Inhaled magnesium sulfate in the treatment of acute asthma

Inhaled magnesium sulfate might possibly have some effect on the pulmonary function and hospital admission of patients with acute asthma exacerbations when added to inhaled β₂-agonists and ipratropium bromide, but the evidence is insufficient.

The quality of evidence is downgraded by study limitations (unclear allocation concealment), by inconsistency (variability in results), and by imprecise results (few patients and wide confidence intervals).

Summary

A Cochrane review included 25 studies with a total of 2 907 subjects. Nine of the 25 studies involved adults, 4 included adult and paediatric patients, 8 paediatric patients, and in 4 studies the age of participants was not stated. The design, definitions, intervention and outcomes were different in all 25 studies.

Inhaled magnesium sulfate in addition to inhaled β₂-agonist and ipratropium (7 studies): Some individual studies reported improvement in lung function indices favouring the intervention group, but results were inconsistent overall and the largest study found no between-group difference at 60 minutes. Admissions to hospital at initial presentation may be reduced by the addition of inhaled magnesium sulfate (RR 0.95, 95% CI 0.91 to 1.00, statistical heterogeneity I² = 52%; 4 studies, n=1 308) but no difference was detected for re-admissions or escalation of care to ITU/HDU. Serious adverse events during admission were rare. There was no difference between groups for all adverse events during admission (RD 0.01, 95% CI −0.03 to 0.05; 2 studies, n=1 197).

Inhaled magnesium sulfate in addition to inhaled β₂-agonist (13 studies): Although some individual studies reported improvement in lung function indices favouring the intervention group, none of the pooled results showed a conclusive benefit as measured by FEV1 or predicted peak expiratory flow rate (PEFR). Pooled results for hospital admission showed a point estimate that favoured the combination of MgSO₄ and β₂-agonist, but it was not statistically significant (RR 0.78, 95% CI 0.52 to 1.15; 6 studies, n=375). There were no serious adverse events reported by any of the included studies and no between-group difference for all adverse events (RD −0.01, 95% CI −0.05 to 0.03; 5 studies, n=694).

Inhaled magnesium sulfate versus inhaled β₂-agonist (4 studies): Two studies reported a benefit of β₂-agonist over MgSO₄ alone for PEFR and 2 studies reported no difference; the results were not pooled. Admissions to hospital were only reported by 1 small study and events were rare, leading to an uncertain result. No serious adverse events were reported in any of the studies; 1 small study reported mild to moderate adverse events but the result was imprecise