The term supraglottic airway (SGA) or supraglottic airway device (SAD) describes a heterogeneous group of airway devices that allow ventilation and oxygenation by sitting above the glottis. The first device of this kind was the laryngeal mask airway (LMA). SGAs are classified according to their characteristics into first-generation and second-generation devices. First-generation devices include the LMA Classic, LMA Unique, LMA ProSeal, LMA Supreme, and the first version of the Air-Q. Second-generation devices generally have an additional conduit for orogastric tube insertion and higher oropharyngeal leak pressures, and some of them allow SGA-guided fiberoptic intubation.1,2 SADs result in less cervical spine movement than traditional laryngoscopes.3 This can be useful for prehospital providers and the Emergency Department patient with potential cervical spine injury.
The 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. The LMA was approved for use in the United States by the Food and Drug Administration in 1991.
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.4 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. Pressures of up to 30 cmH2O may be administered safely with the introduction of the LMA ProSeal (A. I. J. Brain, MD, personal communication). The LMA may be used as a conduit for fiberoptically guided ET intubation or to place an ET tube blindly.5 The LMA has come to be viewed as a viable method of airway management, with over 1000 articles and case reports describing the advantages and disadvantages of the device.6 A more recent Medline search for articles involving the use of LMAs yielded over 6000 results.
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.7 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.7,8
There are approximately nine different models of the LMA ...