Virtual Disaster Medicine

Training Center (VDMTC)

Module 3

Complications of Managing the Airway

Complications with Intubation

ENDOTRACHEAL INTUBATION

The main injury associated with use of laryngoscopes is damage to the teeth.  Laryngoscopy usually requires deep anesthesia because it causes stimulation of physiological reflexes, and adverse respiratory, cardiovascular and neurological effects are possible (Table 2).  Patients with a history of hypertension, pregnancy-induced hypertension and ischemic heart disease are at additional risk.  Deep anesthesia, application of topical anesthetics, drug prevention of the sympathoadrenal response using atropine or intravenous lidocaine, as well as minimizing mechanical stimulation, attenuate these adverse effects.  Rigid optical instruments such as the Bonfils Retromolar Intubation Fiberscope, the Bullard, Upsher and WuScope laryngoscopes and the rigid bronchoscope have similar complications. 

Table 2 - Pathophysiological effects and complications of laryngoscopy and endotracheal intubation.  Modified from Shang Ng,W. (1997, in Latto I.P, Vaughan RS (eds) Difficulties in Tracheal Intubation, pp. 000–000. London: Saunders) with permission.

There is a close relationship between difficult intubation and traumatic intubation.  In cases of difficult intubation (poor view of the vocal cords), the practitioner tends to increase the lifting forces of the laryngoscope blade, which may lead to damage of the intraoral tissues and osseous structures.  A difficult intubation may thus become a traumatic intubation. Use of increasing force may induce swelling, bleeding or perforation as the intubation becomes more and more difficult and may turn into a ‘cannot intubate’ and possibly even a ‘cannot ventilate’ situation.  If intubation fails after three attempts, another technique should be used in accordance with the airway management algorithm.¹⁴

Lip injuries include lacerations, hematomas, edema, and teeth abrasions.  They are usually secondary to inattentive laryngoscopy performed by inexperienced practitioners.  These lesions are annoying to the patient, but are usually self-limited.

The incidence of dental injuries associated with anesthesia is greater than 1:4500.¹⁵  Maxillary central incisors are at most risk. Fifty percent of dental trauma happens during laryngoscopy, 23% following extubation, 8% during emergence, and 5% in the context of regional anesthesia.  Dental trauma is also associated with LMA devices and oropharyngeal airways.  Dental injuries are most common in small children, patients with periodontal disease or fixed dental work, and patients in whom intubation is difficult.  Pre-existing dental pathology (protrusion of the upper incisors, carious teeth, paradentosis or periodontitis) should be thoroughly explored before the induction of anesthesia, and the patient must be advised of the risk of dental damage.  Although tooth guards may possibly obstruct vision, their use may be indicated in certain situations.

In the event that an entire tooth is avulsed, it should be retrieved and saved in a moist gauze or in normal saline.  Aspiration of the tooth may induce serious complications requiring bronchoscopy for removal.  With a rapid response from an oral surgeon or dentist, an intact tooth can often be reimplanted and saved, but only when performed within 1 hour.

Massive tongue swelling, or macroglossia, has been reported in numerous instances in both adult and pediatric patients.  Although macroglossia (occasionally of lifethreatening proportions) is associated with angiotensin-converting enzyme inhibitors, some cases have occurred while a bite block was in place and when there was substantial neck flexion during endotracheal intubation.  Loss of tongue sensation is possible after a compression injury to the lingual nerve during forceful laryngoscopy or after LMA placement with an over-inflated or malpositioned cuff.  Reduced sense of taste and cyanosis of the tongue caused by lingual artery compression are additional injuries that may be caused by an oversized, malpositioned, or overinflated LMA.

Damage to the uvula (edema and necrosis) is usually associated with an endotracheal tube, oro- and nasopharyngeal airways, an LMA, or an alternative supraglottic airway device, or by overzealous use of a suction catheter. Sore throat, odynophagia, painful swallowing, coughing, foreign body sensation and serious life-threatening airway obstruction have been reported.

The incidence of sore throat after intubation is approximately 40% and >65% when blood is noted on the airway instruments.¹⁶  The incidence of sore throat following LMA placement is 20–42%, depending on cuff inflation, and 8% with face mask ventilation.¹⁷  Fortunately, pain on swallowing usually lasts no more than 24–48 hours. Topical anesthesia, such as lidocaine jelly, applied to the endotracheal tube does not lessen the incidence of this problem and may actually worsen it.

Trauma to the larynx and vocal cords is not uncommon following endotracheal intubation.  It depends on the experience and skill of the intubator, as well as the degree of difficulty.  In one large study, 6.2% of patients sustained severe lesions, 4.5% developed a hematoma of the vocal cords, 1% developed a hematoma of the supraglottic region, and 1% sustained lacerations and scars of the vocal cord mucosa.¹⁸  Recovery is generally prompt with conservative therapy, although hoarseness may appear even after a 2-week interval.¹⁹  Granulations usually occur as a complication of long-term intubation but may occur with short-term intubation as well.  Injuries of the laryngeal muscles and suspensory ligaments are also possible.  Patients with hoarseness should be examined preoperatively by an ENT specialist.

Arytenoid dislocation and subluxation have been reported as rare complications.²⁰  Mitigating factors include traumatic and difficult intubations, repeated attempts at intubation, and attempted intubation using blind techniques such as light-guided intubation, retrograde intubation, and the use of the McCoy laryngoscope.  However, these complications are also found after easy intubations.  Early diagnosis and operative repositioning of arytenoid dislocation is necessary, because fibrosation with consecutive malposition and ankylosis may occur after 48 hours.

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