Figure 1.

Protrusion or “ballooning” of the palate into the velopharynx during expiration (palatal prolapse (PP)). The two endoscopic images on the left displays the palatal prolapse from the velopharyngeal view of the airway during expiration in two different breaths. The third endoscopic image from the left shows an open airway during normal expiration. The right endoscopic image also displays an open airway just before the occurrence of the palatal prolapse. The top panel shows the pneumotachograph-measured airflow (V̇) and the bottom panel demonstrates the simultaneously measured epiglottic pressure (P_epi). This figure clearly shows a distinct and reproducible expiratory flow pattern whenever the palate prolapses (balloons) into the velopharynx. Expiratory flow limitation (EFL) is observed from the lack of increase in expiratory flow despite an increase in epiglottic pressure during a period with repeated palatal prolapse (arrows identified with PP). During palatal prolapse, expiratory positive airway pressure develops at the level of the epiglottis and is not associated with a corresponding increase in the expiratory nasal flow.