Intravenous magnesium sulfate treatment for acute asthma in the emergency department: A systematic review of the literature

Study objectives: There is some evidence that magnesium, when infused into asthmatic patients, can produce bronchodilation in addition to that obtaine d from standard treatments. This systematic review examined the effect of i ntravenous magnesium sulfate used for patients with acute asthma managed in the emergency department. Methods: Only randomized controlled trials were eligible for inclusion. Stu dies were included if patients presented with acute asthma and were treated with intravenous magnesium sulfate versus placebo. Trials were identified from the Cochrane Airways Review Group register, which consists of a combin ed search of EMBASE, MEDLINE, and CINAHL databases and hand-searching of 20 key respiratory journals. Bibliographies from included studies and known r eviews were searched. Primary authors and content experts were contacted. D ata were extracted and methodologic quality was assessed independently by 2 reviewers. Missing data were obtained from authors. Results: Seven trials (5 adult, 2 pediatric) involving a total of 668 patie nts were included. Overall, admission to hospital was not statistically red uced using magnesium sulfate (odds ratio [OR] 0.31, 95% confidence interval [CI] 0.09 to 1.02). In the severe subgroup, admissions were reduced in tho se receiving magnesium sulfate (OR 0.10, 95% CI 0.04 to 0.27). Overall, pat ients receiving magnesium sulfate demonstrated nonsignificant improvements in peak expiratory flow rates (PEFR) when all studies were pooled (weighted mean difference [WMD] 29 L/min, 95% CI -3 to 62). In studies of patients w ith severe acute asthma, PEFR WMD improved by 52 L/min (95% CI 27 to 78) fa voring magnesium sulfate treatment. The absolute FEV, also improved by 10% predicted (95% CI 4 to 16) in patients with severe acute asthma. No clinica lly important changes in vital signs or side effects were reported. Conclusion: Current evidence does not clearly support routine use of intrav enous magnesium sulfate in all patients with acute asthma presenting to the ED. However, magnesium sulfate appears to be safe and beneficial for patie nts who present with severe acute asthma. Practice guidelines need to be ch anged to reflect these results.