Short-term transcutaneous electrical nerve stimulation after cardiac surgery: effect on pain, pulmonary function and electrical muscle activity.

This study aimed to evaluate the effectiveness of transcutaneous electrical nerve stimulation (TENS) for treatment of postoperative pain in patients who underwent cardiac surgery. In addition, we sought to determine whether TENS would be related to improved pulmonary function and muscle electrical activity in this patient population. Forty-five patients, 32 males and 13 females, aged 41-74 years were randomly allocated to receive TENS (n=23) or sham treatment (n=22) during 4 h on the third postoperative day. A 0-10 visual analogic scale was used to assess pain; lung function was evaluated by spirometry and surface electromyography (n=10 in each group) was used to quantify electrically-induced muscle activity (trapezius and pectoralis major). TENS was associated with significant reductions on spontaneous and cough-induced postoperative pain as compared to sham (P<0.05). There was also improvement in chest wall-pulmonary mechanics after TENS with proportional increases in tidal volume and vital capacity (P<0.05). In addition, electrical activity of both muscle groups was enhanced after TENS, but not post sham (P<0.05). TENS is a valuable strategy to alleviate postoperative pain following cardiac surgery with positive effects on pulmonary ventilatory function and electrical activity of thoracic and girdle muscles.