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INDIAN JOURNAL OF ANAESTHESIA, DECEMBER 2006 430 Indian J. Anaesth. 2006; 50 (6) : 430 - 434
1. M.D.,FAMS. Hony. Consultant Anaesthesiologist,
Apollo Gleneagles Hospital, Kolkata.
2. M.D., Asst. Prof.,
Calcutta Medical College & Hospital; Kolkata.
Correspond to :
Dr. Suman Chatterjee
BC - 103, Salt Lake, Kolkata –700064.
E-mail : [email protected]
(Accepted for publication on 20 - 10 - 2006 )
REVIEW ARTICLE
TRACHEAL EXTUBATION IN THE DIFFICULT AIRWAY
Dr. A. Rudra1 Dr. S. Chatterjee2
Management of the difficult airway does not end
with the placement of an endotracheal tube. The anaesthesia
practitioner is faced daily with the extubation of patients
in the operating room, the postanaesthesia care unit, or in
the intensive care unit. On occasion one is faced with
extubation of a difficult airway. For most operating room
patients, the likelihood of a patient requiring tracheal
reintubation is in the order of 0.1 to 0.2 percent.
1,2 In
patients undergoing diagnostic panendoscopy, particularly if
a biopsy is obtained, this increase to 1 to 3 percent.
3-7 For
intensive care unit patients, tracheal reintubation is required
between 6 to 25 percent depending upon extubation criteria
and case mix.
8 The ASA Task Force9 regards the concept
of an extubation strategy as a logical extension of intubation
strategy which is strongly supported by consultants opinion.
ASA9 and Canadian Airway Focus Group10
recommends
the preformulated strategy for extubation of the difficult
airway would depend in part on the surgery, the condition
of the patient, and the skills and preferences of the
anasethesia practitioner. They further recommended that
the preformulated strategy should include :
1. Consideration of relative merits of awake intubation
versus extubation before the return of consciousness.
2. An evaluation of factors that may impair ventilation
after extubation.
3. Formulation of an airway management plan that can
be implemented if the patient is not able to maintain
adequate ventilation after extubation.
4. Consideration of the short term use of a hollow device
that can serve as a guide for reintubation and
ventilation, or both, if extubation is not successful.
This article reviews to identify patients at high risk
at the time of extubation and strategies to minimize such
risk, and also potential complications associated with
extubation.
The difficult airway
A difficult airway, as defined by the ASA Task
Force, is the clinial situation in which a conventionally
trained anaesthesia practitioner experiences difficulty with
mask ventilation, difficulty with tracheal intubation, or
both.
11 Obviously, if one had difficulty with ventilation or
initial endotracheal intubation, particular caution should be
exercised at the time of extubation. Usually this scenario
is seen due to airway trauma leading to oedema and trauma
following multiple attempts at securing the airway.
Risk factors for difficult tracheal reintubation include
a history of previous difficult intubation, airway oedema
secondary to surgical manipulation or volume resuscitation,
morbid obesity, inexperienced personnel, airway injury,
burns or smoke inhalation, limited access or anatomical
derangement, and an immobilized or unstable cervcal spine.
12
Reestablishing and securing the airway in these patient can
be extremely challenging, often resulting in considerable
morbidity and mortality.
13,14 Indeed, adverse outcomes
constituted the single largest class of injury in the American
Society of Anesthesiologists Closed Claims Study (34%),
with death or brain damage occuring in 85% of these cases.
15
The main goal of extubating the difficult airway, as with
any airway, is to avoid reintubation if at all possible.
Otherwise, that may lead to a less than desirable outcome.
The extubation in a difficult airway depend on both
airway and nonairway issues. The usual criteria should be
met, for example, haemodynamic stability, a satisfactory
oxygen-carrying capacity, normothermia, an adequate
respiratory rate and tidal volume, good oxygen saturation,
and a conscious alert patient who is able to clear secretions
and protect the airway. Patients at high risk for failed
extubation are those with any potential for hypoventilation,
a ventilation – pefusion mismatch, a failure of the pulmonary
toilet, or airway obstruction. One should also take into
cosideration the patient’s future operative schedule. It makes
no sense to extubate a patient with a difficult airway and
later find out that the patient will be returning the next
morning for follow-up surgery.
15
Commonly practiced maneuvers to determine the
feasibility of extubation are direct laryngoscopy and cuff
leak before extubation to detect oedema around the airway.
Direct laryngosopy in this scinerio has a limited value, as
because, the endotracheal tube blocks the operators view of
the laryngeal inlet. Moreover, the endotracheal tube in situ
will deform the anatomy, leading to an underestimation of
430RUDRA, CHATTERJEE : TRACHEAL EXTUBATION IN DIFFICULT AIRWAY 431
the difficulty of reintubation. The second maneuver commonly
performed is testing for a cuff leak.
16 This is accomplished
in a spontaneously ventilating patient by removing the patient
from the ventilation circuit and occluding the end of the
endotracheal tube with a finger while simultaneously
deflating the cuff. If no significant oedema is present, the
patient will be able to breathe around the endotracheal
tube. A cuff leak test should be performed on any patient
who it is felt may demonstrate obstruction after extubation.
The incidence of reintubation and the need for tracheostomy
is greater in the absence of a cuff leak.
17,18
Strategies for exutubation
Since the majority of patients, even those at high
risk, will be tracheally extubated with success, it is essential
that any proposed strategy entails less risks than simply
removing the tracheal tube and hoping for the best. A safe
tracheal extubation strategy should also involve minimal
discomfort, at acceptable costs, and facilitate oxygenation,
ventilation in a failing pateint even while the airway is
being reestablished; and tracheal reintubation, if
necessary.
14 These strategies are not evidence-based;
most are derived from case reports or small series. Therefore,
the anaesthesia practitioner must understand the various
options for extubation and formulate a plan of action to
regain control of the airway if extubation fails. Benumof
considers a controlled, gradual, step-by-step, reversible
withdrawal of airway support as the optional approach to
the difficult airway extubation.
19 There are basically three
approaches to extubation of the difficult airway:
20,21 a)
extubate conventionally with the patient awake, b) extubate
in a deep plane of anaesthesia followed by the placement
of a laryngeal mask airway to decrease the risk of
laryngospasm or bronchospasm, c) extubate with the patient
awake with a “bridge” to full extubation.
In a spontaneously breathing patient, extubation
over a fibreoptic bronchoscope offers the possibility of
visually assessing vocal cord function. This can be very
helpful for the patient suspected of having a vocal cord
palsy. It also permits an assessment of anatomic injury to
the trachea, glottis, or supraglottic structures. When
significant abnormalities are noted, a decision must be
made whether to immediately reinsert the tracheal tube or
withdraw the bronchoscope and manage the patient with
agents such as racemic epinephrine and helium/oxygen.
22
Other than bronchoscope many devices have
been used in the extubation of the difficult airway. These
are long hollow catheters which may include connections
for jet and/or manual ventilation; most have distance
and radiopaque markers. They also have end and/or distal
side holes, though these differ in number. Oxygen
insufflation or jet ventilaition can be provided through the
lumen of catheter. Respiratory monitoring can also be
achieved by connecting to a capnograph. Spontaneous
breathing may take place around the device. In most reports,
tracheal tube exchange catheters have been tolerated well
enough that they can be left in place until it is probable
that tracheal ventilation will not be required.
23,24 Properly
securing the airway exchange (and ventilation) catheters at
the same depth as the previously replaced endotracheal
tube prevents it from coming out even if the patient coughs.
Clarifying to the nursing staff and labeling these catheters
as an airway device will avert a potent disaster if mistaken
for a feeding tube. Even with the catheter in the trachea,
most patients will be able to talk or cough. If tracheal
reintubation or a tracheal tube exchange is required, this
can be facilitated with gentle direct laryngoscopy, not
necessarily to reveal the glottis but to retract the tongue
and to detect any airway pathology.
These devices are consistent with the recommendation
of the American Society of Anesthesiologists Task Force
on Management of Difficult Airway9 and the Canadian
Airway Focus Group10 regarding tracheal extubation of the
difficult airway. The device will provide a means whereby
oxygen by insufflation or ventilation, if necessary, can be
accomplished while altenative techniques are explored. This
may be thought of as a “reversible tracheal extubation”.
With the device in place, other option can be persued,
including an evaluation of the benefits of helium/oxygen or
the inhalation of racemic epinephrine. Knowing that the
patient is satisfactorily oxygenated (and ventilated), additional
information, equipment, or expertise can be recruited. There
are numerous manufacturers for these types of catheters, but
all basically work on the same principle.
Table - 1 : Endotracheal ventilation & exchange catheters.
• Bedger “jet stylet”
• METTRO (Mizus Endotracheal Tube Replacement Obturator)
• Airway exchange catheter (Cook)
• Patil two-part intubation catheter (Cook)
• Tracheal Tube Exchanger (TTX, Sheridan)
• Endotracheal ventilation catheter ( ETVC, CardioMed)
• Jet Tracheal Tube Exchanger (JETTX)
• E.T.X. catheter for double lumen endotracheal tube exchange (Sheridan )
Endotracheal exchangers should be handled with
caution: the rate of failures seems to be higher than expected
depending on the type of airway exchange catheter, technique
and experience of the operator. The user should be aware
that endotracheal tube exchange can lead to major
complications that include laceration of the lateral wall,
bronchial perforation with pneumothorax, loss of airway
with hypoxaemia and/or bradycardia, potential need of aINDIAN JOURNAL OF ANAESTHESIA, DECEMBER 2006 432
surgical airway, cardiac arrest or death. A clear algorithm
and equipment for alternative ways to control the airway
should be readily available before an endotracheal tube
exchange is performed.
There are differences between these commercial
products and such differences may be important. Essential
points for consideration include the security of the connection
and the number of distal side ports (if jet ventilation is to
be used) and the length and diameter of the device
(particularly if a tracheal tube exchange is contemplated or
a double-lumen tracheal tube is involved). In general, the
greater the diameter, the more alike is the device to a long
tracheal tube but the simpler it is to perform a tracheal
tube exchange. Long devices with narrow inner diameter
allow for positive pressure ventilation but offer high
resistance. While such ventilation may be life-saving, it
may not be adequate for severely compromised patients.
This may necessitate jet ventilation. When jet ventilating
through a tracheal tube exchange catheter, it is important
to ensure the device is proximal to the carina, to reduce
the driving pressure and inspiratory time to that required
to expand the lungs, and to provide a sufficiently time to
allow for complete exhalation. A device with multiple end-
holes results in lower injection pressure and reduces catheter
whip. The objective of jet ventilation is to provide life-
saving oxygenation rather than normal blood gases. Such an
objective will reduce the likelihood of barotrauma.
25
However, till today fibreoptic endoscopy has been suggested
as a better and safer option to exchange endotracheal tubes.
26,27
Recommended Technique by the ASA for Extubation
of the Difficult Airway
1. Administer 100% oxygen.
2. Suction the oropharynx.
3. Deflate cuff of the endotracheal tube for cuff leakage
check.
4. Insert an airway excange catheter through the
endotracheal tube to a predetermined depth.
5. Extubate the patient over a jet ventilation catheter.
6. Apply oxygen by face mask or insufflation through a
jet ventilation catheter.
7. Tape the proximal end to the patient’s shoulder to
stabilize it.
8. Remove the jet ventilation catheter after 30 to 60
minutes if no obstruction appears.
Complications associated with extubation
Rarely, attempts to remove a tracheal tube cannot
be achieved due to entrapment by fixation devices or sutures,
cuffs that cannot be deflated, or a barb resulting from a
partly severed tracheal tube.
28
Haemodynamic changes
Extubation is accompanied by transient hypertension
and tachycardia in most adults. Catecholamine release due
to endotracheal tube stimulation is thought to be responsible
for the change in haeodynamics. The clinical importance
and optimal management of these problems will depend
upon the context in which the event occurs. Patients with
cardiac disease, pregnancy - induced hypertensions,
12 and
raised intracranial pressure29 may be at particular risk for
adverse consequences. Patients with cardiac disease have
shown decreased ejection fractions at the time of
extubation.
30 Strategies to attenuate such responses include
the use of intratracheal lignocaine or intravenous lignocaine,
nitrates, beta-blockers, and extubation while in a surgical
anaesthetic plane. Extubation in the deeper plane is
inappropriate for those with a difficult airway, those with
a high risk for aspiration, and those in whom airway access
is reduced.
Laryngospasm
Laryngospasm is a common cause of upper airway
obstruction particularly when stimuli are encountered during
emergence. A variety of triggers are recognized including
vagal, trigeminal, auditory, phrenic, sciatic and splanchnic
nerve stimulation. Cervical flexion or extension with an
indwelling tracheal tube, and vocal cord irritation from
blood, vomitus or oral secretions cause laryngospasm.
Various techniques have been used in attempt to decrease
the incidence of this event. Management consists of suctioning
the oropharynx before extubation, disconnection of painful
stimulation, and administering 100% oxygen with sustained
positive pressure at the time of extubation. Severe cases
may require a small does of suxamethouicum to “break”
the spasm along with reintubation.
31,32
Glottic oedema
Tracheal and laryngeal trauma may result in glottic
oedema, which is an important cause of postextubation
obstruction. Glottic oedema has been subsclassified as
supraglottic, retroarytenoidal, and subglottic.
33 Supraglottic
oedema results in posterior displacement of the epiglottis
reducing the laryngeal inlet and causing inspiratory
obstruction. Retroarytenoidal oedema restricts movement
of the arytenoid cartilages, limiting vocal cord abduction
on inspiration. Subglottic oedema, a particular problem in
neonates and infants results in swelling of the loose
submucosal connective tissue and is confined by the
nonexpandable cricoid cartilage. In neonates, this is the
narrowest part of the upper airway, and small reductions in
diameter results in a significant increase in airway
resistance. Management of laryngeal oedema depends upon
its severity. Treatment options range from head-up
positioning, supplemental humidified oxygen, racemic
epinephrine, helium-oxygen administration and reintubationRUDRA, CHATTERJEE : TRACHEAL EXTUBATION IN DIFFICULT AIRWAY 433
with a smaller endotrachel tube. The practice of
administering systemic steroids in the hopes of reducing
oedema is controversial, and studies are divided on their
efficiency.
34
Vocal cord malfunctions
Vocal cord malfunctions from injury to the vagus or
one of its branches (the recurrent laryngeal nerve or the
external division of the superior laryngeal nerve) is a
relatively rare complication associated mostly with
head and neck, thyroid, or thoracic surgery.
12
Vocal cord
malfunction can also be caused by cuff pressure from the
endotracheal tube near the anterior division of the recurrent
laryngeal nerve.
35 Unilateral vocal cord paralysis generally
produces little other than hoarseness and usually improves
without treatment. Bilateral vocal cord paralysis can cause
airway obstruction requiring immediate reintubation and
subsequent tracheostomy. Diagnosis can be confirmed by
fibreoptic evaluation.
Acute pulmonary oedema
Acute pulmonary ordema may complicate tracheal
extubation when significant airway obstruction occurs.
36-39
Generally, it occurs in adults following severe laryngospasm.
However, in children, acute pulmonary oedema occurs
following croup or epiglottitis.
38 This occurs when a forceful
inspiratory effort is made against a closed glottis, generating
high intrapleural pressures promoting venous return. It may
also result in a rightward shift of interatrial and
interventricular septums, raising left atrial and ventricular
pressures. This condition is seen within minutes after
extubation and usually presents with pink frothy sputum and
a decrease in oxygen saturation (SpO2). Management involves
removing the obstruction, oxygen support, close monitoring,
and afterload reduction with frusemide or morphine, or
both. Reintubation is rarely needed and most cases resolve
without complications.
Airway compression
External compression of the airway after extubation
may lead to obstruction.
• An excessively tight postsurgical neck dressing cause
external compression that can be easily resolved.
• A rapidly expanding haematoma in proximity to the
airway. Situation may be seen after certain surgeries
(e.g. carotid endarterectomy, thyroidectomy). Condition
must be quickly diagnosed and properly treated before
total airway obstruction occur.
40
• Tracheomalacia, may occur for a number of reasons
including prolonged compression from a goiter.
41
This condition is usually seen after the removal of the
goiter. Airway obstruction becomes apparent soon after
extubation and management includes reintubation,
surgical tracheal support, or tracheostomy below the
obstruction.
Aspiration
Alteration in laryngeal function, along with residual
anaesthesia, may make the patient more vulnerable to
aspiration at the time of extubation. Management consists
of supportive measures and depending on the extent of
aspiration may include reintubation and ventilation with
positive end-expiratory pressure.
Macroglossia
It may complicate prolonged posterior fossa surgery
performed in the sitting, prone, or park-bench position.
42
Tongue enlargement may also be traumatic, haemorrhagic,
vascular, or inflammatory. It may worsen after tracheal
tube removal, leading to partial or complete airway
obstruction.
43 Tracheal reintubation may prove difficult or
impossible.
Conclusion
Many tracheal extubations are accompanied by
relatively benign, transient complications. In certain settings,
the risk of the patient requiring tracheal reintubation are
increased. Tracheal reintubation are generally more
complex because of associated hypoxia, hypercarbia,
haemodynamic problems, agitation, and airway obstruction.
Tracheal reintubation over tube changers is neither
without complications nor 100% successful; therefore, who
use these devices should be familiar with the equipment
and techniques, their potential complications, and alternatives
in case of reintubation failure. Finally, the high risk patients
should be identified if at all possible. Moreover, a senior
anaesthesiologist with experience in difficult airway and a
trained nurse should always be present alongside the airway
manager, which may improve patient safety.
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