In pediatric torsades de pointes arrest, what is the magnesium sulfate dose?

• A. 4 mg/kg
• B. 8 mg/kg
• C. 20 mg/kg
• D. 40 mg/kg

Answer: (D)

Magnesium sulfate is used in pediatric torsades de pointes arrest to stabilize cardiac membranes and suppress the arrhythmia by correcting magnesium deficiency and reducing abnormal calcium influx that fuels the arrhythmia. In children, the dose is weight-based and given IV: typically 25–50 mg/kg, with a maximum total dose of about 2 g. The 40 mg/kg option sits squarely in that therapeutic range and provides a rapid, effective dose during arrest. For example, a child weighing 20 kg would get about 800 mg, while a 50 kg child would reach the 2 g max. Lower doses risk under-treating the rhythm, while the upper end stays within safe limits.