Heart rate variability and autonomic modulation in children with obstructive sleep apnea syndrome

Abstract

To investigate whether obstructive sleep apnea syndrome (OSAS) is associated with impaired heart rate variability (HRV) indices, indicating impairment of cardiac autonomic modulation in children. Children with snoring and 5 years of age or elder who came to the Sleep center of Beijing Children’s Hospital were enrolled. All subjects underwent polysomnography and 24-h Holter monitoring with continuous time dependent and spectral analysis of heart rate variability. HRV analysis included time and frequency domain indices. Ninety-three subjects were recruited into the study. Forty-seven met the criteria for OSAS, 46 were non-OSAS. There were no difference between the two groups with respect to age and gender. The OSAS group had significantly higher apnea hyopnea index (AHI), obstructive apnea index (OAI) and oxygen desaturation index (ODI) than the non-OSAS group. The HRV analysis showed that OSAS children had decreased N-N interval, SDNN (the standard deviation of NN intervals) and SDANN (the standard deviation of the average NN intervals calculated over 5 min) with P value of 0.007, 0.003, and 0.01 respectively. SDNN was significantly different and declined with the degree of severity of OSAS ( P value < 0.01). In children with OSAS, the nocturnal PNN50 was decreased while low frequency/high frequency (LF/HF) was elevated compared to the non- OSAS controls ( p value 0.025 and 0.026 respectively). Multiple regression analysis showed that SDNN was related to AHI and age ( p value 0.03 and 0.006). OSAS in children is significantly associated with impaired cardiac autonomic modulation, i.e., sympathetic overflow and weaker parasympathetic modulation. Thanks to Ms. Yunxiao WU and Bei Li for their helping with ECG monitoring.