Autonomic cardiovascular control in children with obstructive sleep apnea

Autonomic cardiorespiratory control changes with sleep-wake states and is i nfluenced by sleep-related breathing disorders. Power spectrum (PS) analysi s of instantaneous fluctuations in heart rate (HR) is used to investigate t he role of the autonomic nervous system (ANS) in cardiorespiratory control. The two spectral regions of interest are the low frequency component (LF) and high frequency component (HF). The aim of the present study was to investigate the autonomic cardiorespira tory control in children with obstructive sleep apnea (OSA) syndrome. We st udied 10 children with OSA versus 10 normal children. All subjects underwen t whole night polysomnography. Spectral analysis of the HR and breathing si gnals was performed for 256 second long, artifact-free epochs in each sleep -wake state. The LF power was higher in the OSA group compared with control subjects for all states, reflecting enhanced sympathetic activity in OSA s ubjects. The results indicated sympathetic predominance during REM sleep in all subjects and parasympathetic predominance in slow wave sleep only in c ontrols. The autonomic balance (LF/HF) was significantly higher in OSA pati ents than in control subjects, at all stages during night sleep, and while awake before sleep onset. An index of overall autonomic balance (ABI) was c omputed for each subject and correlated well with the measured respiratory disturbance index (RDI).