Intravenous magnesium as an adjuvant in acute bronchospasm: A meta-analysis

Study objective: Although several trials have been published evaluating int ravenous magnesium sulfate as treatment for acute bronchospasm, its effecti veness for this indication remains unclear, prompting this meta-analysis. Methods: All randomized controlled trials of adjuvant bolus intravenous mag nesium sulfate for acute bronchospasm in the emergency department were elig ible. Trials were identified using MEDLINE, EMBASE, bibliographies of selec ted articles, and review of abstracts of 4 scientific societies. Two review ers abstracted data, one of whom was blinded to author and journal. Because studies used different spirometric outcome measures, effect size was calcu lated for each study by Hedges' method. The analysis used a fixed-effects m odel. One-way sensitivity analyses were performed to assess the influence o f study quality and to search for publication bias. Results: Abstracts from 210 articles were reviewed, yielding 40 trials, of which 9 were specific to bolus intravenous magnesium sulfate in the ED, in doses from 1.2 to 2 g, or an equivalent pediatric dose. Combined results ac ross 9 studies including 859 patients showed a posttreatment effect size of 0.162 for patients treated with intravenous magnesium sulfate (95% confide nce interval 0.028, 0.297; P=.02). In sensitivity analyses exploring the ef fects of study quality and publication bias, the summary effect ranged from 0.127 to 0.206. No serious adverse events were reported. Conclusion: Adjuvant bolus intravenous magnesium sulfate in acute bronchosp asm appears statistically beneficial in improving spirometric airway functi on by 16% of a SD. Although the clinical significance of this is uncertain, given the safety of intravenous magnesium sulfate therapy and its relative ly low cost, it should be considered, absent contraindications, in patients with moderate to severe acute bronchospasm.