EXTUBATION

Guidelines

Extubation of the trachea may be performed while the patient is deeply anesthetized or is nearly fully awake. Deep or, more precisely, anesthetized extubation is performed after muscle relaxants have been fully reversed and the patient is maintaining an acceptable respiratory rate and depth. A difficult mask airway, difficult intubation, risk of aspiration, or surgery that may produce airway edema or maintenance problems are contraindications to such extubation. Adequate recovery of the ability to maintain and protect the airway must be demonstrated after the use of neuromuscular relaxants.^[56] Adequate ventilation through an endotracheal tube does not guarantee the muscle strength to maintain the airway. Sustained tetanus using a nerve stimulator is very painful in the conscious patient, but a sustained (5-second) head lift is an excellent way to assess clinically adequate reversal. If head lift is contraindicated or painful, leg lift or sustained tongue protrusion can be similarly assessed. As the anesthetic level diminishes, the patient is suctioned, and the tube is removed after a positive-pressure breath has been given with the anesthesia bag to allow subsequent expulsion or secretions out of the glottis. Advantages include reduced coughing on the endotracheal tube that may lessen laryngotracheal trauma and cause less adverse effects. However, the airway must be scrupulously maintained because obstruction and aspiration remain possibilities. As the patient awakens, laryngospasm and cough may occur anyway. Because there is no way to entirely avoid such coughing after an anesthetic, many physicians regard deep extubations merely as premature extubations. The perspective appears valid because current anesthetic practice seldom uses techniques of truly deep anesthesia.

When such extubations in the anesthetized state are contraindicated, awake extubation is essential. The patient is not extubated until judged ready to maintain and protect the airway. The patient who is unresponsive to verbal stimuli, has deviation of the eyes, or is breathholding is not ready for extubation and is prone to laryngospasm, which is most likely to occur when patients are extubated in between awake and anesthetized states. Coughing and bucking probably indicate the ability to protect the airway, but the timing of awake extubation remains a matter of clinical judgment. Lidocaine (1 to 1.5 mg/kg given intravenously) or a small dose of narcotic may help smooth out awake extubation at the cost of prolonging the process of awakening. After extubation, the patient may be maintained in the supine or lateral position. After anesthetized extubation, oral or nasal airways are usually left in place until the patient can no longer tolerate them. Vigilance should not be relaxed at this time.

Difficult removal is usually the result of leaving the endotracheal tube cuff inflated. If the cuff cannot deflate because of obstruction in the tubing, it can be punctured by a needle placed through the cricothyroid membrane after the cuff is raised to this level. More serious and somewhat unusual causes of difficult extubation include fixation of the endotracheal tube or pilot tube by a Kirschner wire used in head and neck surgery or a suture placed from the pulmonary artery through the trachea into the endotracheal tube. A tangled nasogastric tube, swollen or tense vocal cords, or a "barb" accidentally cut on the endotracheal tube can interfere with extubation. The nature of the surgical procedure must be kept in mind when a tube does not come out after cuff deflation or rupture to avoid trauma from vigorous extubation attempts. Direct or fiberoptic examination may be required.

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Special care must be taken in a variety of potential high-risk extubations when the ability to immediately reestablish the airway is questionable. The endotracheal tube may be removed while leaving a device such as a tube changer, nasogastric tube, or bronchoscope within the trachea so that the airway can be immediately reestablished if necessary.^[57] A variety of tube changer devices are available and may be employed with jet ventilation (Cook Airway Exchange Catheter, Cook Critical Care; Sheridan TTX Tracheal Tube Exchanger, Sheridan Catheter Corp., Argyle, NY; Endotracheal Ventilation Catheter, CardioMed Supplies, Gormley, Ontario, Canada). The presence of such a device does not guarantee that the tracheal tube can be replaced. Supraglottic devices such as the LMA may or may not be successful in establishing an airway because the pathology may be at the supraglottic level or below. The presence of an individual who can establish a surgical airway (along with the necessary equipment) may be reasonable in selected instances of anticipated difficult extubation, particularly if there is no leak when the endotracheal tube cuff is let down.^[58] The latter suggests the likelihood of glottic or subglottic edema.