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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

Effects of different levels of positive airway pressure on breathing pattern and heart rate variability after coronary artery bypass grafting surgery

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Author(s):
Pantoni, C. B. F. [1] ; Di Thommazo, L. [1] ; Mendes, R. G. [1] ; Catai, A. M. [1] ; Luzzi, S. [2] ; Amaral Neto, O. [2] ; Borghi-Silva, A. [1]
Total Authors: 7
Affiliation:
[1] Univ Fed Sao Carlos, Lab Fisioterapia Cardiopulm, Nucleo Pesquisas Exercicio Fis, Dept Fisioterapia, BR-13565905 Sao Carlos, SP - Brazil
[2] Irmandade Santa Casa de Misericordia Araraquara, Araraquara, SP - Brazil
Total Affiliations: 2
Document type: Journal article
Source: Brazilian Journal of Medical and Biological Research; v. 44, n. 1, p. 38-45, JAN 2011.
Web of Science Citations: 10
Abstract

The application of continuous positive airway pressure (CPAP) produces important hemodynamic alterations, which can influence breathing pattern (BP) and heart rate variability (HRV). The aim of this study was to evaluate the effects of different levels of CPAP on postoperative BP and HRV after coronary artery bypass grafting (CABG) surgery and the impact of CABG surgery on these variables. Eighteen patients undergoing CABG were evaluated postoperatively during spontaneous breathing (SB) and application of four levels of CPAP applied in random order: sham (3 cmH(2)O), 5 cmH(2)O, 8 cmH(2)O, and 12 cmH(2)O. HRV was analyzed in time and frequency domains and by nonlinear methods and BP was analyzed in different variables (breathing frequency, inspiratory tidal volume, inspiratory and expiratory time, total breath time, fractional inspiratory time, percent rib cage inspiratory contribution to tidal volume, phase relation during inspiration, phase relation during expiration). There was significant postoperative impairment in HRV and BP after CABG surgery compared to the preoperative period and improvement of DFA alpha 1, DFA alpha 2 and SD2 indexes, and ventilatory variables during postoperative CPAP application, with a greater effect when 8 and 12 cmH(2)O were applied. A positive correlation (P < 0.05 and r = 0.64; Spearman) was found between DFA alpha 1 and inspiratory time to the delta of 12 cmH(2)O and SB of HRV and respiratory values. Acute application of CPAP was able to alter cardiac autonomic nervous system control and BP of patients undergoing CABG surgery and 8 and 12 cmH(2)O of CPAP provided the best performance of pulmonary and cardiac autonomic functions. (AU)