Effect of modulated-frequency and modulated-intensity transcutaneous electrical nerve stimulation after abdominal surgery: a randomized controlled trial.

This study aimed to evaluate the effectiveness of transcutaneous electrical nerve stimulation (TENS) for treatment of postoperative pain and pulmonary functions (vital capacity [VC]; cough peak flow, [CPF]) in patients who underwent abdominal surgery. Forty-eight patients were randomly allocated to receive TENS, placebo TENS, or no TENS (control) 1 hour a day for 3 days postoperatively. A 0-100 visual analog scale was used to assess pain at preintervention, mid-intervention, and postintervention on the third postoperative day. Pulmonary functions (VC, CPF) were evaluated by spirometer at preoperation (baseline) and at preintervention, mid-intervention, and postintervention on the third postoperative day. One-way analysis of variance was used to assess differences between groups at baseline. Mann-Whitney test was used to compare the control group with the placebo-TENS and TENS group, at each assessment timepoint. Two-way analysis of variance and Bonferroni post hoc test assessed the difference between the 2 (placebo-TENS×TENS) groups. A value of P<0.01 was considered statistically significant. The baselines were not significantly different between any groups. The TENS group had significant reductions in postoperative pain compared with the placebo group (P<0.01) and control group (P<0.01). There was also improvement in pulmonary functions (VC, CPF) at mid-TENS and post-TENS, but not in the placebo-TENS (P<0.01) or control groups (P<0.01). TENS is a valuable treatment to alleviate postoperative pain and improve pulmonary functions (ie, VC, CPF) in patients following abdominal surgery.