Correlation between change in respiratory muscle strength and cough ability in patients submitted to open-heart surgery

INTRODUCTION: The purpose of this study was to determine the correlation between change in respiratory muscle strength and change in cough ability in patients submitted to open-heart surgery.
METHODS: An observational cross-sectional study was conducted among 52 participants. Respiratory muscle strength was assessed by maximal inspiratory pressure (MIP) and maximal expiratory pressure (MEP) using a respiratory pressure meter. Cough ability was evaluated by voluntary expiratory peak flow (PEF) using a digital spirometer. Evaluations were performed on the day of admission and discharge.
RESULTS: Post-operative MIP, MEP, and PEF were significantly lower than those evaluated preoperatively (all p < 0.001). The difference of MIP and MEP was substantial positively correlated with the change in PEF in both absolute and predicted values (all p < 0.001) with the changes in MIP was highly relation.
DISCUSSION AND CONCLUSION: This study demonstrated that weakness of respiratory muscles, especially inspiratory muscle, was correlated to declining in cough ability in patients who had undergone open-heart surgery.