To prolong the duration of brachial plexus block, different adjuvants have been used. We evaluated the effect of adding magnesium sulfate to local anesthetic ropivacaine 0.4% for institution of supraclavicular brachia plexus block. Onset of sensory and motor block, duration of motor block, and rescue analgesia were observed.

Total 120 patients (20–50 years) scheduled for elective surgeries of upper limb under supraclavicular brachial plexus block were randomized into two groups. Group I received 24 mL 0.5% ropivacaine (120 mg) + 6.0 mL normal saline (NS) to make total volume of 30 mL. Group II received 24 mL 0.5% ropivacaine (120 mg) + 150 mg magnesium sulfate + 5.5 mL NS to make total volume of 30 mL.

Onset of sensory block in group I was 16.63 ± 2.79 min and in group II was 17.33 ± 2.25 min (statistically not significant, p > 0.05). Onset of motor block in group I was 18.63 ± 2.79 min and in group II was 19.76 ± 2.18 min (statistically significant, p < 0.05). The duration of motor block was significantly longer in group II; 322.00 ± 81.35 min than group I; 260.25 ± 66.79 min (p < 0.05). Similarly, time of rescue analgesia was significantly prolonged in group II; 491 ± 100.22 min than group I; 377.67 ± 73.31 min (p < 0.05).

From our study, we concluded that the addition of 150 mg magnesium sulfate as adjuvant to 30 mL of 0.4% ropivacaine in comparison to 30 mL of 0.4% ropivacaine provides longer duration of analgesia. Although the onset of sensory block is not affected, onset of motor block is delayed. Motor block lasts for longer duration.

Gupta D, Mangal V, Sharma G, Kulshestha A, Kalra P. Efficacy of Magnesium Sulfate as Adjuvant to Ropivacaine 0.4% for Supraclavicular Brachial Plexus Block in Patients undergoing Upper Limb Surgery: A Randomized Controlled Trial. J Recent Adv Pain 2017;3(2):85-89.