Signs of sympathetic dominance in sleep and wake based on spectral analysis of heart rate variability in children with obstructive sleep apnea.

Background: The low- to high-frequency components ratio (LF/HF) of heart rate variability reflects the balance between sympathetic and parasympathetic activity. The autonomic response in individuals with obstructive sleep apnea (OSA) may lead to sympathetic activation demonstrated by an increase in the LF/HF ratio. Studies examining autonomic function during sleep and wake in children with OSA are relatively scarce. Aim: A meta-analysis of the relevant available publications. Methods: A MEDLINE search from 2000 through 2013 at PubMed (NLM) was performed. A search for the index terms ('sleep disordered breathing' OR 'obstructive sleep apnea') AND 'heart rate' in all fields was done. Studies that included comparisons between children with and without diagnosed OSA were included into the analysis. Types of 'outcome measures' were the values of the LF/HF indices in different states of the sleep-wake cycle. Results: Four studies met the inclusion criteria. A total of 518 control children and 272 children with different degrees of OSA whose mean age ranged between 4.2 and 9.8 years were reported in the studies. Large inconsistencies concerning the effect sizes across publications were found. Meta-regression revealed a statistically significant association between calculated values of the effect sizes and the reported mean values of the apnea-hypopnea indices in the OSA groups (intercept: − 0.11826, regression coefficient: 0.01667, p = 0.048). Conclusion: Power analysis of heart rate variability in children with OSA may help to provide further information regarding neural control mechanisms that are altered in OSA. The LF/HF index may serve as an indicator of OSA severity and as a possible marker for risk stratification in children with OSA. [ABSTRACT FROM AUTHOR]