Methods
palate, OSA, epiglottis
SECONDARY, COLLAPSE, SALIVATION
This study is a secondary analysis of a prospective trial (NCT04232410) that was approved by the ethics committee of the University of Antwerp and Antwerp University Hospital. Written informed consent was obtained from all participants. The parent trial included patients with moderate to severe OSA who required evaluation by DISE.The study design and set-up were described in detail by Kazemeini et al. [Artificial sleep was induced by intravenous bolus injection of midazolam and maintained by target-controlled infusion of propofol. Additionally, glycopyrrolate was administered to reduce salivation. Once stable sleep was achieved, positive pressure was applied by a modified CPAP device (Pcrit3000, Philips, Amsterdam, Netherlands) and adjusted in increments of 1 to 2 cmHFor each CPAP level, we selected one breath segment consisting of three consecutive, high-quality breaths, accompanied by clear endoscopic footage. Subsequently, the degree of collapse was assessed for each corresponding segment at the levels of the soft palate, lateral walls, tongue base and epiglottis using a semi-quantitative scale (i.e. 0%, 25%, 50%, 75%, 100%). All measurements were made by one experienced examiner (EVDP) who was blinded to baseline characteristics and CPAP levels.Two features were extracted from the pneumotachograph signal using custom-made software (MATLAB, The MathWorks, Natick, MA, USA) to define flow limitation: peak inspiratory flow (PIF), which was calculated as the difference between maximum and average inspiratory flow, and median inspiratory ventilation (VThe primary analysis evaluated the relationship between P