ANAESTHESIA FOR MRI

PROCEDURES, ECT&
CARDIOVERSION
 Introduction
Non operating room anesthesia (NORA) refers to
administration of sedation/anesthesia outside the
operating room to patients undergoing painful or
uncomfortable procedures.
 Objectives
To provide safe and qualified anesthetic care in the
NORA.
Understanding that the standards of anesthesia care
and patient monitoring are the same regardless of
location.
To remember that the key to efficient and safe remote
anesthetic relies on open communication between the
anesthesiologist and non‐operating room personnel.
Realize that remote locations have different safety
concerns, such as radiation and powerful magnetic
fields.
 OUR AIMS:
Guard the patient's safety and welfare
Minimise physical discomfort and pain
Control anxiety, minimise psychological trauma and
maximize the potential for amnesia
Control movement to allow safe completion of the
procedure
Return the patient to a state in which safe discharge
from medical supervision is possible.
.
 P AT I E N T S R E L AT E D
CHALLANGES
The reason for which they require the intervention
Associated co-morbidities(Eg.
DM/HTN/CKD/CHF/COPD/CVA/LIVER CIRRHOSIS/POST
CARDIAC INTERVENTION PATIENTS)
Fasting status
A quick airway assessment : unanticipated difficult
airway is very challenging in remote locations
Presence of dentures
Children ( may have-URTI/CHD etc)
 Anxious patients
 Claustrophobic patients (especially in MRI suites)
 Elderly or confused patients
 Patients undergoing painful procedures
 Patients requiring burns dressings.
 ENVIRONMENTAL RELATED CHALLENGES:

Limited working place, limited access to the patient,

Electrical interference with monitors and phones,
lighting and temperature inadequacy,
Use outdated , old equipment
Staff less familiar with the management of patients
Lack of skilled personnel, drugs and supplies
There is often no regular check up of the anaesthesia
inventory.
 Poor illumination-

Many procedures are carried out in darkened rooms

[e.g. interventional radiology or endoscopy]
Should be able to visualise the flow meters and to check
accurate gas flows.
we must be vigilant to detect unexpected events such
as cessation of oxygen delivery and ETT disconnection
A trained anaesthesiologist should provide
anaesthesia in remote locations within the hospital.
However non anaesthesiologists are allowed to
provide ‘conscious sedation'.
It is mandatory that all providers should be
Advanced Cardiac Life Support (ACLS) certified.
 EQUIPMENTS RELATED CHALLENGES:

In remote areas, where darkness and big machines

prevails, ETCO2 can be very helpful.
If possible, mobilise end-tidal CO2 monitoring from the
operating theatres.
Monitoring may be a particular challenge in the MRI
suite
Certain procedures require circuits and monitors with
long extension tubings e.g. Interventional
neuroradiology.
An AMBU should also be available to provide positive
pressure ventilation in case of oxygen failure.
 STAFF RELATED CHALLENGES:

Staff  trained only in their speciality

Sole responsibility of the anaesthesiologist to check and
ensure safety
Ensure that rapid communication to colleagues in the
main theatre suite is possible.
Identify an assitant to help
Check consent
 PROCEDURE RELATED CHALLENGES:

Beware of the situation where the anesthesiologist is

called after the intervention has started and the patient
is found to be uncooperative.
Without a prior plan or airway assessment the
situation is hazardous – if situation allows, it is better to
abort the procedure and come back another day when
things can be planned properly.
Some areas are poorly equipped to deal with any kind
of emergency e.g. Burn dressings, muscle biopsies etc
done at bedside
 Positioning
Patients undergoing ERCP, Endoscopy and CT guided
biopsies  lateral or prone position.
 Pillows should be available for safe prone positioning &
All other routine precautions for prone position..
Prone position becomes difficult if the patient requires
routine resuscitation – reposition the patient rapidly if
this is the case.
 Duration of the procedure

Duration : difficult to predict

They may finish very abruptly : Avoid long-acting
muscle relaxants and maintain close communication
with the specialist performing the procedure.
 Post-procedure care
Transport to a standard recovery room with the
monitors along with the anaesthesiologist
Oxygen during transport.
Patients who require elective postoperative ventilation
must be transferred with continuous monitoring.
Patients undergoing aneurysm coiling may need to be
ventilated in the postoperative period.
The availability of an ICU bed has to be confirmed prior
to the procedure.
 SOME SPECIAL CONSIDERATIONS

Anaphylaxis to iodinated dyes is possible. All the drugs

for Rx of anaphylaxis should be immediately available.
Radiation exposure - anaesthesia personnel should be
aware of the radiation hazards and take precautions to
avoid radiation exposure.
Intermittently check, whether your syringe pump is
running and adequate amount of drug is remaining, 3-
ways are turned in the proper direction, breathing
pattern is normal.
ASA Guidelines for Non-operating Room Anesthesia:
 Each location should have
- Reliable source of oxygen adequate for the length of the procedure, with a
backup supply
- Adequate and reliable source of suction
- Adequate and reliable system for scavenging waste anesthetic gases
- Self-inflating hand resuscitator bag capable of administering > 90% oxygen
- Adequate anesthesia drugs, supplies, and equipment for the intended
anesthesia care
- Adequate monitoring equipment to allow adherence to the “Standards for
Basic Anesthetic Monitoring”
- Sufficient electrical outlets to satisfy anesthesia machine and monitoring
equipment requirements
 Provision for adequate illumination
- The patient, anesthesia machine, and monitoring equipment
- Battery-powered illumination other than a laryngoscope immediately
available
 Sufficient space
- Accommodate necessary equipment and personnel
- Allow expeditious access to the patient, anesthesia machine,
and monitoring equipment
 Immediate availability of an emergency cart
- Defibrillator, emergency drugs, and other equipment to provide
cardiopulmonary resuscitation
 Staff
- Trained anesthesiologist
- Adequate staff trained to support the anesthesiologist
 Appropriate post-anesthetic management
- Adequate number of trained staff
- Appropriate equipment available to safely transport the patient
to a post-anesthesia care unit
Complications of Non-operating Room Anesthesia:
• Stridor  Laryngospasm
 Wheezing  Airway obstruction
 Coughing  Agitation/delirium
 Aspiration  Inadequate
 Desaturation analgesia/anesthesia
 Allergic reaction  Iv related complications
 Cardiac arrest  Unplanned intubation
 Hypothermia  Prolonged anesthesia
 Death
Secretions requiring treatment
Unintended deep level of anesthesia
Use of reversal agents-unplanned
Vomiting (non-gastrointestinal procedure)
Unexpected need for bag-mask ventilation
Emergency sedation/anesthesia consultation required
Unplanned admission to hospital or increase in level of
care
Unexpected change in heart rate, blood pressure,
respiratory rate of 30%
EQUIPMENTS CHECK(SOAPME)-ASA guidelines

S (suction) – Appropriate size suction catheters and

functioning suction apparatus.
O (oxygen) – Reliable oxygen sources with a
functioning flowmeter with at least one spare E‐type oxygen
cylinder.
A (airway) – Size appropriate airway equipment:
• Face mask
• Nasopharyngeal and oropharyngeal airways
• Laryngoscope blades
• ETT
• Stylets
• Bag‐valve‐mask or equivalent device.
P (pharmacy) – Basic drugs needed for life support
during emergency:
• Epinephrine (adrenaline)
• Atropine
• Glucose
• Naloxone (reversal agent for opioid drugs)
• Flumazenil (reversal agent for benzodiazepines).
M (monitors):
• Pulse oximeter
• NIBP
• End‐tidal CO2(capnography)
• Temperature
• ECG
E (equipment):
• Defibrillator with paddles
• Gas scavenging
• Safe electrical outlets (earthed)
• Adequate lighting (torch with battery backup)
• Means of reliable communication to main theatre site.
Personnel Requirements for Non-operating Room Anesthesia:

Anesthesia staff
- Trained in pre-anesthetic assessment of patients
- Trained and experienced in airway management and
cardiopulmonary resuscitation
- Trained in the use of anesthetic and resuscitation drugs
Non anesthesia staff
- Trained to deal with cardiopulmonary emergencies
- Trained to assist anesthesiologists—familiar with
anesthetic procedures and equipment
- Trained in postoperative anesthetic care and resuscitation
 .

ANAESTHESIA FOR MRI

PROCEDURES
MRI
 MRI is a noninvasive diagnostic technique that
uses magnetic properties of atomic nuclei to
produce high-resolution, multi planar cross- -
sectional images of the body.

 Hydrogen is the atom most often used for

imaging.
MRI ZONES
 MRI -Limitations and Hazards
Time consuming,
• Any patient movement, even that resulting from physiologic
motion(e.g., cardiac and vascular flow pulsations, cerebrospinal fluid
Flow and pulsation, respiratory excursion, and peristalsis in the
gastrointestinal tract), can produce artifacts on the image.
• To optimize information when imaging the cardiovascular system,
the signal acquisition is synchronized or “gated” with phases of the
cardiac cycle (R wave of ECG) to virtually freeze cardiac motion.
• The magnet generating the large static magnetic field has a
smalldiameter hollow bore, typically 50 to 65 cm in diameter.
• Switching the RF generators on and off produces loud noises
(>90 dB).
• Antenna effect
 Limitations and Hazards of MRI…
Dislodgement and malfunction of implanted biological devices:
– vascular clips and shunts,
– wire spiral endotracheal tubes,
– pacemakers,
– automatic implantable cardioverter-defibrillators (ICDs),
– mechanical heart valves,
– implanted biologic pumps.
• Tattoo ink (high concentrations of iron oxide): may cause burns
• Intraoccular ferromagnetic foreign body migration.
• Rapid movement of ferromagnetic objects: Scissors, pens, keys
ATM cards, mobiles, cyllinders
 Anaesthetic concerns
1.Limited patient access and visibility
2. Absolute need to exclude ferromagnetic components
3. Interference/malfunction of monitoring equipment
4. Potential degradation of the imaging caused by the stray RF
currents from monitoring equipment and leads
5. The necessity to not move the anesthetic and monitoring
equipment when the examination has started to prevent
degradation of magnetic field homogeneity
6. Limited access to the MRI suite for emergency personnel in
accordance with recommended policies
MONITORING DIFFICULTIES
MR SAFE – equipment possess no known risk to the patient &
environment under MR conditions, , but functionality is not
tested.

MR COMPATIBLE –equipment is safe and functions adequately

under such conditions.

MR UNSAFE –Not to be used .

Previously , ferromagnetic anaesthesia machines used to

ventilate with long circuits passed through waveguides.

Currently , MR compatible anaesthesia machines ,vaporisers

and ventilators are available .
All leads and wires have current induced by the
changing magnetic fields – risk of burns .

It should be ensured that the wires and leads are made

of a braided material with minimal contact with the
patients skin ..

Shortest leads possible must be used keeping in mind

that the scanner bed moves in and out of the scanner
portal .

The wires can also be placed on top of linen to minimise

skin contact, as any type of ECG lead may still cause
burns .
ECG monitoring- affected by magnetic fields –mimic
hyperkalemic changes during period of activation .

Pulse Oximeters -Burns– only MRI compatible pulse

oximeters to be used .
Cables to placed as far away from scanner as possible.

BP monitoring –compatible transducers and plastic

connectors used.

Capnography-Longer lines needed -20 s delay

expected.
 ANAESTHESIA
Aim is to make patient motionless in a noisy, confined environment
for long duration.

Majority of patients under go MRI scanning without anaesthesia .

Patient group or conditions predisposed to requiring anaesthetic

care
-Infants and children
-patients with learning difficulties
-Movement disorders
-Claustrophobic patients
-Critically ill patients
SEDATION
Sedation for MRI is delivered with great success.

Goal for sedation :

Guard the patient safety &welfare .
Minimise patient discomfort /pain .
Control anxiety .
Maximise the potential for amnesia.
Control behaviour and movement .

Light levels may result in airway complications such as laryngospasm,coughing

that may necessitate interruption of the scan for urgent treatment and alteration
of anaesthetic depth.

Monitioring of exhaled CO2 to be considered for deeply sedated patients .

Appropriate equipments for size and age to be used .

GENERAL ANAESTHESIA
Understand the quality and detail of the images required , and
also the likely duration of the scan , and determine whether
spontaneous ventilation with LMA or ETT /mechanical
ventilation is required.

Anaesthesia should be induced in a dedicated Anaesthetic

room adjacent to the MRI scanner outside the 5 G contour.

Provides area where anaesthetic and resuscitation

equipment can be stored.

Location of the Anaesthetic room should be such that the

patients can be rapidly transferred in an emergency.

Transferred in MRI safe non ferrous trolley .

Airway of the patient goes first into the scanner –
inaccessible –Receiver coil placed around further restricts
access particularly in head scans .

Security of the airway to be ensured before the

commencement of the scan.

LMA –most used during MRI GA

mask with no ferromagnetic components must be

chosen .

Pilot balloons of cuffed ETT contain a small ferromagnetic

spring –taped away from the area to be scanned .
Maintenance of anaesthesia - IV or inhalational
anaesthetics.

Standard infusion pumps are strongly ferromagnetic –

projectile /malfunction.

MRI safe infusion pumps have been developed .

MRI compatible anaesthesia station –minimises the length

of the breathing system , safe delivery of inhalational
anaesthetics.

If unavailable , standard anaesthesia station can be secured

firmly to the wall outside the 5 G contour ,exact location
determined by the Physicist.
Electroconvulsive therapy (ECT)
Principle:
– ECT consists of programmed electrical stimulation of
the central nervous
system to initiate seizure activity.
– The seizure is monitored by observation of the patient
and by an
electroencephalogram on the ECT machine.
• Periods: 6 to 12 treatments over 2 to 4 weeks
 Electroconvulsive therapy (ECT)
Indications
– Major depression
– Mania
– Certain forms of schizophrenia
– Parkinson’s syndrome
• Contraindications
– Pheochromocytoma
– Increased ICP
– Recent CVA
– Cardiovascular conduction defects
– High risk pregnancy
– Aortic and cerebral aneurysms
Physiologic effects:
– Increases in cerebral blood flow and intracranial pressure.
– Initial parasympathetic discharge manifested by bradycardia,
Occasional asystole, premature atrial and ventricular
contractions.
– Hypotension and salivation may be noted.
– Followed by sympathetic discharge associated with
tachycardia,
hypertension, PVCs, and rarely, ventricular tachycardia.
– ECG changes, including ST-segment depression and T-wave
inversion(Self limited)
 General considerations of ECT
Antidepressants:
• TCA (block reuptake of catecholamines)-anticholinergic,
antihistaminic, sedative, slow cardiac conduction
• MAOI (blocks metabolism of catecholamines)-
Hypertensive crises,inhibit hepatic microsomal enzymes
• Lithium-prolongs NMB , bzd, barbiturates
duration;cognitive effects post ECT (discontinue pre ECT)
• Newer antidepressents (trazadone, bupripion, fluxetine):
less side effects; preferred
 Anesthetic Management of ECT
Pre operative evaluation: CNS/ CVS evaluation
• Anticholinergic pretreatment- glycopyrrolate/atropine:
To prevent transient asystole, bradycardia, antisialogogue
• Induction : Intravenous anaesthetics
– Methohexital (.75-1 mg/kg)---Gold standard
– Propofol,etomidate, thiopental, Bzd, ketamine not usually
a choice
• Volatile anesthetics- Sevoflurane agent of choice in
children specially
• Opoids- Remifentanil
Neuromuscular blockers:
– Sch 0.5 mg/kg, (DOC)
– Mivacurium :alternative to Sch, but not be as effective as
Sch in preventing tonic-clonic muscle contractions
– Atracurium/cisatracurium: pseudocholinesterase
deficiency.
• Esmolol and labetalol have been successfully used to
control hypertension and tachycardia after ECT: routinely
not recommended because the hypertension and
tachycardia are usually self-limited
Complications Regarding Patient Management
Respiratory complications

 It is evident that respiratory depression is more frequent during sedation or

anesthesia outside the OR.
 Respiratory complications are associated with nonvigilance, choice of an
inappropriate anesthetic technique, use of non anesthesia staff in complex
medical cases, esophageal intubation, and unexplained bradycardia
 .The most common specific damaging event in NORA claims were
inadequate oxygenation/ventilation, which are preventable with better
monitoring, such as pulse oximetry and capnography.
 Techniques in reducing deoxygenation due to apnea and/or difficult airways
such as preoxygenation should be performed especially in patients with
severe diffuse emphysema or the elderly
 Maintaining an appropriate seal between the face mask and face is also
important in oxygen delivery
Hypothermia
 Hypothermia occurs frequently in areas heavily air-conditioned to avoid
equipment overheating. Pediatric patients are vulnerable to hypothermia
when exposed for prolonged periods.
 Methods of reducing hypothermia include warming blankets with surface
heating, administering heated fluids, and preemptive warming.
 Although massive bleeding is rare in the NORA setting, mild hypothermia
is known to increase surgical blood loss and the risk of transfusion
emphasizing the importance of maintaining normothermia in anesthetized
patients.

Aspiration
 Aspiration of gastric contents is an issue when administering sedatives,
hypnotics, or anesthetics because protective airway reflexes are blunted.
 Preoperative fasting is as important as in patients preparing for elective
surgery.
 Clear fluids are allowed 2 hours before induction, whereas solids regarded
as a meals are withheld for at least 6 hours.
Hypovolemia
 Patients preparing for colonoscopy on fluid restriction and a
strict diet to prevent aspiration are at risk of dehydration,
hypovolemia, and may show vigorous responses to
vasodilating or cardiac depressant drugs. Thus,
maintenance of a sufficient volume status before the
procedure by prehydration and slow injection of drugs may
prevent adverse events.

Postoperative nausea and vomiting (PONV)

 Postoperative nausea and vomiting is one of the primary
causes of unplanned hospitalization, and is easily
recognizable and preventable.
Discharge criteria - Safety NORA cases is
optimised by:

• Patient selection
• Procedure selection
• Anaesthetic choice (GA Vs. LA etc.)
• Discharge planning