Figure 2.

Examples of different patterns of obstructive respiratory events for people with AHI in the range 20–30 events/hour: (a) Short events (AHI = 21.3 events/hour, Average hypopnea duration 20 seconds, maximum duration 55 seconds), (b) Long events (AHI = 25.6 events/hour: Average hypopnea duration 31 seconds, maximum duration 92 seconds), (c) REM predominant (AHI= 21.5 events/hour: REM AHI = 67.5 events/hour, NREM AHI = 5.5 events/hour). The images show cut-down PSG montage signals (a, b) = EEG, sub-mental EMG and ECG signals at 30 seconds per page and pulse oximeter (SaO₂), nasal pressure transducer (prongs), oronasal thermal flow sensor (AIRFLOW), respiratory effort thoracic (THOR), respiratory effort abdominal (ABDO), sound intensity and body position at 5 minutes per page or hypnogram signals (c) = study time (Time), Epoch number (Epoch), Sleep stage summary, body position, pulse oximetry (SaO₂), scored Central (Cn. A), Obstructive (Ob. A), Mixed (Mx. A), hypopnea (Hyp), unsure (Uns), and respiratory event-related arousals (RERA). Abbreviations: AHI: apnea-hypopnea index, REM: rapid eye movement, NREM: non-rapid eye movement, PSG: polysomnography.