Autotitrating nasal CPAP in obstructing sleep apnoea decreases during the luteal phase of the menstrual cycle

Abstract

Introduction: Previous studies suggest that nasal CPAP requirements may periodically fluctuate in rhythm with the menstrual cycle in women with OSA. Methods: We conducted a preliminary study over ≥4 weeks with 4 women with moderately severe OSA (42 to 44 years of age; AHI 16 to 30 events/hr) and prescribed nasal CPAP therapy (10.2 to 12.8cm H₂O). During the study, nasal CPAP was delivered with autotitrating CPAP machines (ResMED Autoset Spirit S7) that recorded 95% of the maximum nightly CPAP (CPAPmax95) via a ResMed ResLink and Smart Media card. Subjects were not taking hormonal contraceptives and measured their oral temperature on arising each morning to plot menstrual cycle phase. Results: CPAPmax95 started to decrease within one day of the onset of the luteal phase of the menstrual cycle in three sleeping subjects, with a maximum decrease of 1.6 ± 0.6cm H₂O (mean ± SD, p = 0.02) occurring 1.3 ± 0.6 days later. The decreases in CPAPmax95 fully reversed over 4 ± 1 days. Weekly measurements of plasma oestradiol and progesterone levels confirmed premenopausal status in these 3 subjects. The fourth subject had atypical oestradiol and progesterone profiles, perimenopausal symptoms, and no cyclical fluctuation in CPAPmax95 or oral temperature. Discussion: We speculate that progesterone mediated recruitment of genioglossal muscle activity and increased luteinising hormone levels may contribute to the modest and transient decrease in nasal CPAP observed during the luteal phase. The preliminary data raises the possibility of hormonal therapy for the clinical management of OSA, and suggests that menstrual cycle phase may need to be considered when clinically assessing premenopausal women with OSA.