ABSTRACT
BACKGROUND: Patient-controlled epidural analgesia (PCEA), using a local anesthetic-opioid mixture, has been effectively applied after total knee replacement (TKR) surgery, which is associated with intense postoperative pain that requires postoperative analgesia for both rehabilitation and the pain itself. However, adverse opioid-related effects, such as nausea, vomiting and pruritus, are commonly encountered. It was our hypothesis that the adverse opioid-related effects could be reduced by the addition of naloxone, an opioid antagonist, to a mixture of fentanyl-ropivacaine PCEA. METHODS: In 120 patients undergoing elective TKR surgery, epidural or combined spinal-epidural (CSE) anesthesia was performed and PCEA applied. In the control group (n = 65), 0.16% ropivacaine and 3microgram/ml fentanyl (2.4microgram/ml for those older than 65 yrs) were administered. In the naloxone group (n = 55), naloxone (2microgram/ml) was coadministered with the above regimen. The incidence and severity of postoperative nausea and vomiting, and the frequency of pruritus, the visual analog score (VAS) and the PCEA volume used were assessed 6 and 24 hrs after surgery. RESULTS: The incidence of nausea and vomiting during the early postoperative period, and those of pruritus during the late postoperative period were significantly lower in the naloxone group. The VAS pain scores, the PCEA volume used and amount of rescue IV meperidine were similar in the two groups. CONCLUSIONS: A small dose of naloxone mixed with an opioid significantly reduces the incidence and severity of adverse opioid-related effects in PCEA, without reducing the analgesic effect