Epidural Naloxone Attenuates Fentanyl Induced PONV in Patients Undergoing Lower Limb Orthopaedic Surgeries. a Prospective Randomized Double-Blind Comparative Study.

Background and aim: Epidural administration of opioids with local anaesthetics is a popular choice for perioperative pain relief. But opioid induced side effects limit their use for postoperative analgesia. Hence, this study was designed to evaluate the effectiveness of epidural naloxone, an opioid receptor antagonist, in reducing PONV in patients receiving epidural fentanyl.

Methods: After obtaining the Institutional Ethics Committee approval and written informed consent, 46 patients, between 18-80 years, of either sex, with ASA physical status 1-3, undergoing lower limb orthopaedic surgeries were enlisted for this prospective, randomized, double blind comparative study. Subjects were allocated to one of the two groups and received epidurally, either fentanyl with bupivacaine (Group C, n = 23) or fentanyl with bupivacaine and naloxone 2 mcg (Group N, n = 25), for reducing postoperative pain. PONV score and Wong Bakers Scale (WBS) for pain score were recorded at 6, 12 and 18hrs, postoperatively.

Results: All patients were comparable with respect to age, gender, ASA PS, height, body weight as well as duration of surgery. A statistically significant decrease in PONV score was observed in Group N at 6 and 12 hours, postoperatively. The patients who required rescue antiemetic were also significantly lower in Group N at 6 and 12 hours. The mean WBS score for pain also showed significant reduction in Group N at 6 hours, postoperatively.

Conclusion: Concomitant use of low dose epidural naloxone and fentanyl is effective in attenuating PONV, besides enhancing analgesia in the earlypostoperative period.