Cardiac autonomic modulation assessed by heart rate variability in children with asthma

Objective : To assess cardiac autonomic modulation, measured by short‐term frequency domain analysis of heart rate variability (HRV), in children with asthma. Methods : We conducted an observational study at a tertiary care teaching hospital. The sample consisted of 119 children aged 7 to 15 years with asthma and 56 age‐matched healthy controls. Frequency domain HRV measures included low‐frequency (LF; 0.04‐0.15 Hz), high‐frequency (HF; 0.15‐0.4 Hz), and LF/HF ratio. The LF and HF components were expressed in both absolute values of power (ms 2 ) and in normalized units (nu). Results : Compared with healthy controls, asthmatic children had significantly higher value of HF (nu) (mean ± standard deviation: 45.9 ± 14.6 vs 40.7 ± 13.6; P = .02), and lower values of LF (nu) (54.1 ± 14.6 vs 59.3 ± 13.6; P = .02) and LF/HF ratio (median, interquartile range: 1.12, 0.82‐1.88 vs 1.59, 1.02‐2.08; P = .03). We did not find significant differences between children with persistent and intermittent asthma, and between children with well‐controlled and partially‐controlled or uncontrolled asthma, in terms of HRV measures. Conclusions : Children with stable chronic asthma may have a cardiac autonomic imbalance with a possible enhanced parasympathetic modulation, as assessed by short‐term frequency domain analysis of HRV. Neither asthma severity nor asthma control was significantly associated with HRV measures, but the study did not have enough power to draw a firm conclusion on this point.