title: Noninvasive ventilation acutely modifies heart rate variability in chronic obstructive pulmonary disease patients.
abstract: OBJECTIVE
  The purpose of present study was to evaluate the acute effects of bi-level positive airway pressure (BiPAP) on heart rate variability (HRV) of stable chronic obstructive pulmonary disease patients (COPD).
  
  
  METHODS
  Nineteen males with COPD (69+/-8 years and with forced expiratory volume in 1s <50% of predicted) and eight healthy sedentary age-matched (69 years) males in the control group (CG) were evaluated during two conditions of controlled respiratory rate: spontaneous breathing (SB) and BiPAP (inspiratory and expiratory levels between 12-14 cmH(2)O and 4-6 cmH(2)O, respectively). Peripheral oxygen saturation (SpO(2)), end-tidal of carbon dioxide (ETCO(2)), systolic blood pressure (SBP) and R-R interval were obtained. HRV was analyzed by time (RMSSD and SDNN index) and frequency domains (high frequency - HF, low frequency - LF and HF/LF ratio).
  
  
  RESULTS
  Significant reduction of ETCO(2) and SBP in both groups and increase of SpO(2) in COPD group was observed during BiPAP ventilation (p<0.05). During spontaneous breathing, patients with COPD presented lower values of LF, LF/HF and higher values of HF when compared to CG (p<0.05). However, HF was significantly reduced and LF increased during BiPAP ventilation (58+/-19-48+/-15 and 41+/-19-52+/-15 un, respectively) in COPD group. Significant correlations between delta BiPAP-SB (Delta) ETCO(2) and DeltaHF were found (r=0.89).
  
  
  CONCLUSIONS
  Sympathetic and parasympathetic neural control of heart rate is altered in COPD patients and that BiPAP acutely improves ventilation, enhances sympathetic response and decreases vagal tonus. The improvement of ventilation caused by BiPAP was associated with reduced cardiac vagal activity in stable moderate-to-severe COPD patients.
authors.affiliation: Cardiopulmonary Physiotherapy Laboratory, Nucleus of Research in Physical Exercise, Department of Physiotherapy, Federal University of São Carlos, UFSCar, Rodovia Washington Luis, São Carlos, SP, Brazil. audrey@power.ufscar.br
authors.forename: Audrey
authors.initials: A
authors.lastname: Borghi-Silva
authors.forename: Michel Silva
authors.initials: MS
authors.lastname: Reis
authors.forename: Renata Gonçalves
authors.initials: RG
authors.lastname: Mendes
authors.forename: Camila Bianca Falasco
authors.initials: CB
authors.lastname: Pantoni
authors.forename: Rodrigo Polaquini
authors.initials: RP
authors.lastname: Simões
authors.forename: Luis Eduardo Barreto
authors.initials: LE
authors.lastname: Martins
authors.forename: Aparecida Maria
authors.initials: AM
authors.lastname: Catai
mesh_terms: D000368:Aged; D000886:Anthropometry; D002245:Carbon Dioxide / Q000502:physiology; D016022:Case-Control Studies; D005260:Female; D005541:Forced Expiratory Volume; D006339:Heart Rate; D006801:Humans; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000097:blood; D010313:Partial Pressure; D011175:Positive-Pressure Respiration / Q000379:methods*; D029424:Pulmonary Disease, Chronic Obstructive / Q000503:physiopathology* / Q000628:therapy*; D014797:Vital Capacity
chemical_list: D002245:Carbon Dioxide; D010100:Oxygen