title: 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).
  
  
  CONCLUSIONS
  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.
authors.affiliation: Physiotherapy Department, Universidade Federal de São Carlos , São Carlos SP , Brazil.
authors.forename: Adriana Sanches
authors.initials: AS
authors.lastname: Garcia-Araújo
authors.forename: Valéria Amorim
authors.initials: VA
authors.lastname: Pires Di Lorenzo
authors.forename: Ivana Gonçalves
authors.initials: IG
authors.lastname: Labadessa
authors.forename: Soraia Pilon
authors.initials: SP
authors.lastname: Jürgensen
authors.forename: Luciana
authors.initials: L
authors.lastname: Di Thommazo-Luporini
authors.forename: Cristiane Lubk
authors.initials: CL
authors.lastname: Garbim
authors.forename: Audrey
authors.initials: A
authors.lastname: Borghi-Silva
mesh_terms: D000293:Adolescent; D000328:Adult; D001249:Asthma / Q000503:physiopathology*; D001341:Autonomic Nervous System / Q000503:physiopathology*; D003430:Cross-Sectional Studies; D005260:Female; D005541:Forced Expiratory Volume; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D013147:Spirometry; D055815:Young Adult
keywords: Autonomic nervous system; heart rate control; lung obstructive diseases; physical therapy