Ondansetron added to lidocaine for intravenous regional anaesthesia

The aim of this study was to evaluate the effect of ondansetron when added to lidocaine for intravenous regional anaesthesia (IVRA).

Thirty patients undergoing hand surgery were randomly assigned to two groups. IVRA was achieved with 3 mg kg lidocaine 2% w/v diluted with saline to a total volume of 40 ml in the control group or with 4 mg ondansetron 2 mg ml plus 3 mg kg lidocaine 2% w/v diluted with saline to a total volume of 40 ml in the ondansetron group. Sensory and motor block onset and recovery times, tourniquet pain score according to a visual analogue scale (VAS), intraoperative analgesic requirements and anaesthesia quality were recorded. Postoperative VAS pain score, time to first analgesic requirements and total diclofenac consumption in the first 24 h were noted.

Onset times were slightly but significantly shorter [1.4 min (95% confidence interval (CI) 0.5-2.3) and 1.5 min (95% CI 0.45-2.55)] and recovery times were slightly but significantly prolonged [2.6 min (95% CI 1.66-3.54) and 2.8 min (95% CI 1.83-3.78)] in patients receiving ondansetron. Tourniquet pain scores according to the VAS were slightly but significantly lower at 10, 15, 20 and 30 min, the time to intraoperative analgesic rescue was prolonged (35.0 +/- 7.1 min vs. 18.9 +/- 8.9 min, P = 0.043), a significantly lower number of patients (2 vs. 9) required additional analgesic and significantly less supplemental fentanyl was given [0 microg (0-0) vs. 59 microg (0-76), P = 0.015] in the ondansetron group. First intake of analgesic intake was longer (172 +/- 51 vs. 85 +/- 35 min, P = 0.0001), number of patients (7 vs. 15) requiring postoperative diclofenac was significantly lower and diclofenac requirements [0 mg (0-75) vs. 75 mg (75-150), P = 0.002) was significantly lower in the ondansetron group. Postoperative VAS scores were lower for the first 4 h in the ondansetron group.

Addition of ondansetron to lidocaine may improve the quality of IVRA and prolong postoperative analgesia in patients undergoing hand surgery.