Effects of Preoperative Electroacupuncture on Remifentanil-Induced Post-Infusion Hyperalgesia in Patients Undergoing Thyroidectomy: A Double-Blind Randomized Controlled Trial

OBJECTIVE: Electroacupuncture (EA) delivered one day before surgery could reduce postoperative pain. Remifentanil-induced post-infusion hyperalgesia (RPH) was occurred after exposure to high-dose remifentanil. This study aimed to investigate the effects of preoperative EA on RPH in patients undergoing thyroidectomy. METHODS: A total of 80 patients who were scheduled to undergo elective thyroidectomy were randomly assigned to two groups: an EA group and a sham EA (SEA) group. EA was delivered at the Zusanli (ST36) and Neiguan (PC6) acupoints 24 h before the surgery. To ensure uniformity across all patients, remifentanil was administered at the same set rate (0.3 μg/kg/min) to all patients. Mechanical pain thresholds were recorded by an electronic von Frey device around the skin incision and on the arm before surgery as well as at 30 min and 6, 24, and 48 h after surgery. RESULTS: At 30 min and 6 h after surgery, the EA group showed considerably greater mechanical pain thresholds surrounding the surgical site compared with the SEA group. At 30 min and 6 h after surgery, the patients in the SEA group showed a greater incidence of postoperative hyperalgesia surrounding the surgical site than those in the EA group. At 24 and 48 h after surgery, no significant differences were found between the two groups, although the pain intensity of the EA group was less than that of the SEA group. There were also no substantial differences between the two groups in the frequency of postoperative adverse reactions and rescue analgesia needed. CONCLUSION: EA administered 24 h before surgery could alleviate RPH in patients undergoing thyroidectomy.