Adding magnesium to lidocaine for intravenous regional anesthesia

Abstract

• BACKGROUND: Magnesium (Mg) has been used as an adjuvant medication in postoperative analgesia. We planed this study to assess the effects of Mg, when added to lidocaine in intravenous regional anesthesia (IVRA) on the tourniquet pain.
• METHODS: Forty patients undertaking hand surgery were randomly allocated into 2 groups to be given IVRA. They received 20 ml lidocaine 1% diluted with 20 ml saline to a total of 40 ml in the group L (n = 20) or 7.5 ml magnesium sulfate 20% plus 20 ml lidocaine 1% diluted with 12.5 ml saline to a total of 40 ml in the group M (n = 20). Sensory and motor block onset and recovery times, anesthesia and operation qualities were recorded. Before and after the tourniquet use at 5, 10, 15, 20, 30, 40, and 50 minutes, hemodynamic variables, tourniquet pain, and analgesic use were noted. Subsequent to the tourniquet deflation, at 6, 12, and 24 hours, hemodynamic variables, pain, time to first analgesic requirement, analgesic use and side effects were recorded.
• RESULTS: Shortened sensory and motor block onset times were established in group M (P < 0.05). Visual analog scale (VAS) scores were less in group M at 20, 30, 40, and 50 minutes after tourniquet inflation (P < 0.05). Intraoperative, analgesic requirement was less in group M (P < 0.05). Anesthesia excellence, as determined by the anesthesiologist and surgeon, was significantly better in group M (P < 0.05). Time to the first analgesic requirement in group M was 53.75 ± 6.94 minutes and in group L was 40.76 ± 14.55 minutes (P < 0.05). Postoperative VAS scores were higher at 6, 12, and 24 hours in group L (P < 0.05).
• CONCLUSIONS: Adding Mg to lidocaine for IVRA enhanced the quality of anesthesia and analgesia without causing side effects.
• KEYWORDS: Magnesium sulfate, intravenous regional anesthesia, postoperative pain.