Anatomical and/or neuromuscular abnormalities may cause obstructive sleep apnea (OSA). We have developed a unique method to separate these two factors in order to evaluate the intrinsic mechanical properties of the pharynx. In this method, we depressed pharyngeal dilator muscle activities by providing sufficient muscle blockade under general anesthesia. During experimentally-induced apnea, airway pressure was manipulated from 20 cmH2O to velopharyngeal closing pressure while we endoscopically observed one of the pharyngeal segments. The collapsibility of the pharynx was assessed via the static pressure/area relationships of the pharynx. Employing this method, we attempted to predict the UPPP outcome. We hypothesized that the severity of sleep disordered breathing after UPPP may be related to the collapsibility of the oropharynx. Our preliminary results from 24 patients with OSA supported the hypothesis : We found a direct relationship between the collapsibility of the oropharynx and the severity of the sleep-disordered breathing. Accordingly, our endoscopic evaluation of the pharyngeal mechanics during anesthesia may be useful for the prediction of UPPP outcomes.
