Figure 1.
An example of determining the arousal threshold during polysomnogram (PSG). C3–A2, C4–A1: electroencephalograms; CHIN, chin electromyogram; Pnasal, nasal pressure; SaO2, arterial blood oxygen saturation; Therm, thermistor; Pepi, epiglottic pressure trace. The respiratory arousal threshold was taken as the delta pressure swing immediately prior to arousal (PA, the solid arrow); the magnitude of the first pressure swing during the respiratory events in the epiglottic pressure trace was also taken (PT, the hollow arrow); The interval from the first pressure swing to the breath with nadir epiglottic pressure (the interval between the hollow arrow and the solid arrow).