Transcutaneous electrical nerve stimulation after thoracic surgery: systematic review and meta-analysis of randomized trials

Objectives: To evaluate the effects of transcutaneous electric nerve stimulation (TENS) on pain and pulmonary function during the postoperative period after thoracic surgery by performing a systematic review and meta-analysis of randomized trials. Methods: The search strategy included MEDLINE, PEDro, Cochrane CENTRAL, EMBASE and LILACS, in addition to a manual search, from inception to August, 2011. Randomized trials were included, comparing TENS associated or not with pharmacological analgesia vs. placebo TENS associated or not with pharmacological analgesia or vs. pharmacological analgesia alone to assess pain (visual analog scale - VAS) and/or pulmonary function represented by forced vital capacity (FVC) in postoperative thoracic surgery patients (pulmonary or cardiac with approach by thoracotomy or sternotomy). Results: Of the 2.489 articles identified, 11 studies were included. In the approach by thoracotomy, TENS associated with pharmacological analgesia reduced pain compared to the placebo TENS associated with pharmacological analgesia (VAS -1.29; 95% CI: -1.94 to -0.65). In the approach by sternotomy, TENS associated with pharmacological analgesia also reduced pain compared to the placebo TENS associated with pharmacological analgesia (VAS -1.33; 95% CI: -1.89 to -0.77) and compared to pharmacological analgesia alone (VAS -1.23; 95% CI: -1.79 to -0.67). There was no significant improvement in FVC (0.12 L; 95% CI: 0.27 to 0.51). Conclusion: TENS associated with pharmacological analgesia provides pain relief compared to the placebo TENS in postoperative thoracic surgery patients both approached by thoracotomy and sternotomy. In sternotomy it also provides more effective pain relief compared to pharmacological analgesia alone, but it has no significant effect on pulmonary function.