Effects of intraoperative high-dose vs low-dose remifentanil for postoperative epidural analgesia after gynecological abdominal surgery: a randomized clinical trial.

Study Objectives: To evaluate whether intraoperative high-dose remifentanil infusion increased local anesthetic consumption in postoperative epidural analgesia and postoperative pain scores compared with low-dose remifentanil infusion.

Design: Prospective, randomized controlled study.

Setting: Operating room, university hospital.

Patients: Thirty female patients scheduled for elective gynecological abdominal surgery.

Interventions: After epidural catheter placement and induction of general anesthesia, patients were randomly assigned to 2 anesthetic regimens. In the first group (high-dose remifentanil group), sevoflurane concentration was held constant at 1.2%, and the remifentanil infusion rate was titrated to maintain systolic blood pressure within 20% of baseline. In the second group (low-dose remifentanil group), the remifentanil infusion rate was held constant at 0.1μg/(kg min), and the sevoflurane concentration was titrated to maintain systolic blood pressure within 20% of baseline. As abdominal wall closure began, 6mL of 0.2% ropivacaine was administrated via epidural catheter; a patient-controlled analgesia device was set to deliver 4mL/h of 0.2% ropivacaine with 3μg/mL of fentanyl, with 2-mL incremental doses and a 15-minute lockout time.

Measurements: Local anesthetic consumption via postoperative epidural catheter and pain intensity with the Prince Henry pain scale were assessed for 48hours after surgery.

Main Results: The mean remifentanil infusion rate was 0.23μg/(kg min) in the high-dose remifentanil group, 2.3 times the rate used in the low-dose remifentanil group. The cumulative amount of local anesthetic used within 48hours of surgery was significant greater in the high-dose remifentanil group than in the low-dose remifentanil group (212±25mL vs. 181±35mL, respectively; P<.05), but postoperative pain scores were similar in each group.

Conclusions: Intraoperative high-dose remifentanil infusion increased local anesthetic consumption in postoperative epidural analgesia relative to low-dose remifentanil.