Effect of Preoperative Inspiratory Muscle Training on Alveolar-Arterial Oxygen Gradients After Coronary Artery Bypass Surgery

Purpose: Gas exchange abnormalities and inspiratory muscle dysfunction are common postoperative pulmonary complications after cardiac surgery. The aim of this study was to investigate the changes in the alveolar arterial oxygen gradients and inspiratory muscle power after preoperative inspiratory muscle training (IMT) followed by postoperative IMT and early mobilization after coronary artery bypass graft surgery. Methods: Patients were randomly assigned to the intervention group (n = 20) or the usual care group (n = 20). The intervention group received preoperative IMT by a threshold load inspiratory muscle trainer and education followed by postoperative IMT and early mobilization. The usual care group received preoperative education and postoperative routine physical therapy care. Alveolar-arterial oxygen gradients and oxygen saturation were measured before induction of anesthesia and postoperatively immediately after extubation, at 24 hours, 48 hours, and on day 8 postsurgery. Inspiratory muscle power was measured before surgery, after 48 hours, and on day 8. Results: Forty male patients underwent coronary artery bypass graft surgery. The intervention group showed significant (P < .05) improvement of alveolar arterial-oxygen gradients and inspiratory muscle power at all measurement points. The mean of inspiratory muscle power at discharge was significantly higher than at baseline but not statistically significantly different from the preoperative measurement. Conclusion: Pre- and postoperative IMT by the threshold load inspiratory muscle trainer resulted in improvement of inspiratory muscle power, alveolar-arterial gradient, and oxygen saturation.