High-frequency, high intensity transcutaneous electrical nerve stimulation for postoperative pain - evaluating a new treatment regime and a clinical bedside prediction test in outpatient surgery.

Abstract

Abstract The incidence of postoperative pain is high, even after minor surgery, despite multimodal analgesic treatment plans. The aim of this thesis is to explore ways to improve postoperative pain in outpatient surgery. Study I examined a clinical bedside test, the assessment of pain during peripheral venous cannula insertion, in an observational study to predict postoperative pain intensity in the post-anesthesia care unit (PACU). The findings indicate that this test is useful for predicting pain and time in the PACU. Study II evaluated the pain-relieving effects of high-frequency, high-intensity transcutaneous electrical nerve stimulation (HFHI TENS) compared to opioids after outpatient gynecological surgery in a systematic review and a meta-analysis. Findings revealed no difference in pain relief between HFHI TENS and opioids. HFHI TENS was opioid-sparing and reduced time in the PACU. Study III investigated the effects on time in the PACU and pain relief of HFHI TENS compared to opioids after laparoscopic cholecystectomy in a randomized controlled trial. The time in the PACU and pain intensity when leaving the PACU did not differ between randomized groups, but patients randomized to HFHI TENS consumed significantly less opioids than patients randomized to opioids. Study IV explored patients’ experiences of using HFHI TENS for postoperative pain relief in a qualitative interview study. Results showed that patients desire alternatives to pharmaceuticals for pain relief after surgery and that HFHI TENS increases feelings of safety and autonomy. Study V investigated healthcare professionals’ experiences of using HFHI TENS for postoperative pain relief in an interview study. Opioids were considered simpler to administer than HFHI TENS, but HFHI TENS was acknowledged due to its prompt effect in responders and limited adverse effects. Conclusion: Postoperative pain and time in the PACU can be predicted using a simple clinical preoperative test. HFHI TENS is an effective, opioid sparing alternative for postoperative pain relief, an option that is desired by the patients. Keywords: Prediction of postoperative pain, Transcutaneous electrical nerve stimulation, Postoperative pain, Opioids,Outpatient surgery.