- Pulmonary complications after cardiac surgery are a leading cause of postoperative morbidity and mortality. Respiratory muscle weakness may contribute to the postoperative pulmonary abnormalities. We hypothesized that: inspiratory muscle strength (PImax at RV) and endurance (PmPeak/PImax) decrease following coronary artery bypass grafting (CABG); that this weakness is associated with impaired pulmonary function tests (PFT), impaired gas exchange and a higher rate of pulmonary complications; and that prophylactic inspiratory muscle training (PIMT) will prevent these changes. 30 candidates for CABG, ranging in age from 33 to 79, were evaluated and randomized into 2 groups: 15 received PIMT using a threshold trainer for 30 min/day for 1 month before operation, while 15 served as controls and received sham training. There was a significant decrease in respiratory muscle function, PFT, and gas exchange in the control group following CABG, while in the trained group these parameters where similar to those before entering the study. The differences between the groups were statistically significant. In addition, 4 (27%) in the control group, but only 1 (7%) in the trained group had postoperative pulmonary complications. We conclude that CABG is followed by significant deterioration in inspiratory muscle function, PFT and arterial blood gases. Decrease in these parameters can be prevented by PIMT, which may also prevent postoperative pulmonary complications.