Advancement of the mandible improves velopharyngeal airway patency. Isono, Shiroh, Atsuko Tanaka, Yasuhide Sho, Akiyoshi Konno, Takashi Nishino. Department of Anesthesiology and Otolaryngology, Chiba University School of Medicine, Chiba, Japan
APStracts 2:0363A, 1995.
The velopharynx is the most common site of obstruction in patients with obstructive sleep apnea (OSA). Advancement of the mandible effectively reverses the pharyngeal obstruction. Accordingly, we hypothesized that mandibular advancement increases cross-sectional area of several segments of the upper airway, including the velopharynx and the oropharynx. We examinedhe pressure/area properties of the pharyngeal airway in 13 patients with OSA. Under general anesthesia and total muscle paralysis, the pharynx was visualized with an endoscope connecting to video recording system. During an experimentally-induced apnea, we manipulated the nasal pressure from 20 cmH2O to the point of total closure at the velopharynx. The procedure was repeated after maximal forward displacement of the mandible. Measurements of the cross-sectional area at different levels of nasal pressure allowed construction of static pressure/area relationship of the "passive pharynx", where active neuromuscular factors are suppressed. In 12 of 13 patients with OSA, advancement of the mandible stabilized the airway by reducing the closing pressure, and increases the area at any airway pressure. Thus, the maneuver shifted the static pressure/area curve of the velopharynx and the oropharynx upward in these patients. We conclude that anterior movement of the mandible widens the retropalatal airway as well as that at the base of the tongue in passive pharynx of OSA patients. 

Received 5 May 1995; accepted in final form 3 August 1995.
APS Manuscript Number A475-4.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 24 August 1995.