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19
C H A P T E R
Airway Management
KEY CONCEPTS
1 Improper face mask technique can result postoperative hoarseness and increases the
in continued deflation of the anesthesia risk of accidental extubation.
reservoir bag despite the adjustable
6 Unrecognized esophageal intubation can
pressure-limiting valve being closed, usually
produce catastrophic results. Prevention
indicating a substantial leak around the
of this complication depends on direct
mask. In contrast, the generation of high
visualization of the tip of the ETT passing
breathing circuit pressures with minimal
through the vocal cords, careful auscultation
chest movement and breath sounds implies
for the presence of bilateral breath sounds
an obstructed airway or obstructed tubing.
and the absence of gastric gurgling while
2 The laryngeal mask airway partially protects ventilating through the ETT, analysis of
the larynx from pharyngeal secretions, but exhaled gas for the presence of CO2 (the
not gastric regurgitation. most reliable automated method), chest
3 After insertion of an endotracheal tube (ETT), radiography, airway ultrasonography, or use
the cuff is inflated with the least amount of of fiberoptic bronchoscopy.
air necessary to create a seal during positive- 7 Clues to the diagnosis of bronchial
pressure ventilation to minimize the pressure intubation include unilateral breath sounds,
transmitted to the tracheal mucosa. unexpected hypoxia with pulse oximetry
4 Although the persistent detection of CO2 (unreliable with high inspired oxygen
by a capnograph is the best confirmation concentrations), inability to palpate the ETT
of tracheal placement of an ETT, it cannot cuff in the sternal notch during cuff inflation,
exclude bronchial intubation. The earliest and decreased breathing bag compliance
evidence of bronchial intubation often is an (high peak inspiratory pressures).
increase in peak inspiratory pressure. 8 The large negative intrathoracic pressures
5 After intubation, the cuff of an ETT generated by a struggling patient in
should not be felt above the level of the laryngospasm can result in the development
cricoid cartilage, because a prolonged of negative-pressure pulmonary edema,
intralaryngeal location may result in particularly in healthy patients.
Expert airway management is an essential skill management techniques, and discusses complica-
in anesthetic practice. This chapter reviews the tions of laryngoscopy, intubation, and extubation.
anatomy of the upper respiratory tract, describes Patient safety depends on a thorough understanding
necessary airway equipment, presents various of each of these topics.
307

308 SECTION III Anesthetic Management
ANATOMY The epiglottis prevents aspiration by covering the

glottis—the opening of the larynx—during swal-
The upper airway consists of the pharynx, nose,
lowing. The larynx is a cartilaginous skeleton held
mouth, larynx, trachea, and mainstem bronchi. The
together by ligaments and muscle. The larynx is
mouth and pharynx are also a part of the upper gas-
composed of nine cartilages (Figure 19–2): thyroid,
trointestinal tract. The laryngeal structures in part
cricoid, epiglottic, and (in pairs) arytenoid, cornicu-
serve to prevent aspiration into the trachea.
late, and cuneiform. The thyroid cartilage shields the
There are two openings to the human airway:
conus elasticus, which forms the vocal cords.
the nose, which leads to the nasopharynx, and the
The sensory supply to the upper airway is
mouth, which leads to the oropharynx. These pas-
derived from the cranial nerves (Figure 19–3). The
sages are separated anteriorly by the palate, but they
mucous membranes of the nose are innervated by
join posteriorly in the pharynx (Figure 19–1). The
the ophthalmic division (V1) of the trigeminal nerve
pharynx is a U-shaped fibromuscular structure that
anteriorly (anterior ethmoidal nerve) and by the
extends from the base of the skull to the cricoid car-
maxillary division (V2) posteriorly (sphenopalatine
tilage at the entrance to the esophagus. It opens ante-
nerves). The palatine nerves provide sensory fibers
riorly into the nasal cavity, the mouth, the larynx,
from the trigeminal nerve (V2) to the superior and
and the nasopharynx, oropharynx, and laryngo-
inferior surfaces of the hard and soft palate. The
pharynx, respectively. The nasopharynx is separated
olfactory nerve (cranial nerve I) innervates the
from the oropharynx by an imaginary plane that
nasal mucosa to provide the sense of smell. The lin-
extends posteriorly. At the base of the tongue,
gual nerve (a branch of the mandibular division [V3]
the epiglottis functionally separates the orophar-
of the trigeminal nerve) and the glossopharyngeal
ynx from the laryngopharynx (or hypopharynx).
nerve (cranial nerve IX) provide general sensation
to the anterior two-thirds and posterior one-third of
the tongue, respectively. Branches of the facial nerve
Hard palate (VII) and glossopharyngeal nerve provide the sensa-
tion of taste to those areas, respectively. The glos-
Soft palate sopharyngeal nerve also innervates the roof of the
pharynx, the tonsils, and the undersurface of the soft
palate. The vagus nerve (cranial nerve X) provides
sensation to the airway below the epiglottis. The
Nasopharynx
superior laryngeal branch of the vagus divides into
Tongue an external (motor) nerve and an internal (sensory)
Oropharynx laryngeal nerve that provide sensory supply to the
larynx between the epiglottis and the vocal cords.
Another branch of the vagus, the recurrent laryn-
Hypopharynx geal nerve, innervates the larynx below the vocal
cords and the trachea.
Epiglottis The muscles of the larynx are innervated by
the recurrent laryngeal nerve, with the exception
of the cricothyroid muscle, which is innervated by
Vocal cords
the external (motor) laryngeal nerve, a branch of
Larynx the superior laryngeal nerve. The posterior crico-
arytenoid muscles abduct the vocal cords, whereas
the lateral cricoarytenoid muscles are the principal
Trachea
adductors.
Phonation involves complex simultaneous
FIGURE 19–1 Anatomy of the airway. actions by several laryngeal muscles. Damage to

CHAPTER 19 Airway Management 309
Epiglottis
Hyoid bone
Thyrohyoid membrane
Superior cornu of
thyroid cartilage
Cuneiform cartilage (paired)
Thyroid cartilage lamina
Corniculate cartilage (paired)
Arytenoid cartilage (paired)
Cricothyroid ligament
Inferior cornu of
thyroid cartilage
Cricoid cartilage
Trachea
Anterior Posterior
FIGURE 19–2 Cartilaginous structures comprising the larynx. (With permission from The Mayo Foundation.)
V1
V2
V3
IX
V1 Ophthalmic division of trigeminal nerve

SL
(anterior ethmoidal nerve)
V2 Maxillary division of trigeminal nerve
(sphenopalatine nerves)
V3 Mandibular division of trigeminal nerve
IL (lingual nerve)
X
IX Glossopharyngeal nerve
X Vagus nerve
SL Superior laryngeal nerve
IL Internal laryngeal nerve
RL Recurrent laryngeal nerve
RL
FIGURE 19–3 Sensory nerve supply of the airway.

TABLE 19–1 The effects of laryngeal nerve Left Right

injury on the voice.
Nerve Effect of Nerve Injury
Superior laryngeal nerve

Unilateral Minimal effects
Bilateral Hoarseness, tiring of voice
Recurrent laryngeal nerve

Unilateral Hoarseness
Bilateral
Acute Stridor, respiratory distress FIGURE 19–4 Carina.
Chronic Aphonia
Vagus nerve
Unilateral Hoarseness the thyroid cartilage. The superior thyroid artery is
Bilateral Aphonia found along the lateral edge of the CTM.
The trachea begins beneath the cricoid cartilage
and extends to the carina, the point at which the right
the motor nerves innervating the larynx leads to a and left mainstem bronchi divide (Figure 19–4).
spectrum of speech disorders (Table 19–1). Uni- Anteriorly, the trachea consists of cartilaginous
lateral denervation of a cricothyroid muscle causes rings; posteriorly, the trachea is membranous.
very subtle clinical findings. Bilateral palsy of the
superior laryngeal nerve may result in hoarseness
or easy tiring of the voice, but airway control is not ROUTINE AIRWAY
jeopardized. MANAGEMENT
Unilateral injury to a recurrent laryngeal nerve
results in paralysis of the ipsilateral vocal cord, caus- Routine airway management associated with gen-
ing deterioration in voice quality. Assuming intact eral anesthesia consists of:
superior laryngeal nerves, acute bilateral recurrent • Preanesthetic airway assessment
laryngeal nerve palsy can result in stridor and respi- • Preparation and equipment check
ratory distress because of the remaining unopposed
tension of the cricothyroid muscles. Airway prob- • Patient positioning
lems are less frequent in chronic bilateral recurrent • Preoxygenation (denitrogenation)
laryngeal nerve loss because of the development of • Bag and mask ventilation
various compensatory mechanisms (eg, atrophy of • Intubation or placement of a laryngeal mask
the laryngeal musculature). airway (if indicated)
Bilateral injury to the vagus nerve affects both
the superior and the recurrent laryngeal nerves. • Confirmation of proper tube or airway
Thus, bilateral vagal denervation produces flaccid, placement
midpositioned vocal cords similar to those seen • Extubation
after administration of succinylcholine. Although
phonation is severely impaired in these patients, air-
way control is rarely a problem. AIRWAY ASSESSMENT
The blood supply of the larynx is derived from A preanesthetic airway assessment is mandatory
branches of the thyroid arteries. The cricothyroid before every anesthetic procedure. Several ana-
artery arises from the superior thyroid artery itself, tomical and functional maneuvers can be per-
the first branch given off from the external carotid formed to estimate the difficulty of endotracheal
artery, and crosses the upper cricothyroid membrane intubation; successful ventilation (with or without
(CTM), which extends from the cricoid cartilage to intubation) must be achieved by the anesthetist if

Hard palate
Uvula
Soft palate Hard palate
Pillars
A CLASS I CLASS II CLASS III CLASS IV
Vocal cords
Epiglottis
B GRADE I GRADE II GRADE III GRADE IV
FIGURE 19–5 A: Mallampati classification of oral opening. B: Grading of the laryngeal view. A difficult orotracheal
intubation (grade III or IV) may be predicted by the inability to visualize certain pharyngeal structures (class III or IV) during
the preoperative examination of a seated patient. (Reproduced with permission from Mallampati SR, Gatt SP, Gugino LD, et al. A clinical
sign to predict difficult tracheal intubation: A prospective study. Can Anaesth Soc J. 1985 Jul;32(4):429-434)
mortality and morbidity are to be avoided. Assess- • Thyromental distance: This is the distance
ments include: between the mentum (chin) and the superior
thyroid notch. A distance greater than 3
• Mouth opening: an incisor distance of 3 cm or
fingerbreadths is desirable.
greater is desirable in an adult.
• Neck circumference: A neck circumference
• Mallampati classification: a frequently
of greater than 17 inches is associated with
performed test that examines the size of
difficulties in visualization of the glottic opening.
the tongue in relation to the oral cavity. The
more the tongue obstructs the view of the Although the presence of these examination
pharyngeal structures, the more difficult findings may not be particularly sensitive for detect-
intubation may be (Figure 19–5). ing a difficult intubation, the absence of these find-
■■ Class I: The entire palatal arch, including the ings is predictive for relative ease of intubation.
bilateral faucial pillars, is visible down to the Increasingly, patients present with mor-
bases of the pillars. bid obesity and body mass indices of 30 kg/m2 or
■■ Class II: The upper part of the faucial pillars greater. Although some morbidly obese patients
and most of the uvula are visible. have relatively normal head and neck anatomy,
■■ Class III: Only the soft and hard palates are others have much redundant pharyngeal tissue
visible. and increased neck circumference. Not only may
■■ Class IV: Only the hard palate is visible. these patients prove to be difficult to intubate, but

FIGURE 19–6 A transverse view of the trachea with FIGURE 19–7 The trachea during intubation as
landmarks. The anechoic area posterior to the trachea the tube passes underneath the probe. The arrow
represents shadowing resulting from an attenuation of points to a subtle area of increased echogenicity
the ultrasound beam through the dense cartilage of the just distal to the tracheal cartilage. This area is where
rings. (Reproduced with permission from Carmody KA, Moore CL, movement is most often visualized in real time during
Feller-Kopman D. Handbook of Critical Care and Emergency Ultrasound. an intubation. (Reproduced with permission from Carmody KA,
New York, NY: McGraw-Hill Education; 2011.) Moore CL, Feller-Kopman D. Handbook of Critical Care and Emergency
Ultrasound. New York, NY: McGraw-Hill Education; 2011.)
routine ventilation with bag and mask also may be

problematic.
Ultrasound examination of the airway has also
been suggested to be of assistance in airway assess-
ment and management (Figures 19–6 through
19–8). Ultrasound can be used as an adjunct to con-
firm ETT placement as well as to assist in identifica-
tion of the cricothyroid membrane during emergent
cricothyroidotomy.
EQUIPMENT
The following equipment should be routinely avail-
able for airway management:
• An oxygen source
• Capability to ventilate with bag and mask
• Laryngoscopes (direct and video)
• Several ETTs of different sizes with available
stylets and bougies FIGURE 19–8 A transverse view of the trachea
and esophagus during an esophageal intubation.
• Other (not ETT) airway devices (eg, oral, In this image the esophagus is visualized posterior and
nasal, supraglottic airways) lateral to the trachea. Two parallel echogenic lines are
seen in the proximal esophagus, representing the
• Suction inner and outer walls of the endotracheal (ET) tube as
• Pulse oximetry and CO2 detection it passes through the lumen of the esophagus.
(Reproduced with permission from Carmody KA, Moore CL,
• Stethoscope Feller-Kopman D. Handbook of Critical Care and Emergency Ultrasound.
• Tape New York, NY: McGraw-Hill Education; 2011.)

A B
FIGURE 19–9 A: The oropharyngeal airway in place. The airway follows the curvature of the tongue, pulling
it and the epiglottis away from the posterior pharyngeal wall and providing a channel for air passage. B: The
nasopharyngeal airway in place. The airway passes through the nose and extends to just above the epiglottis. (Modified
with permission from Dorsch JA, Dorsch SE. Face masks and airways. In: Understanding Anesthesia Equipment. 4th ed. Philadelphia, PA: Lippincott
Williams & Wilkins; 1999.)
• Blood pressure and electrocardiography (ECG) than oral airways. Because of the risk of epistaxis,
monitors nasal airways are less desirable in anticoagulated
• Intravenous access or thrombocytopenic patients. Also, nasal airways
(and nasogastric tubes) should be used with cau-
A flexible fiberoptic bronchoscope should be tion in patients with basilar skull fractures, as there
immediately available when difficult intubation is has been a case report of a nasogastric tube enter-
anticipated but need not be present during all rou- ing the cranial vault. All tubes inserted through the
tine intubations. nose (eg, nasal airways, nasogastric catheters, naso-
tracheal tubes) should be lubricated before being
Oral & Nasal Airways advanced along the floor of the nasal passage.
Loss of upper airway muscle tone (eg, weakness of the
genioglossus muscle) in anesthetized patients allows Face Mask Design & Technique
the tongue and epiglottis to fall back against the pos- The use of a face mask can facilitate the delivery of
terior wall of the pharynx. Repositioning the head oxygen or an anesthetic gas from a breathing system to
or a jaw thrust is the preferred technique for open- a patient by creating an airtight seal with the patient’s
ing the airway. To maintain the opening, an artificial face (Figure 19–10). The rim of the mask is contoured
airway can be inserted through the mouth or nose
to maintain an air passage between the tongue and
the posterior pharyngeal wall (Figure 19–9). Awake Orifice Retaining
or lightly anesthetized patients with intact laryngeal hooks
reflexes may cough or even develop laryngospasm
during airway insertion. Placement of an oral air-
way is sometimes facilitated by suppressing airway
reflexes, and, in addition, sometimes by depressing
the tongue with a tongue blade. Adult oral airways
typically come in small (80 mm [Guedel No. 3]),
medium (90 mm [Guedel No. 4]), and large (100 mm
[Guedel No. 5]) sizes.
The length of a nasal airway can be estimated
Body Rim
as the distance from the nares to the meatus of the
ear and should be approximately 2 to 4 cm longer FIGURE 19–10 Clear adult face mask.

Orifice the functional residual capacity, the patient’s oxygen

reserve, is purged of nitrogen. Up to 90% of the nor-
mal FRC of 2 L following preoxygenation is filled with
Body
oxygen. Considering the normal oxygen demand of
200 to 250 mL/min, the preoxygenated patient may
have a 5 to 8 min oxygen reserve. Increasing the
duration of apnea without desaturation improves
Rim safety, if ventilation following anesthetic induc-
tion is delayed. Conditions that increase oxygen
FIGURE 19–11 The Rendell–Baker–Soucek pediatric demand (eg, sepsis, pregnancy) and decrease FRC
face mask has a shallow body and minimal dead space. (eg, morbid obesity, pregnancy, ascites) reduce the
apneic period before desaturation ensues. Assum-
ing a patent air passage is present, oxygen insufflated
and conforms to a variety of facial features. The mask’s into the pharynx may increase the duration of apnea
22-mm orifice attaches to the breathing circuit of the tolerated by the patient. Because oxygen enters the
anesthesia machine through a right-angle connector. blood from the FRC at a rate faster than CO2 leaves
Several mask designs are available. Transparent masks the blood, a negative pressure is generated in the
allow observation of exhaled humidified gas and alveolus, drawing oxygen into the lung (apneic oxy-
immediate recognition of vomitus. Retaining hooks genation). With flow of 100% oxygen and a patent
surrounding the orifice can be attached to a head strap airway, arterial saturation can be maintained for a
so that the mask does not have to be continually held longer period despite no ventilation, permitting
in place. Some pediatric masks are specially designed multiple airway interventions should a difficult air-
to minimize apparatus dead space (Figure 19–11). way be encountered.
POSITIONING BAG AND MASK VENTILATION

When manipulating the airway, correct patient Bag and mask ventilation (BMV) is the first step
positioning is very helpful. Relative alignment of in airway management in most situations, with the
the oral and pharyngeal axes is achieved by having exception of patients undergoing rapid sequence
the patient in the “sniffing” position. When cervical intubation or elective awake intubation. Rapid
spine pathology is suspected, the head must be kept sequence inductions avoid BMV to minimize stom-
in a neutral position during all airway manipula- ach inflation and to reduce the potential for the aspi-
tions. In-line stabilization of the neck must be main- ration of gastric contents in nonfasted patients and
tained during airway management in these patients, those with delayed gastric emptying. In emergency
unless appropriate cervical radiographs have been situations, BMV precedes attempts at intubation in
reviewed and cleared by an appropriate specialist. an effort to oxygenate the patient, with the under-
Patients with morbid obesity should be positioned standing that there is an implicit risk of aspiration.
on a 30° upward ramp (see Figure 41–2), as the Effective mask ventilation requires both a gas-
functional residual capacity (FRC) of obese patients
deteriorates in the supine position, leading to more 1 tight mask fit and a patent airway. Improper face
mask technique can result in continued defla-
rapid deoxygenation should ventilation be impaired. tion of the anesthesia reservoir bag despite the adjust-
able pressure-limiting valve being closed, usually
indicating a substantial leak around the mask. In con-
PREOXYGENATION trast, the generation of high breathing circuit pressures
When possible, preoxygenation with face mask oxy- with minimal chest movement and breath sounds
gen should precede all airway management inter- implies an obstructed airway or obstructed tubing.
ventions. Oxygen is delivered by mask for several If the mask is held with the left hand, the right
minutes prior to anesthetic induction. In this way, hand can be used to generate positive-pressure

FIGURE 19–12 One-handed face mask technique.
ventilation by squeezing the breathing bag. The mask

is held against the face by downward pressure on FIGURE 19–13 A difficult airway can often be
the mask exerted by the left thumb and index finger managed with a two-handed technique.
(Figure 19–12). The middle and ring finger grasp the
mandible to facilitate extension of the atlantooccipi-
tal joint. This is a maneuver that is easier to teach with spontaneous ventilation, only minimal downward
a mannequin or patient than to describe. Finger pres- force on the face mask is required to create an ade-
sure should be placed on the bony mandible and not quate seal. If the face mask and mask straps are used
on the soft tissues. The little finger is placed under the for extended periods, the position should be regu-
angle of the jaw and used to thrust the jaw anteriorly, larly changed to prevent injury. Care should be used
the most important maneuver to open the airway. to avoid mask or finger contact with the eye, and
In difficult situations, two hands may be needed the eyes should be taped shut as soon as possible to
to provide adequate jaw thrust and to create a minimize the risk of corneal abrasions.
mask seal. Therefore, an assistant may be needed to If the airway is patent, squeezing the bag will
squeeze the bag, or the machine’s ventilator can be result in the rise of the chest. If ventilation is inef-
used. In such cases, the thumbs hold the mask down, fective (no sign of chest rising, no end-tidal CO2
and the fingertips or knuckles displace the jaw for- detected, no condensation in the clear mask), oral
ward (Figure 19–13). Obstruction during expiration or nasal airways can be placed to relieve airway
may be due to excessive downward pressure from the obstruction secondary to lax upper airway muscle
mask or from a ball-valve effect of the jaw thrust. The tone or redundant pharyngeal tissues. Difficult mask
former can be relieved by decreasing the pressure on ventilation is often found in patients with morbid
the mask, and the latter by releasing the jaw thrust obesity, beards, and craniofacial deformities. It is
during this phase of the respiratory cycle. Positive- sometimes difficult to form an adequate mask fit
pressure ventilation using a mask should normally be with the cheeks of edentulous patients.
limited to 20 cm of H2O to avoid stomach inflation. In years past, anesthetics were routinely deliv-
Most patients’ airways can be maintained with a ered solely by mask or ETT administration. In
face mask and an oral or nasal airway. Mask ventila- recent decades, a variety of supraglottic devices has
tion for long periods may result in pressure injury to permitted both airway rescue (when adequate BMV
branches of the trigeminal or facial nerves. Because is not possible) and routine anesthetic airway man-
of the absence of positive airway pressures during agement (when intubation is not necessary).

SUPRAGLOTTIC secretions (but not gastric regurgitation), and it

should remain in place until the patient has regained
AIRWAY DEVICES airway reflexes. This is usually signaled by coughing
Supraglottic airway devices (SADs) are used with and mouth opening on command. The LMA is avail-
both spontaneously breathing and ventilated patients able in many sizes (Table 19–3).
during anesthesia. They have also been employed as The LMA provides an alternative to ventilation
conduits to aid endotracheal intubation when both through a face mask or an ETT (Table 19–4). Rela-
BMV and endotracheal intubation have failed. All tive contraindications for the LMA include patients
SADs consist of a tube that is connected to a respira- with pharyngeal pathology (eg, abscess), pharyngeal
tory circuit or breathing bag, which is attached to obstruction, aspiration risk (eg, pregnancy, hiatal
a hypopharyngeal device that seals and directs air- hernia), or low pulmonary compliance (eg, restric-
flow to the glottis, trachea, and lungs. Additionally, tive airways disease) requiring peak inspiratory
these airway devices occlude the esophagus with pressures greater than 30 cm H2O. The LMA may be
varying degrees of effectiveness, reducing gas dis- associated with less frequent bronchospasm than an
tention of the stomach. Different sealing devices to ETT. Although it is clearly not a substitute for endo-
prevent airflow from exiting through the mouth are tracheal intubation, the LMA has proven particu-
also available. Some are equipped with a port to suc- larly helpful as a lifesaving, temporizing measure in
tion gastric contents. None offer the protection from patients with difficult airways (those who cannot be
aspiration pneumonitis offered by a properly sited, mask ventilated or intubated) because of its ease of
cuffed endotracheal tube. insertion and relatively high success rate (95–99%).
It has been used as a conduit for an intubating sty-
Laryngeal Mask Airway let (eg, gum-elastic bougie), ventilating jet stylet,
A laryngeal mask airway (LMA) consists of a wide- flexible fiberoptic bronchoscope, or small-diameter
bore tube whose proximal end connects to a breath- (6.0 mm) ETT. Several LMAs are available that have
ing circuit with a standard 15-mm connector, and been modified to facilitate placement of a larger
whose distal end is attached to an elliptical cuff that ETT, with or without the use of a bronchoscope.
can be inflated through a pilot tube. The deflated cuff Insertion can be performed under topical anesthesia
is lubricated and inserted blindly into the hypophar- and bilateral superior laryngeal nerve blocks, if the
ynx so that, once inflated, the cuff forms a low- airway must be secured while the patient is awake.
pressure seal around the entrance to the larynx. This Some newer supraglottic devices incorporate a
requires anesthetic depth and muscle relaxation channel to facilitate gastric decompression.
slightly greater than that required for the insertion Variations in LMA design include:
of an oral airway. Although insertion is relatively
simple (Figure 19–14), attention to detail will • The ProSeal LMA, which permits passage of a
improve the success rate (Table 19–2). An ideally gastric tube to decompress the stomach
positioned cuff is bordered by the base of the tongue • The I-Gel, which uses a gel occluder rather
superiorly, the pyriform sinuses laterally, and the than inflatable cuff
upper esophageal sphincter inferiorly. If the esopha- • The Fastrach intubation LMA, which is
gus lies within the rim of the cuff, gastric distention designed to facilitate endotracheal intubation
and regurgitation become possible. Anatomic varia- through the LMA device
tions prevent adequate functioning in some patients. • The LMA CTrach, which incorporates a
However, if an LMA is not functioning properly camera to facilitate passage of an endotracheal
after attempts to improve the “fit” of the LMA have tube
failed, most practitioners will try another LMA one
size larger or smaller. The shaft can be secured with Sore throat is a common side effect following
SAD use. Injuries to the lingual, hypoglossal, and
2 tape to the skin of the face. The LMA partially recurrent laryngeal nerves have been reported.
protects the larynx from pharyngeal

A B
C D
FIGURE 19–14 A: The laryngeal mask ready for insertion. The cuff should be deflated tightly with the rim facing away
from the mask aperture. There should be no folds near the tip. B: Initial insertion of the laryngeal mask. Under direct vision,
the mask tip is pressed upward against the hard palate. The middle finger may be used to push the lower jaw downward. The
mask is pressed forward as it is advanced into the pharynx to ensure that the tip remains flattened and avoids the tongue. The
jaw should not be held open once the mask is inside the mouth. The nonintubating hand can be used to stabilize the occiput.
C: By withdrawing the other fingers and with a slight pronation of the forearm, it is usually possible to push the mask fully into
position in one fluid movement. Note that the neck is kept flexed and the head extended. D: The laryngeal mask is grasped
with the other hand and the index finger withdrawn. The hand holding the tube presses gently downward until resistance is
encountered. (Reproduced with permission from LMA North America.)
Correct device sizing, avoidance of cuff hyperinfla- Esophageal–Tracheal Combitube

tion, adequate lubrication, and gentle movement of The esophageal–tracheal Combitube consists of
the jaw during placement may reduce the likelihood two fused tubes, each with a 15-mm connector on
of such injuries. its proximal end (Figure 19–15). The longer blue

TABLE 19–2 Successful insertion of a TABLE 19–3 A variety of laryngeal masks

laryngeal mask airway depends upon with different cuff volumes are available for
attention to several details. different sized patients.
1. Choose the appropriate size (Table 19–3) and check for Cuff
leaks before insertion. Mask Size Patient Size Weight (kg) Volume (mL)
2. The leading edge of the deflated cuff should be
1 Infant <6.5 2–4
wrinkle free and facing away from the aperture
(Figure 19–14A). 2 Child 6.5–20 Up to 10
3. Lubricate only the back side of the cuff.
4. Ensure adequate anesthesia before attempting 2½ Child 20–30 Up to 15
insertion.
3 Small adult >30 Up to 20
5. Place patient’s head in sniffing position (Figure 19–14B
and Figure 19–26).
4 Normal adult <70 Up to 30
6. Use your index finger to guide the cuff along
the hard palate and down into the hypopharynx 5 Larger adult >70 Up to 30
until an increased resistance is felt (Figure 19–14C).
The longitudinal black line should always be
pointing directly cephalad (ie, facing the patient’s
upper lip). tube has an occluded distal tip that forces gas to exit
7. Inflate with the correct amount of air (Table 19–3).
through a series of side perforations. The shorter
8. Ensure adequate anesthetic depth during patient
positioning.
clear tube has an open tip and no side perforations.
9. Obstruction after insertion is usually due to a down-
The Combitube is usually inserted blindly through
folded epiglottis or transient laryngospasm. the mouth and advanced until the two black rings
10. Avoid pharyngeal suction, cuff deflation, or laryngeal on the shaft lie between the upper and lower teeth.
mask removal until the patient is awake (eg, opening The Combitube has two inflatable cuffs, a 100-mL
mouth on command). proximal cuff and a 15-mL distal cuff, both of which
TABLE 19–4 Advantages and disadvantages of the laryngeal mask airway compared with face
mask ventilation or tracheal intubation.1
Advantages Disadvantages
Compared with face mask Hands-free operation More invasive

Better seal in bearded patients More risk of airway trauma
Less cumbersome in ENT surgery Requires new skill
Often easier to maintain airway Deeper anesthesia required
Protects against airway secretions Requires some TMJ mobility
Less facial nerve and eye trauma N2O diffusion into cuff
Less operating room pollution Multiple contraindications
Compared with tracheal Less invasive Increased risk of gastrointestinal aspiration

intubation Very useful in difficult intubations Less safe in prone or jackknife positions
Less tooth and laryngeal trauma Limits maximum PPV
Less laryngospasm and bronchospasm Less secure airway
Does not require muscle relaxation Greater risk of gas leak and pollution
Does not require neck mobility Can cause gastric distention
No risk of esophageal or endobronchial
intubation
1
ENT, ear, nose, and throat; TMJ, temporomandibular joint; PPV, positive-pressure ventilation.

FIGURE 19–16 King laryngeal tube.
FIGURE 19–15 Combitube. ENDOTRACHEAL INTUBATION

Endotracheal intubation is employed both for the
should be fully inflated after placement. The distal conduct of general anesthesia and to facilitate the
lumen of the Combitube usually comes to lie in ventilator management of the critically ill.
the esophagus approximately 95% of the time so
that ventilation through the longer blue tube will Endotracheal Tubes (ETTs)
force gas out of the side perforations and into the Standards govern ETT manufacturing (in the United
larynx. The shorter, clear tube can be used for gas- States, American National Standard for Anesthetic
tric decompression. Alternatively, if the Combitube Equipment; ANSI Z–79). ETTs are most commonly
enters the trachea, ventilation through the clear tube made from polyvinyl chloride. The shape and rigid-
will direct gas into the trachea. ity of ETTs can be altered by inserting a stylet. The
patient end of the tube is beveled to aid visualiza-
King Laryngeal Tube tion and insertion through the vocal cords. Murphy
The King laryngeal tube consists of a tube with a tubes have a hole (the Murphy eye) to decrease the
small esophageal balloon and a larger balloon for risk of occlusion, should the distal tube opening
placement in the hypopharynx (Figure 19–16). abut the carina or trachea (Figure 19–17).
Both balloons inflate through one inflation line. The Resistance to airflow depends primarily on tube
lungs are inflated with gas that exits between the diameter, but is also affected by tube length and cur-
two balloons. A suction port distal to the esopha- vature. ETT size is usually designated in millimeters
geal balloon is present, permitting decompression of of internal diameter, or, less commonly, in the French
the stomach. If ventilation proves difficult after the scale (external diameter in millimeters multiplied by
King tube is inserted and the cuffs are inflated, the 3). The choice of tube diameter is always a compromise
tube is likely inserted too deeply. Slowly withdraw between maximizing flow with a larger size and mini-
the device until compliance improves. mizing airway trauma with a smaller size (Table 19–5).

Cuff Connector
Beveled tip
Murphy eye
Inflating tube
Pilot balloon
Valve
FIGURE 19–17 Murphy endotracheal tube.
Most adult ETTs have a cuff inflation system cuffs may increase the likelihood of sore throat
consisting of a valve, pilot balloon, inflating tube, (larger mucosal contact area), aspiration, spontane-
and cuff (Figure 19–17). The valve prevents air loss ous extubation, and difficult insertion (because of
after cuff inflation. The pilot balloon provides a gross the floppy cuff). Nonetheless, because of their lower
indication of cuff inflation. The inflating tube con- incidence of mucosal damage, low-pressure cuffs are
nects the valve to the cuff and is incorporated into the most frequently employed.
tube’s wall. By creating a tracheal seal, ETT cuffs per- Cuff pressure depends on several factors: infla-
mit positive-pressure ventilation and reduce the like- tion volume, the diameter of the cuff in relation
lihood of aspiration. Uncuffed tubes are often used in to the trachea, tracheal and cuff compliance, and
infants and young children; however, in recent years, intrathoracic pressure (cuff pressures increase with
cuffed pediatric tubes have been increasingly favored. coughing). Cuff pressure may increase during gen-
There are two major types of cuffs: high pres- eral anesthesia from diffusion of nitrous oxide from
sure (low volume) and low pressure (high volume). the tracheal mucosa into the ETT cuff.
High-pressure cuffs are associated with more isch- ETTs have been modified for a variety of spe-
emic damage to the tracheal mucosa and are less suit- cialized applications. Flexible, spiral-wound, wire-
able for intubations of long duration. Low-pressure reinforced ETTs (armored tubes) resist kinking and
may prove valuable in some head and neck surgical
TABLE 19–5 Oral endotracheal tube size procedures or in the prone patient. If an armored
guidelines. tube becomes kinked from extreme pressure (eg, an
awake patient biting it), however, the lumen will often
Internal
Age Diameter (mm) Cut Length (cm) remain permanently occluded, and the tube will
need replacement. Other specialized tubes include
Full-term infant 3.5 12 microlaryngeal tubes, double-lumen endotracheal
Child Age Age
tubes (to facilitate lung isolation and one-lung ven-
4+ 4+ tilation), ETTs equipped with bronchial blockers (to
4 2
facilitate lung isolation and one-lung ventilation),
Adult metal tubes designed for laser airway surgery to
Female 7.0–7.5 24 reduce fire hazards, and preformed curved tubes for
Male 7.5–9.0 24
nasal and oral intubation in head and neck surgery.

LARYNGOSCOPES Various maneuvers, such as the “sniffing” position

and external movement of the larynx with cricoid
A laryngoscope is an instrument used to examine
pressure during direct laryngoscopy, are used to
the larynx and to facilitate intubation of the tra-
improve the view. Video- or optically based laryngo-
chea. The handle usually contains batteries to light
scopes have either a video chip (DCI system, Glide-
a bulb on the blade tip (Figure 19–18), or, alter-
Scope, McGrath, Airway) or a lens/mirror (Airtraq)
nately, to power a fiberoptic bundle that terminates
at the tip of the intubation blade to transmit a view
at the tip of the blade. Laryngoscopes with fiberop-
of the glottis to the operator. These devices differ in
tic light bundles in their blades can be made mag-
the angulation of the blade, the presence of a chan-
netic resonance imaging compatible. The Macintosh
nel to guide the tube to the glottis, and the single use
and Miller blades are the most popular curved and
or multiuse nature of the device.
straight designs, respectively, in the United States.
Video or indirect laryngoscopy most likely
The choice of blade depends on personal preference
offers minimal advantage to patients with uncompli-
and patient anatomy. Because no blade is perfect for
cated airways. However, use in these patients is valu-
all situations, the clinician should become famil-
able as a training guide for learners, especially when
iar and proficient with a variety of blade designs
the trainee is performing a direct laryngoscopy with
(Figure 19–19).
the device while the instructor views the glottis
on the video screen. Additionally, use in uncom-
VIDEO LARYNGOSCOPES plicated airway management patients improves
familiarity with the device for times when direct
In recent years, myriad laryngoscopy devices that
laryngoscopy is not possible.
utilize video technology have revolutionized man-
Indirect laryngoscopes generally improve visu-
agement of the airway. Direct laryngoscopy with
alization of laryngeal structures in difficult airways;
a Macintosh or Miller blade mandates appropriate
however, visualization does not always lead to suc-
alignment of the oral, pharyngeal, and laryngeal
structures to facilitate a direct view of the glottis. cessful intubation. An ETT stylet is recommended
when video laryngoscopy is to be performed. Some
devices come with stylets designed to facilitate intu-
bation with that particular device. Bending the sty-
Flange
let and ETT in a manner similar to the bend in the
curve of the blade often facilitates passage of the
Bulb
ETT into the trachea. Even when the glottic open-
Electrical ing is seen clearly, directing the ETT into the trachea
contact
can be difficult.
Blade Indirect laryngoscopy may result in less dis-
placement of the cervical spine than direct laryngos-
copy; nevertheless, all precautions associated with
airway manipulation in a patient with a possible cer-
Handle vical spine fracture should be maintained.
Varieties of indirect laryngoscopes include:
• Various Macintosh and Miller blades in
pediatric and adult sizes have video capability
in the Storz DCI system. The system can
also incorporate an optical intubating stylet
(Figure 19–20). The blades are similar to
conventional intubation blades, permitting
FIGURE 19–18 A rigid laryngoscope. direct laryngoscopy and indirect video

Macintosh
Miller
Wisconsin
FIGURE 19–19 An assortment of laryngoscope blades.
laryngoscopy. Assistants and instructors are adjusted to accommodate the airway of a child
able to see the view obtained by the operator of age 5 years up to an adult (Figure 19–21).
and adjust their maneuvers accordingly to The blade can be disconnected from the handle
facilitate intubation or to provide instruction, to facilitate its insertion in morbidly obese
respectively. patients in whom the space between the upper
• The McGrath laryngoscope is a portable video chest and head is reduced. The blade is inserted
laryngoscope with a blade length that can be midline, with the laryngeal structures viewed
at a distance to enhance intubation success.
• The GlideScope comes with disposable adult-
and pediatric-sized blades (Figure 19–22).
The blade is inserted midline and advanced
until glottic structures are identified. The
GlideScope has a 60° angle, preventing direct
laryngoscopy and necessitating the use of stylet
that is similar in shape to the blade.
• Airtraq is a single-use optical laryngoscope
available in pediatric and adult sizes
(Figure 19–23). The device has a channel to
guide the endotracheal tube to the glottis. This
device is inserted midline. Success is more
likely when the device is not positioned too
FIGURE 19–20 Optical intubating stylet. close to the glottis.

FIGURE 19–21 McGrath laryngoscope.

FIGURE 19–22 Glidescope.
• Video intubating stylets have a video capability device or contained within the handle (Figure 19–24B),
and light source. The stylet is introduced, whereas the other provides a high-resolution image
and the glottis identified. Intubation with a (image or coherent bundle). Directional manipulation
video stylet may result in less cervical spine of the insertion tube is accomplished with angulation
movement than with other techniques. wires. Aspiration channels allow suctioning of secre-
tions, insufflation of oxygen, or instillation of local
Flexible Fiberoptic Bronchoscopes anesthetic. Aspiration channels can be difficult to
In some situations—for example, patients with unstable
cervical spines, poor range of motion of the temporo-
mandibular joint, or certain congenital or acquired
upper airway anomalies—laryngoscopy with direct or
indirect laryngoscopes may be undesirable or impos-
sible. A flexible fiberoptic bronchoscope (FOB) allows
indirect visualization of the larynx in such cases or in
any situation in which awake intubation is planned
(Figure 19–24). Bronchoscopes are constructed of
coated glass fibers that transmit light and images by
internal reflection (ie, a light beam becomes trapped
within a fiber and exits unchanged at the opposite
end). The insertion tube contains two bundles of fibers,
each consisting of 10,000 to 15,000 fibers. One bundle
transmits light from the light source (light source or
incoherent bundle), which is either external to the FIGURE 19–23 Airtraq optical laryngoscope.

A Aspiration channel B
Light source
Light source bundle
Objective lens covering

image bundle
Insertion tube
Eyepiece
FIGURE 19–24 A: Cross section of a fiberoptic bronchoscope. B: A flexible fiberoptic bronchoscope with a fixed light
source.
clean, and, if not properly cleaned and sterilized after Mask ventilation or ventilation with an LMA is usu-
each use, may promote infection. ally satisfactory for short minor procedures such as
cystoscopy, examination under anesthesia, inguinal
hernia repairs, extremity surgery, and so forth. Nev-
TECHNIQUES OF DIRECT & ertheless, the indications for use of supraglottic air-
INDIRECT LARYNGOSCOPY & way devices during anesthesia continues to expand.
INTUBATION Preparation for Direct Laryngoscopy
Indications for Intubation Preparation for intubation includes checking equip-
Inserting a tube into the trachea has become a routine ment and properly positioning the patient. The ETT
part of delivering a general anesthetic. Intubation is should be examined. The tube’s cuff can be tested by
not a risk-free procedure, and it is not a requirement inflating the cuff using a syringe. Maintenance of cuff
for all patients receiving general anesthesia. An ETT pressure after detaching the syringe ensures proper
is generally placed to protect the airway and for air- cuff and valve function. Some anesthesiologists cut
way access. Intubation is indicated in patients who the ETT to a preset length to decrease the dead space,
are at risk of aspiration and in those undergoing sur- the risk of bronchial intubation, and the risk of occlu-
gical procedures involving body cavities, the head sion from tube kinking (Table 19–5). The connector
and neck, and those who will be positioned so that should be pushed firmly into the tube to decrease
the airway will be less accessible (eg, those under- the likelihood of disconnection. If a stylet is used, it
going surgery in the prone position, or whose head should be inserted into the ETT, which is then bent to
is rotated away from the anesthesia workstation). resemble a hockey stick (Figure 19–25). This shape

Stylet
jiggled. A blinking light signals a poor electrical con-
tact, whereas fading indicates depleted batteries. An
extra handle, blade, ETT (one size smaller than the
anticipated optimal size), stylet, and intubating bou-
gie should be immediately available. A functioning
suction unit is needed to clear the airway in case of
unexpected secretions, blood, or emesis.
Adequate glottis exposure during laryngoscopy
often depends on correct patient positioning. The
patient’s head should be level with the anesthesiolo-
gist’s waist or higher to prevent unnecessary back
FIGURE 19–25 An endotracheal tube with a stylet
bent to resemble a hockey stick.
strain during laryngoscopy.
Direct laryngoscopy displaces pharyngeal soft
tissues to create a direct line of vision from the
facilitates intubation of an anteriorly positioned lar- mouth to the glottic opening. Moderate head eleva-
ynx. The desired blade is locked onto the laryngo- tion (5–10 cm above the surgical table) and exten-
scope handle, and bulb function is tested. The light sion of the atlantooccipital joint place the patient
intensity should remain constant even if the bulb is in the desired sniffing position (Figure 19–26). The
10 cm
FIGURE 19–26 The sniffing position and intubation with a Macintosh blade. (Modified with permission from Dorsch JA, Dorsch
SE. Understanding Anesthesia Equipment: Construction, Care, and Complications. Philadelphia, PA: Lippincott Williams & Wilkins, 1991.)

Epiglottis
Aryepiglottic fold
Ventricular fold
Vocal fold
Cuneiform
Glottis cartilage
Corniculate cartilage
FIGURE 19–27 Typical view of the glottis during laryngoscopy with a curved blade. (Modified with permission from
Barash PG. Clinical Anesthesia. 4th ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2001.)
lower portion of the cervical spine is flexed by rest- the right side of the oropharynx—with care to avoid
ing the head on a pillow or other soft support. the teeth. The tongue is swept to the left and up
As previously discussed, preparation for induc- into the floor of the pharynx by the blade’s flange.
tion and intubation also involves routine preoxy- Successful sweeping of the tongue leftward clears
genation. Preoxygenation can be omitted in patients the view for ETT placement. The tip of a curved
who object to the face mask; however, failing to pre- blade is usually inserted into the vallecula, and the
oxygenate increases the risk of rapid desaturation straight blade tip covers the epiglottis. With either
following apnea. blade, the handle is raised up and away from the
Because general anesthesia abolishes the pro- patient in a plane perpendicular to the patient’s
tective corneal reflex, care must be taken during mandible to expose the vocal cords (Figure 19–27).
this period not to injure the patient’s eyes by unin- Trapping a lip between the teeth and the blade and
tentionally abrading the cornea. Thus, the eyes are leverage on the teeth are avoided. The ETT is taken
routinely taped shut as soon as possible, often after with the right hand, and its tip is passed through
applying an ophthalmic ointment before manipula- the abducted vocal cords. The “backward, upward,
tion of the airway. rightward, pressure” (BURP) maneuver applied
externally moves an anteriorly positioned glottis
Orotracheal Intubation posterior to facilitate visualization of the glottis. The
The laryngoscope is held in the left hand. With the ETT cuff should lie in the upper trachea, but beyond
patient’s mouth opened the blade is introduced into the larynx. The laryngoscope is withdrawn, again

3 with care to avoid tooth damage. The cuff is repeat the laryngoscopy to confirm placement. End-
inflated with the least amount of air necessary tidal CO2 will not be produced if there is no cardiac
to create a seal during positive-pressure ventilation output. FOB through the tube and visualization of
to minimize the pressure transmitted to the tracheal the tracheal rings and carina will likewise confirm
mucosa. Overinflation may inhibit capillary blood correct placement. Otherwise, the tube is taped or
flow, injuring the trachea. Compressing the pilot
4 tied to secure its position. Although the persis-
balloon with the fingers is not a reliable method of tent detection of CO2 by a capnograph is the
determining whether cuff pressure is either suffi- best confirmation of tracheal placement of an ETT,
cient or excessive. it cannot exclude bronchial intubation. The earliest
After intubation, the chest and epigastrium are evidence of bronchial intubation often is an increase
immediately auscultated, and a capnographic trac- in peak inspiratory pressure. Proper tube location
ing (the definitive test) is monitored to ensure intra- can be reconfirmed by palpating the cuff in the ster-
tracheal location (Figure 19–28). If there is doubt as nal notch while compressing the pilot balloon with
to whether the tube is in the esophagus or trachea,
5 the other hand. The cuff should not be felt
above the level of the cricoid cartilage, because
a prolonged intralaryngeal location may result in
postoperative hoarseness and increases the risk of
accidental extubation. Tube position can also be
documented by chest radiography.
The description presented here assumes an
unconscious patient. Oral intubation is usually
poorly tolerated by awake, fit patients. Intravenous
sedation, application of a local anesthetic spray in
the oropharynx, regional nerve block, and constant
reassurance will improve patient acceptance.
A failed intubation should not be followed
by identical repeated attempts. Changes must be
made to increase the likelihood of success, such as
repositioning the patient, decreasing the tube size,
adding a stylet, selecting a different blade, using an
indirect laryngoscope, attempting a nasal route, or
requesting the assistance of another anesthesia pro-
vider. If the patient is also difficult to ventilate with a
mask, alternative forms of airway management (eg,
second-generation supraglottic airway devices, jet
ventilation via percutaneous tracheal catheter, cri-
cothyrotomy, tracheostomy) must be immediately
pursued. The guidelines developed by the American
Society of Anesthesiologists for the management of
a difficult airway include a treatment plan algorithm
(Figure 19–29).
The Difficult Airway Society (DAS) also pro-
vides a useful approach for the management of the
unanticipated difficult airway (Figure 19–30).
The combined use of a video laryngoscope and
FIGURE 19–28 Sites for auscultation of breath sounds an intubation bougie often can facilitate intubation,
at the apices and over the stomach. when the endotracheal tube cannot be directed into

American Society of
Anesthesiologists®
DIFFICULT AIRWAY ALGORITHM
1. Assess the likelihood and clinical impact of basic management problems:
• Difficulty with patient cooperation or consent
• Difficult mask ventilation
• Difficult supraglottic airway placement
• Difficult laryngoscopy
• Difficult intubation
• Difficult surgical airway access
2. Actively pursue opportunities to deliver supplemental oxygen throughout the process of difficult airway
management.
3. Consider the relative merits and feasibility of basic management choices:
• Awake intubation vs. intubation after induction of general anesthesia
• Non-invasive technique vs. invasive techniques for the initial approach to intubation
• Video-assisted laryngoscopy as an initial approach to intubation
• Preservation vs. ablation of spontaneous ventilation
4. Develop primary and alternative strategies:
AWAKE INTUBATION INTUBATION AFTER

INDUCTION OF GENERAL ANESTHESIA
Airway approached by Invasive airway
noninvasive intubation access(b)* Initial intubation Initial intubation
attempts successful* attempts UNSUCCESSFUL
FROM THIS POINT
Succeed* FAIL ONWARDS CONSIDER:
1. Calling for help.
2. Returning to
Cancel Consider feasibility Invasive spontaneous ventilation.
case of other options(a) airway access(b)* 3. Awakening the patient.
FACE MASK VENTILATION ADEQUATE FACE MASK VENTILATION ADEQUATE
CONSIDER/ATTEMPT SGA
SGA ADEQUATE* SGA NOT ADEQUATE

OR NOT FEASIBLE
NONEMERGENCY PATHWAY EMERGENCY PATHWAY
Ventilation adequate, intubation unsuccessful Ventilation not adequate, intubation unsuccessful
IF BOTH
Alternative approaches FACE MASK Call for help
to intubation(c) AND SGA
VENTILATION
BECOME Emergency noninvasive airway ventilation(e)
INADEQUATE
Successful FAIL after

intubation* multiple attempts Successful ventilation* FAIL
Emergency
Invasive Consider feasibility Awaken invasive airway
airway access(b)* of other options(a) patient(d) access(b)*
*Confirm ventilation, tracheal intubation, or SGA placement with exhaled CO2.
FIGURE 19–29 Difficult airway algorithm. Notes: (a) Other options include (but are not limited to): surgery utilizing
face mask or supraglottic airway (SGA) anesthesia (eg, laryngeal mask airway [LMA], intubating LMA [ILMA], laryngeal tube),
local anesthesia infiltration, or regional nerve blockade. Pursuit of these options usually implies that mask ventilation will
not be problematic. Therefore, these options may be of limited value if this step in the algorithm has been reached via the
emergency pathway. (b) Invasive airway access includes surgical or percutaneous airway, jet ventilation, and retrograde
intubation. (c) Alternative difficult intubation approaches include (but are not limited to) video-assisted laryngoscopy,
alternative laryngoscope blades, SGA (eg, LMA or ILMA) as an intubation conduit (with or without fiberoptic guidance),
fiberoptic intubation, intubating stylet or tube changer, light wand, and blind oral or nasal intubation. (d) Consider
re-preparation of the patient for awake intubation or canceling surgery. (e) Emergency noninvasive airway ventilation
consists of an SGA. (Reproduced with permission from American Society of Anesthesiologists Task Force on the Management of the Difficult
Airway. Practice guidelines for management of the difficult airway: An updated report by the American Society of Anesthesiologists Task Force on the
Management of the Difficult Airway. Anesthesiology. 2003 May;98(5):1269-1277.)

Management of unanticipated difficult tracheal intubation in adults

2015
Plan A: Facemask ventilation and tracheal intubation If in difficulty call for help
Optimise head and neck position
Preoxygenate
Adequate neuromuscular blockade Succeed
Direct/Video Laryngoscopy (maximum 3+1 attempts) Confirm tracheal intubation with capnography
External laryngeal manipulation
Bougie
Remove cricoid pressure
Maintain oxygenation and anaesthesia
Declare failed intubation

Stop and Think
Plan B: Maintaining oxygenation: SAD insertion
Options (consider risks and benefits):
2nd generation device recommended
Succeed 1. Wake the patient up
Change device or size (maximum 3 attempts) 2. Intubate trachea via the SAD
Oxygenate and ventilate 3. Proceed without intubating the trachea
4. Tracheostomy or cricothyroidotomy
Declare failed SAD ventilation
Plan C: Facemask ventilation

If facemask ventilation impossible, paralyse
Succeed
Wake the patient up
Final attempt at facemask ventilation
Use 2 person technique and adjuncts
Declare CICO Post-operative care and follow up

• Formulate immediate airway management
Plan D: Emergency front of neck access plan
• Monitor for complications
Scalpel cricothyroidotomy • Complete airway alert form
• Explain to the patient in person and in writing
• Send written report to GP and local database
This flowchart forms part of the DAS Guidelines for unanticipated difficult intubation in adults 2015 and should be used in conjunction with the text.
FIGURE 19–30 Difficult Airway Society difficult intubation guidelines: overview. CICO, can’t intubate can’t oxygenate;
SAD, supraglottic airway device. (Reproduced with permission from Frerk C, Mitchell V, McNarry A, et al. Difficult Airway Society 2015
guidelines for management of unanticipated difficult intubation in adults. Br J Anaesth. 2015 Dec;115(6):827-848.)
the glottis despite good visualization of the laryngeal an ointment-coated nasopharyngeal airway), spray
opening (Figure 19–31). Progression through the DAS (for the oropharynx), and nerve blocks can also be
plans A to D prevents the anesthetist from unneces- utilized.
sarily repeating the same failed approaches to airway An ETT lubricated with water-soluble jelly
management and maximizes the possibility of preserv- is introduced along the floor of the nose, below
ing patient oxygenation as the airway is secured. the inferior turbinate, at an angle perpendicular to
the face. The tube’s bevel should be directed later-
Nasotracheal Intubation ally away from the turbinates. To ensure that the
Nasal intubation is similar to oral intubation except
that the ETT is advanced through the nose and
nasopharynx into the oropharynx before laryn-
goscopy. The nostril through which the patient
breathes most easily is selected in advance and pre-
pared. Phenylephrine (0.5% or 0.25%) or tolazo-
line nose drops constrict blood vessels and shrink
mucous membranes. If the patient is awake, local
anesthetic ointment (for the nostril, delivered via FIGURE 19–31 Bougie.

Flexible Fiberoptic Intubation

Fiberoptic intubation (FOI) is routinely performed
in awake or sedated patients with problematic air-
ways. FOI is ideal for:
• A small mouth opening
• Minimizing cervical spine movement in
trauma or rheumatoid arthritis
• Upper airway obstruction, such as angioedema
or tumor mass
• Facial deformities, facial trauma
FOI can be performed awake or asleep via oral
or nasal routes in the following scenarios:
• Awake FOI—Predicted inability to ventilate by
mask, upper airway obstruction
• Asleep FOI—Failed intubation, desire for
minimal cervical spine movement in patients
who refuse awake intubation, anticipated difficult
intubation when ventilation by mask appears easy
FIGURE 19–32 Radiograph demonstrating a 7.0-mm
endotracheal tube placed through the cribriform plate into • Oral FOI—Facial, skull injuries
the cranial vault in a patient with a basilar skull fracture. • Nasal FOI—A poor mouth opening
When FOI is considered, careful planning is
tube passes along the floor of the nasal cavity, the necessary, as it will otherwise add to the anesthesia
proximal end of the ETT should be pulled cephalad. time prior to surgery. Patients should be informed
The tube is gradually advanced, until its tip can be of the need for awake intubation as a part of the
visualized in the oropharynx. Laryngoscopy, as dis- informed consent process.
cussed, reveals the abducted vocal cords. Often the The airway is anesthetized with a local anes-
distal end of the ETT can be pushed into the trachea thetic spray, and patient sedation is provided, as
without difficulty. If difficulty is encountered, the tip tolerated. Dexmedetomidine has the advantage of
of the tube may be directed through the vocal cords preserving respiration while providing sedation.
with Magill forceps, being careful not to damage the Airway anesthesia is discussed in the Case Discus-
cuff. Nasal passage of ETTs, airways, or nasogastric sion at the end of this chapter.
catheters carries greater risk in patients with severe If nasal FOI is planned, both nostrils are prepared
midfacial trauma because of the risk of intracranial with vasoconstrictive spray. The nostril through which
placement (Figure 19–32). the patient breathes more easily is identified. Oxygen
Although less used today, blind nasal intuba- can be insufflated through the suction port and down
tion of spontaneously breathing patients can be the aspiration channel of the FOB to improve oxygen-
employed. In this technique, after applying topical ation and blow secretions away from the tip.
anesthetic to the nostril and pharynx, a breath- Alternatively, a large nasal airway (eg, 36FR)
ing tube is passed through the nasopharynx. Using can be inserted in the contralateral nostril. The
breath sounds as a guide, it is directed toward the breathing circuit can be directly connected to the
glottis. When breath sounds are maximal, the anes- end of this nasal airway to administer 100% oxygen
thetist advances the tube during inspiration in an during laryngoscopy. If the patient is unconscious
effort to blindly pass the tube into the trachea. and not breathing spontaneously, the mouth can be

closed and ventilation attempted through the single rings and the carina is proof of proper positioning.
nasal airway. When this technique is used, adequacy The ETT is pushed off the FOB. The acute angle
of ventilation and oxygenation should be confirmed around the arytenoid cartilage and epiglottis may
by capnography and pulse oximetry. The lubricated prevent easy advancement of the tube. Use of an
shaft of the FOB is introduced into the ETT lumen. armored tube usually decreases this problem due
It is important to keep the shaft of the bronchoscope to its greater lateral flexibility and more obtusely
relatively straight (Figure 19–33) so that if the head angled distal end. Proper ETT position is confirmed
of the bronchoscope is rotated in one direction, the by viewing the tip of the tube an appropriate dis-
distal end will move to a similar degree and in the tance (3 cm in adults) above the carina before the
same direction. As the tip of the FOB passes through FOB is withdrawn.
the distal end of the ETT, the epiglottis or glottis Oral FOI proceeds similarly, with the aid of
should be visible. The tip of the bronchoscope is various oral airway devices to direct the FOB toward
manipulated, as needed, to pass the abducted cords. the glottis and to reduce obstruction of the view by
Having an assistant thrust the jaw forward or the tongue.
apply cricoid pressure may improve visualization in
difficult cases. Grasping the tongue with gauze and
pulling it forward may also facilitate intubation.
SURGICAL AIRWAY
Once in the trachea, the FOB is advanced to TECHNIQUES
within sight of the carina. The presence of tracheal “Invasive” airways are required when the “can’t intu-
bate, can’t ventilate” scenario presents and may be
performed in anticipation of such circumstances in
selected patients. The options include surgical crico-
thyrotomy, catheter or needle cricothyrotomy, trans-
tracheal catheter with jet ventilation, and retrograde
intubation.
Surgical cricothyrotomy refers to surgical inci-
sion of the cricothyroid membrane (CTM) and
placement of a breathing tube. More recently, sev-
eral needle/dilator cricothyrotomy kits have become
available. Unlike surgical cricothyrotomy, where a
horizontal incision is made across the CTM, these
kits utilize the Seldinger catheter/wire/dilator tech-
nique. A catheter attached to a syringe is inserted
across the CTM (Figure 19–34). When air is aspi-
rated, a guidewire is passed through the catheter
into the trachea (Figure 19–35). A dilator is then
passed over the guidewire, and a breathing tube
placed (Figure 19–36).
Catheter-based salvage procedures can also
be performed. A 16- or 14-gauge intravenous can-
nula is attached to a syringe and passed through the
CTM toward the carina. Air is aspirated. If a jet ven-
tilation system is available, it can be attached. The
catheter must be secured, otherwise the jet pressure
FIGURE 19–33 Correct technique for manipulating
a fiberoptic bronchoscope through an endotracheal will push the catheter out of the airway, leading to
tube is shown in the top panel; avoid curvature in the potentially disastrous subcutaneous emphysema.
bronchoscope, which makes manipulation difficult. Short (1-s) bursts of oxygen ventilate the patient.

FIGURE 19–34 Cricothyrotomy. Slide catheter into FIGURE 19–36 Cricothyrotomy. Insert tracheostomy
trachea. (Used with permission from Lawrence B. Stack, MD.) tube/introducer. Insert both devices over the wire and into
the trachea. (Used with permission from Lawrence B. Stack, MD.)
Sufficient outflow of expired air must be assured AMBU bag. As with the jet ventilation system, ade-
to avoid barotrauma. Patients ventilated in this quate exhalation must occur to avoid barotraumas.
manner may develop subcutaneous or mediastinal Retrograde intubation is another approach to
emphysema and may become hypercapneic despite secure an airway. A wire is passed via a catheter placed
adequate oxygenation. Transtracheal jet ventilation in the CTM. The wire is angulated cephalad and
will usually require conversion to a surgical airway emerges either through the mouth or nose. The distal
or tracheal intubation. end of the wire is secured with a clamp to prevent it
Should a jet ventilation system not be available, from passing through the CTM. The wire can then
a 3-mL syringe can be attached to the catheter and be threaded into an FOB with a loaded endotracheal
the syringe plunger removed. A 7.0-mm internal tube to facilitate and confirm placement. Conversely,
diameter ETT connector can be inserted into the a small endotracheal tube can be guided by the wire
syringe and attached to a breathing circuit or an into the trachea. Once placed, the wire is removed.
PROBLEMS FOLLOWING
INTUBATION
Following apparently successful intubation, several
scenarios may develop that require immediate atten-
tion. Anesthesia staff must confirm that the tube is
correctly placed with auscultation of bilateral breath
sounds immediately following placement. Detection
of end-tidal CO2 remains the gold standard in this
regard, with the caveat that cardiac output must be
present for end-tidal CO2 production.
Decreases in oxygen saturation can occur fol-
lowing tube placement. This is often secondary
FIGURE 19–35 Cricothyrotomy. Incision at wire entry to endobronchial intubation, especially in small
site. Remove catheter and make incision at the wire entry children and infants. Decreased oxygen saturation
site. (Used with permission from Lawrence B. Stack, MD.) perioperatively may be due to inadequate oxygen

delivery (oxygen not turned on, patient not venti- reaction to suctioning (eg, breath holding, cough-
lated) or to ventilation/perfusion mismatch (almost ing) signals a light plane of anesthesia, whereas no
any form of lung disease). When saturation declines, reaction is characteristic of a deep plane. Similarly,
the patient’s chest is auscultated to confirm bilateral eye opening or purposeful movements imply that
tube placement and to listen for wheezes, rhon- the patient is sufficiently awake for extubation.
chi, and rales consistent with lung pathology. The Extubating an awake patient is usually associ-
breathing circuit is checked. An intraoperative chest ated with coughing (bucking) on the ETT. This reac-
radiograph may be needed to identify the cause of tion increases the heart rate, central venous pressure,
desaturation. Intraoperative fiberoptic bronchos- arterial blood pressure, intracranial pressure,
copy can also be performed and used to confirm intraabdominal pressure, and intraocular pressure.
proper tube placement and to clear mucous plugs. It may also cause wound dehiscence and increased
Bronchodilators and deeper planes of inhalation bleeding. The presence of a ETT in an awake asth-
anesthetics are administered to treat bronchospasm. matic patient may trigger bronchospasm. Some
Obese patients may desaturate secondary to a practitioners attempt to decrease the likelihood of
reduced FRC and atelectasis. Application of positive these effects by administering 1.5 mg/kg of intrave-
end-expiratory pressure may improve oxygenation. nous lidocaine 1–2 min before suctioning and extu-
Should the end-tidal CO2 decline suddenly, pul- bation; however, extubation during deep anesthesia
monary (thrombus) or venous air embolism should may be preferable in patients who cannot tolerate
be considered. Likewise, other causes of a sudden these effects (provided such patients are not at risk
decline in cardiac output or a leak in the circuit of aspiration and/or do not have airways that may be
should be considered. difficult to maintain after removal of the ETT).
A rising end-tidal CO2 may be secondary to Regardless of whether the tube is removed
hypoventilation or increased CO2 production, as when the patient is deeply anesthetized or awake,
occurs with malignant hyperthermia, sepsis, a depleted the patient’s pharynx should be thoroughly suc-
CO2 absorber, or breathing circuit malfunction. tioned before extubation to decrease the potential
Increases in airway pressure may indicate an for aspiration of blood and secretions. In addition,
obstructed or kinked endotracheal tube or reduced pul- patients should be ventilated with 100% oxygen in
monary compliance. The endotracheal tube should be case it becomes difficult to establish an airway after
suctioned to confirm that it is patent and the lungs aus- the ETT is removed. Just prior to extubation, the
cultated to detect signs of bronchospasm, pulmonary ETT is untaped or untied and its cuff is deflated. The
edema, endobronchial intubation, or pneumothorax. tube is withdrawn in a single smooth motion, and a
Decreases in airway pressure can occur second- face mask is applied to deliver oxygen. Oxygen deliv-
ary to leaks in the breathing circuit or inadvertent ery by face mask is maintained during the period of
extubation. transportation to the postanesthesia care area.
TECHNIQUES OF EXTUBATION COMPLICATIONS OF

Most often, extubation should be performed when
a patient is either deeply anesthetized or awake. In
LARYNGOSCOPY &
either case, adequate recovery from neuromuscu- INTUBATION
lar blocking agents should be established prior to The complications of laryngoscopy and intuba-
extubation. tion include hypoxia, hypercarbia, dental and air-
Extubation during a light plane of anesthe- way trauma, tube malpositioning, physiological
sia (ie, a state between deep and awake) is avoided responses to airway instrumentation, and tube
because of an increased risk of laryngospasm. The malfunction. These complications can occur during
distinction between deep and light anesthesia is laryngoscopy and intubation, while the tube is in
usually apparent during pharyngeal suctioning: any place, or following extubation (Table 19–6).

TABLE 19–6 Complications of intubation. inflammation, ulceration, granulation, and stenosis.

During laryngoscopy and intubation
Inflation of an ETT cuff to the minimum pressure
Malpositioning that creates a seal during routine positive-pressure
Esophageal intubation ventilation (usually at least 20 mm Hg) reduces tra-
Bronchial intubation cheal blood flow by 75% at the cuff site. Further cuff
Laryngeal cuff position
Airway trauma
inflation or induced hypotension can totally elimi-
Dental damage nate mucosal blood flow.
Lip, tongue, or mucosal laceration Postintubation croup caused by glottic, laryn-
Sore throat geal, or tracheal edema is particularly serious in
Dislocated mandible
Retropharyngeal dissection children. The efficacy of corticosteroids (eg, dexa-
Physiological reflexes methasone—0.2 mg/kg, up to a maximum of 12 mg)
Hypoxia, hypercarbia in preventing postextubation airway edema remains
Hypertension, tachycardia controversial, but this approach is often used. Vocal
Intracranial hypertension
Intraocular hypertension cord paralysis from cuff compression or other
Laryngospasm trauma to the recurrent laryngeal nerve results in
Tube malfunction hoarseness and increases the risk of aspiration. The
Cuff perforation
incidence of postoperative hoarseness seems to
While the tube is in place increase with obesity, difficult intubations, and anes-
Malpositioning
Unintentional extubation thetics of long duration. Curiously, applying a water-
Bronchial intubation soluble lubricant or a local anesthetic-containing gel
Laryngeal cuff position to the tip or cuff of the ETT does not decrease the
Airway trauma
incidence of postoperative sore throat or hoarse-
Mucosal inflammation and ulceration
Excoriation of nose ness, and, in some studies, actually increased the
Tube malfunction incidence of these complications. Smaller tubes (size
Fire/explosion 6.5 in women and size 7.0 in men) are associated
Obstruction
with fewer complaints of postoperative sore throat.
Following extubation
Repeated attempts at laryngoscopy during a difficult
Airway trauma
Edema and stenosis (glottic, subglottic, or tracheal) intubation may lead to periglottic edema and the
Hoarseness (vocal cord granuloma or paralysis) inability to ventilate with a face mask, thus turning a
Laryngeal malfunction and aspiration bad situation into a life-threatening one.
Laryngospasm
Negative-pressure pulmonary edema
Errors of Endotracheal
Tube Positioning
6 Unrecognized esophageal intubation can pro-
Airway Trauma duce catastrophic results. Prevention of this
Instrumentation with a metal laryngoscope blade complication depends on direct visualization of the
and insertion of a stiff ETT often traumatizes tip of the ETT passing through the vocal cords, careful
delicate airway tissues. Tooth damage is a com- auscultation for the presence of bilateral breath sounds
mon cause of (relatively small) malpractice claims and the absence of gastric gurgling while ventilating
against anesthesiologists. Laryngoscopy and intuba- through the ETT, detection of CO2 in exhaled gas (the
tion can lead to a range of complications from sore most reliable automated method), chest radiography,
throat to tracheal stenosis. Most of these are due airway ultrasonography, or the use of an FOB.
to prolonged external pressure on sensitive airway Even though it is confirmed that the tube is in
structures. When these pressures exceed the capil- the trachea, it may not be correctly positioned. Overly
lary–arteriolar blood pressure (approximately 30 “deep” insertion usually results in intubation of the
mm Hg), tissue ischemia can lead to a sequence of right mainstem bronchus because the right bronchus

forms a less acute angle with the trachea than the left and clevidipine, can attenuate the transient hyper-
7 bronchus. Clues to the diagnosis of bronchial tensive response associated with laryngoscopy and
intubation include unilateral breath sounds, intubation. Cardiac arrhythmias—particularly ven-
unexpected hypoxia with pulse oximetry (unreliable tricular premature beats—sometimes occur during
with high inspired oxygen concentrations), inability intubation and may indicate light anesthesia.
to palpate the ETT cuff in the sternal notch during Laryngospasm is a forceful involuntary spasm
cuff inflation, and decreased breathing-bag compli- of the laryngeal musculature caused by sensory
ance (high peak inspiratory pressures). stimulation of the superior laryngeal nerve. Trigger-
In contrast, inadequate insertion depth will posi- ing stimuli include pharyngeal secretions or passing
tion the cuff in the larynx, predisposing the patient an ETT through the larynx during extubation.
to laryngeal trauma. Inadequate depth of insertion Laryngospasm is usually prevented by extubating
can be detected by palpating the cuff over the thyroid patients either deeply asleep or fully awake, but it
cartilage. Because no one technique protects against can occur—albeit rarely—in an awake patient. Treat-
all possibilities for misplacing an ETT, minimal test- ment of laryngospasm includes providing gentle
ing should include chest auscultation, routine cap- positive-pressure ventilation with an anesthesia bag
nography, and occasionally cuff palpation. and mask using 100% oxygen or administering
If the patient is repositioned, tube placement intravenous lidocaine (1–1.5 mg/kg). If laryngo-
must be reconfirmed. Neck extension or lateral spasm persists and hypoxia develops, small doses of
rotation most often moves an ETT away from the succinylcholine (0.25–0.5 mg/kg) may be required
carina, whereas neck flexion most often moves the (perhaps in combination with small doses of propo-
tube toward the carina. fol or another anesthetic) to relax the laryngeal mus-
At no time should excessive force be employed
8 cles and to allow controlled ventilation. The
during intubation. Esophageal intubations can result large negative intrathoracic pressures gener-
in esophageal rupture and mediastinitis. Mediasti- ated by a struggling patient during laryngospasm
nitis presents as severe sore throat, fever, sepsis, can result in the development of negative-pressure
and subcutaneous air often manifesting as crepitus. pulmonary edema, particularly in healthy patients.
Early intervention is necessary to avoid mortality. Whereas laryngospasm may result from an
If esophageal perforation is suspected, consultation abnormally sensitive reflex, aspiration can result
with an otolaryngologist or thoracic surgeon is rec- from depression of laryngeal reflexes following pro-
ommended. Vocal cord injury can likewise result longed intubation and general anesthesia.
from repeated, forceful attempts at endotracheal Bronchospasm is another reflex response
intubation. to intubation and is most common in asthmatic
patients. Bronchospasm can sometimes be a clue
Physiological Responses to to bronchial intubation. Other pathophysiological
Airway Instrumentation effects of intubation include increased intracranial
Laryngoscopy and tracheal intubation violate the and intraocular pressures.
patient’s protective airway reflexes and predictably
lead to hypertension and tachycardia when per- Endotracheal Tube Malfunction
formed under “light” planes of general anesthesia. ETTs do not always function as intended. Polyvinyl
The insertion of an LMA is typically associated with chloride tubes may be ignited by cautery or laser in
less hemodynamic change. Hemodynamic changes an oxygen/nitrous oxide–enriched environment.
can be attenuated by intravenous administration of Valve or cuff damage is not unusual and should be
lidocaine, opioids, or β-blockers, or deeper planes of excluded by careful inspection of the ETT prior to
inhalation anesthesia in the minutes before laryn- insertion. Obstruction of the ETT can result from
goscopy. Hypotensive agents, including sodium kinking, from foreign body aspiration, or from thick
nitroprusside, nitroglycerin, esmolol, nicardipine, or inspissated secretions in the lumen.

TABLE 19–7 Conditions associated with

CASE DISCUSSION difficult intubations.
Tumors
Evaluation & Management Cystic hygroma
of a Difficult Airway Hemangioma
A 47-year-old man with a long history of tobacco Hematoma1
and alcohol abuse presents for emergency drain- Infections
Submandibular abscess
age of a right-sided submandibular abscess. Peritonsillar abscess
What are some important anesthetic Epiglottitis
considerations during the preoperative Congenital anomalies
Pierre Robin syndrome
evaluation of a patient with an abnormal Treacher Collins syndrome
airway? Laryngeal atresia
Goldenhar syndrome
Induction of general anesthesia followed by Craniofacial dysostosis
direct laryngoscopy and oral intubation is dan- Foreign body
gerous, if not impossible, in several situations. Trauma
(Table 19–7). To determine the optimal intubation Laryngeal fracture
technique, the anesthesiologist must elicit an airway Mandibular or maxillary fracture
Inhalation burn
history and carefully examine the patient’s head and
Cervical spine injury
neck. Any available prior anesthesia records should Obesity
be reviewed for previous problems in airway man- Inadequate neck extension
agement. If a facial deformity is severe enough to Rheumatoid arthritis2
preclude a good mask seal, positive-pressure ven- Ankylosing spondylitis
tilation may be impossible. Furthermore, patients Halo traction
Anatomic variations
with hypopharyngeal disease are more dependent
Micrognathia
on awake muscle tone to maintain airway patency. Prognathism
These two groups of patients should generally not Large tongue
be allowed to become apneic—including induc- Arched palate
Short neck
tion of anesthesia, sedation, or muscle paralysis—
Prominent upper incisors
until their airway is secured.
Can occur postoperatively in patients who have had any neck surgery.
1
If there is an abnormal limitation of the tem-
Also affects arytenoids making them immobile.
2
poromandibular joint that may not improve with

muscle paralysis, a nasal approach with an FOB
should be considered. Infection confined to the
floor of the mouth usually does not preclude nasal the anesthesiologist must always be prepared for
intubation. If the hypopharynx is involved to the unanticipated difficulties.
level of the hyoid bone, however, any transla- The anesthesiologist should also evaluate the
ryngeal attempt will be difficult. Other clues to a patient for signs of airway obstruction (eg, chest
potentially difficult laryngoscopy include limited retraction, stridor) and hypoxia (agitation, restless-
neck extension (<35°), a distance between the tip ness, anxiety, lethargy). Aspiration pneumonia is
of the patient’s mandible and hyoid bone of less more likely if the patient has recently eaten or if
than 7 cm, a sternomental distance of less than 12.5 pus is draining from an abscess into the mouth.
cm with the head fully extended and the mouth In either case, techniques that ablate laryngeal
closed, and a poorly visualized uvula during vol- reflexes (eg, topical anesthesia) should be avoided.
untary tongue protrusion. It must be stressed that Cervical trauma or disease is a factor that
because no examination technique is foolproof should be evaluated prior to direct laryngoscopy.
and the signs of a difficult airway may be subtle, Cervical arthritis or previous cervical fusion may

make it difficult for the head to be put in the sniff- Regardless of which alternative is chosen, an
ing position; these patients are candidates for emergency surgical airway may be necessary. An
bronchoscopy to secure the airway, as discussed experienced team, including a surgeon, should be
previously. Trauma patients with unstable necks or in the operating room and all necessary equipment
whose neck has not yet been “cleared” are also can- should be available and unwrapped. The neck can
didates for bronchoscopy for tracheal intubation. be prepped and draped.
Alternatively, laryngoscopy with in-line stabiliza- What premedication would be
tion can be performed (Figure 19–37). appropriate for this patient?
In the case under discussion, physical examina-
tion reveals swelling below the mandible and trismus Any loss of consciousness or interference with
that limits the patient’s ability to open his mouth. airway reflexes could result in airway obstruction or
Mask fit does not seem to be impaired. CT of the head aspiration. Glycopyrrolate would be a good choice
and neck suggests that the infection has spread along of premedication because it minimizes upper air-
tissue planes and is displacing the airway to the left. way secretions without crossing the blood–brain
barrier. Parenteral sedatives should be very care-
Which intubation technique is indicated? fully titrated. Dexmedetomidine and ketamine
Oral and nasal intubations can be performed preserve respiratory effort and could be used as
in awake patients. Whether the patient is awake or sedatives. Psychological preparation of the patient,
asleep or whether intubation is to be oral or nasal, it including explaining each step planned in securing
can be performed with direct laryngoscopy, fiberop- the airway, may improve patient cooperation.
tic visualization, or video laryngoscopy techniques. What nerve blocks could be helpful
Intubation may be difficult in this patient, during an awake intubation?
however, because of limited mouth opening and
distortion/displacement of the glottis. Induction of The lingual and some pharyngeal branches of
anesthesia should, therefore, be delayed until after the glossopharyngeal nerve that provide sensation
the airway has been secured. Useful alternatives to the posterior third of the tongue and orophar-
include awake fiberoptic intubation, awake video ynx are easily blocked by bilateral injection of 2 mL
laryngoscopy, or awake use of optical stylets. The of local anesthetic into the base of the palatoglos-
final decision depends on the availability of equip- sal arch (also known as the anterior tonsillar pillar)
ment and the experiences and preferences of the with a 25-gauge spinal needle (Figure 19–38).
anesthesia caregivers. Bilateral superior laryngeal nerve blocks and
a transtracheal block would anesthetize the airway
FIGURE 19–37 Technique for airway

management of a patient with suspected spinal
cord injury. One individual holds the head
firmly with the patient on a backboard, the
cervical collar left alone if in place, ensuring
that neither the head nor neck moves with
direct laryngoscopy. A second person applies
cricoid pressure and the third performs
laryngoscopy and intubation.

FIGURE 19–38 Nerve block. While the tongue is

laterally retracted with a tongue blade, the base of the
palatoglossal arch is infiltrated with local anesthetic FIGURE 19–39 Superior laryngeal nerve block and
to block the lingual and pharyngeal branches of the transtracheal block.
glossopharyngeal nerve. Note that the lingual branches
of the glossopharyngeal nerve are not the same as the
lingual nerve, which is a branch of the trigeminal nerve.
Because of this patient’s increased risk for aspi-

ration, local anesthesia might best be limited to the
below the epiglottis (Figure 19–39). The hyoid nasal passages. Four percent cocaine has no advan-
bone is located, and 3 mL of 2% lidocaine is infil- tages compared with a mixture of 4% lidocaine and
trated 1 cm below each greater cornu, where the 0.25% phenylephrine and can cause cardiovascular
internal branch of the superior laryngeal nerves side effects. The maximum safe dose of local anes-
penetrates the thyrohyoid membrane. thetic should be calculated—and not exceeded.
A transtracheal block is performed by identi- Local anesthetic is applied to the nasal mucosa
fying and penetrating the CTM while the neck is with cotton-tipped applicators until a nasal airway
extended. After confirmation of an intratracheal that has been lubricated with lidocaine jelly can be
position by aspiration of air, 4 mL of 4% lidocaine placed into the naris with minimal discomfort. Ben-
is injected into the trachea at end expiration. A zocaine spray is frequently used to topicalize the
deep inhalation and cough immediately follow- airway, but can produce methemoglobinemia, and
ing injection distribute the anesthetic throughout for this reason we prefer lidocaine.
the trachea. Although these blocks may allow the
awake patient to tolerate intubation better, they Why is it necessary to be prepared
also obtund protective cough reflexes, depress the for a surgical airway?
swallowing reflex, and may lead to aspiration. Topi- Laryngospasm is always a possible complica-
cal anesthesia of the pharynx may induce a tran- tion of intubation in the nonparalyzed patient,
sient obstruction from the loss of reflex regulation even if the patient remains awake. Laryngospasm
of airway caliber at the level of the glottis. may make positive-pressure ventilation with a
A relatively simple alternative to all of these is mask impossible. If succinylcholine is administered
to allow the patient to breath atomized lidocaine to break the spasm, the consequent relaxation
for several minutes prior to instrumentation as is of pharyngeal muscles may lead to upper airway
typically done for outpatient bronchoscopy. obstruction and continued inability to ventilate. In

TABLE 19–8 Suggested contents of the portable storage unit for difficult airway management.1,2
• Rigid laryngoscope blades of alternate design and size from those routinely used.
• Endotracheal tubes (ETTs) of assorted size.
• ETT guides. Examples include (but are not limited to) semirigid stylets with or without a hollow core for jet ventilation, light
wands, and forceps designed to manipulate the distal portion of the ETT.
• Laryngeal mask airways of assorted sizes.
• Fiberoptic intubation equipment and assorted video and indirect laryngoscopes.
• Retrograde intubation equipment.
• At least one device suitable for emergency nonsurgical airway ventilation. Examples include (but are not limited to)
transtracheal jet ventilator, hollow jet ventilation stylet, and Combitube.
• Equipment suitable for emergency surgical airway access (eg, cricothyrotomy).
• An exhaled CO2 detector.
1
Modified with permission from the American Society of Anesthesiologists Task Force on Management of the Difficult Airway. Practice guidelines for
management of the difficult airway: A report by the American Society of Anesthesiologists Task Force on Management of the Difficult Airway. Anes-
thesiology. 2003 May;98(5):1269-1277.
2
The items listed in this table are suggestions. The contents of the portable storage unit should be customized to meet the specific needs, prefer-
ences, and skills of the practitioner and healthcare facility.
this situation, an emergency cricothyrotomy may

be lifesaving.
What are some alternative techniques
that might be successful?
Other possible strategies include the retro-
grade passage of a long guidewire or epidural
catheter through a needle inserted across the
CTM. The catheter is guided cephalad into the
pharynx and out through the nose or mouth. An
ETT is passed over the catheter, which is withdrawn
after the tube has entered the larynx. Variations of
this technique include passing the retrograde wire FIGURE 19–40 Intubating laryngeal mask airway.
through the suction port of a flexible FOB or the
lumen of a reintubation stylet that has been pre-
loaded with an ETT. These thicker shafts help the
Should video laryngoscopy fail even after attempts
ETT negotiate the bend into the larynx more easily.
with an intubating bougie, an intubating LMA
Obviously, a vast array of specialized airway equip-
should be attempted (Figure 19–40). If ventilation
ment exists and must be readily available for man-
is adequate, an FOB can be loaded with an ETT and
agement of difficult airways (Table 19–8). Either of
passed through the LMA into the trachea. Correct
these techniques would have been difficult in the
tube position is confirmed by visualization of the
patient described in this case because of the swell-
carina.
ing and anatomic distortion of the neck that can
accompany a submandibular abscess.
What are some approaches when
the airway is unexpectedly difficult? GUIDELINES
The unexpected difficult airway can pres- Apfelbaum J, Hagberg C, Caplan RA, et al. Practice
ent both in elective surgical patients and also in guidelines for management of the difficult airway:
An updated report by the American Society of
emergency intubations in intensive care units, the
Anesthesiologists Task Force on the Management of
emergency department, or general hospital wards.
the Difficult Airway. Anesthesiology. 2013;118:1.

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Butterworth_Ch18_p0295-0306.indd 306 02/05/18 2:44 pm

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ANATOMY The epiglottis prevents aspiration by covering the

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V1 Ophthalmic division of trigeminal nerve

FIGURE 19–3 Sensory nerve supply of the airway.

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TABLE 19–1 The effects of laryngeal nerve Left Right

Superior laryngeal nerve

Recurrent laryngeal nerve

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A CLASS I CLASS II CLASS III CLASS IV

B GRADE I GRADE II GRADE III GRADE IV

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routine ventilation with bag and mask also may be

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Butterworth_Ch19_p0307-0342.indd 313 01/05/18 5:15 pm

Orifice the functional residual capacity, the patient’s oxygen

POSITIONING BAG AND MASK VENTILATION

Butterworth_Ch19_p0307-0342.indd 314 01/05/18 5:15 pm

FIGURE 19–12 One-handed face mask technique.

ventilation by squeezing the breathing bag. The mask

Butterworth_Ch19_p0307-0342.indd 315 01/05/18 5:15 pm

SUPRAGLOTTIC secretions (but not gastric regurgitation), and it

Butterworth_Ch19_p0307-0342.indd 316 01/05/18 5:15 pm

Correct device sizing, avoidance of cuff hyperinfla- Esophageal–Tracheal Combitube

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TABLE 19–2 Successful insertion of a TABLE 19–3 A variety of laryngeal masks

Compared with face mask Hands-free operation More invasive

Compared with tracheal Less invasive Increased risk of gastrointestinal aspiration

Butterworth_Ch19_p0307-0342.indd 318 01/05/18 5:16 pm

FIGURE 19–16 King laryngeal tube.

FIGURE 19–15 Combitube. ENDOTRACHEAL INTUBATION

Butterworth_Ch19_p0307-0342.indd 319 01/05/18 5:16 pm

FIGURE 19–17 Murphy endotracheal tube.

Butterworth_Ch19_p0307-0342.indd 320 01/05/18 5:16 pm

LARYNGOSCOPES Various maneuvers, such as the “sniffing” position

Butterworth_Ch19_p0307-0342.indd 321 01/05/18 5:16 pm

FIGURE 19–19 An assortment of laryngoscope blades.

Butterworth_Ch19_p0307-0342.indd 322 01/05/18 5:16 pm

FIGURE 19–21 McGrath laryngoscope.

Butterworth_Ch19_p0307-0342.indd 323 01/05/18 5:16 pm

Light source bundle

Objective lens covering

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AWAKE INTUBATION INTUBATION AFTER

FACE MASK VENTILATION ADEQUATE FACE MASK VENTILATION ADEQUATE

SGA ADEQUATE* SGA NOT ADEQUATE

Successful FAIL after

*Confirm ventilation, tracheal intubation, or SGA placement with exhaled CO2.

Butterworth_Ch19_p0307-0342.indd 328 01/05/18 5:16 pm

Management of unanticipated difficult tracheal intubation in adults

Declare failed intubation

Plan C: Facemask ventilation

Declare CICO Post-operative care and follow up