Intravenous regional anesthesia : effect of magnesium using two different routes of administratio

Abstract EN

Background Magnesium has been reported as an adjuvant to local anesthetics to improve the quality of intravenous regional anesthesia (IVRA); however, different routes of administration have not been compared before.

The aim of this study was to compare between the effect of intravenous infusion of magnesium and the effect when it is added to a local anesthetic on the quality of analgesia and opioid consumption during IVRA in patients undergoing hand surgery.

Patients and methods Fifty-nine patients undergoing elective hand surgery were randomly allocated to one of three groups: the R group (n = 20 patients), which received IVRA using ropivacaine 0.2%; the RM group (n = 20 patients), which received IVRA using ropivacaine 0.2% and magnesium sulfate 10 mg/kg; and the RMV group (n = 19 patients), which received IVR using ropivacaine 0.2% and a systemic intravenous single dose of magnesium sulfate 30 mg/kg.

The primary outcome measure included morphine consumption in the first 24 h andthe secondary outcome measure included onset of both sensory and motor blockade, tourniquet pain, intraoperative fentanyl consumption, and postoperative pain using the Verbal Rating Scale (VRS).

Results Onset times of sensory and motor blockades were shorter in the RM group (10.5 ± 4 and 14 ± 5 min) than in the R group (16.5 ± 6 and 21 ± 6 min) and RMV group (16 ± 5.5 and 20.5 ± 5.3 min).

Time to first analgesic requirement was significantly longer in the RMV group (98 ± 12 min) than in the R group (70 ± 11 min) and RM group (75 ± 13 min), whereas the 24 h morphine consumption in the RMV group (14.5 ± 8.7 mg) was significantly lower than that in the RM group (25 ± 10 mg)and Rgroup (27 ± 15 mg).

Tourniquet discomfort was significantly lower in the RM group [1 (0–2)] than in the R group [2 (1–4)] and RMV group [3 (1–4)].

Intraoperative fentanyl consumption was lower in the RM group (20.5 ± 9) than in the Rgroup (43.8 ± 9) and RMV group (38 ± 15),whereas VRS was significantly lower in the RM Vgroup at 1, 3, 6, and 12 h (P < 0.05) in comparison with the other groups.

Conclusion The addition of magnesium to ropivacine in the IVRA improved the quality of block and reduced the tourniquet discomfort,and the systemic magnesium administration reduced the postoperative pain and morphine consumption.