Effectiveness of adding magnesium sulfate to bupivacaine in ultrasound guided serratus anterior plane block in patients undergoing modified radical mastectomy

Background
This research work investigated the effect of magnesium sulfate added to bupivacaine in serratus anterior block in cases of modified radical mastectomy.
Patients and method
A total of 80 female patients of ASA I and II were randomly assigned into two equal groups depending on the adjuvant added to bupivacaine. B group: patients received 20 ml 0.5% bupivacaine with 5 ml 0.9% normal saline. BM group: patients received 20 ml 0.5% bupivacaine+150 mg magnesium sulfate in 0.9% normal saline with a total volume of 25 ml in both groups. Primary aim was to test the effect of magnesium sulfate when added to bupivacaine on pain intensity. Secondary targets were to detect the haemodynamics, safety and any side effects of magnesium sulfate.
Results
Visual analogue scale measurement showed statistical significant decrease after 4 hours till 24 hours postoperatively in BM group more than in B group. Mean time to first rescue analgesia in BM group was 11.73 ± 1.91 hours versus 8.13 ± 1.38 hours in B group with P value < 0.001. The mean total dose of nalbuphine used was statistically significantly decreased in BM group, as it was 15.50 ± 3.89 mg in B group and 9.63 ± 4.44 mg in BM group with P value < 0.001. Occurrence of complications in both groups showed insignificant statistical difference.
Conclusions
Magnesium sulfate with bupivacaine in serratus anterior plane block produced prolonged analgesia postoperatively without significant haemodynamic instability with significant decline in the total dose of rescue analgesic with minimal side effects.