Increased sympathetic modulation and decreased response of the heart rate variability in controlled asthma

Abstract

Objective: To compare the autonomic modulation of heart rate (HR) in asthmatic and healthy volunteers to correlate it with the forced expiratory volume in the first second (FEV₁). Methods: Ten healthy and 14 asthmatic volunteers were included in this cross-sectional study. The volunteers underwent a cardiopulmonary exercise test, spirometry and a register of both resting heart rate variability (HRV) in the supine and seated positions along with HRV during the respiratory sinus arrhythmia maneuver (M-RSA). Results: At rest in supine, asthmatic volunteers presented a higher HR (77.1 ± 9.9 vs. 68.7 ± 8.7 bpm), shorter interval between two R waves (R-Ri) (807.5 ± 107.2 vs. 887.5 ± 112.7 ms) when compared with the healthy volunteers, respectively. Moreover, in the frequency domain of HRV, there was increased low frequency (LF) index (50.4 ± 17.1 vs. 29.2 ± 11.1 n.u.) and decreased high frequency (HF) index (49.4 ± 17.1 vs. 70.7 ± 11.1 n.u.). During the M-RSA, the asthmatic presented higher HR (82.6 ± 10.0 vs. 72.4 ± 7.6 bpm) and lower values of R-Ri (746.4 ± 92.1 vs. 846.4 ± 81.4 ms) and approximate entropy (ApEn) (0.7 ± 0.0 vs. 0.8 ± 0.1). FEV₁ was strongly correlated with the change of the continuous beat-to-beat variability of HR (SD2) index from the seated to the supine position (r = 0.78). Conclusion: Controlled asthma in adults appears to induce an increased sympathetic modulation and attenuated response to the postural changes and the M-RSA. Furthermore, there is a correlation between the airways’ obstruction and HRV, especially during postural changes.

• Autonomic nervous system
• heart rate control
• lung obstructive diseases
• physical therapy

Acknowledgements

The authors are grateful to the subjects who participated in the study, and Juliano Ferreira Arcuri for the paper translation.

Declaration of interest

The authors would like to thank FAPESP for the financial support.