Effects of neuromuscular electrical stimulation on functional capacity and quality of life among patients after cardiac surgery: A systematic review and meta-analysis.

BACKGROUND: Neuromuscular electrical stimulation (NMES) is a possible adjunctive therapy applied to cardiac surgery patients to improve physical function, but the results are still controversial. A systematic review and meta-analysis was conducted to investigate the effects of NMES on functional capacity and quality of life (QoL) in cardiac surgery patients. METHODS: The following databases PubMed, Embase, Medicine, CINAHL, and the Cochrane Central Register of Controlled Trials were searched for the English language from inception up to March 2021. A systematic targeted literature search evaluating the effects of NMES on physical function and QoL in cardiac surgery patients. The effect size of NMES was presented as the mean difference (MD)/standardized mean difference (SMD) and its 95% confidence interval using fixed/random effect models according to heterogeneity. Two reviewers independently screened and appraised each study by using the Cochrane Risk of Bias Tool. RESULTS: Six studies were included involving 400 cardiac surgery patients. The meta-analysis showed that NMES had effect on knee extensor strength (SMD=1.68; p=0.05), but had no effects on 6-minute walking distance (MD=44.08; p=0.22), walking speed (MD=0.05; p=0.24), grip strength (MD=3.01; p=0.39), or QoL (SMD=0.53; p=0.19). CONCLUSIONS: NMES use in cardiac surgery patients is limited by low to moderate quality. Existing evidence shows that NMES is safe and effective for improving knee extensor strength.