Effect of TENS on Postoperative Pain and Pulmonary Function in Patients Undergoing Coronary Artery Bypass Surgery

Background: The aim of this study was to determine the effect of electrical nerve stimulation on pain intensity and pulmonary function in patients undergoing coronary artery bypass surgery. Materials and Methods: In a randomized clinical trial, a total of 100 patients undergoing coronary artery bypass surgery at Masih Daneshvari Hospital, Tehran, Iran, from February to May 2014, were divided into two groups. In the intervention group (n = 50), patients received routine care along with transcutaneous electrical nerve stimulation (TENS) immediately after admission to the intensive care unit (ICU). In the placebo group (n = 50), patients only received routine care. The pain intensity was measured using a visual analog scale (VAS) every 6 hours for 72 hours after surgery in two conditions of rest and coughing. Pulmonary function was assessed through forced expiratory volume in 1 second (FEV1) and forced volume capacity (FVC) at 24, 48, and 72 hours after surgery. Age, gender, body mass index, narcotic consumption, ICU length of stay, and requests for chest radiographs were recorded. The statistical level of significance was set at p < .05. Results: There were no significant differences between the two groups in terms of age, gender, and body mass index (p > .05). Pain intensity was significantly lower in the TENS group than the placebo group in both resting and coughing condition (p < .05). FVC and FEV1 were significantly better and faster in the TENS group than in the placebo group at 24, 48, and 72 hours after surgery (p < .05). Patients in the TENS group had significantly lower narcotic use and requests for chest radiographs compared with placebo group. Conclusions: TENS may reduce postoperative pain in resting and coughing conditions, improve pulmonary function, and reduce narcotic use in patients undergoing coronary artery bypass surgery.