Inspiratory Muscle Training in Phase 1 and 2 Postoperative Cardiac Rehabilitation Following Coronary Artery Bypass Graft Surgery: Systematic Review With Meta-Analysis

Objective This study aimed to determine the effects of inspiratory muscle training (IMT) on exercise capacity, respiratory muscle strength, length of hospital stay (LOS), and quality of life (QOL) following coronary artery bypass graft surgery.Methods The search was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses and the Cochrane Handbook and included the databases MEDLINE, EMBASE, CINAHL, Scopus, and CENTRAL. The review included randomized controlled trials utilizing IMT during phase 1 or 2 postoperative cardiac rehabilitation (PoCR) versus alternative treatment (active or passive control) in patients following coronary artery bypass graft surgery.Results Fifteen studies were included (11 phase 1 studies, 4 phase 2 studies) with no reported adverse events. In phase 1 PoCR, IMT reduced the LOS (-1.02 days; 95% CI = -2.00 to -0.03) and increased exercise capacity (6-minute walk distance) (+75.46 m; 95% CI = 52.34 to 98.57), and maximal inspiratory pressure (MIP) (10.46 cm H2O; 95% CI = 2.83 to 18.10), but had no effect on maximal expiratory pressure. In phase 2 PoCR, IMT increased 6-minute walk distance (45.84 m; 95% CI = 10.89 to 80.80), MIP (-23.19 cm H2O; 95% CI = -31.31 to -15), maximal expiratory pressure (20.18 cm H2O; 95% CI = 9.60 to 30.76), and QOL (-11.17; 95% CI = -17.98 to -4.36), with no effect on peak oxygen uptake. There was a high risk of bias for MIP (75% of the phase 1 studies) and 6MWT (1 of 4 phase 2 studies). The quality of the evidence ranged from very low to moderate.Conclusion IMT significantly improves exercise capacity, respiratory muscle strength, LOS, and QOL in phase 1 and 2 PoCR.Impact IMT may benefit patients during phase 1 and 2 of PoCR, considering the safety, low cost, and potential benefits.