Three studies (one weak(23), one moderate(21), and one strong(22) quality) examined the effectiveness of inspiratory muscle training (IMT) in patients awaiting coronary artery bypass graft (CABG) and aortic valve replacement surgeries.
The interventions lasted between two and six weeks, all were daily sessions using a threshold inspiratory muscle trainer. In one study, IMT was home-based and self directed (22). In the second, it was performed at home with one session per week being supervised(23). In the final study, all IMT sessions were performed under the supervision of a physician (21). The control groups for comparison were usual care(23), sham training(21), and a low-intensity inspiratory muscle training
group (LI-IMT) (22).
Inspiratory muscle strength:
Inconsistent (two studies [one weak (23), one moderate (21) quality] showing a significant effect for the intervention compared to control).
Inspiratory Muscle Endurance:
Might be effective (one moderate(21) quality study showing a significant effect for the intervention, compared to control).
Arterial Blood gases:
Inconsistent (one moderate(21) quality study, inconsistent effects across different measures of arterial blood gases).
Pulmonary Function:
Inconsistent (one strong(22) quality study, inconsistent effects across different measures of pulmonary function).
Health-Related Quality of Life:
Might not be effective (one weak(23) quality study, showing no effect for intervention when compared to control).
Spirometry (improving lung function):
Might not be effective (one moderate(21) quality study, showing no effect for intervention when compared to control).
Inflammatory Response:
Might not be effective (one strong(22) quality study, showing no effect for intervention when compared to control).