Transcutaneous electrical nerve stimulation for pain treatment after cardiac surgery: a systematic review

Abstract

INTRODUCTION: Sternotomy in cardiac surgery is marked by postoperative pain. Analgesic drugs are widely used to relieve this symptom, however, with several adverse effects that vary according to the drug therapeutic class used. Therefore, the use of Transcutaneous Electrical Nerve Stimulation (TENS) appears as a noninvasive and easily applicable alternative for reducing the use of drugs in patients undergoing cardiac surgery. OBJECTIVE: To systematically review the effects of TENS in the treatment of pain in patients in the postoperative cardiac surgery and its repercussion on respiratory parameters. METHODOLOGY: Systematic review using the PICO methodology and keywords (TENS, pain, patients in the postoperative,cardiac surgery). Published studies that addressed the effects of TENS on the pain of patients after cardiac surgery were included and, as a secondary variable, its impact on respiratory parameters, published in Portuguese or English, in the years 2008 to 2019. Excluded nonrandomized studies, case reports, clinical observations and reviews.  In addition, the Boolean operators “and” and “or” were used. RESULTS: The search initially resulted in 265 articles, of which 253 were excluded, 12 articles remained. At the end, 5 articles were included. The search initially resulted in 2165 articles. Of these, 2160 were excluded, of which 5 were selected. The samples ranged from 20 to 120 participants. Of the five studies selected, four demonstrated a reduction in the level of pain after cardiac surgery, varying its application from the first day to the third postoperative day. This reduction in pain favored a decrease in the use of drugs such as morphine. In addition, with the reduction of pain, there was an improvement in ventilatory muscle strength and lung volumes and capacities. CONCLUSION: It is concluded that TENS is a non-drug option that can be used as an adjunct in pain reduction and, consequently , improving respiratory muscle strength,  lung volume and capacity , among other parameters, in patients undergoing cardiac surgery.