ADVANCEMENT OF THE MANDIBLE IMPROVES VELOPHARYNGEAL AIRWAY PATENCY

The velopharynx is the most common site of obstruction in patients wit h obstructive sleep apnea (OSA). Advancement of the mandible effective ly reverses the pharyngeal obstruction. Accordingly, we hypothesized t hat mandibular advancement increases cross-sectional area of several s egments of the upper airway, including the velopharynx and the orophar ynx. We examined the pressure-area properties of the pharyngeal airway in 13 patients with OSA. Under general anesthesia and total muscle pa ralysis, the pharynx was visualized with an endoscope connected to a v ideo-recording system. During an experimentally induced apnea, we mani pulated the nasal pressure from 20 cmH(2)O to the point of total closu re at the velopharynx. The procedure was repeated after maximal forwar d displacement of the mandible. Measurements of the cross-sectional ar ea at different levels of nasal pressure allowed construction of a sta tic pressure-area relationship of the ''passive pharynx,'' where activ e neuromuscular factors are suppressed. In 12 of 13 patients with OSA, advancement of the mandible stabilized the airway by reducing the clo sing pressure and increasing the area at any airway pressure. Thus the maneuver shifted the static pressure-area curve of the velopharynx an d the oropharynx upward in these patients. We conclude that anterior m ovement of the mandible widens the retropalatal airway as well as that at the base of the tongue in the passive pharynx of OSA patients.