Hemodynamic changes due to expiratory positive airway pressure by facial mask in the postoperative period of cardiac surgery

Introduction

Expiratory positive airway pressure (EPAP) is used as physiotherapic tool in the management of patients after major surgeries such as cardiac surgery but its hemodynamic effect is not well studied. The goal of this study was to evaluate hemodynamic changes caused by EPAP use after cardiac surgery in patients monitored by Swan-Ganz catheter.

Methods

Patients in the first or second day after cardiac surgery, with respiratory and hemodynamic stability and with a Swan-Ganz catheter, were included. They were evaluated at rest and after using EPAP of 10 cm, by facial mask, in a randomized order. Variables studied were oxygen saturation (SPO₂), heart rate (HR), respiratory rate (RR), mean arterial systemic and pulmonary pressures (MAP and MPAP), central venous pressure (CVP), pulmonary capillary wedge pressure (PCWP), cardiac index, stroke index, stroke work index from left and right ventricles, and systemic and pulmonary vascular resistance. Patients were studied as a whole group and divided into subgroups (with ejection fraction <50% or >50%) and values were compared with a t test and analysis of variance. Results are shown as the mean ± standard deviation. The significance level was P < 0.05.

Results

Twenty-eight patients were studied (22 men, mean age 68 ± 11 years). The most common surgery was myocardial revascularization (n = 17). EPAP was well tolerated in the patients studied. Comparing rest and EPAP periods, increases were observed in: PCWP (11.9 ± 3.8 to 17.1 ± 4.9 mmHg, P < 0.001); CVP (8.7 ± 4.1 to 10.9 ± 4.3 mmHg, P = 0.014); MPAP (21.5 ± 4.2 to 26.5 ± 5.8 mmHg, P < 0.001); MAP (76 ± 10 to 80 ± 10 mmHg, P < 0.035). All other variables did not show significant changes. These results were observed in the total group and when divided concerning ejection fraction >50% or <50%.

Conclusion

EPAP was well tolerated in this group of stable patients after cardiac surgery and the hemodynamic changes due to its use were an increase in the measurement of right and left filling pressures as well as a small increase in arterial pressure.