EFFECTS OF A PREOPERATIVE INSPIRATORY MUSCLE TRAINING PROTOCOL ON RESPIRATORY FUNCTION AND CLINICAL OUTCOMES IN PATIENTS UNDERGOING CARDIAC SURGERY

Abstract

INTRODUCTION: Cardiac surgeries have increased in Brazil and are associated with a higher risk of postoperative respiratory complications, reinforcing the importance of preventive strategies. Among these, physiotherapy plays a prominent role, particularly inspiratory muscle training (IMT), which has shown positive results in the recovery of these patients. OBJECTIVE: To analyze the effects of a preoperative IMT protocol in patients undergoing cardiac surgery at HU-UFPI. METHODOLOGY: This is a randomized clinical trial conducted with patients undergoing coronary artery bypass grafting and/or valve replacement surgery between January and May 2025. Sociodemographic and clinical variables, hospitalization data, and respiratory function parameters were analyzed, including manovacuometry (Maximal Inspiratory Pressure – MIP and Maximal Expiratory Pressure – MEP) and Peak Expiratory Flow (PEF). The study was approved by the Research Ethics Committee of HU-UFPI. RESULTS: Twenty-nine patients were randomly allocated to receive either IMT or Flow-Oriented Incentive Spirometry (FIS). The mean age was 59.67 years, with a predominance of males (71.4%), and comorbidities were present in 85% of the sample. Coronary artery bypass grafting was the most frequently performed procedure (76.2%). Regarding respiratory function variables, MIP increased in both groups; however, no statistically significant difference was observed (p=0.508). Nevertheless, the IMT group presented slightly higher mean values (84.58 cmH₂O) compared to the FIS group (83.56 cmH₂O). Similarly, MEP showed comparable mean values between groups (FIS: 74.00 cmH₂O; IMT: 87.83 cmH₂O), with no statistically significant difference (p=0.219). PEF increased in the IMT group; however, no statistically significant difference was observed between groups in the post-intervention period (p=0.345), with an overall mean of 233 L/min (241.78 L/min in the FIS group and 226.42 L/min in the IMT group). Postoperative respiratory complications occurred in only 14.3% of the sample, with no significant difference between groups (p=0.719). The mean length of hospital stay was similar between groups, with an overall mean of 26.81 days (27.22 days in the FIS group and 26.50 days in the IMT group; p=0.917). The duration of mechanical ventilation was low in both groups, with no statistically significant difference (p=0.345). CONCLUSION: A preoperative IMT protocol, when compared to FIS in patients undergoing cardiac surgery, did not demonstrate a statistically significant impact. IMT did not significantly contribute to increases in MIP, MEP, or PEF, nor did it influence postoperative clinical outcomes such as reduction in respiratory complications, duration of mechanical ventilation, or length of hospital stay.