The Leech airway: precursor to the modern supraglottic airway
The main driving force for inventing what came to be called the Leech airway was the increasing popularity of cyclopropane-based anesthesia, which required a semi-closed system for administration due to its volatility and relative expense.2 Leech’s objective was to design a one-size-fits-all device that could create a tight seal within the airway without the need for intubation (which was a relatively tedious and time-consuming procedure compared with today’s intubations).2 To achieve this goal, Leech created pharyngeal wax casts from cadavers to assess the general size and shape of the human adult pharynx and determine its “average size”.1 The Leech airway was used in patients undergoing ear, nose, head and neck, and ophthalmic procedures.2 It was especially noted for its superiority over other means of administering nitrous oxide during minor dental procedures and tooth extractions.3
The Leech airway is often regarded as the inspiration for, and precursor to, the original Laryngeal Mask Airway (LMA™; Teleflex Inc.), which was developed during the early 1980s by the British anesthesiologist Archie Brain, who cited Leech’s airway in his own patent application.3 The main difference between the two devices is that the Leech airway was positioned higher in the pharynx than the LMA. The Leech airway was widely used well into the late 1950s, after which its use declined. The primary reason for its waning use was the introduction of suxamethonium. In a letter4 written by Leech in 1957, he said “I rarely use it myself anymore, since rapid acting relaxants have made intubation so simple”.4
Leech BC. Pharyngeal bulb gasway. Patent for the Leech airway filed on December 30th, 1936. Patent was granted on November 16th, 1937 (US patent number 2099127 A). Available from URL: https://www.google.com/patents/US2099127 (accessed December 2017).
Maltby JR. Leech pharyngeal bulb gasway. The History of Anaesthesia Society Proceedings. Proceedings of the Summer Scientific Meeting - 25th and 26th June 2010 - volume 42: 95-101. Available from URL: http://www.histansoc.org.uk/uploads/9/5/5/2/9552670/9865-1.pdf (accessed December 2017).
Brain AI. Artificial airway device. Patent for supraglottic airway device filed on December 16th, 1981. Patent was granted on December 14th, 1982 (US patent number 4509514 A). Available from URL: https://www.google.com/patents/US4509514 (accessed December 2017).
Leech BC. Letter to Dr. Intress 13 March 1957. Wood Library - Museum of Anesthesiology, Park Ridge, Illinois.
Conflicts of interest
This submission was handled by Dr. Hilary P. Grocott, Editor-in-Chief, Canadian Journal of Anesthesia.