Postoperative pain management in patients undergoing major surgery after remifentanil vs fentanyl anesthesia

Abstract

Purpose: To determine if morphine sulphate was an effective transition analgesic in patients receiving a remifentanil-based anesthetic regimen. Methods: Open-label remifentanil or fentanyl was administered to 210 randomized patients undergoing inpatient surgery. Isoflurane and nitrous oxide was administered to all patients. Thirty minutes before the end of surgery, patients receiving remifentanil were randomized to receive morphine 0.15 mg·kg-1 (R/M15 group) or 0.20 mg·kg-1 (R/M20 group). Following extubation and prior to patient-controlled analgesia (PCA) initiation, 2 mg boluses of morphine were administered for moderate/severe pain. Efficacy endpoints were total morphine used in the post anesthesia care unit (PACU) and 24 and 48 hr postoperatively; postoperative pain; time to first morphine bolus; time to first PCA administration; and time to recovery endpoints. Results: Mean total morphine used in PACU was not different among groups (15.5 mg, 16.5 mg and 13.3 mg in R/M15, R/M20 and F groups, respectively). Mean total 24 hr morphine use (58.1 mg, 56.93 mg and 53.6 mg in R/M15, R/M20 and F groups) and mean total morphine used at 48 hr were not different (69.8 mg, 64.7 mg and 62.1 mg in R/M15, R/M20 and F/l groups). Groups were similar with respect to pain severity ratings at all postoperative times. Patients in the fentanyl arm experienced faster times to some recovery endpoints than patients receiving either remifentanil regimen. Conclusion: Morphine sulphate regimens of 0.15 or 0.20 mg·kg-1 administered 30 min before the end of surgery are equally effective transition regimens for inpatient procedures.