Analgesic effect of magnesium sulfate as an adjuvant to ropivacaine in pectoral nerve block

Abstract

Background: Pectoral nerve (Pecs) block is an effective component of multimodal analgesia regimens for breast surgeries. It has been used as a supplement to general anesthesia for intraoperative and postoperative analgesia. In the present study, we aimed to evaluate and compare the analgesic effect of magnesium sulfate 150 mg as an adjuvant to 0.25% ropivacaine in pecs block. Patients and Methods: A total of 60 American Society of Anaesthesiologists Grades I and II female patients with age between 18 and 65 years were enrolled in this study. Group A received ultrasound (US)-guided Pecs block with 40 ml volume containing 30 ml of 0.25% ropivacaine with 10 ml of normal saline as a placebo. Group B received US-guided Pecs block with 40 ml volume containing 30 ml of 0.25% ropivacaine and 150 mg of magnesium sulfate diluted to 10 ml of normal saline. Postoperative pain was assessed using the visual analog scale. Duration of analgesia and total analgesic consumption was noted in 24 h. Student's t-test, Mann–Whitney U–test, and Chi-square test were used for the statistical analysis. Results: The mean duration of analgesia was prolonged in Group B as compared to Group A (493.17 ± 12.54 min vs. 307.70 ± 22.37 min). Total analgesic consumption in the first 24 h postoperatively was also statistically lower in Group B as compared to Group A (132.50 ± 32.26 vs. 167 ± 32.26 mg in Group A) (P ≤ 0.001). Hemodynamics were comparable. Conclusion: The addition of 150 mg magnesium sulfate as adjuvant to 0.25% ropivacaine for Pecs block increases the duration of analgesia and significantly reduces the amount of analgesic requirement.