Respiratory paradox as an indicator of arousal from non-REM sleep

Increasing respiratory effort is the likely stimulus for arousal in patients with sleep-disordered breathing. Changes in the phase angle waveform (an indirect measure of respiratory effort) may provide a useful non-EEG indicator of respiratory-related arousal. The aim of this study was to investigate the relationship between phase angle change (using a continuous measurement technique) and EEG arousal. Polysomnographic sleep recordings (including: EEG, EOG, EMG, respiratory effort [ribcage and abdominal movement], respiratory paradox [continuous phase angle measurement], oral-nasal airflow, and oxygen saturation) were performed in a purpose built laboratory on 30 patients with sleep-disordered breathing (15 patients with obstructive sleep apnoea/hypopnoea syndrome [OSAHS]; 15 chronic heavy snorers without OSAHS) and 15 age and weight matched, non-snoring normal subjects. All data, including the temporal relationship between phase angle change and EEG arousal, were analyzed manually (4,545 phase angle changes and 6,473 EEG arousals). There was a highly significant correlation (p