Module 3
Complications of Managing the Airway
Complications with Extubation
Primary and secondary responses to
extubation are possible. The primary effects include local
and systemic responses. The same responses that follow
intubation may be observed at extubation. During
intubation the patient is more protected by anesthesia induction
than during extubation, therefore the cardiovascular responses
may be even more exaggerated. The most serious
complication after extubation is the occurrence of acute airway
obstruction. Decrease in consciousness, central
respiratory depression, decrease in muscle tone, and tongue
obstruction may lead to inspiratory or expiratory stridor,
dyspnea, cyanosis, tachycardia, hypertension, agitation and
sweating.
HEMODYNAMIC CHANGES
Hemodynamic changes, including a 20%
increase in heart rate and blood pressure, occur in most
patients at the time of extubation. Patients with cardiac
disease, pregnancy-induced hypertension30
and increased intracranial pressure may be at particular risk
for life-threatening ischemic myocardial episodes.
Management consists of deep extubation or pharmacologic therapy.
LARYNGOSPASM
Laryngospasm, a protective reflex mediated
by the vagus nerve, is the most frequent cause of postextubation
airway obstruction. It may be provoked by movement of the
cervical spine, pain, vocal cord irritation by secretions, or
sudden stimulation while the patient is still in a light plane
of anesthesia. In a large study in 136,929 patients, the
incidence of laryngospasm was 50/1000 in children with bronchial
asthma and airway infection and 25/1000 in children in the age
group of 1–3 months when endotracheal intubation had been
performed.44
The optimal course for dealing with
laryngospasm is to avoid it. It is imperative that no
saliva, blood, or gastric contents touch the glottis while the
patient is lightly anesthetized. In cases in which
laryngospasm is anticipated, the patient may undergo a deep
extubation. A patient undergoing deep extubation should be
placed in the lateral position with the head down to keep the
vocal cords clear of secretions during emergence. Because
suctioning of the oropharynx does not adequately remove
secretions around the vocal cords, it is best to extubate
patients during a positive-pressure breath. This is the
procedure of choice in children too. In a recent study,
children could be safely extubated in deep anesthesia from 1.5
minimum effective alveolar anesthetic concentration of either
sevoflurane or desflurane.45
In a survey of United States
anesthesiologists deep extubation is performed by 64% of the
interviewed practitioners.46
The study of Koga et al47
has shown that the rate of airway obstruction in patients
extubated during deep anesthesia (17/20) was not higher than in
patients extubated after regaining consciousness (18/20).
LARYNGEAL EDEMA
Laryngeal edema is an important cause of
postextubation obstruction, especially in neonates and infants.
Supraglottic edema most commonly results from surgical
manipulation, positioning, hematoma formation, overaggressive
fluid management, impaired venous drainage, or coexisting
conditions (such as pre-eclampsia or angioneurotic edema).
Retroarytenoidal edema typically results from local trauma or
irritation. Subglottic edema occurs most often in
children, particularly neonates and infants. Factors
associated with the development of subglottic edema include
traumatic intubation, intubation lasting longer than 1 hour,
bucking on the endotracheal tube, changes in head position, or
tight-fitting endotracheal tubes. Laryngeal edema usually
presents as stridor within 30–60 minutes after extubation,
although it may start as late as 6 hour postextubation.48
Regardless of the cause of laryngeal edema, management depends
on the severity of the condition. Therapy consists of
humidified oxygen, racemic epinephrine, head-up positioning, and
occasionally reintubation with a smaller endotracheal tube.
The practice of administering parenteral steroids with the goal
of preventing or reducing edema is controversial.48
BRONCHOSPASM
In patients at risk for bronchospasm the
timing of extubation is of equal concern. These patients may be
extubated either during deep anesthesia (if this approach can be
used safely) or when they are fully awake and the own airway
reflexes are present. Although the degree of spasm in this
condition may be severe, it is usually self-limited and
shortlived.
NEGATIVE-PRESSURE PULMONARY EDEMA
When airway obstruction occurs after
extubation, such as in case of laryngospasm, negative-pressure
pulmonary edema may occur in the spontaneously breathing
patient. As a result of inspiratory effort against the
closed glottis, these patients generate negative intrapleural
pressure >100 cmH2O. Increases in left
ventricular preload and afterload, altered pulmonary vascular
resistance, increased adrenergic state, right ventricle
dilatation, intraventricular septum shift to the left, left
ventricular diastolic dysfunction, increased left heart loading
conditions, enhanced microvascular intramural hydrostatic
pressure, negative pleural pressure, and transmission to the
lung interstitium may result in a marked increase in transmural
pressure, fluid filtration into the lung and development of
pulmonary edema.49
The condition is seen within minutes after
extubation. Management involves removing the obstruction,
supporting the patient with oxygen, monitoring the patient
closely, and reducing the afterload. Reintubation is
rarely necessary; most cases resolve spontaneously without
further complications.
ASPIRATION
Pulmonary aspiration of gastric contents
is a constant threat for any patient who has a full stomach or
is at risk for postoperative vomiting. Laryngeal function
is altered for at least 4 hour after tracheal extubation.
Depression of coughing reflexes, along with the presence of
residual anesthetic agents, places almost all recently extubated
patients at risk. Aspiration is probably more
prevalent than is currently thought. Most cases are so
minor that they do not affect the patient’s postoperative
course. Reducing gastric contents by suctioning through a
gastric tube and extubation with the patient placed in the
lateral position with a head-down tilt is the safest protection
against aspiration.
AIRWAY COMPRESSION
External compression of the airway after
extubation may lead to obstruction. A rapidly expanding
hematoma in close proximity to the airway is a very dangerous
situation. This may occur after certain surgeries, such as
carotid endarterectomy, and must be quickly diagnosed and
treated before total airway obstruction occurs. Immediate
surgical re-exploration is indicated, although the airway
concerns in these patients should be approached with extreme
caution.
External compression of the neck, such as
chronic compression of a goiter, may also result from
tracheomalacia. Management includes reintubation,
surgical tracheal support (stenting), or tracheostomy below the
level of obstruction.
DIFFICULT EXTUBATION AND ACCIDENTAL EXTUBATION
Possible causes of difficult removal of
the endotracheal tube are failure to deflate the cuff, use of an
oversized tube, adhesion of the tube to the tracheal wall, or
transfixation of the tube by an inadvertent suture to a nearby
organ or a screw in the oro-maxillofacial surgery.
Possible sequelae of these complications include airway leak,
aspiration, tube obstruction, and trauma from attempts at
forceful extubation. In most cases the problem arises from an
inability to deflate the cuff, commonly as a result of failure
in the cuff-deflating mechanism. Should this problem
occur, the cuff should be punctured with a transtracheal needle.
Forceful removal of an endotracheal tube with the cuff inflated
may result in damage to the vocal cords and arytenoid
dislocation.
Accidental extubation during anesthesia
may occur with disposable tonsillectomy instruments and change
of the patient’s head position. Most accidental
extubations were reported from intensive care unit patients.50
Complications after accidental extubation may include hypoxia,
hypercarbic respiratory failure, aspiration, retention of
pulmonary secretion, arrhythmia and tachycardia.
Reintubation may be very difficult, especially after a difficult
intubation. The use of the combitube or the LMA may be
very useful in this critical situation.
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