Airway patency in the unconscious patient.

Airway patency was explored in patients breathing spontaneously under deep halothane anaesthesia. Opening and closing of the airway was observed with a flexible bronchoscope looking proximally from the nasopharynx at the epiglottis and the tongue. With the occiput elevated at various angles the smallest angle of retroflexion of the neck necessary to open the airway was measured. The influence of artificial airways on this angle of retroflexion was measured. Cadaveric preparations of the upper airway were studied to assess the mechanisms involved in airway patency. The results indicate that the epiglottis and not the tongue is the main cause of obstruction of the upper airway. When methods are applied to displace the hyoid anteriorly, the airway will be cleared on most occasions.