Peripheral opioid receptor mediated enhancement of analgesia by buprenorphine in intravenous regional anaesthesia

Background: Recent demonstration of opioid receptors along peripheral sensory nerves especially after painful inflammatory conditions forms the basis of peripheral opioid analgesia. This form of opioid antinociception has the potential to help overcome one of the disadvantages of intravenous regional anesthesia (IVRA) that is lack of postoperative analgesia. The aim of the study was to assess the efficacy of Buprenorphine as an adjunct to Lignocaine in (IVRA) for postoperative analgesia. Methods: Seventy-five consenting patients undergoing hand and forearm surgery were randomly allocated into three groups of twenty-five each: group A received 0.5% 40 ml Lignocaine for IVRA, group B received 0.5% 40 ml Lignocaine for IVRA and Buprenorphine 0.3 mg intramuscularly and group C received 0.5% 40 ml Lignocaine with Buprenorphine 0.3 mg for IVRA. Postoperative analgesia was assessed using visual analog scale (VAS) on a 0 to 100 mm scale in the immediate postoperative period and 1 hourly thereafter for 24 hours. Patients were given Declofenac 1 mg/kg orally whenever VAS score exceeded 25 or patient demanded analgesic. Results: Onset time for sensory block was longer in group C as compared to group A and B (5.0±1.0 min versus 4.0±0.6 and 4.0±0.4) whereas motor block onset time was comparable in all the three groups. Quality of sensory and motor block was similar in all the groups. Duration of postoperative analgesia was significantly longer in group C (1200 ±120 min.) as compared to 42±12 and 420±36 minutes for group A and B respectively (p=0.001). Analgesic consumption was also significantly lower in group C (56±9 mg versus 201±27 and 120±24 mg for group A and B respectively (p=0.001). Incidence of nausea/vomiting and sedation was much higher in group B as compared to other groups (p=0.002).Conclusion: We concluded that addition of Buprenorphine 0.3 mg to Lignocaine for IVRA significantly prolongs analgesia without causing systemic side effects.