[Effects of surface anesthesia of the pharyngeal mucous membrane on negative pressure airway reflex].
BACKGROUND
Upper airway reflexes include a reflex protecting the airway as well as another one dilating the airway. The latter reflex, the pharyngeal dilator reflex to negative airway pressure (NPAR), plays an important role in maintaining airway patency, although the peripheral receptors involved in NPAR have not been specified.


METHODS
The effects of surface anesthesia of the pharyngeal mucous membrane on NPAR were evaluated by observing activity of the musculus genioglossus (GG) in rabbits. Following anesthesia with thiopental, two incisions were made on the trachea of each rabbit. Through these incisions, a tube connected to the anesthetic circuit was inserted into the lung and another tube connected to an aspirator into the pharynx. Effects of negative pressure on the myelogram of the GG were recorded with and without surface anesthesia with 1% lidocaine.


RESULTS
Electric discharge from the GG was increased in the sessions with exposure to negative pressure without surface anesthesia, but was significantly decreased in those with surface anesthesia.


CONCLUSIONS
These findings suggest that the peripheral receptors of NPAR are located in the pharyngeal mucous membrane.
Matsuda
Yoshiko
Y
Department of Anesthesiology, Osaka Dental University, Osaka 540-0008.
Kamada
Takashi
T
Murata
Kenji
K
Kotani
Junichiro
J
D000403:Airway Resistance / Q000502:physiology*; D000772:Anesthesia, Local; D000818:Animals; D004576:Electromyography; D008012:Lidocaine; D008297:Male; D008465:Mechanoreceptors / Q000502:physiology*; D009092:Mucous Membrane; D010609:Pharyngeal Muscles / Q000502:physiology; D010614:Pharynx; D011817:Rabbits; D012018:Reflex / Q000502:physiology*
D008012:Lidocaine