RELATIONSHIP BETWEEN VELOPHARYNGEAL DIMENSIONS AND PALATAL EMG DURINGPROGRESSIVE HYPERCAPNIA

To examine the contribution of specific palatal muscles to velopharyng eal dimensions, we recorded electromyographic (EMG) activity in the le vator veli palatini, the tensor veli palatini, and the palatoglossus w hile examining the velopharynx (VP) with videoendoscopy in eight awake normal adults. Simultaneous display of VP images and airflow provided precise timing of events. Video images and EMG signals were recorded during progressive hypercapnia. Every tenth breath was analyzed. For e ach selected breath, VP area, anteroposterior and lateral diameters, a nd EMG activity were determined at five points: beginning, middle, and end of inspiration and middle and end of expiration. VP measurements changed significantly during the respiratory cycle. Although maximum a rea was measured at end inspiration or middle expiration and minimum a rea at the beginning or end of the breath, respiratory-related changes in VP measurements and EMG activity were characterized by substantial inter- and intrasubject variability. This variability is similar to v elopharyngeal behavior during nonrespiratory tasks and suggests that u pper airway patency is determined by multiple factors.