Comparison between magnesium and paracetamol when added as adjuvants to lidocaine for intravenous regional anesthesia

The aim of this study was to compare the effect of magnesium and paracetamol on tourniquet pain, onset times of both sensory and motor blocks and recovery, and on postoperative pain, when added as adjuvants to lidocaine for intravenous regional anesthesia. Sixty patients scheduled for hand surgery were randomly assigned into 3 groups, IVRA was achieved with 3mg/kg lidocaine hydrochloride 0.5% plus normal saline 0.9% in group -C-, with 3mg/kg lidocaine hydrochloride 0.5% plus 20% magnesium sulfate [16.2 mmol] in group -M-, or with 3mg/kg lidocaine hydrochloride 0.5% plus intravenous paracetamol 250 mg [Perfalgan] in group -P-. The onset times of both sensory and motor block and recovery were recorded. Tourniquet and post-operative pains were assessed by using the visual analog scale [VAS], and the onset time of tourniquet pain was recorded. The postoperative analgesic consumption and the first analgesic requirement time were noted. During the intraoperative and postoperative periods, any local or systemic complications were recorded for 24 hours in the ward. Sensory and motor block onset times were statistically shorter in group M than both groups P and C, while sensory and motor recovery onset times were statistically prolonged in this group. Tourniquet pain onset time was significantly longer in group M and group P than in group C. There were statistically significant differences in VAS scores for tourniquet pain at 10, 20, 30, and 40 minutes after tourniquet inflation and in VAS scores for postoperative pain between both study groups and control group, they were lower in both M and P groups. The total consumption of diclofenac was significantly lower in group M and group P compared with group C. The times to first postoperative analgesic request in group C was 69.6 +/- 12.8 min and in group M and group P were 100.2 +/- 15.8 min, and 102.2 +/- 17.0 min respectively; which was statistically significant. no any adverse events detected intra-operatively and postoperatively over a period of 24 hours in ward. The addiction of magnesium to lidocaine in IVRA demonstrated more shortened sensory and motor block onset times and more prolonged sensory and motor block recovery times, in comparison with the addition of paracetamol to lidocaine in IVRA. Also their addition similarly, decreased pain associated with tourniquet and postoperative pain, and prolonged the time to the first postoperative analgesic requirement