To the Editor:—
New extraglottic airway devices have been described at a rate of one per year for the last 25 yr, increasing to two per year since the turn of the century. I would like to propose a classification system for this increasingly complex family of devices. It involves three main criteria. First: whether the device is uncuffed or cuffed. This relates to its suitability as a ventilatory device; those without cuffs require a face or nasal mask (extracorporeal devices) to facilitate ventilation. Second: whether it is inserted through the mouth or nose. Third: the anatomic location of the distal portion in relation to the hypopharynx.*This relates to the potential degree of isolation of the respiratory and gastrointestinal tracts. If the distal portion sits above the hypopharynx (oral cavity, nasal cavity, nasopharynx, oropharynx and laryngopharynx†) there is no isolation. If the distal portion sits in the hypopharynx there is some isolation. If the distal portion sits below the hypopharynx (esophagus) there is moderate isolation. In contrast, with a cuffed endotracheal tube there is considerable isolation.
There are four other potential criteria for classification, but these are less suitable. First: the anatomic location of the distal airway aperture. This relates to its efficacy to provide a clear airway and for ease of instrumentation of the respiratory tract; the shorter the distance between the distal airway aperture and the glottic inlet, the greater the efficacy of both—however, the distal airway aperture of most extraglottic airway devices is located in the laryngopharynx. Second: whether the extraglottic airway device is used as an airway intubator; however, most extraglottic airway devices are capable of facilitating intubation. Third: whether the device is disposable or reusable; however, this provides no information about function. Fourth: whether the cuff is in the proximal pharynx (e.g. , laryngeal tube airway) or surrounds the periglottic tissues (e.g. , laryngeal mask airway); however, this only applies to the subset of cuffed extraglottic devices.
Finally, it is worth noting that the term “extraglottic airway device” is more appropriate than “supraglottic airway device,” since many have components that are infraglottic, but all lie outside the glottis. The modern extraglottic airway devices (post-1980) are listed in table 1according to the proposed classification.
James Cook University, Cairns Base Hospital, The Esplanade, Cairns, Australia. email@example.com