Figure 1.

Representative polysomnographic recording during transition from non-REM (NREM) to REM to NREM sleep in an obstructive sleep apnea (OSA) patient with daytime pulmonary hypertension (PH) (adapted from [14]). Increase in pulmonary artery pressure is more exaggerated during REM sleep than NREM sleep. Moreover, the rapid rise of pulmonary arterial pressure (PAP) associated with the appearance of phasic REM and its recovery to the initial level immediately after the disappearance of REM are evident. The record of the area surrounded by the red square lines represents REM sleep. SpO₂; arterial oxygen saturation by pulse oximeter, Rib; rib cage movement, Abdo; abdominal movement, Flow; nasal airflow, HR; heart rate, EMG_GG; genioglossal electromyogram, P_PA; pulmonary artery pressure, P_SA; systemic artery pressure, EOG; electrooculogram, EEG; electroencephalogram. Phasic; phasic REM, tonic; tonic REM.