Effect of magnesium sulphate on propofol requirement in abdominal surgeries under general anesthesia

Abstract

Background & Objective: Magnesium sulphate (MgSO4) has the potential to be used as a part of balanced anesthesia due to its inherent pharmacological actions. Its judicial use can enhance patient safety. We evaluated the effect of MgSO4 on the total dose of propofol used under bispectral index (BIS) targeted general anesthesia for abdominal surgeries. Methodology: This prospective randomized controlled trial was conducted on 60 adult patients of either sex, scheduled for elective surgery under general anesthesia. Patients were allocated to two study groups of 30 patients each. In Group I, MgSO4 was administered as 30 mg/kg intravenously (IV) in 100 ml normal saline (NS) over 15 min followed by 10 mg/kg/h infusion intraoperatively. In Group II 100 ml NS was administered over 15 min followed by NS infusion intraoperatively. Anesthesia was induced with propofol, fentanyl, and atracurium in both groups. Intraoperative propofol infusion was started to keep BIS values within 45-55. Data was compared for total dose of propofol used, Ramsay sedation score, recovery characteristics and hemodynamic parameters. Data so collected was statistically analyzed. Results: The mean quantity of propofol required for induction was less in Group I as compared to Group II, being 1.70 ± 0.19 mg/kg and 2.39 ± 0.58 mg/kg respectively (P < 0.001). Group I achieved BIS 60 (59.20 ± 7.63 seconds) faster than Group II (78.36 ± 13.03 sec) (P < 0.001). The requirement of propofol for maintenance was less in Group I (4.48 ± 0.95 mg/kg/h) as compared to Group II (6.63 ± 1.65 mg/kg/h) (P < 0.001). During recovery, the MgSO4 group needed more time to reach BIS 70 as compared to control group with their mean values being 8.86 ± 1.48 min and 6.88 ± 1.54 min respectively. Response to verbal commands and orientation was also significantly delayed in MgSO4 group as compared to control group (P < 0.001). Conclusion: Magnesium sulphate co-administration with propofol decreases the dosage of propofol to maintain a constant BIS value at 45–55. Sedation and delayed recovery are the notable drawbacks of using magnesium sulphate. Abbreviations: NMDA - N-methyl-D-aspartate; BIS - Bi‑spectral index; HR - Heart rate; MAP - mean arterial pressure Preregistration: Clinical Trial Registry-India (CTRI/2020/11/029315) Key words: Magnesium Sulphate; Propofol; BIS Target; Balanced Anesthesia Citation: Kaur H, Singh A, Prasad V, Singh A, Gupta KK, Sharma P. Effect of magnesium sulphate on propofol requirement in abdominal surgeries under general anesthesia. Anaesth. pain intensive care 2023;27(5):471−477. DOI: 10.35975/apic.v27i5.2118 Received: January 14, 2023; Reviewed: July 17, 2023; Accepted: July 20, 2023