Sleep-related abdominal muscle behavior during partial or complete obstructed breathing in prepubertal children

We have evaluated the influence of nonrapid eye movement (NREM), REM sleep, and arousal on abdominal muscle contractions during snoring and/or obstructive apnea in 10 prepubertal children. All children were known habitual snorers and eight had a sleep apnea index above 10. During stage 3-4 non-REM sleep, non-apneic breathing with snoring was always associated with the presence of expiratory abdominal muscle electromyogram (EMG) discharges. During non-REM sleep apneas, abdominal muscle EMG discharges increased from the beginning to the end of each apnea. Termination of non-REM sleep apnea was marked by an "EEG arousal" in 12% of the apneic events and by a "movement arousal" in the other 88%. The highest abdominal muscle EMG discharge was always observed during the arousal response. During "phasic" REM sleep, abdominal muscle EMG discharges were absent during both nonapneic breathing (with or without snoring) and obstructive apneas. All REM sleep apneas ended with a "movement arousal," during which abdominal muscle EMG discharges were observed. Thus, abdominal muscle EMG discharges associated with "arousal" were seen independent of the immediately preceding sleep state.