Session P93.3

Interaction between Sleep EEG and ECG Signals during and after Obstructive Sleep Apnea Events with or without Arousals

AH Khandoker*, CK Karmakar, M Palaniswami

The University of Melbourne
Melbourne, Australia

Arousal from sleep is an important mechanism for reestablishing upper airway patency in obstructive sleep apnea (OSA).This study presents the first successful preliminary attempt to directly investigate the interactions of sleep EEG and ECG signals during normal, OSA breathing event and events following its termination with or without arousal in non-REM(NREM) and REM sleep stages. ECG and EEG signals (sample rate=256 Hz) were collected from 8 patients with OSA and 5 healthy subjects. Coherence between two signals over different frequency bands(range:0~128 Hz) were calculated for normal breathing events, OSA events and events following OSA terminations (with/without arousals) in NREM as well as REM sleep. Overall coherence of ECG and EEG in REM sleep is higher than that in NREM sleep. A significant (p=0.0164) difference of coherence in the range of 10-15 Hz was found among normal, OSA and termination events in REM sleep. Coherences in no bands are found to be significantly different between NREM and REM sleep for the events following OSA terminations with arousals. There were no significant differences in coherence values found between the events following OSA terminations with and without arousals in NREM or REM sleep. In this study, 71% per cent of apnoeas during NREM sleep were associated with arousal and 86% during REM sleep. However, it is unclear what terminates OSAs which are not terminated by visible cortical arousals. It is thought that autonomic arousals which are not represented at cortex, may actually be represented at the cortex but the changes cannot be detected with standard techniques. The results could be useful in detecting OSA events or OSA related arousals to characterize sleep fragmentation from ECG and EEG signals.

(Abstract Control Number: 86)