Anesthesia Management |
|Part C:||Anesthesia Techniques|
|Chapter 39:||Airway Management|
Complications of Extubation
Airway obstruction, laryngospasm, and aspiration are complications that have been previously discussed. Note that after intubations lasting 8 hours or more, airway protection may be impaired for 4 to 8 hours. 159 Sore throat is a complication of anesthesia that may have pharyngeal, laryngeal and/or tracheal sources and may occur in the absence of endotracheal intubation. 160 Factors that may affect the incidence of sore throat include area of cuff-trachea contact (tracheitis), use of lidocaine ointment and size of the endotracheal tube (laryngitis), and the use of succinylcholine (pharyngitis). Cuffs with a longer cuff-trachea interface appear to cause a higher incidence of sore throat. 161 The incidence of sore throat may also be related to intracuff pressures. 162 As previously noted, lidocaine ointment has a questionable effect on the incidence of sore throat. The higher incidence of sore throat in women is probably related to the tube size/laryngeal size relationship. One study demonstrated that tube size is related to the incidence and severity of sore throat in both sexes. 163 This study did not find that the use of succinylcholine was related to sore throat but other workers have reported succinylcholine to be a contributing factor and that nondepolarizing pretreatment reduced the incidence somewhat (from 68 to 45%). 63 The mechanism for succinylcholine-related sore throat is postulated to be myalgias due to fasciculation of peripharyngeal muscles. Sore throat is a minor side effect that should resolve within 72 hours and should not be a factor in determining whether endotracheal intubation is required. It may also occur with the use of an LMA. Hoarseness is another minor side effect correlated with endotracheal tube size and should be investigated if persistent.
Laryngeal edema is most commonly symptomatic in children because their small airway size is more severely reduced by edema; i.e. edema producing only hoarseness in an adult may cause a significant reduction in laryngeal cross-sectional area in a small child. Subglottic edema is particularly more common in children as the nonexpandable cricoid cartilage is the narrowest part of the pediatric airway. Edema may also be uvular, supraglottic, retroarytenoid, or at the level of the vocal cords. The precise diagnosis may be made with fiberoptic laryngoscopy, but this is not usually necessary. Stridor is produced by the extrathoracic obstruction that produces mainly inspiratory wheezing. Diminished stridor may represent total airway obstruction, and movement of air must be repeatedly confirmed. The contributing factors to the production of laryngeal edema are somewhat controversial but include too large a tube, trauma from laryngoscopy and/or intubation, excessive neck manipulation during intubation and surgery, excessive coughing or bucking on the tube, and present or recent upper respiratory infection. The prophylactic use of steroids before extubation to reduce edema is an unproven but frequently utilized treatment if the likelihood of postextubation stridor is suspected. Treatment includes warmed, humidified oxygen, nebulized racemic epinephrine (.251mL), and IV dexa-methasone (.5 mg/kg up to 10 mg). If obstruction is severe and persistent, reintubation must be considered.
Vocal cord paralysis may be due to surgical injury of the recurrent laryngeal nerve or from the endotracheal tube cuff. 164 Vocal cord edema occurring in the presence of a paralyzed cord may precipitate complete airway obstruction as can bilateral cord paralysis. It may be prudent to pursue preoperative otolaryngologic evaluation of the hoarse patient for elective surgery so that important pathology is detected and so that subsequent vocal problems are not entirely attributed to the anesthesiologist. The arytenoid cartilage may be dislocated by the laryngoscope blade and result in a weak voice after extubation that may require surgical correction. 165, 166 Other complications include ulcerations or granulomas of the vocal cords that may result in persistent hoarseness. 167 More serious complications resulting in laryngeal or tracheal stenosis are extremely rare sequelae of short-term perioperative intubation. 168
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