High-Dose Magnesium Sulfate Infusion for Severe Asthma in the Emergency Department: Efficacy Study.

Objective: To assess the efficacy of a high-dose prolonged magnesium sulfate infusion in patients with severe, noninfectious-mediated asthma. Design: Prospective, randomized, open-label study. Setting: Twenty-nine-bed pediatric emergency department located in a children's hospital in Asuncion, Paraguay. Patients: All patients of 6-16 years old who failed to improve after 2 hours of standard therapy for asthma. Interventions: Subjects were randomized to receive magnesium sulfate, 50 mg/kg over 1 hour (bolus) or high-dose prolonged magnesium sulfate infusion of 50 mg/kg/hr for 4 hours (max, 8.000 mg/4 hr). Patients were monitored for cardiorespiratory complications. Measurements and Main Results: Asthma severity was assessed via asthma scores and peak expiratory flow rates at 0-2-6 hours. The primary outcome was discharge to home at 24 hours. An analysis of the hospital length of stay and costs was a secondary outcome. Thirty-eight patients were enrolled, 19 in each group. The groups were of similar ages, past medical history of asthma, asthma score, and peak expiratory flow rate. There was a significant difference in the patients discharged at 24 hours: 47% in high-dose prolonged magnesium sulfate infusion (9/19) versus 10% (2/21) in the bolus group (p = 0.032) with an absolute risk reduction 37% (95% CI, 10-63) and a number needed to treat of 2.7 (95% CI, 1.6-9.5) to facilitate a discharge at or before 24 hours. The length of stay was shorter in the high-dose prolonged magnesium sulfate infusion group (mean sd in hr: high-dose prolonged magnesium sulfate infusion, 34.13 +/- 19.54; bolus, 48.05 +/- 18.72; p = 0.013; 95% CI, 1.3-26.5). The cost per patient in the high-dose prolonged magnesium sulfate infusion group was one third lower than the bolus group (mean +/- sd: high-dose prolonged magnesium sulfate infusion, $603.16 +/- 338.47; bolus, $834.37 +/- 306.73; p < 0.016). There were no interventions or discontinuations of magnesium sulfate due to adverse events. Conclusions: The early utilization of high-dose prolonged magnesium sulfate infusion (50 mg/kg/hr/4 hr), for non-infectious mediated asthma, expedites discharges from the emergency department with significant reduction in healthcare cost.