Post operative analgesia after incisional infiltration of bupivacaine v/s bupivacaine with buprenorphine

Introduction: Opioid receptors have been demonstrated in the peripheral nerve endings of afferent neurons. Blockade of these receptors with peripherally administered opioid is believed to result in analgesia. Aim: To evaluate whether buprenorphine added to bupivacaine for wound infiltration can enhance post-operative analgesia via peripheral mechanisms. Materials and Methods: Forty ASA I and II adult patients scheduled for open donor nephrectomy were enrolled in this randomized double blind prospective study. In group A ( n=20) patients, the wound was infiltrated with bupivacaine 0.5% (2 mg/kg) and in group B ( n=20) with bupivacaine 0.5% (2 mg/kg) and buprenorphine (2 μg/kg). All patients were given diclofenac 75 mg IM at 8 h interval. Post-operative quality of analgesia was assessed by VAS (0-10) for 24 h and when VAS > 4 rescue analgesic was administered. Total dose of rescue analgesic and side effects were noted. Results: The time of administration of first rescue analgesic was significantly higher in group B (10.52±5.54 h) as compared to group A (3.275±1.8 h). Mean VAS was significantly lower in group B as compared to group A. The total dosage of rescue analgesic was more in group A as compared to group B patients. Conclusion: Addition of buprenorphine to the local anesthetic significantly prolonged the time to first rescue analgesic requirement and the total consumption of rescue analgesic in 24 h, thus providing evidence in support of the existence of peripheral opioid receptors.