P054 The effect of head up bed-tilt (HUT) on sleep disordered breathing (SDB) in patients with supine dominant sleep apnoea (SDOSA): an exploratory study

SDB severity is reduced in SDOSA when posture changes from supine to lateral. Sleeping with a head up bed-tilt(HUT) is known to reduce SDB in some OSA patients. In this exploratory study, we tested whether HUT could be used to reduce SDB in SDOSA patients who had refused continuous positive airway pressure therapy(CPAP). We studied 5 male patients (age: 60 to 72years, BMI: 25.8 to 32.2kg/m2). Standard, in-laboratory, overnight-polysomnography was performed (Compumedics Ltd, Australia). Posture was monitored, but not restricted, and bed position was set at horizontal(HB) for half the night and at 7° HUT for the remainder (randomised). Polysomnograms were scored by a sleep technician using AASM criteria. SDB severity was quantified using the apnoea hypopnoea index(AHI) and apnoea index(AI). For this analysis, we focus on periods of supine, stage 2 sleep (S2S) only. Participants spent 23 to 60minutes (range) in S2S with HB and 11 to 36minutes with HUT. AHI was 49 to 138events/hr with HB and 24 to 120events/hr with HUT, representing a fall of 2 to 62events/hr across all patients. AI was 19 to 111events/hr with HB and 0 to 48 events/hr with HUT, a fall of 15 to 96events/hr across all patients. In these CPAP non-compliant, SDOSA patients, S2S in HUT was associated with a reduction in SDB severity that varied between individuals. Notably apnoeic events were reduced in all patients and eliminated in two patients. We conclude that HUT warrants further investigation as a potential alternative therapy for SDOSA patients intolerant of CPAP.