Inspiratory Muscle Training Based on Anaerobic Threshold on the Functional Capacity of Patients After Coronary Artery Bypass Grafting: Clinical Trial

Abstract

Introduction

Coronary artery bypass grafting (CABG) is associated with reduced ventilatory muscle strength and consequent worsening of functional capacity (FC). Inspiratory Muscle Training (IMT) can be indicated, but there is still a lack of knowledge about the use of the anaerobic threshold (AT) as a basis for prescription. The objective of this study is to evaluate if IMT based on AT modifies FC and inspiratory muscle strength of patients submitted to CABG.

Methods

This is a clinical trial. On the first postoperative day, the patients were divided into two groups: the conventional group (IMT-C), which performed IMT based on 40% of maximal inspiratory pressure (MIP), and the IMT-AT group, which performed IMT based on AT. All patients underwent preoperative and postoperative assessment of MIP and performed a six-minute walk test (6MWT).

Results

Forty-two patients were evaluated, 21 in each group. Their mean age was 61.4±10 years and 27 (64%) of them were male. There was a reduction of inspiratory muscle strength with a delta of 23±13 cmH2O in the IMT-C group vs. 11±10 cmH2O in the IMT-AT group ( P<0.01) and of the walking distance with a delta of 94±34 meters in the IMT-C group vs. 57±30 meters in the IMT-AT group ( P=0.04).

Conclusion

IMT based on AT minimized the loss of FC and inspiratory muscle strength of patients submitted to CABG.