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CHAPTER 37

Anesthesia for Otolaryngology–Head &

Neck Surgery

KEY CONCEPTS

The anesthetic goals for laryngeal endoscopy include an immobile surgical field
and adequate masseter muscle relaxation for the introduction of the suspension
laryngoscope (typically profound muscle paralysis will be sought), adequate
oxygenation and ventilation, and cardiovascular stability despite periods of
rapidly varying procedural stimulation.
During jet ventilation, chest wall motion must be monitored and sufficient
exhalation time allowed to avoid air trapping and barotrauma.
The greatest concern of laser airway surgery is an airway fire. This risk can be
moderated by minimizing the fraction of inspired oxygen (FiO2 <30% if
tolerated by the patient) and can be eliminated when there is no combustible
material (eg, flammable endotracheal tube, catheter, or dry cotton pledget) in the
airway.
Techniques to minimize intraoperative blood loss include topical
vasoconstriction with cocaine or an epinephrine-containing local anesthetic for
vasoconstriction, maintaining a slightly head-up position, and providing a mild
degree of controlled hypotension.
If there is serious preoperative concern regarding potential airway problems,
intravenous induction may be avoided in favor of awake direct or fiberoptic
laryngoscopy (cooperative patient) or direct or fiberoptic intubation following an
inhalational induction, maintaining spontaneous ventilation (uncooperative
patient). In any case, the appropriate equipment and qualified personnel required
for emergency tracheostomy must be immediately available.
The surgeon may request the omission of neuromuscular blockade during
neck dissection, thyroidectomy, or parotidectomy to allow nerve identification (eg,
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spinal accessory, facial nerves) by direct nerve stimulation and thereby

facilitate their preservation.
Manipulation of the carotid sinus and stellate ganglion during radical neck
dissection has been associated with wide swings in blood pressure,
bradycardia, arrhythmias, sinus arrest, and prolonged QT intervals. Infiltration
of the carotid sheath with local anesthetic will usually moderate these problems.
Bilateral neck dissection may result in postoperative hypertension and loss of
hypoxic drive due to denervation of the carotid sinuses and bodies.
Patients undergoing maxillofacial reconstruction or orthognathic surgical
procedures often pose airway challenges. If there are any anticipated signs of
problems with mask ventilation or tracheal intubation, the airway should be
secured prior to induction of general anesthesia.
If there is a risk of postoperative edema involving structures that could obstruct
the airway (eg, tongue, pharynx), the patient should be closely observed and
perhaps kept intubated.
Nitrous oxide is either entirely avoided during tympanoplasty or discontinued
prior to graft placement.

Cooperation and communication between surgeon and anesthesia provider are critical
for all surgery within or near the airway. Establishing, maintaining, and protecting the
airway in the face of abnormal anatomy during a procedural intervention are demanding
tasks. An understanding of airway anatomy (see Chapter 19) and an appreciation of
common otorhinolaryngologic and maxillofacial procedures are invaluable in handling
these anesthetic challenges successfully.

ENDOSCOPY
Endoscopy includes diagnostic and operative laryngoscopy and microlaryngoscopy
(laryngoscopy aided by an operating microscope), esophagoscopy, and bronchoscopy
(discussed in Chapter 25). Endoscopic procedures may be accompanied by laser
surgery.

Preoperative Considerations Patients

presenting for upper airway endoscopic procedures are frequently being evaluated
for voice disorders (often presenting as hoarseness), stridor, or hemoptysis.
Possible diagnoses include foreign body aspiration, trauma to the aerodigestive tract,
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papillomas, tracheal stenosis, tumors, or vocal cord dysfunction. Thus, a preoperative

medical history and physical examination, with particular attention to potential airway
problems, must precede any decisions regarding the anesthetic plan. In some patients,
flow–volume loop (see Chapter 6), radiographic, computed tomography, ultrasound, or
magnetic resonance imaging studies may be available for review or need to be
requested. Many patients will have undergone preoperative indirect laryngoscopy or
fiberoptic nasopharyngoscopy, and the information gained from these procedures is
often of critical importance.
Important initial questions that must be answered are whether positive-pressure
ventilation via face or laryngeal mask is feasible and whether the patient can be
intubated using conventional direct or video laryngoscopy. If the answer to either
question is “no” or “unlikely,” the patient’s airway should be secured prior to induction
using an alternative technique such as awake fiberoptic bronchoscope or tracheostomy
under local anesthesia (see Case Discussion, Chapter 19). However, even the initial
securing of an airway with tracheostomy does not prevent intraoperative airway
obstruction due to surgical manipulation, a foreign body, or hemorrhage.
Sedative premedication should be avoided in a patient with threatening upper
airway obstruction. Glycopyrrolate (0.2–0.3 mg) works more effectively and
persistently when given intramuscularly rather than intravenously 1 h before surgery and
may prove helpful by minimizing secretions, thereby facilitating airway visualization.

Intraoperative Management
The anesthetic goals for laryngeal endoscopy include an immobile surgical field
and adequate masseter muscle relaxation for the introduction of the suspension
laryngoscope (typically profound muscle paralysis will be sought), adequate
oxygenation and ventilation, and cardiovascular stability despite rapidly varying levels
of procedural stimulation.

A. Muscle Relaxation
Intraoperative muscle relaxation can be achieved by intermittent boluses or infusion of
intermediate-duration nondepolarizing neuromuscular blocking agents (NMBs) (eg,
rocuronium, vecuronium, cisatracurium) or with a succinylcholine infusion. Rapid
recovery is important as endoscopy is often an outpatient procedure. Given that
profound muscle relaxation is often needed until the very end of the operative procedure,
endoscopy remains one of the few remaining indications for succinylcholine infusions;
however, the use of sugammadex (Bridion) to reverse profound degrees of rocuronium
or vecuronium neuromuscular blockade has rendered succinylcholine infusion largely
obsolete.
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B. Oxygenation & Ventilation

Several methods have successfully been used to provide oxygenation and ventilation
during endoscopy while simultaneously minimizing interference with the operative
procedure. Most commonly, the patient is intubated with a small-diameter endotracheal
tube through which conventional positive-pressure ventilation is administered. Standard
endotracheal tubes of smaller diameters, however, are designed for pediatric patients
and therefore are too short for the adult trachea and have a low-volume cuff that will
exert increased pressure against the tracheal mucosa. A 4.0-, 5.0-, or 6.0-mm specialized
microlaryngeal endotracheal tube (Mallinckrodt MLT) is the same length as an adult tube,
has a disproportionately large high-volume low-pressure cuff, and is stiffer and less prone
to compression than a conventional endotracheal tube of the same diameter. The
advantages of intubation in endoscopy include protection against aspiration and the
ability to administer inhalational anesthetics and continuously monitor end-tidal CO2 .

In some procedures, such as those involving the posterior commissure or vocal

cords, intubation with an endotracheal tube may interfere with the surgeon’s
visualization or performance of the procedure. A simple alternative is insufflation of
high flows of oxygen through a small catheter placed in the trachea. Although
oxygenation may be maintained in patients with good lung function, ventilation will be
inadequate for longer procedures unless the patient is allowed to breathe spontaneously.
Another option is the intermittent apnea technique, in which positive-pressure
ventilation with oxygen by face mask or endotracheal tube is alternated with periods of
apnea, during which the surgical procedure is performed. The duration of apnea, usually
2 to 3 min, is determined by how well the patient maintains oxygen saturation, as
measured by pulse oximetry. Risks of this technique include hypoventilation with
hypercarbia, failure to reestablish the airway, and pulmonary aspiration.
Another attractive alternative approach involves manual jet ventilation via a
laryngoscope side port. During inspiration (1–2 s), a high-pressure (30–50 psi) jet of
oxygen is directed through the glottic opening and entrains a mixture of oxygen and room
air into the lungs (Venturi effect). Expiration (4–6 s duration) is passive. Chest wall motion
must be monitored and sufficient exhalation time allowed to avoid air trapping and
barotrauma. This technique requires total intravenous anesthesia. A variation of this
technique is high-frequency jet ventilation, which utilizes a small cannula or tube in the
trachea, through which gas is injected 80 to 300 times per minute (see Chapter 58).
Capnography will not provide an accurate estimate of end-tidal CO2 during jet
ventilation because of the constant and sizable dilution of alveolar gases.

C. Cardiovascular Stability
Blood pressure and heart rate often fluctuate markedly during endoscopic procedures
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for two reasons. First, some of the patients undergoing these procedures are older adults
with a long history of heavy tobacco and alcohol use that predisposes them to
cardiovascular disease. In addition, the endoscopic procedure is, in essence, a series of
physiologically stressful laryngoscopies and interventions, separated by varying periods
of minimal surgical stimulation. Attempting to maintain a constant level of anesthesia
invariably results in alternating intervals of hypertension and hypotension. Providing a
modest baseline level of anesthesia allows supplementation with short-acting anesthetics
(eg, propofol, remifentanil) or sympathetic antagonists (eg, esmolol), or both, as needed
during periods of intense stimulation. Less commonly, some anesthesia providers utilize
a regional nerve block of the glossopharyngeal nerve and superior laryngeal nerve to help
minimize intraoperative swings in blood pressure (see Case Discussion, Chapter 19).

Laser Precautions
Laser light differs from ordinary light in three ways: It is monochromatic (possesses one
wavelength), coherent (oscillates in the same phase), and collimated (exists as a narrow
parallel beam). These characteristics offer the surgeon excellent precision and hemostasis
with minimal postoperative edema or pain. Unfortunately, lasers introduce several major
hazards into the operating room environment.
The uses and side effects of a laser vary with its wavelength, which is determined
by the medium in which the laser beam is generated. For example, a CO2 laser produces
a long wavelength (10,600 nm), whereas yttrium–aluminum–garnet (YAG) lasers produce
a shorter wavelength (1064 or 1320 nm). As the wavelength increases, absorption by
water increases, and tissue penetration decreases. Thus, the effects of the CO2 laser
are much more localized and superficial than are those of the YAG laser.
General laser precautions include suction evacuation of toxic fumes (laser plume)
from tissue vaporization because they have the potential to transmit microbial diseases.
When a significant laser plume is generated, individually fitted respiratory filter masks
compliant with U.S. Occupational Safety and Health Administration (OSHA) standards
should be worn by all operating room personnel. In addition, during laser procedures, all
operating room personnel should wear laser eye protection appropriate for the type of
laser used, and the patient’s eyes should be taped shut. Operating room windows should
be covered, and appropriately placed signage should be used to alert those entering the
room that a laser device is in use.
The greatest risk of laser airway surgery is an airway fire. This risk can be
moderated by minimizing the fraction of inspired oxygen (FiO2 <30% if tolerated by the
patient) and can be eliminated when there is no combustible material (eg, flammable
endotracheal tube, catheter, or dry cotton pledget) in the airway. If an endotracheal tube
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is used, it must be relatively resistant to laser ignition (Table 37–1). Such specialized
endotracheal tubes not only resist laser beam strikes but also possess double cuffs that
should be inflated with saline instead of air to better absorb thermal energy and reduce the
risk of ignition. If the proximal cuff is struck by the laser and the saline escapes, the distal
cuff will continue to seal the airway. Alternatively, endotracheal tubes can be wrapped with
a variety of metallic tapes; however, this is a suboptimal practice and should be avoided
whenever the use of a specialized, commercially available, flexible, stainless steel, laser-
resistant endotracheal tube is possible (Table 37–2).

TABLE 37–1 Advantages and disadvantages of various endotracheal tubes for

laser airway surgery.

TABLE 37–2 Disadvantages of wrapping a tracheal tube with metallic tape.

No cuff protection
Adds thickness to tube
Not a device approved by the US Food and Drug Administration
Protection varies with type of metal foil
Adhesive backing may ignite
May reflect laser onto nontargeted tissue
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Rough edges may damage mucosal surfaces

Although specialized, laser-resistant endotracheal tubes may be used, it must be

emphasized that no endotracheal tube or currently available endotracheal tube protection device
is reliably laser-proof. Therefore, whenever laser airway surgery is being performed with an endotracheal
tube in place, the following precautions should be observed:

• Inspired oxygen concentration should be as low as possible by utilizing air in the inspired gas mixture
(many patients tolerate an FiO2 of 21%).

• Nitrous oxide supports combustion and must not be used.

• The endotracheal tube cuffs should be filled with saline. Some practitioners add methylene blue to
the saline to make cuff rupture more obvious. A well-sealed, cuffed endotracheal tube will minimize the
oxygen concentration in the pharynx.

• Laser intensity and duration should be limited as much as possible.

• Saline-saturated pledgets, though potentially flammable, should be placed in the airway to limit the
risk of endotracheal tube ignition and damage to adjacent tissue.

• A source of water (eg, water-filled 60-mL syringe and basin) should be immediately
available in case of fire.

These precautions limit but do not eliminate the risk of an airway fire; anesthesia providers must
proactively address the hazard of fire whenever laser or electrocautery is utilized near the airway (Table
37–3).

TABLE 37–3 Airway fire protocol.

1. Stop ventilation and remove tracheal tube.

2. Turn off oxygen and disconnect circuit from machine.
3. Submerge tube in water.
4. Ventilate with face mask and reintubate.

5. Assess airway damage with bronchoscopy, serial chest x-rays, and arterial blood
gases.
6. Consider bronchial lavage and steroids.

If an airway fire should occur, all air/oxygen should immediately be turned off at the
anesthesia gas machine, and burning combustible material (eg, an endotracheal tube) must be removed
from the airway. The fire can be extinguished with saline, and the
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patient’s airway must be examined to be certain that all foreign body fragments have
been removed.

NASAL & SINUS SURGERY

Common nasal and sinus surgeries include polypectomy, endoscopic sinus surgery,
maxillary sinusotomy (Caldwell–Luc procedure), rhinoplasty, and septoplasty.

Preoperative Considerations Patients

undergoing nasal or sinus surgery may have a considerable degree of
preoperative nasal obstruction caused by polyps, a deviated septum, or mucosal
congestion from infection. This may make face mask ventilation difficult, particularly if
combined with other causes of difficult ventilation (eg, obesity, maxillofacial deformities).

Nasal polyps are often associated with allergic disorders, such as asthma. Patients
who also have a history of allergic reactions to aspirin should not be given any
nonsteroidal anti-inflammatory drugs (including ketorolac) for postoperative analgesia.
Nasal polyps are a common feature of cystic fibrosis.
Because of the rich vascular supply of the nasal mucosa, the preoperative interview
should concentrate on questions concerning medication use (eg, aspirin, clopidogrel)
and any history of bleeding problems.

Intraoperative Management Many nasal

procedures can be satisfactorily performed under local anesthesia with sedation. The
anterior ethmoidal nerve and sphenopalatine nerves (see Figure 19–3) provide
sensory innervation to the nasal septum and lateral walls. Both can be blocked by
packing the nose with gauze or cotton-tipped applicators soaked with local anesthetic.
The topical anesthetic should be allowed to remain in place at least 10 min before
instrumentation is attempted. Supplementation with submucosal injections of local
anesthetic is often required. Use of an epinephrine-containing or cocaine solution will
shrink the nasal mucosa and potentially decrease intraoperative blood loss.
Intranasal cocaine (maximum dose, 3 mg/kg), though providing both excellent anesthesia
and vasoconstriction of the nasal mucosa, is rapidly absorbed, reaching peak systemic
blood levels in 30 min, and may be associated with cardiovascular side effects (see
Chapter 16).
General anesthesia is often preferred for nasal surgery because of the discomfort
and incomplete block that may accompany topical anesthesia. Special considerations
during and shortly following induction include using an oral airway during face mask
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ventilation to mitigate the effects of nasal obstruction, intubating with a reinforced or

preformed Mallinckrodt oral RAE (Ring–Adair–Elwyn) endotracheal tube (see Figure 36–
1), and tucking the patient’s padded arms, with protection of the fingers, to the side.
Because of the proximity of the surgical field, it is important to tape the patient’s eyes
closed to avoid corneal abrasion. One exception to this occurs during dissection in
endoscopic sinus surgery, when the surgeon may wish to periodically check for eye
movement because of the close proximity of the sinuses and orbit (Figure 37–1);
nonetheless, the eyes should remain protected until the surgeon is ready to observe them.
NMBs are often utilized because of potential neurological or ophthalmic injury that may
occur if the patient moves during sinus instrumentation.

FIGURE 37–1 Orbital fracture is a risk of endoscopic sinus surgery because of the proximity of the sinuses to
the orbit (A, frontal view; B, coronalsection). (Modified with permission from Snell RS, Katz J. Clinical Anatomy
for Anesthesiologists. New York, NY: Appleton & Lange; 1988.)

Techniques to minimize intraoperative blood loss include topical

vasoconstriction with cocaine or an epinephrine-containing local anesthetic, maintaining a

slightly head-up position and providing a mild degree of controlled hypotension. A posterior
pharyngeal pack is often placed to limit the risk of aspiration of blood.
Despite these precautions, the anesthesia provider must be prepared for major blood
loss, especially during resection of vascular tumors (eg, juvenile nasopharyngeal
angiofibroma).
Coughing or straining during emergence from anesthesia and extubation should be
avoided as these events will increase venous pressure and increase postoperative
bleeding. However, relatively deep extubation strategies that are commonly and
appropriately utilized to accomplish this goal may increase the risk of aspiration.
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HEAD & NECK CANCER SURGERY

Surgery for cancer of the head and neck includes laryngectomy, glossectomy,
pharyngectomy, parotidectomy, hemimandibulectomy, and radical neck dissection. An
endoscopic examination following induction of anesthesia often precedes these surgical
procedures. Timing of a tracheostomy, if planned, depends upon the patient’s preoperative
airway compromise. Some procedures may include extensive reconstructive surgery,
such as the transplantation of a free microvascular muscle flap, with long surgical time
duration.

Preoperative Considerations The typical

patient presenting for head and neck cancer surgery is older and often has had
many years of heavy tobacco and alcohol use. Those patients without a history of
extensive tobacco and alcohol use will usually have been infected with human
papillomavirus. Common coexisting medical conditions include chronic obstructive
pulmonary disease, coronary artery disease, hypertension, diabetes, alcoholism,
and malnutrition. These patients will benefit from an enhanced recovery after surgery
program that includes preoperative nutritional repletion over the course of several
days and hydration with a carbohydrate–protein drink during the 24 h period prior to surgery.
Airway management may be complicated by abnormal airway anatomy,
possibly including an obstructing lesion, or by preoperative radiation therapy that has
fibrosed and distorted the patient’s airway structures. If there is concern regarding
potential airway problems, intravenous induction may be avoided in favor of awake
direct or fiberoptic laryngoscopy (cooperative patient) or direct or fiberoptic intubation
following an inhalational induction, maintaining spontaneous ventilation (uncooperative
patient). Elective tracheostomy under local anesthesia prior to induction of general
anesthesia is often a prudent option, all the more so since many head and neck cancer
surgeries will conclude with a temporary or permanent tracheostomy, anyway. In any
case, the appropriate equipment and qualified personnel required for emergency
tracheostomy must be immediately available during anesthetic induction for head and
neck cancer operations where a difficult airway is known or suspected and the induction
is not preceded by tracheostomy.

Intraoperative Management A. Monitoring

Because many of these procedures are
lengthy and associated with substantial blood loss and because of the prevalence of
coexisting cardiopulmonary disease, arterial cannulation may be utilized for blood
pressure monitoring and for obtaining blood
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periodically for laboratory analyses. If central venous access is deemed necessary, the
surgeon should be consulted to ascertain that planned internal jugular or subclavian
venous access will not interfere with the intended surgical procedures; antecubital or
femoral veins are reasonable alternatives. Arterial lines and intravenous cannulas
should not be placed in the operative arm if a radial forearm flap is planned. A minimum
of two large-bore intravenous lines and a urinary catheter (preferably with temperature-
monitoring capability) should be placed. As the arms are typically secured next to the
patient’s sides for these procedures, the continued functionality of upper extremity
arterial and intravenous lines should be verified prior to placement of the sterile surgical
drapes. A forced-air warming blanket should be used to help maintain normal body
temperature. Intraoperative hypothermia and consequent vasoconstriction can be
detrimental to the perfusion of a microvascular free flap.
Intraoperative nerve monitoring is increasingly utilized by surgeons in anterior neck
operations to help preserve the superior laryngeal, recurrent laryngeal, and vagus
nerves (Figure 37–2), and the anesthesia provider may be asked to place a specialized
nerve integrity monitor endotracheal tube (Medtronic Xomed NIM endotracheal tube) to
facilitate this process (Figure 37–3).
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FIGURE 37–2 The vagus nerve (cranial nerve X) originates in the medulla oblongata and then ramifies in the
superior and inferior vagal ganglia in the neck. Its first major branch is the pharyngeal plexus of the vagus. The
superior laryngeal nerve divides into the external and internal laryngeal nerves. The internal branch supplies sensory
innervation of the laryngeal mucosa above the vocal cords, and the external branch innervates the inferior pharyngeal
constrictor muscles and the cricothyroid muscle of the larynx. Cricothyroid muscle contraction increases the voice pitch
by lengthening, tensing, and adducting the vocal folds. The superior laryngeal nerve is at risk of damage during
operations of the anterior neck, especially thyroid surgery, and injury to this nerve may result in hoarseness and loss of
vocal volume. The next branch of the vagus is the recurrent laryngeal nerve, which innervates all of the muscles of
the larynx except the cricothyroid, and is responsible for phonation and glottic opening. The recurrent laryngeal nerve
runs immediately behind the thyroid gland and thus is the nerve at greatest risk for injury during thyroid surgery.
Unilateral recurrent laryngeal nerve damage may result in vocal changes or hoarseness, and bilateral nerve damage
may result in aphonia and respiratory distress. Inferior to this nerve, the vagus nerve provides autonomic motor and
sensory nerve fibers to the thoracic and abdominal viscera. (Reproduced with permission from Dillon FX.
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Electromyographic (EMG) neuromonitoring in otolaryngology-head and neck surgery. Anesthesiol Clin. 2010
Sep;28(3):423-442.)

FIGURE 37–3 A: The Medtronic Xomed NIM electromyographic (EMG) nerve integrity monitoring endotracheal tube.
Succinylcholine (or no relaxant at all) should be used for intubation, and the endotracheal tube should be secured in
the midline. If lubricant is used, it must not contain local anesthetics. B: A slightly larger endotracheal tube size should
be used to facilitate mucosal contact with the electrodes, and the electrode band of the NIM tube must be
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positioned at the level of the vocal cords. C: Nerve integrity is continuously monitored via EMG activity (Medtronic
Xomed NIM-Response 3.0 Nerve Integrity Monitor). Nondepolarizing muscle relaxants are contraindicated because
they prevent EMG monitoring. (Reproduced with permission from Medtronic Xomed.)

B. Tracheostomy
Head and neck cancer surgery often includes tracheostomy. Immediately prior to
surgical entry into the trachea, the endotracheal tube and hypopharynx should be
thoroughly suctioned to limit the risk of aspiration of blood and secretions. If
electrocautery is used during the surgical dissection, the Fio2 should be lowered to 30%
or less, if possible, to minimize the risk of fire as the trachea is entered. In any case, the
easiest way to minimize airway fire risk in this circumstance is for the surgeon not to use
electrocautery to enter the trachea. After dissection down to the trachea, the endotracheal
tube cuff is deflated to avoid perforation by the scalpel. When the tracheal wall is
transected, the endotracheal tube is withdrawn so that its tip is immediately cephalad to
the incision. Ventilation during this period is difficult because of the large leak through the
tracheal incision. A sterile, cuffed tracheostomy tube is placed in the trachea, the cuff is
inflated, and the tube is connected to a sterile breathing circuit extension. As soon as the
correct position is confirmed by capnography and bilateral chest auscultation, the original
endotracheal tube may be entirely removed. An increase in peak inspiratory pressure
immediately after tracheostomy usually indicates a malpositioned endotracheal tube,
bronchospasm, debris or secretions in the trachea, or, rarely, pneumothorax.

C. Maintenance of Anesthesia
The surgeon may request the omission of NMBs during neck dissection,
thyroidectomy, or parotidectomy to allow nerve identification (eg, spinal accessory,
facial nerves) by direct nerve stimulation and thereby facilitate their preservation. If a
nerve integrity monitor endotracheal tube is utilized, succinylcholine (or propofol with no
relaxant) may be used to facilitate intubation. Moderate controlled hypotension may be
helpful in limiting blood loss; however, cerebral perfusion may be compromised with
moderate hypotension when a tumor invades the carotid artery or jugular vein (the latter
may increase cerebral venous pressure). If the head-up tilt is utilized, it is important that
the arterial blood pressure transducer be zeroed at the level of the brain (external
auditory meatus) to determine cerebral perfusion pressure most accurately. In addition,
head-up tilt increases the risk of venous air embolism.
Following reanastomosis of a microvascular free flap, blood pressure should be
maintained at the patient’s baseline level. The use of vasoconstrictive agents (eg,
phenylephrine) should be minimized because of the potential decrease in flap perfusion
due to vasoconstriction. Similarly, the use of vasodilators (eg, sodium nitroprusside or
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hydralazine) should be avoided to minimize any decrease in graft perfusion pressure.

D. Transfusion
Transfusion decisions must balance the patient’s immediate surgical risks with the
possibility of an increased cancer recurrence rate resulting from transfusion-induced
immune suppression. Rheological factors make a moderately low hematocrit (eg, 27–
30%) desirable when microvascular free flaps are performed. Excessive diuresis
should be avoided during microvascular free-flap surgery to optimize graft perfusion in
the postoperative period.

E. Cardiovascular Instability
Manipulation of the carotid sinus and stellate ganglion during radical neck
dissection has been associated with wide swings in blood pressure, bradycardia,
arrhythmias, sinus arrest, and prolonged QT intervals. Infiltration of the carotid sheath
with local anesthetic will usually moderate these problems. Bilateral neck dissection
may result in postoperative hypertension and loss of hypoxic drive due to denervation of
the carotid sinuses and carotid bodies.

Postoperative Management The

principal postoperative complications associated with head and neck cancer
surgery include hypocalcemia secondary to acute hypoparathyroidism, threats to airway
integrity secondary to hemorrhage, hematoma formation, and bilateral vocal cord palsy
with stridor resulting from bilateral recurrent laryngeal nerve injury (see Chapter 35).
Postoperative hypoparathyroidism is a common condition, resulting from injury to the
parathyroid glands or their blood supply during thyroidectomy or neck dissection or
from unintentional or intentional removal of all four parathyroid glands. It may be either
symptomatic or asymptomatic, and it occurs transiently in up to 49% of thyroidectomy
patients and is permanent in up to 33% of thyroidectomy patients. Symptoms and signs
depend upon the rate of onset and severity of hypocalcemia. Clinical signs of acute,
severe hypocalcemia include laryngospasm, bronchospasm, QT prolongation-related
arrhythmias, and congestive heart failure. Neurological symptoms and signs range from
circumoral paresthesia, distal extremity numbness, and carpopedal spasm to confusion,
delirium, and seizure activity. Symptomatic hypocalcemia is a medical emergency and
should be treated with intravenous calcium salts, whereas asymptomatic hypocalcemia
may be treated with oral calcium preparations (see Chapter 49).

MAXILLOFACIAL RECONSTRUCTION &

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ORTHOGNATHIC SURGERY
Maxillofacial reconstruction is often required to correct the effects of trauma (eg,
fractures of the mandible or maxilla) or developmental malformations or for radical
cancer surgeries (eg, maxillectomy or mandibulectomy). Orthognathic procedures (eg,
Le Fort osteotomies, mandibular osteotomies) for skeletal malocclusion share many of
the same surgical and anesthetic techniques.

Preoperative Considerations
Patients undergoing maxillofacial reconstruction or orthognathic surgical
procedures often pose airway challenges. Particular attention should be focused on jaw
opening, mask fit, neck mobility, micrognathia, retrognathia, maxillary protrusion
(overbite), macroglossia, dental pathology, nasal patency, and the existence of any
intraoral lesions or debris. If there are any anticipated signs of problems with mask
ventilation or endotracheal intubation, the airway should be secured prior to induction of
general anesthesia. This may involve fiberoptic nasal intubation, fiberoptic oral
intubation, or tracheostomy with local anesthesia facilitated with cautious sedation.
Nasal intubation with a straight tube with a flexible angle connector (Figure 37–4A) or
a preformed nasal RAE (Figure 37–4B) tube is usually preferred in dental and oral
surgery. The endotracheal tube can then be directed cephalad over the patient’s
forehead. With any nasal intubation, care should be taken to prevent the endotracheal
tube from putting pressure on the tissues of the nasal opening, as this situation may
result in local tissue pressure necrosis in the setting of a lengthy surgical procedure.
Nasal intubation should be considered with caution in Le Fort II and III fractures because
of the possibility of a coexisting basilar skull fracture (Figure 37–5).
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FIGURE 37–4 A: A regular straight endotracheal tube can be cut at the level of the nares and a flexible connector
attached. B: Alternatively, a nasal RAE endotracheal tube has a preformed right-angle bend at the level of the nose so
that the tube is directed over the forehead.
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FIGURE 37–5 Diagrammatic representation of Le Fort I, II, and III fractures. Le Fort II and III fractures may
coexist with a basilar skull fracture, a contraindication to nasal intubation.

Intraoperative Management Maxillofacial

reconstructive and orthognathic surgeries can be lengthy and involve substantial
blood loss. An oropharyngeal (“throat”) pack is often placed to minimize the amount
of blood and other debris reaching the larynx and trachea, and one must remember
to remove the pack at the end of surgery before the jaws are wired shut!
Strategies to minimize bleeding include a slight head-up position, controlled
hypotension, and local infiltration with epinephrine solutions. Because the patient’s
arms are typically tucked at the side, two intravenous lines may be established prior to
surgery. An arterial line is typically placed. As previously noted, if head-up tilt is utilized,
it is important that the arterial blood pressure transducer be zeroed at the level of the
brain (external auditory meatus) to determine cerebral perfusion pressure most
accurately. In addition, the anesthesia provider must be alert to the increased risk of
venous air embolism in the setting of head-up tilt.
Because of the proximity of the airway to the surgical field, positioning of
surgical team personnel, and positioning of the patient’s head often 90° or 180° away
from the anesthesia provider, there is an increased risk of critical intraoperative airway
problems, such as endotracheal tube kinking, disconnection, or perforation by a surgical
instrument. Monitoring of end-tidal CO2 , peak inspiratory pressures, and breath sounds
via an esophageal stethoscope assume greater importance in such cases. If the operative
procedure is near the airway, the use of electrocautery or laser increases the risk of fire.
At the end of surgery, the oropharyngeal pack must be removed and the pharynx
suctioned. If there is a risk of postoperative tissue edema involving structures that could
potentially obstruct the airway (eg, tongue, pharynx), the patient should be closely
observed and perhaps kept sedated and intubated for several hours postoperatively or
overnight. In such uncertain situations, extubation may be performed over an
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endotracheal tube exchanger (eg, Cook Airway Exchange Catheter with Rapi-Fit
Adapter, Cook Medical), which can facilitate reintubation and provide oxygenation in the
setting of immediate postextubation respiratory obstruction. In addition, the operating
team must be prepared for emergency tracheotomy or cricothyrotomy.
Otherwise, extubation can be attempted once the patient is fully awake and there are no
signs of continued bleeding. Patients with intermaxillary fixation (eg, maxillomandibular
wiring) must have suction and appropriate wire cutting tools continuously at the bedside
in case of vomiting or other airway emergencies. Extubating a patient whose jaws are
wired shut and whose oropharyngeal pack has not been removed can lead to life-
threatening airway obstruction. “Has the throat pack been removed?” should be asked
before intermaxillary fixation is initiated and again before removing the endotracheal tube.

EAR SURGERY Frequently

performed ear surgeries include stapedectomy or stapedotomy,
tympanoplasty, and mastoidectomy. Myringotomy with insertion of tympanostomy tubes
is the most common pediatric surgical procedure and is discussed in Chapter 42.

Intraoperative Management
A. Nitrous Oxide
Nitrous oxide is not often used in anesthesia for ear surgery. Because nitrous oxide is
more soluble than nitrogen in blood, it diffuses into air-containing cavities more rapidly
than nitrogen (the major component of air) can be absorbed by the bloodstream (see
Chapter 8). Normally, changes in middle ear pressures caused by nitrous oxide are well
tolerated as a result of passive venting through the eustachian tube. However, patients
with a history of chronic ear problems such as otitis media or sinusitis often have
obstructed eustachian tubes and may, on rare occasions, experience hearing loss or
tympanic membrane rupture from the administration of nitrous oxide anesthesia.
During tympanoplasty, the middle ear is open to the atmosphere, and there is

no pressure buildup. However, once the surgeon has placed a tympanic membrane graft,
the middle ear becomes a closed space, and if nitrous oxide is allowed to diffuse into any
gas remaining in this space, middle ear pressure will rise, and the graft may be displaced.
Conversely, discontinuing nitrous oxide after graft placement will create a negative middle
ear pressure that could also cause graft dislodgment. Therefore, nitrous oxide is either
entirely avoided during tympanoplasty (which is our preference) or discontinued prior to
graft placement. Obviously, the exact amount of time required to
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wash out the nitrous oxide depends on many factors, including alveolar ventilation and
fresh gas flows (see Chapter 8), but 15 to 30 min is usually recommended.

B. Hemostasis
As with any form of microsurgery, even tiny amounts of blood can obscure the operating
field. Techniques to minimize blood loss during ear surgery include mild (15°) head
elevation, infiltration or topical application of epinephrine (1:50,000–1:200,000), and
moderate controlled hypotension. Because coughing on the endotracheal tube during
emergence (particularly during neck movement associated with head bandaging) will
increase venous pressure and may cause bleeding and increased middle ear pressure,
deep extubation is often utilized.

C. Facial Nerve Identification

Preservation of the facial nerve is an important consideration during some ear
procedures, such as resection of a glomus tumor or acoustic neuroma. During such
cases, intraoperative paralysis with NMBs will make identification of the facial nerve by
direct nerve stimulation impossible. Thus, intraoperative paralysis should not be
employed without discussion with the surgical team.

D. Postoperative Vertigo, Nausea, & Vomiting

Because the inner ear is intimately involved with the sense of balance, ear surgery may
cause postoperative dizziness (vertigo) and postoperative nausea and vomiting (PONV).
Induction and maintenance with propofol have been shown to decrease PONV in
patients undergoing middle ear surgery. Prophylaxis with decadron prior to induction
and a 5-HT3 blocker prior to emergence should be considered. Patients undergoing ear
surgery should be carefully assessed for vertigo postoperatively, and their ambulation
should be closely monitored to minimize the risk of falling.

Oral Surgical Procedures Most minor

oral surgical procedures are performed in a clinic or office setting utilizing local
anesthesia, augmented with varying degrees of sedation. If intravenous sedation is
employed, or if the procedure is complex, a qualified anesthesia provider should be
present. A qualified anesthesia provider must be present to administer deep sedation or
general anesthesia if either is utilized. Typically, a bite block and an oropharyngeal throat
pack protect the airway. For light to moderate levels of sedation, the oropharyngeal pack
prevents irrigating fluids and dental debris from entering the airway. Deep sedation and
general anesthesia require an increased level of airway management by a qualified
anesthesia provider. Regardless of whether deep sedation or general anesthesia is
inadvertent or intended, appropriate equipment, supplies, and
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medications must be immediately available to help ensure that any anticipated or

unexpected anesthesia-related problem occurring in an office or clinic environment can
be safely addressed with the same standard of care that is required in the hospital or
ambulatory surgery center setting.
Minor oral surgical procedures, such as dental extractions, typically last no longer
than 1 h. A nerve block or local anesthetic infiltration is typically utilized. In adults,
most oral surgeons use 2% lidocaine with 1:100,000 epinephrine or 0.5% bupivacaine
with 1:200,000 epinephrine in quantities no greater than 12 mL and 8 mL, respectively.
Articaine is commonly used in Europe. The anesthesia provider must be informed by the
surgeon of the local anesthetic used and its concentration and volume injected so that
the allowed dosage based on patient weight is not exceeded. Pediatric patients are
particularly at risk of local anesthesia toxicity due to excess local anesthetic dose
administration or accidental intravascular injection.
Intravenous sedation during oral surgical procedures greatly increases the patient’s
comfort and facilitates surgery. Small doses of fentanyl and midazolam are usually
adequate for adults prior to injection of the local anesthetic. The sedation can be further
augmented by additional small dosages of fentanyl, midazolam, or a propofol infusion.
Incremental doses of propofol, 20 to 30 mg for adults, are often used if the surgeon
requires a brief episode of deep sedation or general anesthesia.
These techniques require a high level of cooperation and participation by both the
surgeon and anesthesia provider. If there is the possibility of increased risk due to
preexisting medical conditions, less than ideal airway, or extent of contemplated
surgical procedure, it is safer to perform the procedure in a hospital or ambulatory
surgery center setting with general endotracheal anesthesia.

CASE DISCUSSION

Bleeding Following Sinus Surgery

A 50-year-old man has a paroxysm of coughing in the postanesthesia care
unit while awakening following uneventful endoscopic sinus surgery.
Immediately afterward, his respirations seem labored with a loud inspiratory stridor.

What is the differential diagnosis of inspiratory stridor?

The acute onset of inspiratory stridor in a postoperative patient may be due to

laryngospasm, laryngeal edema, foreign body aspiration, or vocal cord dysfunction.
Laryngospasm, an involuntary spasm of the laryngeal musculature, may be triggered
by blood or secretions stimulating the superior laryngeal nerve (see Chapter 19).
Laryngeal edema may be caused by an allergic drug reaction, hereditary or iatrogenic
angioedema, or a traumatic intubation. Vocal cord dysfunction could be due to
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residual muscle relaxant effect, hypocalcemic alkalotic tetany, intubation trauma, or

paradoxical vocal cord motion.

Another paroxysm of coughing is accompanied by hemoptysis. What is

your immediate management?

Bleeding after nose or throat surgery can be very serious. Patients who are not
fully awake may continue to gag and cough on the secretions, increasing venous
pressure and worsening the bleeding. Furthermore, they may aspirate blood and other
secretions. Fortunately, because of its physiological pH, aspiration of blood is not as
serious as aspiration of acidic gastric contents. Nonetheless, the airway should be
immediately secured in the obtunded patient. This may be accomplished with an
awake intubation or a rapid-sequence induction.
If the patient is awake and alert enough to cough and swallow and does not seem
to be aspirating blood, the first priority should be to decrease the bleeding as quickly
as possible. Immediate measures that should be considered include raising the head
of the bed to decrease venous and arterial pressures at the site of bleeding and
aggressively treating any degree of systolic hypertension with intravenous
antihypertensive agents. Sedation should be avoided so that airway reflexes are not
compromised. The surgeon should be notified, and the operating room should be
alerted as to the possibility of reoperation.

Despite these measures, the bleeding continues, and surgical intervention

seems to be necessary. Describe your strategy for induction of anesthesia in
this patient.

Before induction of general anesthesia in a bleeding patient, hypovolemia should

be corrected. The degree of hypovolemia may be difficult to assess because much of
the blood may be swallowed, but it can be estimated by changes in vital signs, postural
hypotension, and hematocrit. Cross-matched blood should be readily available, and a
second large-bore intravenous line should be secured. From an anesthetic standpoint,
this is an entirely different patient than the one who presented for surgery initially: the
patient now has a full stomach, is hypovolemic, and may be more difficult to intubate.

The preferred technique in this patient is a rapid-sequence induction. Induction

drug choice (eg, ketamine, etomidate) and dosage should anticipate the possibility of
hypotension from persistent hypovolemia. Qualified personnel and appropriate
equipment for an emergency tracheostomy should be immediately available. An
orogastric tube should be passed to decompress the stomach following induction and
intubation.

Which arteries supply blood to the nose?

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The arterial supply of the nose is provided by the internal maxillary artery and the
anterior ethmoid artery. These may have to be ligated in uncontrollable epistaxis.
Describe extubation.

Because this patient is still at risk for aspiration, extubation should not be
attempted until the patient has fully awakened and regained airway reflexes. Although it
is desirable to limit coughing and “bucking” on the endotracheal tube during emergence,
this may be difficult to achieve in the awakening patient. Intravenous lidocaine or
dexmedetomidine may be helpful in this situation.

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