Comparison of Two Different Doses of Prophylactic Intravenous Magnesium Sulphate for the Prevention of Shivering in Patients Undergoing Procedures Under Spinal Anesthesia.

INTRODUCTION: Shivering is a common and distressing complication of spinal anesthesia associated with increased metabolic demand, hemodynamic fluctuations, and impaired monitoring. Magnesium sulfate (MgSO4), an N-methyl-D-aspartate (NMDA) receptor antagonist, has been investigated for its thermoregulatory benefits. This study compared two prophylactic intravenous (IV) doses of magnesium sulfate (25 mg/kg vs 50 mg/kg) for the prevention of shivering in patients undergoing surgeries under spinal anesthesia. MATERIALS AND METHODS: A prospective observational study was conducted at a tertiary care center over one year among 88 adult patients undergoing elective procedures under spinal anesthesia. Participants were allocated into two groups: Group A (50 mg/kg IV magnesium sulfate bolus) and Group B (25 mg/kg IV magnesium sulfate bolus). Hemodynamic parameters, temperature, and shivering grades were monitored intraoperatively and postoperatively. Shivering was graded on a 0-4 scale. Data were analyzed using IBM SPSS Statistics version 20 (IBM Corp., Armonk, USA); p < 0.05 was considered statistically significant. RESULTS: Demographic characteristics were comparable between groups. No significant differences were observed in heart rate, systolic/diastolic blood pressure, peripheral oxygen saturation (SpO2), or temperature at any time point (p > 0.05). Overall, 93.2% of patients did not develop shivering: 42/44 (95.5%) in Group A and 40/44 (90.9%) in Group B, with no statistically significant difference in shivering incidence or grade (p > 0.97). Shivering onset was clinically delayed in Group A, though without statistical significance. CONCLUSION: Both 25 mg/kg and 50 mg/kg prophylactic IV magnesium sulfate effectively prevented shivering after spinal anesthesia without significant hemodynamic instability. The lower dose (25 mg/kg) demonstrated equivalent efficacy and safety, supporting its use as a preferable dose for routine prophylaxis.