Effect of postoperative high load long duration inspiratory muscle training on pulmonary function and functional capacity after mitral valve replacement surgery: A randomized controlled trial with follow-up

Abstract

Objectives Although, pre-operative inspiratory muscle training has been investigated and reported to be an effective strategy to reduce postoperative pulmonary complications, the efficacy of postoperative inspiratory muscle training as well as the proper load, frequency, and duration necessary to reduce the postoperative pulmonary complications has not been fully investigated. This study was designed to investigate the effect of postoperative high-load long-duration inspiratory muscle training on pulmonary function, inspiratory muscle strength, and functional capacity after mitral valve replacement surgeries. Design Prospective randomized controlled trial. Methods A total of one hundred patients (mean age 38.3±3.29years) underwent mitral valve replacement surgery were randomized into experimental (n = 50) and control (n = 50) groups. The control group received conventional physiotherapy care, while experimental group received conventional care in addition to inspiratory muscle training, with 40% of the baseline maximal inspiratory pressure targeting a load of 80% by the end of the 8 weeks intervention protocol. Inspiratory muscle training started on the patient’s first day in the inpatient ward. Lung functions, inspiratory muscle strength, and functional capacity were evaluated using a computer-based spirometry system, maximal inspiratory pressure measurement and 6MWT respectively at 5 time points and a follow-up assessment was performed 6 months after surgery. Repeated measure ANOVA and post-hoc analyses were used (p <0.05). Results Group-time interactions were detected for all the studied variables (p<0.001). Between-group analysis revealed statistically significant postoperative improvements in all studied variables in the experimental group compared to the control group (p <0.001) with large effect size of η2 ˃0.14. Within-group analysis indicated substantial improvements in lung function, inspiratory pressure and functional capacity in the experimental group (p <0.05) over time, and these improvements were maintained at follow-up. Conclusion High intensity, long-duration postoperative inspiratory muscle training is highly effective in improving lung function, inspiratory muscle strength, and functional capacity after mitral valve replacement surgeries.

Inspiratory Muscle and Functional Performance of Patients Entering Cardiac Rehabilitation after Cardiac Valve Replacement

“…Thus, exercise and FP does not recover spontaneously after valve surgery and likely warrants CR. In fact, Westerdahl et al showed a statistically significant decrease in pulmonary function up to one year after surgery and Hegazy et al and Cargnin et al both found a significant decrease in MIP following cardiac valve surgery [8,28]. Furthermore, Weber et al found MIP to be a strong predictor of 90-day mortality and rehospitalization [29] with a reduction in respiratory muscle strength (<75% of predicted) associated with a higher incidence (almost six times greater relative risk) of PPCs.…”

“…Previous research that did not differentiate between VRS techniques found impaired 6MWT, balance, 5xStS, pulmonary function via spirometry, MIP and MEP [8,9,26,28,[30][31][32]. These studies examined IMP and FP either pre-or post-operatively and with or without intervention.…”

“…Following cardiac valve surgery there is significant pulmonary dysfunction which is the primary cause of post-operative pulmonary complications (PPCs), morbidity and mortality [26]. This dysfunction includes impaired ventilation, reduced lung volumes, hypoventilation, and respiratory muscle impairments leading to dyspnea, ineffective cough, impaired gas exchange, increased work of breathing, increased inpatient length of stay, increased mechanical ventilation time, and impaired FP [26][27][28]. Thus, exercise and FP does not recover spontaneously after valve surgery and likely warrants CR.…”

“…Although no pre-operative measures of IMP or FP were possible in our study, our results and the results of previous studies highlight the importance of pre-operative and post-operative examination and management of IMP and FP. Furthermore, early recovery of IMP via IMT has the potential to reduce the risk of PPCs since improvements in lung function, mechanical ventilation duration, length of stay, and FP have been found with IMT [26,28,29].…”

“…Cargnin et al examined the effects of four weeks of IMT after VRS and found a significant improvement in MIP, 6MWT, and lung function[8]. Most recently, Hegazy et al found that the addition of IMT to standard CR significantly improved pulmonary function and MIP to baseline values in 4 weeks, while patients not receiving IMT required 6 months to achieve baseline values[28]. Conversely, Saxena et al and de Menezes et al showed an improvement in a much shorter time frame in which pulmonary function returned to baseline values one month after VRS and MIP returned to baseline values just six days after VRS.…”