WHY SHOULD WE ENLARGE THE PHARYNX IN OBSTRUCTIVE SLEEP-APNEA

Patency of the collapsible segment of the pharynx is dependent upon th e interplay of anatomic and physiologic factors. The upper airway of t he typical patient with obstructive sleep apnea (OSA) is structurally narrowed by fat deposits in the lateral pharyngeal walls. During wakef ulness, the upper airway dilator muscles compensate for the structural ly reduced pharyngeal size by increasing their activity, thereby pulli ng the tongue and soft palate forward. As a consequence, the cross-sec tional area is relatively preserved, but the shape of the pharynx beco mes elliptical along the anteroposterior axis. In the awake patient wi th OSA, patency of the pharynx is largely dependent upon increased dil ator muscle activity. During sleep, the activity of the muscular appar atus of the pharynx decreases causing a critical narrowing. Because an atomic narrowing appears to be a basic feature, enlarging the pharynx should be beneficial, particularly if its lateral diameter can be incr eased. Whereas facial advancement surgery structurally increases the a nteroposterior diameter of the pharynx, thereby accounting for the goo d results reported with this technique, it is doubtful that uvulopalat opharyngoplasty has a similar effect on either the anteroposterior or lateral diameters of the pharynx.