Palatal prolapse as a signature of expiratory flow limitation and inspiratory palatal collapse in patients with obstructive sleep apnoea.

In some individuals with obstructive sleep apnoea (OSA), the palate prolapses into the velopharynx during expiration, limiting airflow through the nose or shunting it out of the mouth. We hypothesised that this phenomenon causes expiratory flow limitation (EFL) and is associated with inspiratory "isolated" palatal collapse. We also wanted to provide a robust noninvasive means to identify this mechanism of obstruction.Using natural sleep endoscopy, 1211 breaths from 22 OSA patients were scored as having or not having palatal prolapse. The patient-level site of collapse (tongue-related, isolated palate, pharyngeal lateral walls and epiglottis) was also characterised. EFL was quantified using expiratory resistance at maximal epiglottic pressure. A noninvasive EFL index (EFLI) was developed to detect the presence of palatal prolapse and EFL using the flow signal alone. In addition, the validity of using nasal pressure was assessed.A cut-off value of EFLI >0.8 detected the presence of palatal prolapse and EFL with an accuracy of >95% and 82%, respectively. The proportion of breaths with palatal prolapse predicted isolated inspiratory palatal collapse with 90% accuracy.This study demonstrates that expiratory palatal prolapse can be quantified noninvasively, is associated with EFL and predicts the presence of inspiratory isolated palatal collapse.
Competing Interests: Conflict of interest: S.A. Sands reports grants from American Heart Association (AHA) and National Institutes of Health (NIH) during the conduct of the study, and personal fees for consultancy from Cambridge Sound Management, outside the submitted work. Conflict of interest: L. Taranto-Montemurro reports grants from the NIH during the conduct of the study, and grants from the AHA and personal fees from Novion Pharmaceuticals and Cambridge Sound Management, outside the submitted work. D.P. White reports personal fees from Philips Respironics (for acting as Chief Scientific Officer), Apnicure (for acting as Chief Medical Officer) and NightBalance (for consultancy), outside the submitted work. Conflict of interest: A. Wellman reports grants from the NIH and Philips Respironics during the conduct of the study, and grants from Varnum Sleep and Breathing Solutions, and Cambridge Sound Management, and personal fees from Bayer, outside the submitted work; in addition, A. Wellman has a patent Airway and Airflow Factors issued.
(Copyright ©ERS 2018.)