O059 A study in Physiological Activation Responses to Posture Shifts in Sleep and The Impact of Supine Avoidance Alarms

INTRODUCTION: This study assessed the frequency and duration of arousal responses associated with posture shifts during sleep and the time taken to resume sleep following posture shifts with versus without a supine-avoidance alarm. METHOD: Sleep and posture shift outcomes during a baseline in-home sleep study (Embletta MPR plus an inactive supine-avoidance alarm device) and subsequent sleep study after 6-8 weeks of supine-avoidance treatment were examined in 66 patients with supine-predominant OSA. A technician blinded to supine-treatment data scored each sleep study, including arousal responses (3-15 and ≥15-sec EEG changes). All posture shifts lasting >5 sec were identified from sleep study and supine-alarm device posture recordings. All sustained (≥30 sec) posture shifts commencing from established sleep during baseline and supine-avoidance nights were assessed for arousal responses (within -30 to +3 sec of each posture shift) and the time taken to resume sleep following each posture shift. RESULTS: The study population was 62.1% males with a mean±SD age 52.8±11.9 years, BMI 31.9.4±7.8 kg/m², AHI 18.0±9.9 /hr (supine AHI=40.2±38.8 /h). From a total of 418 (baseline) vs 283 (supine-avoidance) sustained posture shifts (median [IQR] 6[3-10] vs 6[3-9] per patient), the majority [342/418 vs 244/283; 91[75-100] vs 100[84-100]%) were associated with an arousal, followed by 0.5 [0.0 to 1.0] min before sleep resumed, with no difference with versus without the supine-alarm. CONCLUSION: Posture shifts from sleep are mostly associated with brief arousal prior to any supine-avoidance alarm, after which a supine avoidance alarm effectively discourages supine positioning with minimal disturbance to the resumption of sleep.