# Effect of transcutaneous electrical nerve stimulation on patients after coronary artery bypass grafting: a systematic review and meta-analysis

## TL;DR

This study reviews whether TENS helps reduce pain and opioid use after heart surgery, finding mixed results with high variability across studies.

## Contribution

A systematic review and meta-analysis evaluating TENS effects on analgesic use, pain, and pulmonary function after CABG.

## Key findings

- TENS reduced postoperative opioid consumption significantly but showed high heterogeneity.
- TENS modestly improved forced expiratory volume (FEV1) but not forced vital capacity (FVC) in pulmonary function.
- TENS did not show statistically significant pain relief in acute or chronic postoperative pain.

## Abstract

This study aims to systematically evaluate the potential effects of transcutaneous electrical nerve stimulation (TENS) on analgesic consumption, pain relief, and pulmonary function outcomes in patients following coronary artery bypass grafting (CABG).

A systematic literature search was conducted across four core databases—PubMed, Embase, Web of Science, and the Cochrane Library. Methodological quality was evaluated using the Cochrane Risk of Bias (RoB 2.0) tool, and the certainty of evidence was evaluated using the GRADE system. For statistical analysis, standardized mean differences (SMDs) with 95% confidence intervals (CIs) were calculated for continuous variables. Heterogeneity was assessed via the I2 statistic (threshold: 50%), with fixed-effects models applied when I2 ≤ 50% or random-effects models applied when I2 > 50%. Subgroup analyses stratified by intervention duration were performed for outcomes demonstrating significant heterogeneity (I² ≥ 50%).

First, regarding pain management, TENS demonstrated greater efficacy in postoperative acute pain at rest (within 12 h) than control interventions (SMD = −1.02, 95% CI: −0.23–2.28; P = 0.11), albeit with high heterogeneity (I2 = 88.50%). Postoperative chronic pain at rest (5 days) was more pronounced (SMD = −2.00, 95% CI: −4.15–0.15; P = 0.07). Second, in terms of pulmonary recovery, TENS significantly improved forced expiratory volume within 1 s (FEV1: SMD = 0.85, 95% CI: 0.43–1.26; P = 0.00) but not forced vital capacity (FVC: SMD = −1.02, 95% CI: −0.23–2.28; P = 0.11), with heterogeneity levels of 54.00% and 88.50%, respectively. Third, regarding analgesic use, TENS reduced postoperative opioid consumption (SMD = −4.23, 95% CI: −7.31 to −1.15; P = 0.007), although heterogeneity remained high (I2 = 96.20%).

The current evidence preliminarily suggests that TENS may reduce postoperative analgesic dependence and modestly improve pulmonary function in patients following CABG; however, it has not demonstrated a statistically significant advantage in pain relief. Given the substantial heterogeneity across studies, these findings should be interpreted with caution. Future large-scale RCTs with standardized protocols are needed to validate these findings.

https://www.crd.york.ac.uk/PROSPERO/view/CRD42024594786, PROSPERO CRD42024594786.