Analgesic efficacy of bupivacaine with or without magnesium adjunct in bilateral ilioinguinal and iliohypogastric nerve blocks following cesarean section under subarachnoid block: A randomized controlled trial.

Background: Pain relief is a basic aspect of anesthesia care. Optimal post-cesarean section analgesia should minimize postoperative complications, facilitate infant care, and prevent postoperative morbidity. Bilateral ilioinguinal-iliohypogastric (IIIH) nerve block has been considered as a part of the multimodal approach. This study was designed to explore the efficacy of adding magnesium sulfate as an adjunct to bupivacaine to provide analgesia following cesarean delivery, using bilateral IIIH nerve block.

Materials And Methods: Seventy-two parturients who were scheduled for elective cesarean section were randomized into two groups of 36 patients each. Group MB patients were given bilateral IIIH nerve block with 250 mg of magnesium sulfate and 95 mg of 0.25% plain bupivacaine. Group B patients were given bilateral IIIH nerve block with 0.9% normal saline and 95 mg of 0.25% plain bupivacaine. Postoperative visual analog scale (VAS) pain scores at post-anesthesia care unit (PACU), 2, 4, 6, 12, and 24 h, both at rest and with activity were measured. Rescue doses of opioid (intravenous [IV] tramadol 50 mg) at each time point of assessment, total tramadol consumption, time to patients' first request for rescue analgesic agent, and patients' satisfaction score were recorded.

Results: The demographic and social parameters of patients in both the groups were comparable. The mean postoperative VAS pain score in group MB was significantly lesser both at rest and with movement than in group B at 12 and 24 h after surgery ( < 0.05). Total postoperative tramadol consumed over 24 h was significantly lesser in the magnesium group than in the control group (125.55 ± 20.76 vs. 160.24 ± 25.82 mg), with a value of 0.026. The time to patient's first analgesic request was significantly prolonged in group MB compared to group B (505.2 ± 41.4 vs. 372.6 ± 88.8 min, respectively), with a P value of 0.040. However, patients in both groups expressed good satisfaction scores.

Conclusion: Magnesium sulfate as an adjunct to bupivacaine in bilateral IIIH nerve block reduced VAS pain scores, total tramadol consumption, and prolonged post-cesarean section analgesia.