The leech airway or pharyngeal bulb gasway

Beverley Charles Leech (1898 to 1960) patented the Leech airway or "Pharyngeal Bulb Gasway" in 1937. The Leech airway formed a seal with the pharyngeal tissues, resulting in a closed system during cyclopropane anaesthesia. Two prototypes and four commercially available versions of the airway have been identified.