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The laryngeal mask airway (LMA) is a device that fills the gap in airway management between that of endotracheal (ET) intubation and the use of a face mask. It was introduced in the United Kingdom in 1983 by British anesthesiologist A. I. J. Brain. His goal was to develop an airway apparatus that could rapidly overcome an obstructed airway, is simple to use, and is atraumatic to insert. In 1991, the LMA was approved for use in the United States by the Food and Drug Administration.
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The LMA was designed primarily as a means of providing ventilatory support while avoiding the fundamental disadvantage of the need to visualize and penetrate the vocal cords with an ET tube.1 The LMA is introduced into the hypopharynx without direct visualization. It forms a low-pressure seal around the laryngeal inlet and permits positive-pressure ventilation. With the introduction of the LMA ProSeal, pressures of up to 30 cmH2O may be administered safely (A.I.J. Brain, M.D., personal communication). Once inserted, the LMA may be used as a conduit for fiberoptically guided ET intubation or to place an ET tube blindly.2 The LMA has come to be viewed as a viable method of airway management, with over 800 articles and case reports describing the advantages and disadvantages of the device.3 A more recent Medline search for articles involving the use of LMAs yielded over 3500 results.
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Many disadvantages of the standard LMA became apparent with widespread use of the device. More than 10 years after its introduction, Dr. Brain and colleagues began to work on a new airway system with better intubation characteristics than the standard LMA. The intubating laryngeal mask airway (ILMA) was developed through the aid of analysis of magnetic resonance images of the human pharynx and laboratory testing of ET tubes.4 The new and more “anatomically correct” ILMA effects more precise placement. The design of the ILMA also avoids head and neck manipulation and insertion of the intubator's fingers into the patient's mouth, both of which occur during the placement of the standard LMA.4,5
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There are approximately nine different models of the LMA. The term “laryngeal mask airway” is specific to one brand of laryngeal mask devices produced by LMA North America, San Diego, CA. Several other manufactures also make laryngeal mask devices. Some of these will also be described in this chapter. The LMA Classic (LMA-C) is the original and most commonly used version. The LMA Classic Excel (LMA-CE) is more durable than the original LMA-C and can be reused up to 60 times. The LMA Unique (LMA-U) is a single-use disposable version of the LMA-C. The LMA Flexible is a wire-reinforced version of the LMA that is more flexible than the original version and resists kinking. It is used by Anesthesiologists for patients undergoing head and neck procedures. It is not used in the Emergency Department. The LMA Fastrach is a ...