Comparative study of 0.5% bupivacaine with 150mg MgSO4 versus 0.5% plain bupivacaine in interscalene brachial plexus block for shoulder

Abstract

Objectives: Interscalene brachial plexus block for the shoulder is commonly used for forelimb and hand surgeries. A lot of research is going on to increase the duration of sensory and motor blockade by the addition of adjuvants with the local anesthetics. We evaluated the effect of adding MgSO4 to bupivacaine for Interscalene brachial plexus blockade. Our primary parameters were the onset and duration of sensory and motor block and duration of analgesia. Methods: 60 patients posted for elective forearm and hand surgeries under Interscalene brachial plexus block were divided into two equal groups (Group B and B+M) in a double-blind fashion. Results: The onset of a blockade in Group B was found to be 15.49 ± 2.38 minutes when compared to the onset time of 18.00 ± 2.80 minutes in Group B+M and this difference was found to be statistically significant (p<0.001). The onset of motor blockade found in Group B was 17.75 ± 2.70minutes and Group B+M was19.84 ± 2.50 and it is found to be statistically significant with a p-value of 0.002 The duration of sensory blockade was longer in Group B+M with a duration of 621.60 ± 25.25 minutes compared to Group B having the duration of 503.36 ± 24.51minutes and this difference was found to be statistically significant (p<0.001). Conclusion: We conclude that the addition of 150 mg MgSO4 to ropivacaine 0.5% bupivacaine interscalene brachial plexus block for shoulder prolongs the duration of sensory, motor blockade, and duration of analgesia but results in a slight delay in the onset time of sensory and motor blockade.