Nocturnal autonomic function in preschool children with sleep-disordered breathing

Obstructive sleep apnea (OSA) is associated with autonomic dysfunction in adults and school-aged children; however, this association has not been investigated in preschool children. We aimed to analyze heart rate variability (HRV) and catecholamine levels in preschool children with OSA. METHODS: One hundred and forty-two snoring children aged 3-5years and 38 nonsnoring control group children underwent overnight polysomnography (PSG). Nocturnal urinary catecholamines were measured in 120 children. Children were grouped according to their obstructive apnea-hypopnea index (OAHI) (control [no snoring], OAHI1event/h; primary snoring, OAHI1event/h; mild OSA OAHI>15events/h; moderate to severe [MS] OSA, OAHI>5events/h). The HRV parameters for each child were averaged during rapid eye movement (REM) and non-REM (NREM) sleep. RESULTS: During stable sleep, low-frequency (LF) HRV was similar between groups. High-frequency (HF) HRV was higher in the MS OSA group compared with the control group during all sleep stages (NREM sleep stages 1 and 2 [NREM1/2], 4234+/-523ms2 vs 2604+/-457ms2; NREM sleep stages 3 and 4 [NREM3/4], 4152+/-741ms2 vs 3035+/-647ms2; REM, 1836+/-255ms2 vs 1456+/-292ms2; P