Effect of electroacupuncture combined with dezocine on postoperative hyperalgesia induced by remifentanil

Objective To evaluate the effect of electroacupuncture combined with dezocine on postoperative hyperalgesia induced by remifentanil in patients. Methods One hundred and twenty patients, of American Society of Anesthesiologists physical status ⅠorⅡ, aged 25-64 yr, with body mass index of 18-28 kg/m2, undergoing laparoscopic cholecystectomy, were allocated into 4 groups(n=30 each)using a random number table: control group(group C), dezocine group(group D), electroacupuncture group(group E)and electroacupuncture plus dezocine group(group E+ D). In E and E+ D groups, bilateral Hegu, Neiguan, Zusanli and Yanglinquan acupoints were stimulated with continuous waves(4 Hz)and then with disperse-dense waves(dense wave 20 Hz, disperse wave 4 Hz)after beginning of surgery until the end of surgery.Dezocine 5 mg was intravenously injected at 20 min before the end of surgery in D and E+ D groups and the equal volume of normal saline was given instead of dezocine in C and E groups.When visual analog scale score in post-anesthesia care unit(PACU)>5, dezocine 5 mg was intravenously injected.When visual analog scale score >5 within 1-48 h after surgery, ketorolac tromethamine 30 mg was intravenously injected.The pain threshold in the area around surgical incision was measured on admission to the operating room, at 10 min before anesthesia induction and at 6, 12, 24 and 48 h after surgery.The range of hyperalgesia in the area around surgical incision was recorded at 6, 24 and 48 h after surgery.The occurrence of nausea and vomiting was also recorded within 6, 24 and 48 h after surgery. Results Compared with group C, the pain threshold was significantly increased and the range of hyperalgesia was decreased in the area around surgical incision at each time point in E and E+ D groups, the duration of the first requirement for analgesics in PACU was significantly prolonged in D, E and E+ D groups, the requirement for analgesics was significantly decreased within 6 h after surgery in group D, the requirement for analgesics was significantly decreased within 6, 24 and 48 h after surgery, and the incidence of nausea and vomiting was decreased within 6 h after surgery in group E, and the requirement for analgesics and incidence of nausea and vomiting were significantly decreased at each time point in group E+ D(P<0.05). Compared with group D, the pain threshold in the area around surgical incision was significantly increased at each time point, and the range of hyperalgesia in the area around surgical incision was decreased at 24 and 48 h after surgery, the duration of the first requirement for analgesics in PACU was prolonged, and the requirement for analgesics was decreased within 24 and 48 h after surgery in group E+ D(P<0.05). Compared with group E, the duration of the first requirement for analgesics in PACU was significantly prolonged, and the requirement for analgesics was decreased within 24 h after surgery in group E+ D(P<0.05). Conclusion Electroacupuncture combined with dezocine produces better efficacy than either alone in reducing postoperative hyperalgesia induced by remifentanil in patients. Key words: Electroacupuncture; Analgesics, opioid; Piperidines; Hyperalgesia; Postoperative complications