The Application of Transcutaneous Electric Nerve Stimulation on Acupoints (Acu-TENS) for Pain Relief During Colonoscopy: a Prospective, Randomized, Placebo-controlled Study

Background: Colonoscopy is often regarded as a painful and unpleasant procedure. Transcutaneous Electric Nerve Stimulation on Acupoints (Acu-TENS) is a non-invasive modality that has been used successfully to treat pain of various origins, but few good-quality studies have evaluated its role in treating pain and anxiety during colonoscopy. Objective: To investigate the efficacy of Acu-TENS in reducing procedure-related pain and the consumption of sedatives/analgesics during colonoscopy. Design: Prospective, randomized, placebo-controlled study. Subjects: One hundred and twenty eight consecutive patients undergoing first-time elective day-case colonoscopy without previous experience of acupuncture/Acu-TENS will be recruited. Interventions: Patients will be randomized to receive either 45 minutes of Acu-TENS or placebo-TENS before colonoscopy. The acupoints relevant to the treatment of abdominal pain and distension, including Zusanli, Hegu, Neiguan, Tianshu, and Dachangshu will be used. For the placebo-TENS group, a non-conductive plastic film will be placed between the acupoint and the electrode so that no current will be transmitted. Acu-TENS and placebo-TENS will be continued throughout colonoscopy. A mixture of Propofol and Alfentanil, delivered by a patient-controlled syringe pump, will be used for sedation/analgesia in both groups. Outcome measures: Primary outcome: doses of patient-controlled sedation/analgesia consumed. Secondary outcomes: pain and satisfaction scores according to a visual analog scale, cecal intubation rate/time, and episodes of hypotension/desaturation.