Comparison of two incentive spirometry protocols in postoperative coronary artery bypass surgery: a pilot study ABSTRACT Objective: To compare the effects of incentive spirometry (IS), the flow and volume on respiratory muscle strength, lung volumes and capacities and thoracoabdominal expansion after coronary artery bypass grafting (CABG). Methods: A pilot study with patients undergoing CABG in a private hospital of Santa Maria-RS, Brazil. Were evaluated 11 patients, both genders, aged between 49 and 78 years were randomized in Respiron group (RG, n = 6) and Voldyne group (GV, n = 5). The Physiotherapy was started on the first postoperative day (PD); IS protocol developed in three sets of 10 repetitions; beyond the standardized physiotherapy for both groups. The variables of cirtometry, maximal respiratory pressures and spirometry were collected on the preoperatively, 2nd, 4th and 7th PD. Results: Intragroup comparison showed a reduction in all variables between the preoperative and the 2nd PD with partial recovery until the 7 th PD. There was no difference in the comparison between groups. Conclusion: Both IS techniques, acted similarly in lung function restoring in patients undergoing CABG.