Long-term variability of the apnea-hypopnea index in a patient with mild to moderate obstructive sleep apnea

Abstract

Night-to-night variability (NNV) of the degree of obstructive sleep apnea (OSA) over the long term is not well investigated. In our case, we investigated the NNV of the apnea-hypopnea index (AHI) with regard to sleep structure. Unattended polysomnography (PSG) at home was used to determine the AHI in the course of 4 weeks in a single patient with a mild-to-moderate OSA, by using the Somnocheck R&K system. The mean sleep period was 6.7 ± 1.1 hours and the mean AHI was 14.1 ± 5.7 events/h (range: 5.1-28.3 events/h; coefficient variability [CV] 40.4%). Independent of non-rapid eye movement and rapid eye movement (REM) sleep, the AHI in supine position (43.6 ± 16.9 events/h; CV 38.8%) was greater than during lateral-recumbent sleep (4.8 ± 4.1 events/h; CV 85.4%, P