Assessing the physiological endotypes responsible for REM and NREM based obstructive sleep apnea

BackgroundPatients with obstructive sleep apnea (OSA) can have the majority of their respiratory events in REM (rapid eye movement) sleep or in NREM (non-rapid eye movement) sleep. No previous studies have linked the different physiology in REM and NREM sleep to the common polysomnographic patterns seen in everyday clinical practice, namely REM predominant OSA (REMOSA) and NREM predominant OSA (NREMOSA).Research Question1) How does OSA physiology change with sleep stage in NREMOSA\ua0and REMOSA\ua0patients? 2) Do patients with NREMOSA\ua0and REMOSA\ua0have different underlying OSA pathophysiology?Study Design and MethodsWe recruited patients with three polysomnographic patterns. 1) REMOSA\ua0– twice as many respiratory events in REM sleep; 2) NREMOSA\ua0- twice as many events in NREM sleep 3) Uniform OSA – equal number of events in NREM/REM sleep. We deployed a non-invasive phenotyping method to determine OSA endotype traits (Vpasssive, Vactive, loop gain, arousal threshold) in NREM sleep, REM sleep and total night sleep in each group of patients (NREMOSA, REMOSA, Uniform OSA).ResultsNREMOSA\ua0patients have significantly worse ventilatory control stability in NREM sleep compared with REM sleep (Loop Gain 0.546 [0.456,0.717] in NREM vs 0.365 [0.238,0.459] in REM sleep, p = 0.0026) while REMOSA\ua0patients displayed a significantly more collapsible airway (i.e. lower Vpassive) in REM compared to NREM sleep (98.4 [97.3,99.2] %Veupnea in NREM vs 95.9 [86.4,98.9] %Veupnea in REM sleep,