Intravenous Magnesium: Prompt use for Asthma in Children Treated in the Emergency Department (IMPACT-ED)

This pilot trial is a first step to determine if a simple and inexpensive medicine, intravenous magnesium sulfate (IV Mg), can improve outcomes of children treated in emergency departments for severe acute asthma. This pilot trial will enroll 90 children across three hospitals and evaluate giving IVMg or placebo early in ED treatment when the impact on hospitalization would be greatest, characterize changes in blood pressure when IV Mg is given, and collect information necessary to understand what dose of IV Mg is likely to be most effective.