ischemia-reperfusion injury. Unfortunately, anesthesiologists have little control over most of these
components.

Chapter 6B. The Pre-Bypass, On-Bypass, and Post-Bypass Periods

The Pre-Bypass Period

This time period starts with induction of anesthesia and ends with insertion of the venous and arterial
cannulas. Hemodynamic stability is of paramount importance during induction. Specific agents and goals
should be titrated to the patients underlying disease state (e.g., pulmonary hypertension, aortic
stenosis) and are covered more fully in the section on cardiovascular physiology. The most
hemodynamically labile and stimulating times are during laryngoscopy, skin incision, splitting of the
sternum, and manipulation and dissection around the aorta.

Almost every cardiac patient will need an arterial line placed prior to induction of anesthesia. After
induction and intubation, other lines such as the CVP and PAC are placed. Relevant labs such as the ACT,
baseline ABG, and cardiac output data should be obtained. The TEE probe is placed and an exam
performed. Antifibrinolytic therapy is used on all CPB cases, with the exception of PTEs, with the goal of
limiting blood loss and combating the profibrinolytic effects of CPB. Aminocaproic acid is the agent of
choice at UCSD. Typically, 2.5g of aminocaproic acid is given as a slow bolus loading dose, followed by an
infusion of 1g/h. Aprotinin was previously used, but was taken off the market in the USA due to
concerns about renal injury. More details will be provided prior to starting your cardiac rotation.

CPB requires full systemic heparinization to prevent catastrophic clotting within the pump, which would
be fatal. After surgery has begun, the perfusionist will calculate the dose of heparin needed based on
body weight and the baseline ACT. The patient is allowed to passively cool in preparation for systemic
hypothermia with CPB. A small amount of hemodilution is beneficial to lower blood viscosity, but
typically we limit the amount of fluid we give pre-bypass given the volume of prime solution in the CPB
circuit. The surgeons do as much dissection as possible pre-bypass to minimize time actually spent on
CPB. This may include harvesting of a saphenous vein and dissection of the internal mammary artery.

Prior to insertion of the CPB cannulas, heparin is administered. The surgeons will call for this at the
appropriate time. An ACT should be checked 3 minutes later to ensure proper anticoagulation. An ACT >
400 seconds is generally considered safe. The aortic cannula is placed first. During this time, SBP should
be 100mmHg or less to facilitate placement of the cannula and reduce the chance of aortic dissection.
This can be accomplished in any number of ways, including deepening the anesthetic, slight reverse
Trendelenburg, or by using a short-acting vasodilator such as nitroprusside. Next, the venous cannulae
are placed, and venous flow to the reservoir is confirmed. When good venous flow is established, the
arterial cannula is unclamped and CPB is initiated. Flow is gradually increased as proper cannula
placement, venous return and arterial pressures are confirmed. Cooling is begun immediately, and
cardioplegia will begin shortly thereafter.

The On-Bypass Period

Physiologic management of the patient is largely turned over to the perfusionist at this point. The
ventilator is stopped and infusions other than aminocaproic acid are stopped. Vasoactive drugs are
administered by the perfusionist. Anesthesia is maintained with volatile anesthetic given by the

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perfusionist via a vaporizer on the CPB machine. Because the CPB prime solution dilutes the blood and
reduces concentrations of drugs present, additional muscle relaxant or midazolam may need to be
administered at this time, and are given by the perfusionist into the venous reservoir. The PAC typically
migrates distally as it cools during CPB, and so it should be withdrawn 2-3cm upon initiation of CPB.

The surgeons may pass off a separate line to the anesthesiologist to topically apply a constant stream of
cold topical irrigation to the heart. These cold bags of NS will be provided in the room and should be
continued for as long as the surgeon desires. Urine output should be monitored and reported to the
perfusionist. The perfusionist may also request syringes of vasoactive drugs to manage the patients
physiologic parameters.

As the surgical portion of the bypass period concludes, the surgeons will call for the patient to be
rewarmed. The patient must be rewarmed prior to termination of CPB, but rewarming too soon can
negate the protective effects of hypothermia. Vasodilation can improve pump flow and speed the
warming process. Overly-rapid rewarming reduces the solubility of gases and can lead to the formation
of bubbles, and in turn, gas emboli. Light anesthesia is common during rewarming and most
practitioners administer additional muscle relaxant and/or amnestic agents. The perfusionist will
calculate and tell you the dose of protamine that will be needed for eventual heparin reversal.
Protamine must not be administered while the patient is on CPB, for catastrophic clotting and death
are the likely results. It is safest to just wait to draw up the agreed-upon dose until the surgeons ask for
protamine to actually be given.

Prior to separation from CPB, the patient should be normothermic, the acid/base status and hematocrit
should be normalized, a stable cardiac rhythm and rate must be obtained (generally 80-100bpm; pacing
may be needed), and ventilation is resumed. Coming off CPB is a critical time, and the attending should
and will always be present. The venous return lines are slowly clamped, and the heart fills and begins to
eject blood. The cardiac surgeons usually call for an inotrope at this point, typically low-dose dopamine,
but the choice of agent may depend on the patients physiology. The aortic line is stopped and the
patients vitals and cardiac output are assessed. A TEE exam is done to evaluate volume and contractile
status as well as the function of implanted valves. Assuming all is well, the patient is deemed to be off
bypass successfully and management of circulation is once again turned over to the anesthesiologist.
Once the need for CPB is has been removed and truly terminated and the cannulas removed the
surgeons will call for protamine. Prior to administration, you must announce in a loud, clear voice that
you are about to give protamine. This confirms to the whole team what is about to happen so that
everyone is on the same page (e.g., the perfusionist will shut the CPB suction off). Protamine should be
administered slowly, either in 3-5ml increments over at least 5-10 minutes, or diluted in a 100ml bag
and dripped in slowly. The side effects of protamine include hypotension from vasodilation, pulmonary
hypertension, and myocardial depression, all of which are exacerbated by fast administration. Allergic
reactions can occur, and may be more common in diabetics who previously received insulin containing
protamine (Neutral Protamine Hagedorn, NPH).

At times, the patients heart will not perform adequately coming off bypass and additional measures
may be needed, including the need to reinstitute CPB. These measures include the use of additional
inotropes, an IABP, or rarely, a left or right Ventricular Assist Device (LVAD or RVAD). Possible causes for
poor myocardial performance include poor myocardial protection leading to ischemic injury, long CPB
time, myocardial stunning, ongoing ischemia (e.g., air in the coronaries), continued valvular dysfunction,
and poor baseline cardiac function. The goal is always to make the first attempt to separate from CPB
the best attempt, since each subsequent attempt becomes more difficult and more taxing on the heart.

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The Post-Bypass Period

This period starts with coming off CPB and reversal of heparin and ends with patient transport to the
ICU. It consists of establishment of surgical hemostasis, chest tube placement, closure of the
sternotomy, and transport of the patient to the ICU. An ACT should be checked 3 minutes after
protamine administration to confirm adequate reversal; more protamine may be needed. Cardiac
output data are obtained via the PAC. A typical goal blood pressure is around 100mmHg, in order to
maintain an adequate systemic perfusion pressure while reducing myocardial work, risk to the
aortotomy, risk to coronary bypass suture lines, and the risk of bleeding. Once the chest is closed with
sternal wires, another cardiac output should be obtained. Chest tubes are placed to facilitate drainage
and to monitor for postoperative bleeding, which could necessitate a trip back to the operating room.

The perfusionist will usually be able to hemoconcentrate a significant amount of processed RBCs (cell-
saver blood) from the CPB circuit, and this should be given back to the patient. Indeed, most patients
post CPB require additional volume, the exact status of which can be guided by the TEE, vitals, and PAC
information. The patient should be prepared for transport, with all lines tidied up and a transport
monitor available. Full resuscitation drugs and airway equipment should be ready for transport in case
an emergency arises.

When surgery is concluded, the patient is moved to their ICU bed and transported. This is another
critical time that may appear innocuous for the unprepared. The move to the bed should be smooth and
controlled, and the patient should remain fully monitored. There have been cases of patients who were
alive on the OR table, moved to the ICU bed, and then when monitors were reconnected the patient
was found to be dead. Full monitoring during transport itself is mandatory; hand-ventilation via
Mapleson is usually sufficient for all cardiac cases except PTEs, for whom an RT will provide a transport
ventilator. Once in the ICU, care may be relinquished to the ICU nurse per standard protocol.

Chapter 6C. Anesthesia for Specific Cardiothoracic Surgeries

On-Pump Surgery

Prototypical cases include CABGs (although most CABGs are UCSD are off-pump) and valve replacements
or repairs.

Technique: general. Monitors: standard, plus arterial line, CVP, PAC, TEE, some form of neurologic
monitoring such as BIS or SEDline, urine output, femoral arterial line (mostly for PTEs). IV access: one
large IV to begin, with central access established during the case. Duration: 4-10hrs. EBL: difficult to
quantify secondary to hemodilution, CPB circuit volume, and CPB salvage, but 500ml-2L not uncommon.
Position: supine. Special equipment: multiple IV infusion pumps, cooling jacket for the head in PTEs.
Special considerations: The basic steps for surgery involving CPB are described above. Additionally,
goals for anesthesia in various disease states are described in the cardiovascular physiology section.

Almost every cardiac patient should have an arterial line placed prior to induction of anesthesia. Many
centers also place a central line and PAC before induction. At UCSD, the CVP and PAC are generally
placed after induction. Premedication should be used judiciously and tailored to the patients needs.
Pain, anxiety, and an increased sympathetic state are highly undesirable for most cardiac patients, as are
hypoventilation, hypoxia, and hypercapnia.

Infusion drugs should be prepared prior to bringing the patient back to the OR. Specific drugs will vary

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depending on the practitioner and the patients needs, but in general have at least one pressor (e.g.
phenylephrine), one inotrope (e.g. dopamine), and one vasodilator (e.g. nitroprusside) ready. Prepare a
nitroglycerin infusion for patients with CAD. These infusions are generally attached to the PACs RV
infusion port after placement.

The term cardiac induction is used to imply a gentle and hemodynamically stable choice of anesthetic.
Almost any agent at our disposal is suitable, provided they are titrated appropriately and used
judiciously. In the past, a high-dose narcotic technique (e.g., 50mcg/kg fentanyl) was favored for
induction, but a high incidence of recall and a move towards fast-tracking patients postoperatively
raised serious issues with this technique. Most practitioners use a balanced IV technique, again with
emphasis placed on hemodynamic stability. Etomidate, benzodiazepines, and narcotics are all excellent
agents in this regard. Liberal use of narcotic is still recommended to blunt sympathetic surges in
response to laryngoscopy and other stimulating events. Muscle relaxant should be given early to
facilitate ventilation and intubation and attenuate chestwall rigidity from narcotic administration.

Likewise, anesthetic maintenance should be geared towards maintaining hemodynamic stability and
amnesia, and the choice of agent is less important than judicious use of that agent. Most of us prefer to
ventilate with 100% oxygen throughout the case. The downside to 100% oxygen in the short term is
negligible, while the potential benefits in a class of patient especially intolerant of hypoxemia are
substantial. Volatile anesthetic, additional narcotic, IV agents, and muscle relaxant can all be used for
maintenance. Unfortunately, recall under anesthesia is more common in cardiac cases, as it is in
obstetric and trauma surgery, due to the increased potential for hemodynamic instability and the use of
CPB. Patients should specifically be informed of this rare possibility during the pre-op visit.

Other intensely stimulating points during the surgery include skin incision, sternal splitting, and
dissection around the aorta, and aortotomy for cannulation. Need for additional anesthetic should be
anticipated during these times. Prior to splitting the sternum, the surgeon will request for ventilation to
be held, to avoid lung inflation and possible damage from the saw.

Redo procedures deserve special mention. As the name implies, the patient has had a previous
median sternotomy, with a high likelihood of scar tissue and adhesions of thoracic structures to the
chest wall (e.g., L internal mammary artery, ventricular wall). Sternotomy in a virgin chest can be quite
fast, but redo sternotomies always proceed slowly and carefully. The surgeons do not blithely saw
through the sternum, but rather proceed stepwise in controlled layers, all to avoid inadvertent damage
to critical structures. Despite this, the potential for surgical mishap is still high. Therefore, redo
sternotomy patients should have the perfusionist immediately available to crash onto CPB, and blood
immediately available (e.g., in the OR and checked in).

Assuming adequate revascularization and lack of intraoperative mishaps, most CABG patients generally
respond well to surgery, with adequate or increased cardiac vigor secondary to increased blood supply.
The response of patients with valvular disease upon termination of CPB varies with the preoperative
disease. In general, patients with stenotic lesions tend to perform well after replacement of the diseased
valve. Longstanding pathology and compensation of the atrium or ventricle enable supramaximal
performance once a normal valve is in place. By contrast, patients with regurgitant lesions often do not
perform as well, and may need considerable support to come off CPB. The previous regurgitant valve
had created a low-pressure pop-off situation, which is removed when the new valve is placed. In the
case of MR, the LV must now eject against the aortic valve and the SVR only, without the low-pressure
LA to eject blood into.

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Pulmonary Thromboendarterectomy (PTE)

UCSD is one of the few centers in the world to perform PTEs regularly. In fact, the majority of cases you
will encounter during your first month of cardiac will probably be PTEs. While the essentials of the case
are the same as a standard CPB case, there are enough differences to warrant further description.

As a class, most PTE patients tend to be younger and have fewer comorbidities than other cardiac
patients. The basic pathophysiology of chronic thromboembolic pulmonary hypertension (CTEPH)
involves chronic formation of clot and intimal hyperplasia in the pulmonary arteries, elevating PVR, and
over time, pulmonary hypertension and right heart overload with RV hypertrophy, dilation, and failure.
Regardless of the cause of the pulmonary thrombus, elevated PA and right heart pressures are a
hallmark of these patients. Indeed, it is not uncommon to see a PTE patient with PA pressures close to
or above systemic arterial pressures!

The surgery involves opening the main pulmonary arteries so that clot can be extracted. Standard CPB
will not provide adequate surgical conditions because venous blood from the bronchial and thebesian
circulations returns to the LA and interfere with visualization of pulmonary capillaries. Circulatory arrest
is necessary, and this prompts most of the major anesthetic differences between a PTE and a standard
CPB case. Circulatory arrest must be performed under deep hypothermic conditions (16-18C) for
cellular protection, particularly neurologic protection. As the name implies, deep hypothermic
circulatory arrest (DHCA) involves cessation of the CPB machine and all flow to the patient for periods of
15-20 minutes at a time.

Measures to avoid increases in PVR or overall sympathetic state are key. Premedication is generally
avoided in order to avoid hypercapnia and hypoxemia. A vasopressor infusion is commonly used during
induction to avoid decreases in systemic arterial pressure. Placement of the PAC may prove difficult due
to RV dilation, and the risk of pulmonary rupture from PAC balloon inflation is increased. Indeed, many
practitioners do not wedge the balloon at all in these patients. A femoral arterial line is also placed after
induction, because pressures from the radial arterial line are very different from more central arterial
pressures after deep hypothermia.

As the case proceeds, a cooling jacket is wrapped around the patients head. This should be undisturbed
as much as possible and periodically checked to ensure that it is functioning properly. As discussed in
the neurophysiology section, hypothermia is the only measure that reduces the basal metabolic oxygen
requirements of the brain. Upon initiation of CPB, the patient is cooled to < 20C. It is important to note
that the CPB circuit prime for this case includes mannitol and very high doses of methylprednisolone,
with the goal of reducing ischemia-reperfusion injury particularly in the brain; these drugs may have
consequences such as volume and electrolyte shifts and hyperglycemia that the anesthesiologist will
have to address. Once the patient has reached around 18C, the perfusionist will ask for around 200mg
of propofol, to be administered just prior to DHCA, to flatline the EEG. Temperature is monitored in
multiple locations, including blood (PAC, CPB machine), tympanic membrane (probably best reflection of
brain temperature), bladder (reflects core temperature), and rectum. The bladder and rectal
temperatures typically lag the PAC and tympanic temperatures during warming or cooling.

Immediately before DHCA initiation, a checklist will be run through to ensure it is safe for arrest to
occur. This list includes confirming the patient is cold, the EEG is isoelectric, all transducer stopcocks are
turned off to the patient, the TEE probe is off, and the patients lungs are briefly ventilated with
unwarmed room air. Turning the stopcocks off to the patient ensures that no fluid from the transducers

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can entrain during circulatory arrest. Turning the TEE off prevents inadvertent warming from that
source. Ventilating the patients lungs expels any remaining blood from the bronchial and pulmonary
circulation. This checklist is a time-honored ritual at UCSD and the surgeons expect to hear it repeated
out loud prior to DHCA. While it is an important safety mechanism, the condescending way some of the
CT surgeons use it can be a source of frustration. In this situation, it is best to conform, play along, and
not get upset over a trivial matter, while continuing to act in the best interests of the patient.

DHCA is used in stints of no more than 20 minutes, during which the surgeon is quickly and carefully
performing the thromboendarterectomy itself. Time is of the essence, so distractions and delays are
unwelcome. The surgeons expect us to be especially attentive at this stage, standing at the head of the
bed, so surgery can proceed expeditiously. Typically 1 or 2 stints of DHCA are used for each pulmonary
artery, so a typical maximum time of DHCA is about 80 minutes. In between, CPB is reinstituted to
restore perfusion. Before each stint of DHCA, the entire checklist is repeated.

Once the thromboendarterectomy is complete, CPB is resumed and the patient is actively rewarmed.
This stage can be quite lengthy, depending on the patients body habitus, and can approach 2 hours.
Pulmonary reperfusion injury is an uncommon but devastating complication in PTE patients, and may be
signaled by worsening hypercapnia, hypoxemia, pulmonary edema (via ETT) or frank pulmonary
hemorrhage.

Minimally-invasive Valve Replacement

Technique, monitors, IV access, duration, EBL, position, and special equipment as for standard CPB
cases. Coronary sinus catheter and introducer. Special considerations: see below.

In 2011-2012, CT surgeons at UCSD began to perform minimally-invasive valve replacement, mostly

mitral and aortic valves, which can minimize the impact of a full sternotomy on the patient. CPB is
initiated through a venous cannula and an aortic cannula, each inserted via its respective femoral
vessels. The surgeons place ports for thoracoscopic equipment to assist with surgery, and a right
minithoracotomy is used to gain access to the heart and to initiate CPB. The main difference in the
anesthetic management involves the possible use of a double-lumen ETT (vs. a bronchial blocker) if lung
isolation is desired, as well as the placement of a coronary sinus catheter for introducing retrograde
cardioplegia. The process of placing the coronary sinus catheter can be very time-consuming and can
contribute considerably to the length of the case. The procedure is as follows: 2 central venous
catheters are placed in sequence in the right internal jugular vein. One is the usual sheath/introducer
used for infusions and the PAC; the other is used to place the coronary sinus catheter. The coronary
sinus returns venous blood to the right heart, and can be seen on TEE. Similarly to floating a PAC, the
coronary sinus catheter must be placed under direct TEE visual guidance into the coronary sinus and the
balloon inflated. This can be very difficult at times, due to patient anatomy, pathophysiology, etc. The
surgeon does have the option of placing the coronary sinus intraoperatively if it not possible via TEE
guidance. The rest of the case is similar to all other valve replacement and CPB cases.

Off-pump CABG (OPCAB)

Technique, monitors, IV access, duration, EBL, position, special equipment, and special considerations
as for CPB cases or as below.

Most of the CABGs done at UCSD are done without CPB. OPCAB presents unique challenges to the
anesthesiologist. While previously reserved for select patients with 1-2 vessel disease and good target

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vessels for anastomosis, OPCAB is now being offered to patients with more profound CAD. This
technique demands a fair amount of surgical skill since the surgeon is working on and manipulating a
still-beating heart. CPB and the perfusionist are immediately available in case of emergent need for CPB
or the inability to perform the procedure off-pump.

Because the patient never goes on CPB, physiologic management remains in the anesthesiologists
hands for the entire procedure. Manipulation of the heart has the potential to produce large
hemodynamic swings and arrhythmias which must be handled. Suspension or lifting of the heart to
allow access to posterior and inferior vessels can dramatically reduce venous return with pursuant
hypotenion, of which the surgeons should be notified immediately. The cardiac stabilizer device, which
makes the coronary artery target area motionless during vessel-to-vessel anastamosis, essentially
induces regional myocardial dysfunction and may reduce CO as well. When the heart is lifted out of the
chest cavity, interpretation of the EKG becomes difficult, if not impossible, and TEE is similarly rendered
useless.

The advantages of off-pump surgery are faster surgical times (generally), decreased bleeding, and
perhaps better long-term outcome with avoiding CPB (controversial). Since CPB is not intended to be
used, patients for planned off-pump procedures should be kept near-normothermic from the beginning
of the case with the usual techniques like fluid warmers and warming blankets. In general, anesthetic
management of off-pump cases, including induction, maintenance and hemodynamic stability are the
same as for CPB cases.

Extraction of Pacemaker or AICD Leads

This surgery is typically done to remove and replace infected pacemaker or AICD leads or generators.

Technique: general. Monitors: standard, arterial line, urine output, TEE. IV access: 1 IV plus Cordis
placed after induction. Duration: 2-3hrs. EBL: < 100ml. Position: supine. Special equipment: see below.
Special considerations: at the time of extraction of the lead, a TEE exam is done to rule out acute
hemopericardium and thus rule out cardiac injury.

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This patient population will generally have several cardiovascular comorbidities, one of which was the
indication for the device in the first place, plus an acute condition, e.g. systemic infection or
malfunctioning AICD. Because these leads are actually screwed into the myocardium to fix them
securely when they are first placed, extraction of the lead carries a risk of myocardial injury including
catastrophic events like ventricular wall perforation and tamponade. This low but real risk creates the
anesthetic implications above, and is the reason that a CT surgeon performs the extraction and a
perfusionist is present, while the primary work of lead and generator replacement are done by the
cardiologists.

Thoracic Aortic Surgery

Examples include elective or urgent repair of aortic dissection, aneurysm or trauma, and repair of
coarctation.

Technique: general. Monitors: standard, arterial line, CVP, PAC, urine output, TEE, TEG, EEG. IV access:
multiple large-bore catheters including central access needed. Duration: 4-10hrs. EBL: 1-many liters.
Position: depends on location of the lesion; supine or right lateral decubitus are most common. Special
equipment: need for CPB, need for DHCA, need for lung isolation (e.g., DLT and FOB),
neuromonitoring. Special considerations: see below.

Surgery on the thoracic aorta is rare at UCSD, but is invariably complex. It combines the challenges of
aortic cross-clamp with those of one-lung ventilation, large fluid shifts, and surgery around critical
structures. Additionally, these cases are often emergent in nature. Lesions involving the proximal aorta
or the aortic arch may require CPB to maintain systemic perfusion, or DHCA if flow to the brain must be
interrupted. More distal lesions are generally done without CPB and invariably involve aortic cross-
clamping. See a text for a full discussion.

Thoracic Surgery

Examples include thoracoscopic surgery (VATS), thoracotomy for lobectomy or pneumonectomy, repair
of bronchial trauma, bronchoalveolar lavage, and lung transplant.

Technique: general. Monitors: standard, plus arterial line. More invasive monitoring dictated by patient
needs and nature of the case (e.g., double lung transplantation requires the same monitors as any CPB
case). IV access: at least one large IV. Duration: 2-12hrs. EBL: 100ml-1L. Position: the operative lung is
usually up, with the patient in the lateral decubitus position. Occasionally, supine. Special equipment:
ability to separate the lungs, FOB, CPB, thoracic epidural. Special considerations: indications for and
the physiology of one-lung ventilation and use of DLTs is described in the cardiovascular and pulmonary
physiology section.

Diagnostic thoracoscopy, tissue biopsy, and pleurodesis are three examples of smaller thoracic cases.
Generally these cases are shorter in duration and are not associated with large fluid shifts. An arterial
line is necessary for blood gas samples and BP monitoring, but further invasive monitors such as the PAC
are rarely needed. By contrast, repair of traumatic injury to thoracic structures and lung transplants
require full monitoring, are typically long and involved cases, and have wide physiologic swings.

Preoperative lung function is an excellent predictor of operative risk in patients undergoing lung
resection. Specifically, patients with an FEV1 < 2L, a predicted postoperative FEV1 < 0.8L or < 40% of
predicted, FEV1/FVC < 50%, and room air PaCO2 > 45 or PaO2 < 50mmHg are at high risk for postoperative

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respiratory failure. PFTs are invariably indicated for all but the simplest thoracic cases. Thankfully, the
underlying pathology in these patients means that the vast majority have had extensive pulmonary
workup prior to an anesthesiology consult.

Bronchoalveolar lavage is occasionally performed with the operative lung dependent to minimize
spillage to the other lung. This position reverses the normal V/Q matching in the lateral position and can
result in severe V/Q mismatch and shunting.

In any lung resection or transplantation case, careful attention must be paid to fluid administration and
airway pressures, which may lead to postoperative pulmonary edema and respiratory failure. Whether
for lobectomy or pneumonectomy, the same cardiac output is being applied to fewer total bronchial
segments. Add this to the typical tissue edema that occurs after surgical manipulation, and it is easy to
see how IV fluid can predispose to pulmonary edema. Goals for fluid administration for lung resection
cases should be to provide only is physiologically necessary, and no more. Thoracic surgeons typically
aim for net even or net negative fluid balance during their cases. For airway pressures, the usual
maneuvers to minimize PIP should be taken while also avoiding hypoxemia and hypercapnia.

If patients are to remain intubated postoperatively, which is common in major lung resection cases, a
DLT must be changed to conventional ETT at the end. In this regard, a Univent ETT or a bronchial blocker
passed through a standard ETT may be advantageous, as either may be left in at the end of the case.

Thoracic incisions are intrinsically painful and also obviously interfere with respiratory mechanics and
respiratory effort. This causes patients to take shallow, ineffective breaths (splinting) which
compromises effective ventilation. The use of opioids to treat this pain favors undesirable
hypoventilation, sedation, and atelectasis. Occurrence of any of these issues after lung resection is
clearly deleterious. To combat this problem, aggressive pain control is instituted, often in the form of
thoracic epidural analgesia. An epidural, with a combination of dilute local anesthetic and opioid, is
perhaps the most effective measure at attenuating postoperative pain, and avoids the side effects of IV
opioids. The epidural is generally placed immediately before induction, as patient cooperation and
comfort is likely to be poor postoperatively. Thoracic epidural analgesia is considered for all true
thoracotomy cases, whereas for VATS cases one might consider simple subcutaneous local anesthetic or
intercostal nerve blocks.

Lung Transplantation

Lung transplants are common enough that you may expect to do 1 or 2 during your cardiac month, but
complex and varied enough that they warrant reference of an authoritative text. Briefly, unilateral lung
transplantation is preferred over bilateral for most disease states other than those that predispose to
infection and cross-contamination of the new graft lung, e.g. cystic fibrosis. Bilateral lung
transplantation can theoretically be done without CPB, by sequentially transplanting each new lung, but
in our departments experience this is almost always attempted only to be abandoned in favor of CPB.
For either type of transplant, a double-lumen ETT is always selected to permit excellent lung isolation,
suctioning of the graft lung(s), and endoscopic evaluation of the bronchial anastomoses. TEE is an
indispensable monitor, especially for bilateral transplant, to allow evaluation of right heart function,
volume status, and vascular anastamoses. Strict fluid restriction and minimizing peak inspiratory
pressures are necessary goals to prevent pulmonary edema and trauma to the graft lung(s).

For a unilateral lung transplant, many of the considerations for major thoracic surgery such as
pneumonectomy apply, including the preexisting pulmonary disease, need for one-lung ventilation, fluid

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management, positioning, and need for excellent epidural analgesia.

Bilateral lung transplants are much more involved and more comparable to a complex on-pump cardiac
case. Classically, a bilateral inframammary clamshell incision is used, which necessitates suspension of
the arms above and over the head to allow surgical access. Monitors and vascular access are planned as
such.

Antibiotic and immunosuppression regimens will be discussed with the surgeons preoperatively. For
further information, refer to a cardiac anesthesia text.

Technique: general epidural. Monitors: standard, arterial line, urine output, CVP, PAC, TEE,
BIS/SEDline. IV access: large-bore IV access plus CVP/PAC. Duration: 6-12hrs. EBL: 200ml-1000ml, often
difficult to estimate if on CPB. Position: lateral for unilateral, supine with arms suspended overhead for
bilateral. Special equipment: FOB, double-lumen ETT, possibly nitric oxide, possibly 2nd ventilator.
Special considerations: as above.

Surgery for Pericardial Disease

Cardiac tamponade can be managed surgically by a pericardial window via a subxiphoid, thoracotomy,
or median sternotomy approach. Procedures to relieve constrictive pericarditis include pericardial
stripping or window.

Technique: general. Monitors: standard, arterial line, TEE. Further monitors may be useful but should
not delay an urgent case. IV access: at least one large IV. Duration: 1-4hrs. EBL: usually < 100ml, plus
evacuation of any existing blood. Position: supine. Special equipment: as above. Special considerations:
physiology of anesthetic management of tamponade.

Cardiac tamponade is a physiologic state in which filling of the heart is constricted by the presence of
blood or other fluid around the heart. It can be seen in CT patients postoperatively due to continued
bleeding. Other diseases which may cause tamponade include those that cause pericardial effusions
(cancer, infection, uremia, MI, autoimmune disorders) or hemopericardium (trauma, postop bleeding).
Constrictive pericarditis occurs when the pericardium becomes scarred, stiff, and fibrotic, leading to
impaired ventricular relaxation and filling. Clinically, the two states can appear quite similarly.

Signs of tamponade are frequently tested and include tachycardia; the classic Becks triad (hypotension,
JVD, muffled heart sounds); equalization of diastolic pressures throughout the heart (rare); tachypnea;
intolerance of the supine position; and pulsus paradoxus, which is simply an exaggerated phenomenon
of the normal fall with SBP with inspiration (pathologic is a fall of > 10mmHg). The EKG classically shows
electrical alternans, which is variation of the R wave height over several cardiac cycles, thought to be
from the heart swinging in the pericardial sac. Other EKG findings might include decreased voltages in
all leads, or diffuse ST segment elevation (more associated with pericarditis).

Anesthetic management of cardiac tamponade is critically important and depends on the severity of the
disease. A relatively stable patient with little to no tamponade physiology is on one end of the
spectrum, and a patient in extremis is on the other. The key goal of anesthesia for tamponade is to
preserve CO by avoiding reductions in HR, preload, or contractility. As most of our induction agents
depress CO and sympathetic tone, they are poorly suited for a patient with symptomatic tamponade.
Etomidate or ketamine are the agents of choice, as both avoid sympatholysis and preserve spontaneous,
negative-pressure ventilation. Bear in mind that ketamine is a negative inotrope in vivo, so a

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sympathetically maxed out patient may have unmasked negative inotropic effects if ketamine is
administered.

Typically, IV fluid loading is done to preserve preload, and an arterial line is placed. After induction and
achievement of deep anesthesia, intubation is done without muscle relaxant. Other monitors such as
CVP, a PAC, or TEE may all be useful in providing further information and assisting with patient
management, but unfortunately these are time-consuming and should not delay an urgent case. Severe
tamponade should be alleviated with a pericardiocentesis or subxiphoid window prior to induction of
anesthesia. Once surgery has begun, a subxiphoid window may be sufficient, or the surgeon may have to
enlarge the incision to gain access to the offending fluid.

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Chapter 7. Neuroanesthesia Rotation and Neurophysiology

Chapter 7A. Neuroanesthesia Rotation

The neuroanesthesia rotation at UCSD is a two-month, intense exposure to neurosurgical cases and the
specific anesthetic demands they entail. You will complete the first month during your CA-2 year and the
second month during your CA-3 year. Throughout each month, you will be exposed to craniotomies for
aneurysm repair, resection of tumors, and correction of other intracranial pathology. In addition, spine
surgeries are often assigned to the neuro resident as they also demand knowledge of neurophysiology.
By the time the formal rotation comes around, undoubtedly the resident has had some experience with
craniotomies or spine surgeries simply as a function of previous Main OR duties. This rotation will
solidify past experience into a formal fund of knowledge.

If available, Drs. Drummond or Patel are often assigned to true craniotomies, especially complex cases
(e.g., aneurysms, resection of large tumors). This is typically done at the neurosurgeons request
because, simply put, they are the leaders in their field. Take advantage of their expertise during this
month and avail yourself of the knowledge they command. However, many of our faculty are also
experts in neuroanesthesia and are often assigned to staff these cases as well. Overall, this should be
one of the most educational months in your entire residency.

For the neuroanesthesia residents, the daily schedule assignment is made specifically with the rotation
in mind. The resident will be assigned the most complex or interesting neurosurgical case of the day. In
some cases, this might be a large spine surgery with the use of motor and sensory evoked potentials.
The expectation is that the neuro resident will finish his or her own case, especially since emergence is a
critical portion of most neuroanesthesia procedures. This month can entail some long hours and
challenging days, but it is well worth it. In general, you will also be assigned three to four in-house calls
during the month, similar to a regular Main OR rotation.

The following chapters cover basic neurophysiology and anesthetic techniques for specific procedures.
Anesthesia for spine surgery is covered in the orthopedic surgery section.

Chapter 7B. Neurophysiology and Anesthesia

Most, if not all, anesthetics have profound effects on neurophysiology. Delivering a rational anesthetic,
particularly for neuroanesthesia, requires a thorough understanding of the effect of the drugs,
anesthetic techniques, and the procedure in question. At UCSD, we are fortunate to have world-
renowned faculty in the field of neuroanesthesia. Due to our faculty, we enjoy a particularly harmonious
relationship with most of the neurosurgeons. This is fortunate because close communication is often
critical during neurosurgical procedures. This relationship is predicated on our ability to deliver a safe
and superb neuroanesthetic. This section will cover basic neurophysiology and the effects of anesthesia
on that physiology. Specific anesthetic techniques for neurosurgical procedures will follow in the next
chapter. For more details on the effects of specific agents, see the drug section.

Cerebral Blood Flow and Autoregulation

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Cerebral blood flow (CBF) is usually about
50ml/100g/min and is higher in grey matter,
lower in white matter. An average brain mass
is about 1500g, so CBF for an average
human is about 750ml/min. Flow rates lower
than 25ml/100g/min are associated with EEG
slowing and neurologic impairment. Flow
rates below 20ml/100g/min typically produce
an isoelectric (flat) EEG indicative of zero
cortical electrical activity, and values below
10ml/100g/min are usually associated with
irreversible neurologic damage. At typical
physiologic MAPs, cerebral blood flow is tightly autoregulated. Classic teachings describe fairly tight
control between MAPs of 50-150mmHg. Within this range, autoregulatory mechanisms keep CBF
constant despite potentially wide swings in blood pressure. Beyond this range, CBF becomes MAP-
dependent, rising or falling with similar changes in blood pressure. The cerebral autoregulation curve is
shifted to the right in patients with chronic hypertension.

CBF is directly linked to PaCO2. Each

1mmHg decrease in PaCO2
corresponds with a 1-2ml/100g/min
reduction in CBF. Conversely, each
1mmHg increase in PaCO2
corresponds with a 1-2ml/100g/min
increase in CBF. This effect is due to
CO2 tension within the CSF and is
not seen with acute changes in
HCO3, which cannot cross the blood
brain barrier. Clinically, most
practitioners aim for a PaCO2
between 25-30mmHg to achieve
favorable and safe reductions in
CBF. Prolonged changes in CSF CO2
tension result in a change in CSF bicarbonate concentration, negating any effects on CBF. The reduction
in CBF is typically negated after 12 hours.

Hyperoxia only causes a small decrease in CBF. Hypoxemia, on the other hand, causes profound
increases in CBF.

Hypothermia decreases both CBF and cerebral metabolic rate of oxygen consumption (CMRO2), as
below, while hyperthermia has the opposite effect. CBF changes 5-7% per 1C change in temperature.
Each 10C decrease in temperature reduces CMRO2 by 50%, and each 10C increase doubles CMRO2.
Hypothermia produces an isoelectric EEG at around 20C and is the most effective strategy for
neuroprotection, making it useful in situations of decreased or absent CBF. See the section on
anesthesia for PTE.

CMRO2

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The brain typically receives 20% of total CO and consumes ~50ml/min of oxygen. Glucose is the normal
source of energy, the vast majority of which is metabolized aerobically. CMRO2 thus parallels metabolic
activity and energy consumption. Under periods of starvation, ketone bodies may be consumed. Glucose
deprivation and hypoxia have profound and quick impacts on the brain, with cell death occurring within
3-8 minutes of the insult. The hippocampus and cerebellum are the areas of the brain most sensitive to
hypoxic injury.

Reduced metabolic needs of the brain correlate with reduced CMRO2. Reductions in CMRO2 are thus
favorable in reducing CBF requirements.

Of the total CMRO2, about 60% goes toward energy used for the electrical activity of the brain (neuronal
conduction), whereas about 40% is used in the basal housekeeping cell activities like protein synthesis
and maintenance of transmembrane potential. This is important to note because anesthetics can only
reduce the electrical component of CMRO2, whereas hypothermia can reduce both the electrical and the
housekeeping portion of CMRO2.

Chapter 7C. Intracranial Pressure

The brain can be thought of as being enclosed within a rigid space (the skull). This space is occupied by
brain cells/tissue (80%), interstitial fluid and blood (12%), and CSF (8%). In order to prevent a rise in
intracranial pressure, an increase in any of the components that occupy the space (volume) must be
offset by an equivalent decrease in another component. Examples of increased components include
tumor, bleeding, or hydrocephalus from CSF outflow obstruction. Small increases in volume are
normally compensated for quite well, with little to no increase in ICP.

Compensatory mechanisms include shifting CSF to the spinal space, increased absorption of CSF,
decreased production of CSF, and decreased cerebral blood volume. However, when these
compensatory mechanisms are overcome, small increases in volume correspond with large increases in
ICP; i.e., the intracranial space develops low compliance. Large increases in ICP can lead to brain
ischemia and catastrophic herniation of brain tissue. Herniation may occur at one of four sites, as in the
diagram: 1) the cingulate gyrus under the falx cerebri, 2) the uncinate gyrus through the tentorium
cerebelli, 3) the cerebellar tonsils through the foramen magnum, or 4) any area beneath a defect in the
skull (transcalvarial).

Cerebral perfusion pressure is calculated as CPP = MAP ICP (or CVP, whichever is higher). Typically,
ICP is < 10mmHg. It should be obvious that large increases in ICP have a deleterious effect on CPP. As

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discussed above, decreases in CPP below the autoregulatory threshold will decrease CBF. So, CPP <
50mmHg often leads to EEG slowing, whereas CPP between 25-40mmHg typically show a flat EEG.
Sustained CPP < 25mmHg results in irreversible brain damage.

In general:
Decrease in CBF decrease in cerebral blood volume (CBV) decrease in ICP
Increase in CBF increase in CBV potential increase in ICP
Decrease in CMRO2 decrease in CBF, and vice versa

The underlying goal of all neuroanesthetic strategies is to reduce CMRO2 and safely reduce CBF in
order to reduce ICP, while maintaining MAP and CPP.

Chapter 7D. Effect of Anesthetic Agents on CBF, CMRO2, and ICP

I. Volatile Anesthetics

Volatile anesthetics are generally said to uncouple the normal matching of CBF with CMRO2 in a dose-
dependent fashion. That is, under a dose of about 1 MAC, volatile anesthetics reduce CMRO2 in a dose-
dependent fashion and cause a parallel reduction in CBF. However, above 1 MAC, there is no further
decrease in CMRO2, but CBF actually goes up due to cerebral vasodilation. By altering this CMRO2-CBF
coupling, doses of volatile anesthetics > 1 MAC create a tendency for CBF to parallel MAP. Of the volatile
agents, halothane appears to have the greatest uncoupling effect. MAC 1 of desflurane, sevoflurane,
and isoflurane generally has little effect on CBF-autoregulation coupling.

Dose-dependent CMRO2 = Isoflurane > Desflurane/Sevoflurane > Halothane

Dose-dependent CMRO2 = Halothane > Isoflurane/Desflurane/Sevoflurane

Volatile anesthetics are used in many neuroanesthetic cases, according with the concept that doses <
1MAC do not increase CBF and so do not increase ICP. If elevated ICP is a critical concern, i.e., the brain
is tight, it is prudent to discontinue all volatile anesthetics to eliminate any possibility of
autoregulation-uncoupling or unwanted increases in CBF.

Most IV anesthetic agents CBF and CMRO2 in a parallel fashion (except ketamine)
All IV agents preserve cerebral autoregulation and CBF-CO2 relationship

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II. Nitrous Oxide

Nitrous oxide typically has minimal effects on CBF, CMRO2, and ICP. It may slightly increase CBF if used
alone, but this effect is minimal. Nitrous oxide may even cause a decrease in CBF when combined with
other agents, especially IV agents. When not contraindicated, nitrous oxide is routinely employed in
neuroanesthesia due to its rapid onset and offset, allowing for quick and clean emergence and early
neurologic testing.

III. Opioids

Opioids decrease CMRO2 and CBF to a small extent. They are primarily used to blunt sympathetic
responses to noxious stimuli, such as surgical incision and laryngoscopy, and to create a profound
antitussive effect for a cough- and buck-free emergence. Short-acting opioids (such as remifentanil) are
preferable to allow early neurologic examination and avoid prolonged emergence. Opioids are a
mainstay of neuroanesthesia.

IV. Barbiturates

Barbiturates are ideally suited agents for neuroanesthesia. They produce profound decreases in CBF and
CMRO2, with relatively more reduction in CMRO2. Thus, metabolic supply tends to exceed metabolic
demand; this is known as luxury perfusion. Furthermore, barbiturates have antiepileptic properties,
and can be used in barbiturate coma to produce an isoelectric EEG for neuroprotection. Lastly,
barbiturates cause an increase in CSF absorption, which helps lower ICP.

V. Propofol and Etomidate

These agents also reduce CMRO2 and CBF and are good agents for neuroanesthesia. Propofol has
anticonvulsant properties, while etomidate may activate epileptic foci in patients with seizure disorder.
Propofol has a short elimination half-life, enabling rapid neurologic assessment in the postoperative
period. Etomidate decreases CSF production and enhances absorption.

VI. Benzodiazepines

These agents reduce CBF and CMRO2, but, similar to the ceiling effect they have on depth of
anesthesia, this reduction is small. They have significant anticonvulsant properties. Benzodiazepines are
used sparingly in neuroanesthesia since they can profoundly prolong emergence, especially when used
as an infusion. They are best used as low-dose adjuncts or, more commonly, avoided entirely.

VII. Ketamine

Ketamine increases CBF and may also impede absorption of CSF. The increase in CBF and CSF volume
can markedly increase ICP in patients with decreased intracranial compliance. Whether this is clinically
true when ketamine is used as part of a balanced anesthetic is a matter of controversy. Nevertheless,
dogma persists that ketamine increases ICP, and thus it should be avoided when ICP is an issue.

VIII. Succinylcholine

Succinylcholine can cause transient increases in ICP. A classic neuroanesthetic dilemma is whether or
not to use succinylcholine in a situation of increased ICP. Bear in mind that this increase is usually small

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and is easily attenuated with anesthetic agents. Additionally, the rapidity of muscle relaxation that
succinylcholine achieves is unmatched. So, if rapid control of the airway is necessary to avoid the much-
more-potent ICP effects of hypercapnia or hypoxemia, succinylcholine is a reasonable choice.

IX. Dexmedetomidine

Dexmedetomidine is a selective 2 agonist with sedative and analgesic effects. It decreases CBF via
cerebral vasoconstriction.

Chapter 7E. Neuroprotective Techniques

Ischemic brain injury can be classified as either global (complete) or focal (incomplete). Global ischemia
includes total circulatory arrest as well as global hypoxia. Focal ischemia includes embolic, hemorrhagic,
and atherosclerotic strokes as well as blunt, penetrating, and surgical trauma. With focal ischemia, the
brain tissue surrounding the damaged area, the so-called ischemic penumbra, may suffer marked
functional impairment but may still remain viable. Although these damaged areas are thought to have
marginal perfusion (< 15ml/100g/min), these areas may completely recover if further injury is limited
and normal flow is rapidly restored. Clinical goals in such instances are usually to optimize CPP, decrease
metabolic requirements, and possibly block mediators of cellular injury.

1. Hypothermia
This is the most effective method for protecting the brain during focal or global ischemia by
decreasing both basal and electrical metabolic requirements.
Even mild hypothermia (33-35C) is protective.
Head-injured patients, if cold, should not be rewarmed rapidly.
The beneficial effects of hypothermia must be counterbalanced with possible deleterious effects
(e.g., coagulopathy, arrhythmias, impaired immunity).

2. Maintenance of CPP and Oxygen Delivery

MAP should be maintained in a normal range to ensure appropriate CPP.
Oxygen-carrying capacity should ideally be maintained with a hematocrit of ~30% and a normal
oxygen saturation and PaO2.
Reduction of ICP is discussed below.

3. Reduction in CMRO2
Reduction of metabolic demand is beneficial.
Many anesthetic agents can produce an isoelectric EEG; this can reduce metabolic demand by a
maximum of 60%.
The basal metabolic demand can only be reduced by hypothermia.
See a text on barbiturate coma for more information.

4. Avoidance of Hypoglycemia and Hyperglycemia

Hypoglycemia predisposes to further ischemia and can worsen the neurologic insult, whereas
hyperglycemia is thought to worsen cerebral inflammation following injury or ischemia.

5. Avoidance of Hypoxemia

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Hypoxemia is harmful in at least two ways: it directly limits oxygen-carrying capacity and thus oxygen
delivery, and it also causes cerebral vasoconstriction and reduces CBF.

Chapter 7F. Strategies to Reduce ICP

These techniques all center on reducing the volume of one of the three components of the intracranial
space: brain matter, interstitial fluid and blood, and CSF. Some techniques may be impractical, while
others are under direct surgical, as opposed to anesthetic, control.

1. Reduction of Brain Tissue Volume

Examples include removal of tumor or offending mass by the surgeon. Typically, this is not under our
control and obviously not a factor for reducing ICP prior to surgery. Rarely, a decompressive
craniectomy may be performed to create more space for remaining tissue and to relieve elevated ICP.

2. Reduction of Interstitial Fluid Volume

Osmotic diuretics, such as mannitol, can be used to reduce ICP. By increasing serum osmolality,
mannitol draws intracellular water into the intravascular space and off brain tissue, decreasing brain
volume. Being a hyperosmolal solution (and a fluid bolus), mannitol typically induces a transient
increase in blood volume, which may worsen ICP, which is then followed by hypotension from its
vasodilatory properties and reduced intravascular volume from diuresis. It is thus used with caution.
Mannitol works within 30 minutes to reduce brain volume.

Because of the rapid reduction in brain volume, mannitol may be dangerous before the cranium is
opened in aneurysms, AVMs or intracranial hemorrhage. In such instances, decreases in brain volume
may create more room for expansion of an aneurysm, AVM or hematoma, thereby theoretically
increasing the risk of bleeding.

Loop diuretics like furosemide are also used, but these are slower in onset than mannitol. They are
useful adjuncts since they have a synergistic effect, tend to increase serum sodium and osmolality, and
reduce CSF production.

Glucocorticoids, by limiting inflammation and edema, may also reduce interstitial fluid volume.

3. Reduction of Cerebral Arterial Blood Volume

This can be achieved with the following techniques:

Choice of anesthetic agent to reduce CBF and CMRO2.

Mild hyperventilation to induce vasoconstriction. A PaCO2 of 25-30mmHg reduces ICP for 24-
36hrs without affecting acid-base status and cerebral oxygen delivery.
Avoidance of hypoxemia.
Avoidance of arterial hypertension.

4. Reduction of Cerebral Venous Blood Volume

This is often overlooked, and can be achieved via avoidance of elevated jugular venous pressure. This
includes:

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 Keeping the head of the bed up.
Avoiding extremes of head flexion or rotation.
Avoiding circumferential ETT ties.
Avoiding internal jugular venous catheters.
Avoiding elevated intrathoracic pressure, e.g. coughing, PEEP, pneumothorax, tamponade.

5. Reduction of CSF Volume

Can be achieved with the following techniques:

Drainage of CSF, e.g. ventriculostomy, lumbar drain.

Loop diuretics.
Choice of anesthetic agent, e.g., barbiturates.
Other agents to reduce CSF production (acetazolamide, steroids).

Chapter 7G. Anesthetics and Evoked Potentials

Evoked potentials are a form of electrophysiologic monitoring used to test the integrity of nerve
pathways that may be compromised by the surgical procedure. There are two main categories of evoked
potentials used for neuromonitoring: sensory evoked potentials (SEPs) and motor evoked potentials
(MEPs). Typically, the surgeons employ a neurophysiologist under the supervision of a neurologist to
monitor the evoked potentials during an operation in which neural damage is of great concern.

Somatosensory Evoked Potentials (SSEPs)

SSEPs reflect the ability of a neural pathway to conduct a signal from the periphery to the cerebral
cortex. There are three types of SSEPs:

1. Somatosensory evoked potentials (SSEPs): test sensory cortex and integrity of dorsal columns of
the spinal cord. Used for surgeries that have the potential to compromise the spinal cord (spinal
tumor resection, instrumentation of the spine, aortic surgery, etc.)
2. Brainstem auditory evoked potentials (BAEPs): test integrity of CN VIII and auditory pathways. Used
for surgeries around CN VIII, surgery in the posterior fossa, etc.
3. Visual evoked potentials (VEPs): test optic nerve function and upper brain stem function. Used for
resection of large pituitary tumors.

Generally, SEP responses rely on stimulating the particular nerve in question and monitoring the cortical
response. A good or unchanging response implies an intact neural pathway, while changes in the
response could be a signal of impending nerve damage. Taking the BAEP as an example, the technician
can periodically trigger a sound within the ear canal, which the acoustic nerve should sense. This signal
should travel along the afferent pathway from brainstem all the way to the cortex and can be monitored
along the entire path.

The SSEPs are classified according to their latency (time from stimulus to response) and amplitude
(voltage measurement from peak apex to baseline). Changes in either parameter may be transient and
expected (e.g., irrigation of the area near the nerve) or more sustained and worrisome, such as with
surgical irritation or damage. Any decrease in amplitude by 50% or an increase in latency by 10%
indicates a worrisome disruption of a neural pathway.

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Most anesthetics affect the characteristics of the SSEPs and must be adjusted or omitted entirely.
Briefly, all inhalational agents decrease amplitude and increase latency. This effect is usually minimal at
MAC 0.5 but varies with the agent in question. Nitrous oxide reduces amplitude but does not affect
latency. IV agents also decrease amplitude and increase latency, but to a lesser extent than inhaled
agents. Ketamine and etomidate in particular may
Drug Amplitude Latency
increase amplitude. Opioids have little to no effect on
either parameter. Volatiles

In summary, anesthetic interference with evoked N2O 0

potentials is as follows: VEPs >> SSEPs >> BAEPs.
Propofol or 0
Other than interventions we can make in response to a
worrisome evoked signal (e.g., correct hypoperfusion, Opioids or 0
acidosis, anemia, hypotension, and notify surgeon), much
of our responsibility during the use of SSEPs will be to Etomidate
utilize an anesthetic that has minimal effect on the
Ketamine 0
monitoring and signals. Thus, a typical SSEPs anesthetic
will be similar to a TIVA (i.e. propofol infusion and opioids) Midazolam 0
volatile agent at a MAC 0.5. The neurophysiologists
understand the necessary anesthetic limitations, and Thiopental or 0
preoperative discussion can help you plan the anesthetic
accordingly and avoid later hassles.

Motor Evoked Potentials (MEPs)

MEPs test the integrity of dorsolateral and ventral spinal cord pathways. This is accomplished by
transcranial stimulation of the motor cortex, which elicits contralateral peripheral nerve signals,
electromyelographic signals, and limb movements. MEPs are frequently used in conjunction with SSEPs
for surgeries that have the potential to compromise the spinal cord. The major anesthetic consideration
regarding the use of MEPs is that neuromuscular blockers must be omitted from the anesthetic regimen
in order to observe these motor responses.

Whenever SSEPs or MEPs are to be used for an operation, the specific anesthetic plan should be
discussed with your attending, the surgical team, and the neuromonitoring person to make sure
everyone is on the same page.

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Chapter 8. Anesthesia for Neurosurgery

The following are brief descriptions of the typical neurosurgical procedures encountered at UCSD, as
well as the anesthetic implications. Anesthesia for spine surgery is described in the section on
orthopedic surgery. Basic neurophysiology and anesthesia is addressed in the previous chapter.

Chapter 8A. Anesthesia for Intracranial Vascular Surgery

Examples include open aneurysm clippings and resection of arteriovenous malformations.

Technique: general. Monitors: standard, plus arterial line. CVP may be a useful adjunct to guide fluid
therapy, especially if mannitol is to be used. Urine output. IV access: at least one large IV; the standard
at UCSD is to have one IV for fluids and boluses and another for infusions. Catastrophic bleeding,
although unlikely, is a possibility. Duration: 4-6hrs, potentially more for complicated cases. EBL: 100ml.
There can be much more if there is unanticipated or uncontrollable bleeding. Position: supine, lateral, or
semilateral depending on location of the aneurysm. The head of the bed is 180 away from
anesthesiologist. Special equipment: precordial Doppler if increased risk of venous air embolism; see
the section on posterior fossa craniotomy. A ventriculostomy or subdural bolt may be employed by
the neurosurgeons to monitor ICP; see below. Special considerations: as below.

Most neurosurgical procedures take place with the patients head away from the anesthesiologist and
the anesthesia machine. The implications of this position change are discussed in detail in the sections
on head & neck surgery and emergency craniotomy room setup. They include limited access to the
airway, increased risk of airway dislodgement due to close surgical proximity, and hazards of turning the
OR table 180.

An arterial line is mandatory for all but the simplest neurosurgical procedures. Nowhere is the necessity
of invasive arterial monitoring more evident than in an aneurysm clipping. Broadly, aneurysms can be
classified as ruptured or unruptured. For both types of aneurysms, the hemodynamic goals are similar:
tight control of BP. Profound hypertension can cause catastrophic rupture of an intact aneurysm, or
increase the risk of rebleeding in an already ruptured one. Similarly, hypotension is generally poorly
tolerated because of compromised cerebral perfusion. The potential for bleeding, wide swings in levels
of surgical stimulation (and thus changes in BP), fluid shifts with the use of osmotic diuretics, and need
for blood samples all mandate the use of an arterial line.

Use of central venous catheter (CVC) is not as clear-cut, and many craniotomies are performed without
one. Advantages of a CVC include the ability to monitor CVP, the large and reliable central access it
provides, and the ability to aspirate air in situations of venous air embolism. The disadvantages of
placing a CVC are myriad and include arterial puncture, pneumothorax, infection, and bleeding. Use of a
CVC should be tailored to the individual case, but most craniotomies can be performed without one
unless there is a clear indication (e.g., high risk of venous air embolism, need for hypertonic saline, etc.).
The potential for large blood loss in AVM or aneurysm surgery demands large IVs, but not necessarily a
CVC. Similarly, blood products should be available prior to surgery.

Current neurosurgical management of subarachnoid hematoma involves early (within 72 hours) or late
(after 2 weeks) clipping of ruptured aneurysms. Between these time periods is the window for cerebral
vasospasm, which is generally 4-14 days post-bleed and occurs in about 30% of patients. Vasospasm is
thought to be a response to blood around cerebral vessels, and depending on the severity and
distribution of the vessels involved, can lead to brain ischemia or infarction. Prevention of vasospasm

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involves the use of the calcium channel blocker nimodipine, as well as triple-H therapy: hypertension,
hypervolemia, and hemodilution. Triple-H therapy is done by volume loading with NS and the use of
vasopressors such as dopamine, phenylephrine, or dobutamine to induce a hyperdynamic and
hypertensive state; hemodilution usually occurs passively by the crystalloid load and the acute anemia
of critical illness. Because triple-H therapy may increase the likelihood of rebleeding, most
neurosurgeons attempt to clip or coil ruptured aneurysms in the early period. Typical measures to
reduce ICP are generally not employed in an already-ruptured aneurysm until the dura is opened (e.g.,
mannitol, hyperventilation). The theory behind this is that lowering ICP will increase the transmural
pressure in the aneurysm, increasing aneurysm wall tension, and increase the chance of rupture and
rebleed. After the dura is opened to atmospheric pressure, these considerations are removed and
standard efforts to reduce intracranial volume can be undertaken.

Direct ICP monitoring is often employed in these patients, through use of either a subdural bolt,
subdural pressure catheter (a.k.a., Camino), or ventriculostomy (a.k.a., EVD). The ventriculostomy can
monitor ICP and can drain CSF directly, whereas the bolt and Camino are monitoring devices only. These
monitors are generally placed pre-op or intra-op by the neurosurgeons, but are monitored by us in the
OR. Close communication with the surgeons is necessary for specific management goals such as goal ICP
and CPP.

With all craniotomies, the most stimulating points of the surgery tend to be the same, and it is during
these times that BP must be most closely monitored. In chronologic order, they are: laryngoscopy, head
pinning in the surgical headframe (Mayfield), skin incision, opening of the skull, and opening of the
dura. The brain itself is insensate, and after dural opening, levels of surgical stimulation are typically low,
and the surgeons liberally infiltrate local anesthetic with epinephrine into the scalp to limit bleeding.
With these points in mind, many anesthesiologists tailor the anesthetic in such a way as to blunt the
sympathetic discharge and rises in BP with each of these points. Induction is typically carried out with a
large dose of narcotic (typically at least 10mcg/kg of fentanyl) and muscle relaxation to eliminate the
possibility of coughing or straining. Deep anesthesia is achieved prior to placement of headframe pins by
the surgeon. Most of the neurosurgeons here at UCSD are very good at communicating with us and will
inform us before the pins are to be placed. BP is closely monitored and rises can be attenuated with
more narcotic or a fast acting agent such as propofol. Similarly, a close eye must be kept on the BP
during skin incision and cranial and dural opening. Having quick, titratable IV agents in-line is mandatory
(e.g., nitroprusside and phenylephrine infusions to lower or raise the BP).

Additional anesthetic goals of a standard craniotomy are avoiding hypercapnia and hypoxemia, avoiding
increases in ICP, minimizing brain volume to create an optimal surgical field, preventing spontaneous
patient movement, creating a smooth and cough-free emergence, and allowing for early neurologic
assessment with a quick wakeup. Clearly, there are times when some of these goals may be difficult to
achieve, and sometimes one goal is in direct conflict with another, such as a smooth wakeup vs. a quick
wakeup. Strategies to achieve these goals are discussed below.

Measures and conditions that increase and decrease ICP are discussed in the neurophysiology section.
As mentioned, all of our anesthetic agents have some effect on ICP. Most anesthesiologists employ a
balanced anesthetic approach with a heavy emphasis on IV agents. A typical example would be a MAC
0.5 of volatile anesthetic coupled with nitrous oxide and propofol and opioid infusions with muscle
relaxation. This combination allows relatively quick offset of anesthesia, ensures paralysis, and prevents
increases in ICP. Propofol in particular is favored by our neurosurgeons for its beneficial effects on CBF,
CMRO2, and ICP. You will often be asked to give more propofol in response to a tight brain and to

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achieve better surgical conditions and visualization. An alternative is to eliminate the inhaled agents
altogether and to run a TIVA with propofol, opioid, and muscle relaxant. A significant opioid base should
allow for a smooth emergence, as well as blunt hemodynamic responses to stimulation as above.
Depending on the context-sensitive half-life of the opioid chosen, it may be necessary to discontinue the
opioid several hours before emergence to allow for a timely wake up. Ensuring paralysis is necessary to
avoid potentially catastrophic movement during surgery on the brain.

A smooth emergence is usually achieved with a good base of narcotic, deep neuromuscular blockade
with late reversal, and avoidance of stimulation to the patient during Stage II. The classic Stage II of
intense coughing, breath-holding, and hemodynamic instability is more associated with emergence from
inhalational anesthesia, as opposed to nitrous oxide and propofol. Also, consider that many patients
having craniotomy have altered or depressed mental status at baseline, and that all of them will have
just had some form of amnesia-inducing cortical injury, i.e., brain surgery. Therefore, elimination of
volatile anesthetic relatively early in the emergence while continuing muscle relaxation can be done
with a very low risk of recall.

Tailoring the anesthetic to allow for both a rapid and a smooth wakeup requires considerable
experience, but in general, propofol infusions should be discontinued at least 30min before the end of
the case and fentanyl infusions about 1hr before. This is, of course, variable depending on the doses
used, the length of the case, and the patients comorbidities and physical status. Coughing or bucking
can be attenuated with additional anesthetic or removal of the ETT if conditions allow, but should not be
allowed to persist. Rarely, situations may exist that obviate a quick wakeup or immediate neurological
assessment, such as severely depressed mental status at baseline, severely ill patient, etc.

Chapter 8B. Anesthesia for Emergent Craniotomy

A significant percentage of emergent craniotomies involve situations with acutely raised ICP, usually due
to intracranial hemorrhage with or without trauma. These cases present somewhat different challenges
in regards to anesthetic management. Some of this information is also covered in the trauma section.
Typical cases include acute subdural or epidural hematoma evacuation with burr holes (durotomy) or
formal craniotomy, intraparenchymal hematoma evacuation, and chronic subdural evacuation, all
potentially in the setting of trauma.

Technique: general. Monitors: standard, plus arterial line. CVP may be desirable. Urine output. IV
access: multiple large IVs. Duration: 1-4hrs. EBL: 200ml to potentially much more depending on the
injury. Position: typically supine, head 180 away from the anesthesiologist. Special equipment:
potential ICP monitor placed by neurosurgeons. Special considerations: as below.

Several considerations unique to the trauma patient include: aspiration risk or full stomach, potential for
cervical spine instability, an obtunded or combative patient, and hemodynamic instability. These
problems must all be managed concurrently. Concurrent head injury and known or suspected increased
ICP further complicates matters. Typically, a rapid sequence induction with in-line cervical stabilization
and cricoid pressure is used. Control of the airway must proceed with attenuation of profound increases
and decreases in BP and avoidance of hypercapnia and hypoxemia. Arterial and venous access must also
be achieved as soon as possible. Clearly, this is a team task that often involves several members of the
department. Do not be afraid to call for help.

Measures to reduce ICP should be undertaken as soon as possible and are discussed in detail in the
neurophysiology section. It should be noted that definitive treatment is the opening of the cranium and

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dura. Surgery should not be delayed for want of better IV access, an arterial line, etc. The first priority is
quickly securing an airway and providing deep anesthesia in order to allow the surgery to rapidly
proceed. Other necessary measures such as fluid resuscitation, placing an arterial line, or obtaining
venous access can proceed concurrently while surgery is underway. Note that this is much different than
in an elective craniotomy in which surgery would not proceed before arterial access was first
established.

Unlike elective craniotomies, these patients are often left intubated at the end of the procedure.
Concomitant injuries, instability, or diffuse brain injury may necessitate ongoing intubation and
mechanical ventilation. Similarly, severely increased ICP may require post-op intubation, paralysis, and
mechanical ventilation.

Patients with chronic subdural hematomas represent a class where acute lowering of ICP may be
undesirable. The longstanding presence of the hematoma may produce a tamponade effect that
prevents significant further bleeding. Rapid lowering of brain volume and ICP may remove this effect
and create potential for large bleeding.

Chapter 8C. Anesthesia for Craniotomy for Mass Lesion

Examples include removal of supratentorial tumor or infectious mass, and transsphenoidal resection of
pituitary tumor.

Technique: general. Monitors: standard, plus arterial line. Urine output. CVP may be useful but is not
necessary. IV access: one large IV should suffice. Duration: 2-6hrs. EBL: 100-500ml, typically less than for
vascular malformations and intracerebral hemorrhage. The chance of catastrophic bleeding is lower, but
still present. Position: generally supine or lateral head turned to side. Head 180 away from
anesthesiologist, except transsphenoidal surgery. Special equipment: usually none. Special
considerations: Anesthetic technique and goals are essentially the same as those covered in the
vascular malformation and raised ICP sections, namely, avoidance of hypercapnia and hypoxemia, tight
control of blood pressure, smooth induction and emergence, and early neurological examination.
Depending on the size, rate of expansion, and position of the lesion, the patient may have normal
intracranial compliance or all the signs or symptoms of increased ICP.

Transsphenoidal resection of pituitary tumor is a special type of craniotomy. In this procedure, the
neurosurgeons proceed through an incision through the maxillary gingiva. The incision is small and the
procedure tends to have little hemodynamic consequence to the patient. Most of the neurosurgeons
here at UCSD perform the surgery with good technique. As such, this operation is sometimes performed
without an arterial line, almost a singular exception for neurosurgical procedures. Similarly, large IV
access is generally not required. Of course, one can never be at fault for being too prepared for a case.
Also, this case is done with the head of the bed facing the anesthesiologist, simplifying matters greatly.
Because of large amounts of blood and debris that can fall into the oropharynx, dense throat packs
and/or orogastric tube are placed by us prior to surgery. These throat packs serve to catch most of the
debris that would otherwise drain into the stomach and potentially cause nausea and vomiting on
emergence. They should protrude out of the mouth and be fixed in some way to prevent being lost
down the esophagus and removed prior to emergence. Most other considerations for craniotomy still
apply, such as potential measures to reduce brain volume and the need for a smooth emergence.
Reduction of intracranial volume should be discussed on a case-by-case basis with the surgeon. In
certain cases, reduction of intracranial volume may only serve to cause the mass to retract further into

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the skull cavity, making surgery more difficult. At other times, some reduction in volume may facilitate
surgical conditions.

Other perioperative concerns for transsphenoidal resection of pituitary tumor centers around the mass
itself. The most common functional pituitary mass secretes prolactin, but masses secreting ACTH, TSH,
GH, and others are possible. Many are nonfunctional. Obviously, each type has potential for different
effects on the patients physiology (e.g., gigantism and difficult intubation in a patient with a GH-
secreting mass). Surgery around the pituitary stalk commonly produces a central diabetes insipidus,
which is usually transient. A urinary catheter is necessary and frequently helpful. Lastly, transection of
the pituitary stalk can lead to panhypopituitarism.

Chapter 8D. Anesthesia for Posterior Fossa Surgery

Examples include any craniotomy for structures in the posterior fossa, including cerebellar or occipital
tumor removal and surgery around the brainstem or cranial nerves (e.g., acoustic neuroma removal,
microvascular decompression of the trigeminal nerve).

Technique: general. Monitors: standard, plus arterial line. A specific central venous catheter designed
for aspiration of air from the RA can be used. Urine output. Precordial Doppler. IV access: at least one
large IV. Duration: 4-6hrs. EBL: usually less than 300ml; there is potential for large hemorrhage.
Position: lateral, semilateral, prone, or sitting; head 180 away from the anesthesiologist. Special
equipment: precordial Doppler, potential for monitoring brainstem or cranial nerve potentials. Special
considerations: The previous considerations regarding ICP and goals of anesthesia all apply to these
surgeries as well.

Posterior fossa craniotomies carry an increased risk of venous air embolism (VAE). VAE is possible any
time venous sinuses are open to air. The posterior venous sinuses tend to be tented open by virtue of
being fixed to the posterior dura and bone and thus facilitate entrainment of air. Any time the involved
sinuses are above the level of the heart, the pressure in them is low but they remain open, creating a
situation where air entrainment can occur. Thus, the incidence of VAE is highest in patients in the sitting
position, which is used to facilitate exposure but is thankfully rare in this institution. However, every
posterior fossa craniotomy involves some elevation of the head above the heart to facilitate venous
drainage and thus carries the risk of VAE.

Signs of VAE include hypotension, hypoxia, increased dead space ventilation, circulatory arrest, and
paradoxical embolism if a PFO or other right-to-left shunt exists. Small air emboli typically go unnoticed
and have no effect on the patient. VAE can be monitored in several ways. A reduction in etCO2 and
increase in etN2 may be seen, although this effect may only be noticed with large emboli. A precordial
Doppler is useful and can detect even small emboli; the characteristic whooshing sound of the normal
heart beat is replaced with a whipping-like noise as emboli pass into the heart. TEE is even more
sensitive than a Doppler but requires specific operator skill and may have deleterious consequences for
the patient if left in for a protracted period of time, especially in the sitting position with neck flexion;
see below.

VAE is an emergency. Treatment must be immediate and consists of:

1. Notifying the surgeon, who will flood the field with saline and pack with gauze.
2. Discontinuing nitrous oxide and ventilating with 100% oxygen.
3. Raising cerebral venous pressure with IV fluids, lowering the head, sigh breath, and jugular vein

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 compression.
4. Evacuating the air by aspiration via a central venous catheter.
5. Providing supportive measures like CPR and pressors, as needed.
6. In addition to the above efforts, turning the patient with the right side up may keep the air in the RA
and decrease passage to the RV and pulmonary circulation, preventing air lock.

Other potential complications specific to positioning for posterior fossa surgeries, especially those in the
sitting position, include postoperative macroglossia, quadriplegia, and pneumocephalus. In regards to
the first two complications, excessive neck flexion is thought to play a role. It is extremely important to
ensure that the neck is not completely flexed in these patients prior to the start of surgery (generally at
least two fingerbreadths between the chin and chest). Avoiding unnecessary objects in the mouth may
be desirable, and a bite block, if used, should be placed as far forward as possible. Pneumocephalus can
occur any time the level of the head is raised, which is common in many craniotomies. Nitrous oxide
should not be used if there is a known pneumocephalus due to expansion of the gas pocket and mass
effect. However, in posterior fossa craniotomies with the head up, it can be used until the intracranial
space is completely closed, because prior to this point, there is no trapped gas pocket. Indeed, some feel
that nitrous oxide prior to dural closure may actually be advantageous, as N2O within a potential gas
pocket will be resorbed faster than nitrogen. Finally, the sitting position is associated with reduced
venous return possibly resulting in hypotension.

Surgery around the brainstem, including direct trauma or pressure from retraction, can have profound
physiologic consequences for the patient. Major cardiovascular changes can occur, such as profound
hyper- or hypotension, bradycardia, or other arrhythmias. Injury to fundamental respiratory centers in
the brainstem can cause postoperative respiratory dysfunction. If any of these changes are noticed
intraoperatively, it is imperative to inform the surgeon and treat the condition. Often, removal of
surgical instruments and loosening up on retraction is all that is necessary to correct the problem.
Bradycardia is particularly common and can be treated with cessation of the offending surgical stimulus
followed by ephedrine, glycopyrrolate, atropine, or epinephrine.

Microvascular decompression of the trigeminal nerve is a somewhat uncommon procedure elsewhere

but is done fairly frequently at UCSD. It involves a retromastoid craniotomy to remove vascular
structures thought to be compressing CN V and causing trigeminal neuralgia. Many of these patients are
young and otherwise healthy but may be on a complex regimen of medications for this condition. The
craniotomy has the potential for bradycardia as above and calls for the usual assortment of volume-
reduction techniques such as mannitol and mild hyperventilation. As such, an arterial line is usually
placed. BAEPs are monitored, but given that our anesthetics minimally affect BAEPs, no special
techniques are required.

Injury to cranial nerves arising from the brainstem is also a potential complication of these surgeries.
The postoperative deficit depends on the nerve involved. One feared complication is damage to the
glossopharyngeal nerve, which may result in inability to maintain a patent airway. Neuromonitoring may
include evoked potentials such as auditory evoked potentials for acoustic neuroma resection or facial
nerve EMG for facial dissection, which would preclude neuromuscular blockers.

Chapter 8E. Anesthesia for Minor Neurosurgery, Including Stereotactic Surgery

Examples include placement, revision, or removal of a ventriculoperitoneal shunt or lumboperitoneal

shunt and awake stereotactic surgery including deep brain stimulator placement.

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Technique: general, or general followed by local/MAC for stereotactic surgery. Monitors: standard. IV
access: one IV. Duration: around 1hr for shunts, 4-6hrs for DBS. EBL: < 100ml. Position: Supine or lateral
for shunts, bed 90 or 180 away from the anesthesiologist. Stereotactic surgery is typically done with
the patient sitting up 45-60, head fixed in a rigid frame, and away from the anesthesiologist; see below.
Special equipment: none. Special considerations: see below.

VP or LP shunts are minor procedures. Patients scheduled for placement of a shunt generally have
chronic hydrocephalus, and placement of the shunt will drain intracranial CSF into the abdomen and
reduce ICP. These patients may have signs and symptoms of elevated ICP, which include nausea,
vomiting, confusion, ataxia, and papilledema. Shunt revisions are typically performed on previously
functioning shunts which have now become obstructed or infected. Because these are minor procedures
in patients with chronic obstructive pathology, drastic anesthetic measures to control or reduce ICP are
not necessary. Similarly, an arterial line for precise beat-to-beat measurements is not required for
purposes of the surgery. Of course, it is always desirable to avoid overt hypercapnia or hypoxemia. The
subcutaneous tunneling of the shunt tubing from head to abdomen can be profoundly stimulating.

Stereotactic surgery is performed for diagnostic purposes, intractable epilepsy, for dyskinetic disorders
such as Parkinsons disease, or for tumors near eloquent areas of the brain. As the brain itself is
insensate and the surgeon specifically desires a lucidly awake patient who can interact and respond to
questions, the patient is only minimally sedated during the majority of the operative portion of the case.
However, the head must first be pinned. Often, these cases proceed with an initial period of general
anesthesia while the surgeon injects local anesthetic into the scalp at the intended frame pinning sites
and places the frame. Anesthesia at the surgical incision site is accomplished with local anesthetics by
the surgeon, peripheral nerve blocks by us (scalp blocks), or continuation of general anesthesia. The
patient is then allowed to awake and is kept minimally sedated with low-dose midazolam, opioids,
propofol, dexmedetomidine, or a combination thereof.

Since each of these surgeries has particular needs and protocol, knowledge of the surgery is key, and
your attending will be instrumental for this. Notably, deep brain stimulator cases usually start with head
pinning done under brief GA in the pre-op area followed by transport to the CT scanner, and then on to
the OR for the awake procedure.

It is vital to remember that access to the airway in these cases is nearly impossible. The patients head is
pinned in a frame and is 180 away from the anesthesia machine. Emergently releasing the pinning is
not an option with the cranium open. As such, oversedation, hypoventilation, apnea, or upper airway
obstruction can be catastrophic. Intense monitoring and judicious use of medications during the
sedation phases of the procedure are mandatory to ensure a patent airway and adequate
ventilation/oxygenation.

Stereotactic procedures are typified by long periods of boredom the patient is awake and generally
stable, and the surgery is minimally invasive interspersed with bursts of stress while titrating in
sedation and monitoring the patient for airway issues. Maintaining patient comfort and anxiolysis can be
quite challenging. Remember, the OR table is hard and flat and the patient cannot readjust his or her
position; back pain is common. Likewise, reassurance and psychological preparation of the patient for
the ordeal of an awake brain surgery are crucial.

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Chapter 9. Overview of SICU, Pain, Regional, Pediatrics, and Pre-op Rotations

Chapter 9A. SICU Rotation

The SICU experience consists of two 4-week blocks completed during the CA-1 and CA-2 years. During
this time, you are part of the SICU critical care team which typically consists of 1-2 anesthesiology
residents, 1 surgery resident, 1-2 surgical/OB-GYN interns, medical students, a trauma/critical care
fellow, and an attending. Both surgical and anesthesiology attendings cover the ICU. While on the SICU
rotation, you are not part of the MOR call pool and generally are not responsible for the typical MOR
duties, with a few notable exceptions that will be explained below. A detailed syllabus is available and
the finer points of the rotation will be explained at the start of the rotation.

The defining feature of the SICU is that it is an open unit, and most of the time, the SICU team functions
as consultants. All non-primary patients (e.g. trauma, general surgery, neurosurgery, or neurocritical
care) are seen, daily notes and plans are created, and recommendations are communicated to each
respective primary team. In addition to the consulting aspect provided, the SICU team also serves as
the primary providers for transplant, ENT, orthopedic, vascular, and OB/GYN patients, and is responsible
for daily notes, orders, and administration of care. Therefore, the SICU experience can be less onerous
than at other institutions because, at times, we dont take care of as many primary patients at once.

A typical day on the SICU team is as follows: The residents and medical students show up at the
appropriate time to pre-round on all the patients, typically around 0600, but this may differ depending
on patient census and number of team members present. Rounds are then generally made with the
fellow, the attending, or both, usually starting at 0830, though this may vary with the attending. Notes
and recommendations are written, and any orders or management changes are carried out. There is
usually a lecture shortly after rounds, often with a member of the team presenting a critical care topic.
After the lecture and discussion, the non-call members sign out to the person on call. Thus, most non-
call days are generally very light, usually ending around 1200-1300. Certain days, the call resident is an
intern and this handoff/signout cannot occur until 2000.

Other responsibilities of the rotation are to receive consults from other teams and assist with placement
of lines and airway and ventilator management. At times, certain teams such as neurosurgery get
swamped with patients and they request the SICU teams help in various ways. That being said, no
management should be undertaken on another teams patient without their prior approval.

As anesthesiology residents, we have unique responsibilities while on this rotation that the surgical
members do not have. These include:

Carrying the code pager and responding to it

Helping or being the provider for OR Resuscitation cases
Ensuring the code bags and emergency ORs are set up
Completing all inpatient pre-ops for the next day
Fulfilling requests our anesthesiology attendings may have for us to help move the day along, e.g.
breaks, room setups, etc.

More information on the code pager, emergency OR setups, and OR Resus cases can be found in the
appropriate sections. Generally, the SICU person on call is responsible for all of these things. If an
emergency OR Resuscitation case arises, the floor attending has the discretion to decide who does the

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casewhether it is a MOR resident, the SICU resident, or someone else. Expect to be involved or even
to be the primary resident in any OR Resus. Also, our attendings may occasionally ask the SICU resident
to give breaks in the MOR or even do a case. Remember that even when on the SICU rotation, you are
still an anesthesiology resident, part of our department, and thus subject to its whims. If a conflict arises
between anesthesiology and SICU duties, it can be discussed among the appropriate attendings.

The SICU experience represents a good learning opportunity in a fairly relaxed environment. The
majority of the attendings are pleasant, easy to work with, and excellent at teaching. Many people find
the paucity of primary patients liberating, in that one can still perform the mental exercise of
determining the best course of management, without the burden of actually having to write orders or
answer pages at 0200. Of course, the downside to this is that the learning experience may not be as
rigorous as it would be in a completely closed unit. All that said, make the most of the opportunity to
learn from rounds and enjoy the frequent early days.

As of June 2012, CA-3 residents also take a mandatory one-month rotation in the ICU at Thornton
(TICU). The department is also becoming increasingly involved with neurocritical care at Hillcrest and
Thornton hospitals. These rotations are works in progress and will not be described here.

Chapter 9B. Pain Medicine Rotation

The pain rotation consists of one mandatory month during the CA-1 or CA-2 year. It is also possible to
complete a pain elective during the CA-3 year. During the 4-week rotation, you will help manage
patients on the inpatient pain service, see patients in pain clinic, observe and perform pain procedures,
and take pager call. These duties are usually shared between the resident rotating through pain and the
pain fellows, with whom you will work closely. The typical week generally consists of daily rounding with
the fellow on patients on the pain service at Thornton, followed by morning pain clinics at Perlman Clinic
building, and then afternoon procedure clinics either at the VA and Moores Cancer Center. Assignments
to various clinics and procedure days are made by the program coordinator and available online. In
addition to daily rounding and note-writing on inpatient pain service patients, you are also expected to
round on inpatient regional anesthesia patients (epidurals, peripheral nerve blocks, etc.) on Tuesdays
and Thursdays. A detailed syllabus and the finer points of the rotation will be explained at the beginning
of the rotation.

Clinic patients consist of either new referrals or returning patients. New referrals need a full H+P, with
the obvious emphasis being on the patients pain history. After these patients are seen, they should be
presented to the attending in clinic, who will then complete the interview and decide on the best course
of treatment. Follow-up visits are generally less demanding, and are usually in the clinic for post-
procedure evaluation, a medication refill, or for general maintenance. In these cases, you can consult
the old notes in EPIC to get a quick overview of the patient. While in clinic, you are also responsible for
writing the note and entering orders when the visit is complete. There are EPIC templates that the pain
fellows will share with you at the start of your rotation.

The various procedures performed to treat chronic pain are numerous, and each attending has their
own style as well. Typically, they will show or teach you the procedure first, and after you develop some
experience and procedural skills, will let you perform some of the injections on your own. Depending on
your performance and the attending, you may eventually get to perform virtually every procedure that
comes through the door. The various procedures performed will be explained during the rotation. Listed
below are some of the most common:

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 Lumbar/ thoracic/cervical epidural steroid injections (ESI)
Trigger point injections
Intra-articular injections (knee, shoulder, hip, etc.)
Sacroiliac (SI) joint injections
Medial branch blocks/facet joint blocks
Radiofrequency ablation (RFA) of medial branch
Botox injections
Sympathetic blocks (stellate, celiac, lumbar, etc.)

Pain call is pager call. Typically, residents usually take pain call on 1 or 2 weekends (Friday 1700 through
Monday 0700) during the four-week block. During your call weekend(s), you will be responsible for new
consults and rounding on all inpatients on the pain service at both Thornton and Hillcrest. After pre-
rounding on these patients, you will then be expected to call the on-call attending to discuss the
patients and your management plans. You are responsible for writing the daily progress note on these
patients. While on call, all inpatient consults will be directed to you. Consults received before 1700
should be seen that same day, while consults received after 1700 can be seen the next day, depending
on the urgency. After evaluating the new consult, the attending on call should be contacted for a
definitive plan. The attending is also there to answer any questions you may have on any patients or
new consults. New inpatient consults should be added to the pain patient list in EPIC, and the other
members of the team should be notified so they know who to round on during the weekday mornings
(to be explained when the rotation starts). What this means is that when you are on weekend call, the
days may be long, as you may get called in to see consults up to 1700, in addition to your rounding
responsibilities on pain service patients at both Hillcrest and Thornton.

Patients also call the operator to speak to the pain physician on call, who will then forward the patients
contact number to you. It is your responsibility to call this patient regarding whatever issue or
question(s) the patient has. Always, always dial *67 before dialing the patients number so that your
phone number will be kept private from the patient. It is the policy of the pain department that pain
medication refills or orders cannot be given over the phone, and patients wanting these things will just
have to be told to wait until normal business hours and then call the clinic for an appointment. True
medical emergencies must be asked about, and if present, the patient should be told to go to an ER. An
example would be a patient who had a recent procedure, and now complains of bowel or bladder
incontinence. If a patient has intractable pain, generally we do not recommend that the go to an ED for
exacerbations of chronic pain. However, such a patient cannot be completely evaluated over the
phone. Again, the attending on call is there to answer any questions you may have.

Chapter 9C. Regional Anesthesia Rotation

The regional anesthesia experience at UCSD consists of two mandatory months: one during the CA-1 or
CA-2 years at Hillcrest and one during the CA-3 year at the VA. An additional 1-month advanced
regional elective is available for CA-3s. During the first one-month block, you will perform peripheral
nerve blocks on a variety of patients. Most of the nerve blocks will be for patients going to the OR, but
others might be for patients on the ward, e.g., burn patients having twice-daily dressing changes. As the
resident, you will perform many or most of the blocks, with the fellows doing the others. There is
normally one fellow with you at Hillcrest, with a second fellow if it is an extremely busy day.

Daily duties include performing the blocks, finishing documentation, rounding on inpatients with
catheters, writing progress notes, making phone calls to outpatients with catheters or single-shot blocks,

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and helping to coordinate the next days blocks. Reflecting Hillcrests patient population, blocks are
done on a mix of elective orthopedic upper- and lower-extremity cases or for trauma-related fractures,
debridements, or skin grafting. Most blocks are done pre-op, but occasionally you might wait and see
if a patient needs a block for adequate analgesia, or you might do a block to help with perfusion to a
new flap or graft.

A typical day starts at 0545 in the block area, where you will draw up all the local anesthetic and
midazolam/fentanyl that is likely to be required for the day. Patients for whom a block is planned will be
brought to the block area, receive their block, and then be taken to the OR pre-op holding area. As such,
blocks for the first OR cases of the day should be done by 0700 at the latest. The block RN will place the
patient on monitors, conduct a timeout, and program/set-up the infusion pump as applicable. The
resident is responsible for placing orders for the infusion in EPIC and managing the inpatient census list
in EPIC. Bread and butter blocks at UCSD include:

Brachial plexus: interscalene and infraclavicular

Forearm (median, ulnar, radial)
Intercostobrachial
Transversus abdominis plane (TAP)
Femoral
Sciatic: subgluteal, popliteal
Saphenous

Blocks that are typically reserved for fellows due to complexity, rarity, or risk include lumbar plexus and
paravertebral blocks.

Regional call is a one-week call (Monday 0700 Monday 0700) and is pager call. The resident will field
all pages regarding all patients on the regional service. During the week, there is a fellow at Thornton, so
questions regarding Thornton patients (and there are many) should be forwarded to that fellow. During
the weekend or after hours, the resident covers both locations. On the weekend, you will round at both
locations on the regional patients and write the notes after discussing the patients with the on-call
regional attending. Any blocks that must be done over the weekend will be done by the call person and
the call attending.

The VA regional rotation differs from the rotation at Hillcrest in a few ways. First, there are no regional
anesthesia fellows at the VA; the regional resident is entirely responsible for the service on weekdays,
and the call resident rounds on regional patients on the weekends. Secondly, the logistics of doing
regional blocks are quite different at the VA due to the VAs inherent bureaucracy and paperwork. Third,
the total number of blocks you do is highly dependent on your own initiative.

A typical day starts at 0640 with morning conference. No blocks can be done prior to the huddle,
which happens no earlier than 0700, so typically the huddle occurs and then the block is done in the pre-
op holding area. Also prior to the block, a separate pre-block timeout occurs. The blocks and
equipment themselves are quite similar to those at Hillcrest, with a few more items of paperwork than
Hillcrest. The regional anesthesia patient list is kept in an Excel file, and the daily follow-up phone calls
to outpatients and visits to inpatients are done in a similar fashion to Hillcrest. The day typically ends
fairly early and the regional pager is handed off to the call resident.

ASRA Guidelines

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Neuraxial anesthetic techniques carry a risk of hemorrhagic complications. The worst-case scenario is
spinal/epidural hematoma leading to a devastating outcome like spinal cord compression and
paraplegia. Peripheral nerve blocks carry a similar type risk to the nerves being blocked. However, the
actual incidence of neurologic dysfunction resulting from hemorrhagic complications associated with
neuraxial anesthesia is unknown.

The most recent guidelines published by the American Society of Regional Anesthesia and Pain Medicine
(ASRA) are recommendations based on evidence-based reviews. These are consensus statements based
on case reports, clinical series, and pharmacology. As always, you should use your best judgment as to
when neuraxial anesthesia is appropriate for a patient, and remember that removal of an epidural or
spinal catheter in a coagulopathic patient can be just as risky as placement of one.

2010 ASRA Guidelines (3rd Edition)

Anticoagulant Placement Removal
Subcutaneous No contraindication with 5000U BID dosing. Remove catheters prior to next dose of
heparin Reduce risk of bleeding by starting heparin after heparin and restart heparin 2 hours after.
block. Check platelet count for HIT if patients have
Safety for patients on >10,000U daily or more been receiving heparin for more than 4 days.
than TID dosing has not been established.
IV heparin Can start heparin 1hr after neuraxial block. Remove catheters 2-4hrs after last heparin
dose; can restart heparin 1 hour after
LMWH For patients on daily dosing, wait 10-12hrs after For BID dosing, first dose should be 24hrs
last dose post-op. Remove catheter 2hrs prior to first
For patients on BID dosing (whether prophylactic dose
or treatment), wait at least 24hrs after last dose For daily dosing, remove catheters 10-12hrs
For patients who receive a dose before surgery, after last dose and resume dosing 2hrs after
recommend against neuraxial techniques removal
Warfarin Ensure medication has been discontinued and INR INR < 1.5
has normalized
Antiplatelet drugs NSAIDS: no contraindication
Aspirin: no contraindication
Ticlopidine: discontinue for 14 days
Clopidogrel, prasugrel: discontinue for 7 days
Abciximab: discontinue for 24-48hrs
Eptifibatide/tirofiban: discontinue for 4-8hrs
Thrombolytics Absolute contraindication No definitive recommendation for patients
who have a catheter and unexpectedly
receive these drugs
Consider checking fibrinogen level
Thrombin Due to lack of data, ASRA recommends against
inhibitors neuraxial blocks
Fondaparinux Due to lack of data, ASRA recommends against
neuraxial blocks
Herbals No contraindication
* For patients undergoing deep plexus or peripheral block, ASRA recommends that recommendations regarding neuraxial
techniques be similarly applied.
**Always check the medical record and ensure that the patient is not taking other medications that affect clotting mechanisms.

Chapter 9D. Pediatric Anesthesia Rotation

The vast majority of our experience with pediatric anesthesia takes place at Rady Childrens Hospital San
Diego. While there are sporadic pediatric cases at Hillcrest and these children tend to be quite ill
RCHSD provides intensive, daily exposure to pediatric anesthesia during the rotation. Two one-month

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mandatory rotations are done, one during the CA-2 year and another during the CA-3 year. A third
month, as a CA-3, is an elective option. Additionally, two consecutive months can be spent at Childrens
Hospital of Los Angeles as a CA-3 elective. Pediatric patients differ markedly from adults in physiology,
cognitive ability, and the typical type of case encountered, and that information will not be addressed
here. What follows are the expectations and requirements during the RCHSD experience.

The rotation at RCHSD is quite different than almost every other experience during residency. Nearly all
of the attendings are in a large private practice group with no formal affiliation with UCSD; a few
attendings in our department also work at RCHSD. Each room is staffed by an attending who expects to
be doing the case solo, and there are no formal room assignments for the residents. Residents are
generally free to choose which cases they would like to see during the day, and are not required to stay
in a specific room for the whole day. This affords the luxury of tailoring our experience to our desires for
that day. So, if on one day, two interesting cases are scheduled in different rooms, it is entirely possible
to start one case and then switch to the other room later. If you spent the previous day in the ENT room,
you may spend the next day in the urology room, gaining experience in caudal injections. The flexibility
of being able to tailor your experience is unique to this rotation. Clearly, this is subject to the approval of
whichever attending you happen to be working with at the moment. If you start a case with one
attending, and then ask to go to another room, and they would rather you stay put, you should use your
best judgment. Similarly, if an attending doesnt feel like working with a resident that day, theyll let you
know to find another room. Most of the attendings at RCHSD like to work with residents, are more than
willing to teach, and are flexible with letting us jump from room to room.

The exception to the practice above is when you are assigned to be the diamond (call) resident on a
particular day; this is assigned when you start the rotation. When you are the diamond resident, you are
paired with the attending running the floor so they have the flexibility to leave the room and take care
of floor/PACU/OR issues. Since the floor runner has to stay close to the main OR board, they are usually
assigned to OR1 or OR2, which means you will be in one of those ORs for the day. The floor runner will
keep the diamond resident until things start to wind down. Sometimes, this could be late afternoon but
depending on the attending, it could also be late evening. Once sent home, you must be available by
pager overnight. Typically, the attendings will only call you back in for an exceptionally interesting case;
if this happens, you will have the next day off. When on call during the weekend, the usual expectation
is that you will show up on Saturday mornings to do cases and there are always cases and be
available by pager for the rest of the night and for Sunday. Again, this is dependent on the attending on
call. Some expect you to come in, some will call you if they need you, and others will tell you not to
worry because you definitely wont be called. It may be possible to establish this beforehand with the
attending you will be on call with, but in general, expect to come in on Saturday, but not on Sunday.

While at RCHSD, you are still expected to attend M&M and return to UCSD for lectures or visiting
professor sessions. If you are the diamond resident that day, remind the floor runner that you must
leave for lecture in the afternoon and they will let you know if you need to return after lecture. Most
RCHSD attendings are aware that our residents have lecture on Wednesdays and if you are not the
diamond resident, then they do not expect you to go back.

The downside of the freedom of choosing your own room at RCHSD is that the learning may be quite
unstructured. Often, you have no idea what youll be doing the next day and thus cant tailor your
reading prior to a case. Most of the attendings prefer the residents not participate in the pre-op
evaluation of the patients, since we slow the process down. You will quickly see that RCHSD is devoted
to rapid turnovers and high productivity, and the attendings hate anything that wastes time or slows the

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day down. This same mentality causes a small number of attendings to avoid residents, and you will
quickly learn who those attendings are. RCHSD is definitely a rotation for adult learners. If you have a lot
of initiative and try to get the most out of the rotation it can be a great experience; conversely, if you
find ways to hide, dont expect to learn very much.

There are other notable impacts of the maximizing productivity stance of RCHSD. Almost every patient
emerges and is extubated in the PACU by a PACU nurse. A typical case will end with the patient
breathing spontaneously, still intubated, and brought to PACU unmonitored. After giving report, the
anesthesiologist goes to start the next case, while the PACU nurse extubates the patient when
appropriate. This serves to cut down on turnover time. While most of the PACU nurses are excellent,
there have been several near-disasters when a patient was inappropriately managed with an attending
not present. Furthermore, as residents, we may not get much experience with emergence and
extubation of the pediatric patient.

Another common impact is the attending shuffle which occurs throughout the day. The attending call
system at RCHSD defines the order in which the attendings may leave, with highest call having to stay
the latest. This is a rotational system that is generally balanced. The upside of being a high call is that the
attendings get first choice on high-paying ORs, and can bump any lower call attending during the day.
The impact on the residents is that you may work with several attendings during the day even if you stay
in the same actual OR. Furthermore, if you want to work with the same attending, you may have to
follow him or her from room to room, to the CT scanner, to MRI, and so on and so forth. This can be
somewhat frustrating.

A typical morning at RCHSD is quite different than at our other hospitals. There is little to no setup of the
room beforehand. Most attendings walk in 5 minutes before the cases start and have little to no
knowledge of their patient. Furthermore, they often do not draw up drugs beforehand, or even check
the circuit prior to bringing the patient back into the room. As such, the attendings dont expect the
residents to do this either. From the resident point of view, the morning usually begins with inspecting
the OR board for good cases, figuring out who the attending assigned to that room is, and approaching
that attending. This lack of preparation can be frustrating because from the resident point of view, you
are doing new cases on a scary class of patient with little to no experience. This is part of the challenge
and the learning value of the RCHSD rotation.

In summary, RCHSD can be a great experience, but it takes initiative and maturity on the part of the
resident. A certain comfort level with pediatric anesthesia can only be obtained with repeated, daily
exposure and RCHSD does give us that.

Chapter 9E. Pre-op Clinic and Radiation Therapy

This is a 2- or 4-week rotation in the pre-op clinic at the Perlman Clinic building at Thornton. This duty is
combined with providing anesthesia for pediatric patients undergoing radiation therapy at Moores
Cancer Center. The pre-op clinic experience itself is very much a typical outpatient clinic, where you are
seeing patients for pre-anesthetic evaluation prior to their scheduled, elective cases, on a day where
they are also seeing their surgeon and typically having pre-op labwork drawn. A typical clinic day
consists of 20-30 patients, with the resident and 2 NPs seeing those patients. The anesthesiology
resident is primarily responsible for seeing patients who have already seen a staff member of the
surgery department, and are coming to the clinic purely for anesthesia pre-op evaluation. The NPs
typically see the patients who need both surgical H+P and anesthesia pre-op evaluation. The attending

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running the floor at Thornton is responsible for signing off these pre-ops, and is the one you can contact
with questions or concerns. Clinic starts at 0830, but your ability to attend at this time is determined by
the radiation therapy cases, which are discussed next.

Radiation Therapy is provided at Moores Cancer Center, and the pediatric patients undergoing these
treatments require GA to remain motionless for their irradiation sessions. You will be working very
closely with a pediatric anesthesia attending on this rotation, and they will help you with all of its facets.
A couple of quick comments:

The first case is usually scheduled to start between 0730 and 0800; you should arrive 15 minutes
prior to set up.
The anesthetic typically consists of intermittent propofol boluses (or infusion) to induce and
maintain GA while the child continues to spontaneously ventilate via a simple oxygen facemask.
There is an anesthesia machine in the XRT room itself, but it is rarely used.
Routine monitors, however, are always used.
There may be anywhere from zero to 5 or more cases scheduled each weekday, and typically the
patients come back several times a week.
Most of these patients have vascular access ports (Port-a-cath) which are used for your IV
anesthetic and must be accessed and flushed appropriately.

At the conclusion of these cases, you should report immediately to Thornton pre-op clinic.

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