Phasic Respiratory Muscle Patterns and Sleep-disordered Breathing during Rapid Eye Movement Sleep in the English Bulldog

Abstract

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 SaO2 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 five 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 less than 0.01) and the SH (p less than 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 less than 0.05). Events were associated with changes in respiratory muscle EMG patterns typical of phasic REMS (p less than 0.01 for each muscle). The occurrence and duration of events exhibited no clear pattern or relationship to arousal or SaO2. 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.

The Effects of Trazodone with l-Tryptophan on Sleep-disordered Breathing in the English Bulldog

“…During wakefulness and normal respiration, both humans (38) and bulldogs (15) with sleep apnea have increased activity of their upper airway dilator muscles. It is only in sleep when these muscles are intermittently suppressed that persons (9) and bulldogs (36) with sleep apnea have obstructive sleep-disordered breathing. In this study, we report that like humans, these events may be apneas, hypopneas, and respiratory effort-related arousals and may occur in NREMS as well as in REMS.…”

“…The sternohyoid muscle was chosen as the representative upper airway dilator because this muscle, compared with other upper airway muscles in the bulldog, demonstrates more pronounced respiratoryrelated phasic activity (15) and has been shown to have sleep-statedependent reductions in activity (36). We looked exclusively at respiratory drive, measured as the amplitude of respiratory-related phasic activity (the amplitude difference between the peak amplitude of the moving average minus the tonic end-expiratory amplitude in arbitrary units) (36).…”

“…We looked exclusively at respiratory drive, measured as the amplitude of respiratory-related phasic activity (the amplitude difference between the peak amplitude of the moving average minus the tonic end-expiratory amplitude in arbitrary units) (36). Comparisons were made in respiratory drive across state changes between placebo and the three drug conditions.…”

Modulation of respiratory pattern and upper airway muscle activity by the pedunculopontine tegmentum: role of NMDA receptors

“…For example, electroencephalographic (EEG) desynchronization or gamma activity reflect cortical activation [25]; hippocampal theta activity is prominent during REM sleep or vegetative behaviors [3,26,27]; delta rhythms correlate with deep sleep and high arousal thresholds [2,4]; ponto-geniculo-occipital (PGO) waves, rapid eye movements and muscle twitches reflect brain phasic events [28][29][30]; and motor atonia reflects REM inhibitory processes [9,10,31,32]. These phenomena tend to occur together during REM sleep, leading to the hypothesis that brain phasic events may account for the increased-frequency respiratory disturbances characteristically observed during REM sleep [13,33,34].…”

The cardiovascular effects of obstructive sleep apnoeas: analysis of pathogenic mechanisms

“…Eur Respir J., 1994, 7, 786-805. and development of software for computer analysis has allowed cardiovascular monitoring in ambulatory patients, without major alterations of their sleep pattern [37]. In addition, experimental models of OSA in animals have been established [38][39][40][41], and may help in the study of individual pathogenic factors, despite some limitations such as species differences, or experimental designs which do not entirely mimic human OSA.…”