Intravenous magnesium therapy for moderate to severe pediatric asthma: results of a randomized, placebo-controlled trial.

OBJECTIVE To evaluate the efficacy of intravenous magnesium (IVMg) therapy for moderate to severe asthma exacerbations in pediatric patients. DESIGN Randomized, double-blind, placebo-controlled, clinical trial. SETTING Urban pediatric emergency department. PARTICIPANTS Thirty-one patients aged 6 to 18 years who were being treated for an acute asthma exacerbation with peak expiratory flow rate (PEFR) less than 60% of the predicted value after receiving three beta 2-adrenergic nebulizer treatments. INTERVENTIONS Magnesium sulfate infusion, 25 mg/kg (maximum, 2 gm), or equivolume saline solution for 20 minutes. MEASUREMENTS AND RESULTS Vital signs, O2 saturation by pulse oximetry, PEFR, forced vital capacity, forced expiratory volume at 1 second, and physical examination were serially recorded for 110 minutes, with serum magnesium concentrations measured before and after the 20-minute infusion. At 50 minutes the magnesium group had a significantly greater percentage of improvement from baseline in forced expiratory volume at 1 second (34% vs -1%; p = 0.05); this improvement was sustained and even greater at 110 minutes (75% vs 5%; p = 0.01). Results were similar for PEFR at 80 through 110 minutes (59% vs 20% at 110 minutes; p = 0.05) and for forced vital capacity (55% vs 8% at 80 minutes; p = 0.05). There were no significant intergroup differences in blood pressure at any point. Patients who received intravenous magnesium infusions were more likely to be discharged home from the emergency department than those who received placebo (4/15 vs 0/16; p = 0.03). CONCLUSIONS Children treated with intravenous magnesium infusions for moderate to severe asthma had significantly greater improvement in short-term pulmonary function without any significant alteration in blood pressure, suggesting a role for this agent as an adjunct in the treatment of such patients.