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Dicult Airway Management
forENT Surgery
forNon-anesthesiologists
NabilA.Shallik, OdaiKhamash,
andMohammadAl Nobani
42
42.1 Introduction andFacts
Maintaining airway patency and ensuring a
proper gas exchange is a fundamental role of the
anesthetist. Failure to secure the airway or
achieve any of these goals may end up with catastrophic complications, including airway trauma,
surgical airway, cardiopulmonary arrest, brain
injury, and unfortunately, and possibledeath [1].
Difculties in maintaining the airway can be
related to a problem in mask ventilation, supraglottic airway device (SAD) insertion, laryngoscopy manipulation, or endotracheal tube
insertion.
Many factors could contribute to this issue,
including health provider’s factors, patients’ factors, equipment, and health facilities’ factors.
Proper airway assessment and difculty prediction, well-trained health providers, well preparation, and situation optimization may help
decrease the incidence of these events.
N. A. Shallik (*)
Weill Cornell Medical College in Qatar, Doha, Qatar
O. Khamash · M. Al Nobani
Hamad Medical Corporation, Doha, Qatar
42.2 Denition oftheDicult
Airway
As per the American Society of Anesthesiologists
(ASA), a standard denition of the difcult airway cannot be identied in the available literature.However, they described difcult airway “as
the clinical situation in which a conventionally
trained anesthesiologist experiences difculty
with face mask ventilation of the upper airway,
difculty with tracheal intubation, or both” [2].
Therefore, it is a scenario that represents a
complex interaction between patient factors, the
clinical setting, and the skills of the practitioner.
The difcult airway can be expressed according
to the level we faced:
42.2.1 Dicult Face Mask Ventilation
(DMV)
Mask ventilation is a basic, but a fundamental
airway management skill. It can be a bridge to
denitive airway placement or a temporary rescue maneuver in patients with an unanticipated
difcult airway.
The denition of DMV has been described
over the years through a lot of literature.
Langeron and colleagues dened DMV as “the
inability of an unassisted anesthesiologist to maintain oxygen saturation >92%, as measured by
pulse oximetry, or to prevent or reverse signs of
© Springer Nature Switzerland AG 2021
A. Al-Qahtani et al. (eds.), Textbook of Clinical Otolaryngology,
https://doi.org/10.1007/978-3-030-54088-3_42
487
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N. A. Shallik et al.
inadequate ventilation during positive- pressure
mask ventilation under general anesthesia.” In
their study, mask ventilation was considered difcult if one or more of six criteria were present [2]:
1. failure to maintain oxygen saturation >92%
or performing adequate positive-pressure
mask ventilation by an unassisted
anesthesiologist,
2. signicant leak during face mask ventilation,
3. the necessity to increase gas ow to >15 L/
min or the need to use the oxygen ush valve
more than twice,
4. inadequatechest movement,
5. reverting to the use of a two-handed mask
ventilation technique,
6. the need to switch operators.
Other experts dened it as the “inability to obtain
chest excursion sufcient to maintain a clinically
acceptable capnogram waveform despite optimal
head and neck positioning and use of muscle
paralysis, use of an oral airway, and optimal application of a face mask by anesthesia personnel” [3].
In 2013, the American Society of
Anesthesiologists (ASA) dened it as a situation
in which it is not possible to provide adequate
mask ventilation owing to either inadequate mask
seal, excessive gas leak, or excessive resistance to
the ingress or egress of gas.
42.2.1.1 Incidence ofDicult Mask
Ventilation
Kheterpal and associates published two big studies on difcult and impossible mask ventilation,
which showed that the incidence of DMV was
1.4% in 22,660 patients and 2.2% in a subsequent
study of 50,000 patients. The incidence of impossible ventilation ranged from 0.15% to 0.16% in
these two big studies [1].
42.2.1.2 Causes andRisk Factors
ofDicult Mask Ventilation
There are twoleading reasons of an inadequate
face mask ventilation:
The rst is inadequate seal between the face
and the mask, which results in a leak of respiratory gas. The second is inadequate patency of
the airway at the level of the nasopharynx, oropharynx, hypopharynx, larynx, or trachea.
These conditions manifest as either inability to
generate airway pressure that is adequate to
drive gas into the lungs or failure to move gas
into the lungs despite a sufcient driving pres-
3].
sure [
Langeron and colleagues described specic
factors that may be related to DMV, including
age older than 55years, BMI>26kg/m2, lack
of teeth, history of snoring, and presence of a
beard. In addition, Davide Cattano and colleagues listed seven risk criteria including age
of 47years or older, BMI of 35kg/m2 or greater,
neck circumference of 40cm or higher, history
of difcult intubation, presence of facial hair,
perceived short neck, and OSA. Mallampati
class of 3 or 4 and previous neck radiation
exposure again are important contributors to
DMV [2].
42.2.1.3 Techniques ofMask
Ventilation(MV)
Different methods can be usedto ensure better
MV, including head-tilt, jaw-thrust and chin-lift
maneuvers, oral or nasal airways, choosing a different face mask and using a two-hand or twoperson technique.
When two-persons are needed ideally, the
primary intubator stands at the patient’s head
and initiates jaw thrust with the left hand at the
angle of the left mandible and left-sided mask
seal in contrast, the right hand compresses the
reservoir bag. The secondary (helping) person
stands at the patient’s side, at the level of the
patient’s shoulder, facing the primary intubator.
The right hand of the secondary intubator should
cover the left hand of the primary intubator and
contribute to left-sided jaw thrust and mask seal,
and the left hand of the second person initiates
right-sided jaw thrust and mask seal. In this
way, all four hands are doing something important without interfering with one another, and
there is almost no redundant effort. With this
positioning, the secondary person can watch the
monitors continuously, manipulate the larynx
externally, and hand equipment to the primary
intubator [3].
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42 Dicult Airway Management forENT Surgery forNon-anesthesiologists
489
42.3 Dicult Supraglottic Airway
Device (SAD) Insertion
Supraglottic airway device (SAD) or extraglottic airway device, is a medical device that
maintains upper airway patency during anes-
thesia or unconscious situation. It alsoallows
for limited intermittent positive-pressure ventilation (IPPV), offers some degree of protection
against the aspiration of gastric contents, and
can be used easily especially because it can be
inserted atraumatically by a low-skilled practitioner [4].
Laryngeal mask (LMA) is an excellent example of the widely use of SADs. LMA was
invented by Dr. Archibald (“Archie”) Brain, a
British anesthesiologist in the early 1980s and
rst came to market in the United Kingdom
between 1987–1988, and currently, it is an integral part of difcult airway society guidelines
and algorithms [5].
There are different types and shapes of LMAs;
however, almost all of them are categorized as
either rst and second generation LMAs, and
recently invented the third generation LMAs.
A signicant difference exits between these
generations.
42.3.1 SAD/LMA Generations [6]
(Figs.42.1 and42.2)
• First Generation SGA: Simple breathing tube,
usually with some form of mask or opening at
the larynx. Examples: Classic LMA, LMAUnique, SureSeal LM, Cobra PLA, Laryngeal
Tube Airway.
• Second Generation SGA: In general, it has
provision for gastric drainage, better sealing
through a posterior inatable cuff that
improved protection against aspiration, in
addition to integral bite block. Examples:
Combi-tube, Pro-seal LMA, LMA-Supreme,
I-Gel, LTS-D, Air-Q, Aura-Gain, Protector,
LMA Gastro.
• Third Generation SGA: Has dynamic sealing
mechanism plus double suction ports, in addition to the characteristic of the second
Generation. Examples: Baska, Elisha, and 3G
LM.
With all the development and growth in the
eld of supraglottic airway devices, still, we are
facing difculties when dealing with them; including failure of insertion, improper positioning inside
the mouth, displacement after insertion, loss of air-
Classification of Supra-Glottic Airway devices (SAD)
Cuff
First Second
-Classic
-Fastrack
-Softseal
-Sureseal
-LMA Unique
-Slipa
-Ambu Aura
-PAxpress
-Laryngeal Tube
Fig. 42.1 Classication of supraglottic airway devices (SAD). (Image courtesy Dr. Nabil Shallik)
-Proseal
-Supreme
-I Gel
-Air Q
-LTS-D
-Ambu gain
-protector
-LMA Gastro
Third
-Baska
-Elisha
-3G LM
Cuffed
All except
Non-
cuffed
-I-Gel
-Baska
-Slipa
-3G LM
Suction PortGeneration
Channeled
-Proseal
-Supreme
-I-Gel
-Air Q
-LTS-D
-Ambu gain
-Protector
-LMA Gatro
-Elisha
-3G LM
Non-Channeled
-Classic
-Fastract
-Softseal
-Sureseal
-LMA Unique
-Slipa
-Ambu Aura
-PAxpress
-Laryngeal Tube
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Fig. 42.2 The most common brands of Supraglottic Airway Device (SAD) in the market. (Image courtesy Dr. Nabil
Shallik)
N. A. Shallik et al.
way during maintenance, failure to form an effective seal in the airway and risk of aspiration, airway
trauma, and extubation-related problems [4, 5]. In
most cases, multiple factors such as obesity with a
BMI over 30, traumatic insertion, inappropriate
use of the devices, low operator experience, nonstandard patient positioning, or shallow anesthesia
contributed signicantly to these complications
[6]. Other factors that may contribute to the failure
of SADs to function correctly are male patients,
aged 45 or older, having short thyromental distance, or limited neck movement [7].
42.4 Management ofDicult
Intubation
42.4.1 Dicult Intubation
In the following section we will be discussing the
management and guidelines of difcult intubation and extubation and different strategies to
achieve a safe airway placement, as well as the
common equipment needed to achieve it. Also, a
discussion of some of the conditions associated
with difcult intubation.
42.4.1.1 Management ofAnticipated
Dicult Airway
In 2013 the American Society of Anesthesiologists
issued a practice guideline for the management
of difcult airway focusing on essential preparation that includes [8]: (1) availability of equipment for the management of a difcult airway
(i.e., airway trolley that contains specialized
equipment), (2) informing the patient with a
known or suspected difcult airway, (III) availability of assistance when a difcult airway is
encountered, (IV) preoxygenation by face mask,
and (V) oxygen supplementation throughout the
process of airway management through a nasal
cannula, facemask, LMA or insufation, etc. [9]
42.4.1.2 Strategy forIntubation
oftheDicult Airway
A clear and preplanned strategy is vital for the
successful management of the difficult airway. The strategy should primarily include
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42 Dicult Airway Management forENT Surgery forNon-anesthesiologists
491
preparing the patient and optimizing head
position, preparing appropriate equipment,
medications and monitors; involvement of
experienced assistants and availability of help
by the senior provider is preferable. Following
the difficult airway algorithm and formulating
plans B and C in advance would help mitigate
difficulties during the management of the airway [10].
Always remember that mask ventilation is
considered a fundamental basic skill and lifesaving technique for the patient who requires
assisted ventilation during induction of anesthesia, post-extubation or during other critical conditions when the ventilatory support is required
as infor example cardiac arrest.
Various interventions have been designed to
facilitate intubation should a difcult airway
occur, according to the situation, the experience
of the provider and availability of equipment:
1. Awake intubation through exible broncho-
scope: studies showed a success rate might reach
up to 88–100%, but it is expensive equipment
that requires highly experienced providers.
2. Video-assisted laryngoscopy (VL): is pro-
moted as a rst choice in anticipated difcult
airway where literature described that it
improves laryngeal views, higher frequency
of successful intubations, a higher chance for
rst-attempt intubation, with no differences in
time to intubate, airway trauma, lip/gum
trauma, dental trauma, or sore throat
incidents.
3. Intubating stylets or tube exchangers: some
observational studies showed successful intubation in 78–100% of the difcult airway
using stylets, although associated with mild
mucosal bleeding and sore throat. However,
using tube-exchanger may end up with lung
laceration and gastric perforation.
4. Supraglottic airway device (SAD) for ventila-
tion (e.g., LMA, laryngeal tube): can be used
as a temporary or permanent measure in
patients who cannot be mask ventilated or
intubated.
5. SAD for intubation (e.g., ILMA).
6. Rigid laryngoscopic blades: different designs
and sizes should be available; they improve
glottic visualization and help in intubation.
7. Fiber-optic-guided intubation.
8. Lighted stylets or light wands.
42.4.1.3 Common Equipment
forIntubation
The tracheal intubation is the only denitive airway management type that, could be performedthrough the nose, the mouth or the trachea
directly as in tracheostomy. The tracheal intubation could be done by the Direct Laryngoscopy,
Video-laryngoscopy, Flexible Bronchoscopy, and
Rigid Bronchoscopy.
1. Direct Laryngoscopy (DL): is considered the
most common intubating technique, and rst
choice in 50% of cases in current practice [11].
Using direct laryngoscopy blade, it allows for
alignment of the oral, pharyngeal and laryngeal
axis together by lifting the tongue and the jaw
forward to expose the laryngeal inlet. It is a simple and easy technique using an age appropriate
blade size but has been shown to have very high
failure rate, especially in difcult cases with
anatomical abnormalities that obscure the
required alignment among the three axes. Given
the high failure rate in difcult situation, the recommendation is once difcult airway is suspected, DL should not be the rst choice, trials
by DL should be limited to two, with immediate
availability of more advanced techniques [12].
2. Video-laryngoscopy (VL): is an indirect way
for laryngeal visualization and intubation, by
which the images are displayed, magnied,
and recorded on a monitor. Different devices
have shown variable performance in the airway management as shown in Table 42.1.
Video-assisted visualization currently is promoted as a rst choice in anticipated difcult
airway. Glidescope and C-Mac VL (angulated
VL) for example have shown a similar success rate for intubation at rst attempt
comparable with exible bronchoscopic intubation, signicantly higher success than the
direct laryngoscopy technique. (for more
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Table 42.1 Classication of different video-laryngoscopes (VL) from different manufactures
Rigid blades Guided channels Video stylets
Standard blade
(MAC) Angled blade Channeled blade Channeled airway
– Storz C-Mac
– Storz V-Mac
– Venner APA
– GlideScope
– Storz
D-Blade
– King Vision
– McGrath™
MAC
– Venner APA
– AirTraq
– Pentax-AWS
– Res-Q-Scope
II
– Venner APA
– Total track
Video-Laryngeal
Mask
(VLM)
Rigid
stylet Rigid stylet+Flexing tip
– Bonls – Rigid Intubating Fiber-optic-
Laryngoscope (RIFL)
– Storz VS Video Stylet
N. A. Shallik et al.
detalis, Plesae refer to chapter Anesthetic
considerations for Pediatric ENT surgeries for
Non-anesthesiologists title under 3.4.)
3. Bronchoscopic Intubation: It is the gold standard in adult airway management. Both exible
and rigid bronchoscopies are available. The
main indication for exible bronchoscopic intubation in anesthesia is to secure the placement
of endotracheal tube when there is anticipated
airway difculty and conrmation of tube position after intubation if necessary. It can be used
as well in the management of abnormal airway
anatomy, obstructive upper airway lesion, and
unstable cervical spine to limit the cervical
mobility, and the evaluation of airway obstruction is another anesthetic indication as a preoperative assessment (preoperative nasoendoscopy
in pre-assessment anesthesia clinic (Sect.
42.4.2.3) or directly prior to intubation for
patients with known anatomical abnormalities
in the upper airway. Fiber-optic Intubation can
be done through a Supraglottic Airway Device
(SAD) in difcult cases as well [13].
The choice of the route has its indications as
well, as nasal route is used in a case of limited
mouth opening or a strong gag reex, or if the
surgery needs nasal intubation. Also, intubation
can be done during sleep or awake intubation in
special situations [14].
42.4.2 Causes ofDicult Intubation
Many pathological diseases are associated with
difculties when it comes to managing the airway, paying a particular attention to such condi-
Table 42.2 Congenital disorders associated with dif-
cult airway
Syndrome Anatomical site involved
Down syndrome Oropharynx, larynx, trachea,
Beckwith-Weidmann
syndrome
Pierre Robin syndrome Mandible, maxilla,
Klippel–Feil syndrome Cervical spine
Cri-Du-Chat syndrome Mandible, larynx
Treacher Collins
syndrome
cervical spine
Oropharynx, maxilla,
diaphragm
oropharynx
Mandible, oral opening,
zygomatic bone
tions would make airway management planning
and execution a lot safer and smoother.
Conditions associated with difcult airway
can be divided into congenital and acquired disorders. Acquired disorders include inammatory
disorders, traumatic conditions, infections, metabolic disorders, obesity and obesity-related disorders, burns, and tumors.
42.4.2.1 Congenital Disorders
Associated withDicult
Airway (Table42.2)
There are many congenital disorders that are
related to difculties with managing the airway,
but we will focus on some of the common congenital disorders. Although most of those patients
present during their childhood years, but we still
see syndromic patients present to the operating
theaters during the adulthood period.
Down’s Syndrome (Trisomy 21)
Down syndrome is the most common congenital
anomaly, with incidence up to 1in 600 live births.
Multisystem involvements in those patients such
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42 Dicult Airway Management forENT Surgery forNon-anesthesiologists
493
as congenital heart disease, obesity, hypothyroidism, hematologic malignancies might complicate
the perioperative period.
Airway management difculties arise due to
multiple anatomical abnormalities, including
short neck, relative macroglossia, smaller tracheal diameter, subglottic stenosis, and atlantoaxial instability [15].
During the management of the airway, neck
movements should be kept to a minimum since
those patients have increased incidence of
atlantoaxial instability. In symptomatic patients
or patients with abnormal radiological ndings, full cervical spine precautions should be
implemented during the management of the
airway [16].
Beckwith-Wiedemann Syndrome
Patients with Beckwith-Weidmann syndrome
present a set of challenges for the health care provider during the perioperative period, such as the
risk of hypoglycemia, diaphragmatic herniarelated respiratory complication, and airway
management-related difculties.
Mask ventilation might prove to be challenging in those patients due to the macroglossia.
Direct laryngoscopy is also challenging due to
the macroglossia and maxillary hypoplasia.
Pierre Robin Syndrome
Pierre Robin syndrome is characterized by a
triad of micrognathia, retraction of the tongue
(glossoptosis), and a cleft palate. Patients with
Pierre Robin sequence (PRS) usually present
with respiratory and feeding difculties that is
severed enough to require surgical interventions such as distraction osteogenesis of the
mandible, glossopexy, or even tracheostomies.
In a case series of 74 patients with PRS more
than 50 percent of the patients required airway
intervention, whereas one-third required surgical intervention to manage the airway [17].
Direct laryngoscopy and endotracheal intubation are usually very difcult in patients with
PRS, which warrant proper preparation, and
availability of experienced staff. Elective beroptic intubation is the preferred method in such
patients.
42.4.2.2 Acquired Disorders
Associated withDicult
Airway Management
Many pathological processes can complicate
managing the airway, keeping that in mind of all
cases that were reported to the NAP4 project (a
national audit of major complications of airway
management in the United Kingdom) 40% were
associated with head and neck pathologies [18].
Diabetes Mellitus
Long-standing diabetes mellitus might result in
glycosylation of the tendons which in turn might
result into limited mobility of the cervical spine
and limited mobility of the temporomandibular
joint both of which can contribute to increased
difculty when it comes to managing the airway
in those patients [19].
In a retrospective analysis over a 10-year
period in patients undergoing renal and pancreatic transplant, the frequency of difcult laryngoscopy was reported to be as high as 32%,
warranting proper assessment of the joint mobility before attempting laryngoscopy in diabetic
patients [19]. Prayer sign can be used to assess
the movement of the joint by asking the patient to
approximate the palms as close as possible similar to a prayer position, inability to do so indicate
limited phalangeal extension, which can be used
as an indicator for stiff neck joints.
Rheumatoid Arthritis
Rheumatoid arthritis is an autoimmune disease
that is characterized by widespread arthritis of
the joints. Rheumatoid arthritis can also involve
the larynx and the joints of the airway (vocal
cords nodules, edema, and erythema of the vocal
cords, cricoarytenoid arthritis, arthritis of the
temporomandibular joint, cricothyroid joint
involvement, as well as the involvement of the
atlantoaxial and cervical spine joints).
Radiological studies reported that up to 50% of
patients with long-standing severe rheumatoid
arthritis might have laryngeal involvement. Signs
and symptoms of dysphonia, dysphagia, sore
throat, hoarseness of voice, pain on swallowing,
or stridor might indicate airway involvement.
Mask ventilation and laryngoscopy might prove
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N. A. Shallik et al.
to be challenging in those patients due to the
upper airway obstruction and the difculties to
visualize the glottic opening due to the edema,
stiffness of the larynx, and involvement of the
temporomandibular joint. Upper airway obstruction and exacerbation of laryngeal symptoms
have been reported after endotracheal intubation
or the use of supraglottic devices [20].
Obesity
Airway management in obese patients present a
unique set of challenges, and obese patients tend
to desaturate quickly due to the reduction in functional residual capacity and the increase in closing capacities, warranting proper preoxygenation
and positioning before the induction of
anesthesia.
Moreover, during emergency airway management, obese patients were more likely to have difcult intubations when compared to lean
patients.Furthermore, obesity was also associated
with difculties in mask ventilation [21]. Body
mass index above 30kg/m2 was associated with
difcult mask ventilation [13, 14]. Besides that,
obese patients are more likely to develop other disorders that might complicate airway management
like obstructive sleep apnea and diabetes.
BMI of 40 kg/m2 does not appear to be an
independent predictor of difcult intubation, but
a BMI of 50kg/m2 or higher and measuring the
neck circumference might be of a greater predictive value, neck circumference more than 42 centimeters might predict difcult airway [22].
Obstructive Sleep Apnea
Obstructive sleep apnea (OSA) is a sleep disorder
that is characterized by repetitive closure of the
airway during sleep, resulting in repeated episodes of apnea and hypopnea.
Patients with obstructive sleep apnea were
associated with a higher incidence of difcult tracheal intubation [23]. In a prospective observational study on 22,000 patients investigating
mask ventilation difculties among patients with
conrmed OSA, mask ventilation was more difcult in OSA patients compared to non-OSA
patients. Impossible to ventilate was also higher
in a patient with OSA [24].
History of snoring, daytime fatigue, inability
to concentrate, and observed apnea are suggestive of OSA.Preoperatively the physician should
inquire about polysomnography results, use of
home oxygen, continuous positive airway pressure (CPAP), or the presence of cardiopulmonary
complications related to OSA.
42.4.2.3 Masses oftheHead andNeck
Masses affecting the airway passages should
have a thorough examination and appropriate
imaging studies. Preoperative Nasopharyngeal
endoscopy might be warranted as well.
They can affect multiple sites along the airway, including the nose, nasopharynx, oropharynx, tongue, larynx, vocal cords, or
trachea, and they can be external to the airway
passages like thyroid, esophageal or mediastinal masses.
The examination must be dynamic, assessing
the patients in sitting position as well as in supine
position, inquiring about changes in voice, difculty breathing, or stridor with position change
are of paramount importance (Table42.3).
Pulmonary function testing can be helpful in a
patient with masses affecting the airway passages. It should also be dynamic since static studies might be normal [25].
Supraglottic masses might not be visible during the regular physical exam and might present
after anesthesia induction in the form of difcult
ventilation or difcult intubation.
Masses at the base of the tongue can interfere
with direct laryngoscopy and oral intubation,
nasal video-laryngoscopy and intubation would
be a better strategy to manage the airway.
Table 42.3 Summarizes the characteristic clinical nd-
ings and their implications on airway management
Clinical nding Underlying changes
Voice change Laryngeal involvement
Difculty swallowing Intrinsic or extrinsic mass
Difculty with deep
inspiration
Noisy breathing
changes with body
position
effect
Airway narrowing due to
internal or external mass
effect
Tracheomalacia
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495
Tonsillar masses like lingual tonsillar hypertrophy might result in an anticipated difcult airway, in a case series by Ovassapian and his
colleagues that investigated 33 patients with
unanticipated failed intubation and unremarkable
routine physical examination found that all the
patients had lingual tonsillar hypertrophy on
postoperative ber-optic pharyngoscopy [26].
Subglottic stenosis might present with the
inability to pass the endotracheal tube. It could be
caused by an intratracheal lesion or extratracheal
masses. Thyroid tumors or goiter might invade
the tracheal lumen leading to airway obstruction.
Using smaller endotracheal tubes would be an
appropriate option. The use of rigid or exible
bronchoscopy to assist the intubation might be
needed in some cases.
42.4.2.4 Deep Neck Infections
Ludwig angina is potentially a fatal infection of
the oor of the mouth, as well as other infections
of the airway passages, like epiglottitis, managing the airway must be in a controlled setting like
in the operating theater. Awake ber-optic intubation or even tracheostomy might be appropriate
in such cases. Due to the excessive salivation and
in many cases inability to swallow it, managing
the airway in a sitting position might be proper in
such scenarios [27].
42.4.2.5 Burns
Inhalational injury is a signicant cause of morbidity and mortality in burn victims. The prevalence of inhalational injury in burn patients is
around 15%, with an in-hospital mortality rate of
about 3% [28].
Swelling of the airway passages usually
occurs within 24h after the thermal injury but
can occur as early as 2 h; in severe, erosion
ulcers, and granulation formation might occur.
Carbonaceous material around the mouth, pharynx, or nares should raise suspicion of inhalational injury. Other symptoms include stridor,
hoarseness of voice, difculty breathing, and
respiratory distress. Difcult airway management and airway compromise are not uncommon. Prophylactic elective intubation is often
needed.
Patient with history of inhalational injury
might develop chronic airway problems, including stiff facial and neck scar tissues formation,
limiting mouth opening and neck mobility which
might lead to difcult airway management in the
future.
42.4.3 Extubating Dicult Airway
If intubation is a skill, then tracheal extubation is
the art of this skill. Most morbidity and mortality
incidents that were described in general anesthesia happened at the time of extubation. In general, the majority of extubations are expected to
be uneventful, but even these routine extubations
may be associated with complications as
described in Table42.4.
Problems with extubation can be split into two
categories:
1. Failure to extubate; when an attempt to
remove a tracheal tube is unsuccessful.
2. Failure to reintubate; when extubation is fol-
lowed by an immediate or delayed but unsuccessful attempt to reintubate the trachea.
Many factors are required for proper extubation that is subjective and objective such as
improving or resolving the underlying disease,
hemodynamic stability, regular breathing, normal
respiratory and blood gases parameters, etc.
However, extubating a difcult airway is always
challenging. The accurate decision, proper timing, proper technique is always required [29].
Table 42.4 Complications of routine extubations
Accidental extubation
Fixation of the endotracheal tube
Increase of BP, increase heart rate
Coughing and/or breath-holding
Laryngeal trauma
Laryngospasm or vocal cord paralysis
Stridor, airway obstruction
Negative-pressure pulmonary edema
Laryngeal incompetence
Aspiration
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N. A. Shallik et al.
Proper planning involves identication of
high-risk patients who may develop a difcult
airway, such as those with obesity, obstructive
sleep apnea, major head/neck, and upper airway
surgery, and obstetric and cervical spine.
Preemptive optimization of patients’ conditions, careful timing of extubation, the presence
of experienced personnel trained in advanced airway management, and the availability of the necessary equipment and appropriate post-extubation
monitoring is an effective strategy to minimize
post-extubation airway complications [30].
42.4.3.1 The Dicult Airway Society
(DAS) Issued Guidelines
forManagement ofTracheal
Extubation
The DAS guidelines describe a basic extubation
algorithm consisting of four steps [31]:
1. Plan extubation.
2. Prepare for extubation (risk stratify to at-risk
or low risk).
3. Perform extubation.
4. Post-extubation care and follow-up.
Step 1: consists of assessing airway risk factors (e.g., known difcult airway, obesity,
obstructive sleep apnea, aspiration risk) and general risk factors (e.g., hemodynamic and neurological stability).
Step 2: includes optimizing patient factors
(e.g., cardiovascular, respiratory, metabolic) and
environmental factors (e.g., location, availability
of skilled help, specialized equipment). Once
optimized, patient risk stratication is categorized into “low-risk” and “at-risk” extubation
groups.
Step 3: includes the act of extubation.
Awake extubation is preferable most of the
time, although deep extubation can be considered
in cases of low-risk patients.
When awake extubation is planned, remember
to follow the appropriate steps that include; preoxygenation with 100% oxygen, proper positioning, suctioning if needed, insertion of a bite block
(e.g., oral airway, rolled gauze), a reversal for a
muscle relaxant, establishing regular breathing
with good tidal volume, and monitoring patient
until awake (eye-opening, obeying command).
For at-risk group, where the ability to oxygenate is uncertain or there exists a general and airway risk factor, it is recommended to perform
awake extubation, keep intubated or tracheostomy insertion with help from ENT doctors.
Finally, in step 4: we do post-extubation care
(e.g., proper monitoring, provision of oxygen,
and safe transfer).
42.5 Prediction ofDicult Airway
42.5.1 Traditional Airway
Assessment
Assessment of airway and prediction of difculties is a crucial step in managing the airway to
ensure adequate oxygenation and ventilation and
avoiding respiratory complications that may end
up with life-threatening situation.
The fourth National Audit Project (NAP4)
found that failure to assess for and identify the
potential difculty, or the application of poor
judgment in management planning, may contribute to a poor outcome [18].
A perfect airway assessment tool does not
exist, and unanticipated difculty will still
occur; however, taking a comprehensive history, a proper physical examination, doing relative investigations, and using multiple tests to
predict difculty in airway management is a
better predictor than any single test used in
isolation.
42.5.1.1 Clinical History
Reviewing medical records and previous anesthesia notes would be of great help if available.
Assessing medical, surgical, and anesthesiarelated history is vital in the anticipated difcult
airway.
42.5.1.2 Physical Examination
Clinical examination of the airway is critical; its
purpose is to assess for difcult mask ventilation,
laryngoscopic access, and ease of subsequent
maneuvers. Any gross abnormality of the face,
AL GRAWANY
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