[The postoperative analgesic effects of magnesium infusion on brachial plexus block]

Magnesium sulphate infusion decreases analgesic requirements after general anesthesia. Aim of this study was to assess the effects of postoperative magnesium infusion for 24 hours on duration of the block, sedation and postoperative analgesic consumption after brachial plexus block. After obtaining approval from local ethic committee, 70 ASA class I and II patients were included to the randomised double blind study. Brachial plexus block was performed using axillary approach with lignocaine 1.25% adrenaline 1/200 000 40 ml. Groups received 5 mg/kg bolus and 500 mg/h magnesium sulphate infusion or saline controls at the same volume during 24 hour. Analgesia and sedation were assessed while determining time to first pain and rescue analgesic, time to regain motor capability, visual analogue scale and sedation scores for every 4 hour during postoperative 24 h. period. While time to first pain and rescue analgesic was increased, total analgesic consumption was reduced significantly on magnesium infusion group (Meperidine: C: 36.3 +/- 42.6 mg, Mg: 11.7 +/- 12.2 mg, p: 0.001). Visual analogue scales were also observed to be lower in all periods. Time to motor block resolution, and sedation scores were similar. Magnesium sulphate infusion is thought as a safe and suitable adjunct for reducing analgesic consumption and possible complications without interfering daily activity in patients undergoing brachial plexus block.