Effectiveness of Inspiratory Muscle Training in Reducing Dyspnea in Cardiac Surgery Patients

Background: Postoperative dyspnea is a common complication following cardiac surgery, often attributed to respiratory muscle weakness and impaired pulmonary function. Inspiratory muscle training (IMT) has emerged as a non-invasive rehabilitation strategy to counteract these limitations, yet its efficacy in the immediate postoperative setting remains underexplored. Objective: To determine whether postoperative inspiratory muscle training reduces dyspnea and improves respiratory function in patients undergoing cardiac surgery. Methods: A randomized controlled trial was conducted at two tertiary cardiac centers in Pakistan over 12 months. A total of 148 patients undergoing elective coronary artery bypass grafting or valve replacement were randomized into an intervention group receiving structured IMT from postoperative day three, and a control group receiving standard care. Dyspnea was assessed using the Modified Borg Dyspnea Scale. Pulmonary function was evaluated via forced vital capacity (FVC), forced expiratory volume in one second (FEV₁), and maximal inspiratory pressure (MIP). Assessments were performed at baseline, post-intervention (day 14), and 1-month follow-up. Statistical analysis was conducted using independent and paired t-tests for normally distributed data. Results: Patients in the intervention group showed significantly greater reductions in dyspnea scores at day 14 (2.9 ± 1.0) and at 1 month (1.8 ± 0.9) compared to controls (4.6 ± 1.1 and 3.9 ± 1.0, respectively; p < 0.001). Significant improvements were also observed in FVC, FEV₁, and MIP among the IMT group (p < 0.001). Adverse events were minimal and self-limiting. Conclusion: Postoperative inspiratory muscle training is an effective and safe intervention for reducing dyspnea and enhancing respiratory function in cardiac surgery patients, supporting its routine inclusion in early postoperative rehabilitation.