Objective: To evaluate inspiratory volume in patients undergoing cardiac surgery and to determine the effects that incentive spirometry (IS) and the breath stacking (BS) technique have on the recovery of FVC in such patients. Methods: A prospective, controlled, randomized clinical trial involving 35 patients undergoing cardiac surgery at the Hospital de Força Aérea do Galeão (HFAG, Galeão Air Force Hospital), in the city of Rio de Janeiro, Brazil. The patients, all of whom performed mobilization and cough procedures, were randomly divided into three groups: exercise control (EC), performing only the abovementioned procedures; IS, performing the abovementioned procedures and instructed to take long breaths using an incentive spirometer; and BS, performing the abovementioned procedures, together with successive inspiratory efforts using a facial mask coupled to a unidirectional valve. Forced spirometry was carried out in the preoperative period and on postoperative days 1 to 5. During the maneuvers, inspiratory volume was measured in the IS and BS groups. Results: On postoperative day 1, FVC significantly decreased in all groups (EC: 87.1 vs. 32.0%; IS: 75.3 vs. 29.5%; and BS: 81.9 vs. 33.2%; p < 0.001 for all), as did inspiratory volume in the IS and BS groups (2.29 vs. 0.82 L; and 2.56 vs. 1.34 L, respectively; p < 0.001 for both). Between postoperative days 1 and 5, FVC partially normalized in all groups (EC: 32.0 vs. 51.3%; IS: 29.5 vs. 46.7%; and BS: 33.3 vs. 54.3%; p < 0.001 for all). During the postoperative period, inspiratory volume was significantly higher in the BS group than in the IS group. Conclusions: The three protocols were equivalent concerning the recovery of FVC on the first five postoperative days. When compared with IS, the BS technique promoted higher inspiratory volumes in this sample of postoperative cardiac patients. (ClinicalTrials.gov Identifier:NCT01074957 [http://www.clinicaltrials.gov/])

Keywords: Postoperative complications; Thoracic surgery; Physical therapy modalities.