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[Effects of surface anesthesia of the pharyngeal mucous membrane on negative pressure airway reflex]
Yoshiko Matsuda1, Takashi Kamada, Kenji Murata
1Department of Anesthesiology, Osaka Dental University, Osaka 540-0008.
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.
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