Effect of adding 8 milligrams ondansetron to lidocaine for Bier′s block on post-operative pain

Background: Ondansetron has analgesic properties. The aim of the present study was to assess the analgesic effect of 8 mg ondansetron when added to lidocaine for intravenous regional anesthesia (IVRA). Materials and Methods: Ninety patients undergoing hand surgery were randomly allocated to the three groups to receive 3 mg/kg 2% lidocaine diluted with saline to a total dose of 40 mL (Group L, n = 30) or 8 mg ondansetron plus 3 mg/kg 2% lidocaine diluted with saline to a total dose of 40 mL (group LO, n = 30) or 3 mg/kg 2% lidocaine diluted with saline to a total dose of 40 mL plus 8 mg ondansetron intravenously (Group IO, n = 30). Tourniquet pain and analgesic use were recorded before and after the tourniquet application. Results: The sensory and motor block onset times were significantly shorter in Group LO compared with Group L and Group IO (4.2 ± 1.7 vs. 5.2 ± 0.8 and 5.1 ± 1.2 respectively, P < 0.05; 4.5 ± 1.4 vs. 5.8 ± 1.5 and 5.7 ± 1.4 respectively, P < 0.05). The sensory and motor block recovery times were significantly longer in Group LO compared with Group L and Group IO (6.1 ± 1.1 vs. 4.1 ± 1.3 and 4.5 ± 0.9 respectively, P < 0.05; 6.7 ± 1.4 vs. 4.4 ± 0.9 and 4.7 ± 0.7 respectively, P < 0.05). Post-operative VAS scores were significantly less in Group LO compared with Group L and Group IO till 24 h after tourniquet deflation ( P < 0.05).Conclusion: The addition of 8 mg ondansetron to lidocaine for IVRA reduced intraoperative and post-operative analgesic use till 24 h