PHASIC RESPIRATORY MUSCLE PATTERNS AND SLEEP-DISORDERED BREATHING DURING RAPID EYE-MOVEMENT SLEEP IN THE ENGLISH BULLDOG

Basic mechanisms of sleep-disordered breathing (SDB) during rapid-eye-movement sleep (REMS) have been little investigated, despite the fact that events are often more prolonged and Sa(O2) nadirs lower during REMS. We predicted that the mechanisms of SDB in REMS would be related to the normal phasic changes in respiratory control In that state, rather than to cyclic arousals or responses to hypoxia as postulated for non-REMS SDB. Recordings of the EMG of the diaphragm (DIA) and the sternohyoid (SH), an upper airway dilating muscle, were made in live English bulldogs during sleep. We found that, as predicted, SDB events were associated with phasic influences rather than with arousals or response to hypoxia. The onset of SDB was significantly related to suppression of drive to both the DIA (p < 0.01) and the SH (p < 0.01). The mean drive of the DIA was suppressed to 42% of normal and of the SH to 17% of normal; the suppression of the SH was significantly greater than that of the DIA (p < 0.05). Events were associated with changes in respiratory muscle EMG patterns typical of phasic REMS (p < 0.01 for each muscle). The occurrence and duration of events exhibited no clear pattern or relationship to arousal or Sa(O2). Rather, as would be expected of phenomena associated with phasic REMS, the onset and termination of events were unpredictable. The association of SDB in REMS with phasic REMS influences rather than arousal or hypoxia suggests new directions for therapeutic approaches.