Comparative Analgesic Efficacy of Adding Magnesium Sulphate to Bupivacaine in Serratus Anterior Plane Block to Reduce Pain After Mastectomy: A Prospective Comparative Study at SCB Medical College & Hospital, Cuttack

Abstract

Background: Postoperative pain following mastectomy remains a significant clinical challenge despite advancements in multimodal analgesia. Inadequate pain control may result in delayed recovery, prolonged hospitalization, increased opioid consumption, and development of chronic post-mastectomy pain syndrome. Serratus anterior plane (SAP) block has emerged as an effective regional anesthetic technique for postoperative analgesia in breast surgeries. Magnesium sulphate, an N-methyl-D-aspartate (NMDA) receptor antagonist, has been investigated as an adjuvant to local anesthetics to enhance analgesic efficacy and prolong block duration.
Objective: To compare the analgesic efficacy of bupivacaine alone versus bupivacaine combined with magnesium sulphate in ultrasound-guided serratus anterior plane block for postoperative pain relief after mastectomy.
Materials and Methods: A prospective randomized comparative study was conducted at SCB Medical College & Hospital, Cuttack, from December 2024 to February 2026. A total of 100 female patients undergoing elective mastectomy under general anesthesia were enrolled and divided into two groups of 50 each. Group B received 0.25% bupivacaine in SAP block, while Group BM received 0.25% bupivacaine with magnesium sulphate 150 mg. Postoperative pain was assessed using Visual Analog Scale (VAS) scores at multiple time intervals. Time to first rescue analgesia, total analgesic consumption, hemodynamic parameters, and adverse effects were recorded. Statistical analysis was performed using SPSS version 26. Independent t-test, Chi-square test, and repeated measures ANOVA were applied.
Results: The mean postoperative VAS scores were significantly lower in Group BM compared to Group B at 4, 8, 12, and 24 hours postoperatively (p<0.001). The mean duration of analgesia was significantly prolonged in Group BM (13.6 ± 2.1 hours) compared to Group B (7.2 ± 1.4 hours) (p<0.001). Total rescue analgesic consumption was significantly reduced in Group BM (92 ± 28 mg) compared to Group B (168 ± 34 mg) (p<0.001). Hemodynamic stability was better maintained in Group BM. Incidence of postoperative nausea and vomiting was lower in Group BM, although statistically insignificant.
Conclusion: Addition of magnesium sulphate to bupivacaine in serratus anterior plane block significantly improves postoperative analgesia after mastectomy by reducing pain scores, prolonging duration of analgesia, and decreasing rescue analgesic requirements without significant adverse effects.