Key result
Adding magnesium sulfate to bupivacaine fails to significantly prolong sensory block compared to bupivacaine alone.
Why the study?
The effect of adding magnesium sulfate to 0.5% bupivacaine on the duration of sensory and motor supraclavicular brachial plexus block in upper extremity orthopedic surgeries was investigated.
Does magnesium sulfate added to bupivacaine improve the duration of sensory and motor block in patients undergoing upper extremity orthopedic surgery?
RCT (n=60)
Double-blind
Randomized
No
Does magnesium sulfate added to bupivacaine improve the duration of sensory and motor block in patients undergoing upper extremity orthopedic surgery?
Adding magnesium sulfate to bupivacaine for supraclavicular brachial plexus block increased the duration of motor and sensory block in clinically significant proportions, though the results were not statistically significant.
Magnesium addition to bupivacaine did not significantly prolong supraclavicular block; leaves open adjuvant utility pending larger RCTs.
Background: Magnesium is a physiologic cation that blocks neuromuscular transmission and does not allow the nerve to be stimulated. This study investigates the effect of adding magnesium sulfate to 0.5% bupivacaine to extend the duration of sensory and motor blocks of the supraclavicular brachial plexus in orthopedic surgeries of the upper extremities.Methods: This controlled randomized double-blind study was performed on patients who were candidates for orthopedic surgery of the upper extremities. A total of 60 patients between 18 and 60 years with ASA Class 1 or 2 participated in the study. One Group M received 0.5% bupivacaine (1.5 mg/kg) with magnesium sulfate 20% (3 ml) as the case group, while the second Group P received 0.5% bupivacaine (1.5 mg/kg) with normal saline (3 ml) as a placebo to block the supraclavicular brachial plexus using nerve locator. The duration of the sensory and motor block of the supraclavicular brachial plexus was monitored and evaluated using the pinprick and modified Bromage scale.Results: A total of 60 patients were included in the study with 30 patients having received 0.5% bupivacaine plus magnesium and the other 30 patients having received 0.5% bupivacaine plus normal saline. The mean sensory block duration in the case Group M was 249±9.36 and in control Group P was 160±5.62 (p<0.39). The mean motor block duration in the case Group M was 232±9.64 and in control Group P was 147±26.52 (both p<0.32). The mean onset of sensory block in case Group M was 15.5±2.16 and the onset block in control Group P was 12.73±1.18 (p<0.49; statistically not significant). The mean onset of motor block in case Group M was 23.5±1.1 and the onset block in control Group P was 41±3 (p<0.53; statistically not significant).Conclusions: The addition of magnesium sulfate to 0.5% bupivacaine increased the duration of motor and sensory supraclavicular brachial block in the upper extremities during surgeries when compared to the use of 0.5% bupivacaine alone, though statistically not significant, but definitely in clinically significant proportions.
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Rao et al. (2015) conducted an RCT in Orthopedic surgery of the upper extremities (n=60). Magnesium sulfate added to 0.5% bupivacaine vs. 1.5 mg/kg of 0.5% bupivacaine plus 3 ml of normal saline diluted in 40 ml of normal saline was evaluated on Duration of sensory block (minutes) (p=<0.39). The addition of magnesium sulfate to 0.5% bupivacaine prolonged the mean duration of sensory block to 249 minutes compared to 160 minutes with bupivacaine alone, though reported as statistically not significant.
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