Noninvasive ventilation acutely modifies heart rate variability in chronic obstructive pulmonary disease patients

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 mates with COPD (69 +/- 8 years and with forced expiratory volume in 1 s <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 (ETCO2), 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 ETCO2 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 +/- 15un, respectively) in COPD group. Significant correlations between delta BiPAP-SB (Delta) ETCO2 and Delta HF were found (r = 0.89).