Laryngeal Mask Airway

The laryngeal mask airway (LMA) (Intavent, Ltd.) (Fig 14-6) was developed by Brain in 1983 as another artificial airway that can be placed blindly yet can provide a positive-pressure airway. The LMA consists of a tubular oropharyngeal airway similar to the ETT, but it is shorter and has a distal silicone laryngeal mask (balloon-type bulb) that inflates and provides a seal around the larynx. The LMA, when placed, is similar to other esophageal airways in that it can be inserted without manipulation of the patient's head. Because of its large diameter and short length, intubation of the bronchi or esophagus is circumvented. The hypopharynx, which is adapted to the passage of food, is less sensitive to a foreign body than the larynx and vocal cords, which have sensitive, protective reflexes. Many published cases show the LMA to be an effective alternative when the ETT fails because of nonvisualization of the cords secondary to ETT difficulty, airway masses, or cervical pathology.4 Studies of LMA use by nonphysician emergency personnel in fasting patients found it easier to place than the ETT. The LMA never failed, versus 21 percent of failures for the ETT, required only half as many attempts and one-fifth the time to perform, and was rated equal to the ETT as an airway by anesthesiologists.5 Some of the complications included partial or complete respiratory obstruction (3 percent). In general, failure to protect against aspiration of gastric contents was noted. The LMA was also inadequate in severe chronic obstructive pulmonary disease (COPD) because of the high pressure requirement. 6 Applying cricoid pressure in the acute setting almost always impedes insertion of the LMA and therefore reduces the chance of successful ventilation of the patient. 7 Therefore the LMA seems an effective alternative to the ETT when endotracheal intubation fails or when cervical pathology exists.

FIG. 14-6. A. Laryngeal mask airway (LMA). B. LMA diagram showing placement at the larynx. (Used with permission.)

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