Background: Treatment of acute asthma is based on rapid reversal of bronchospasm and airway inflammation. Magnesium sulphate (MgSO(4)) is known to have a bronchodilator effect on smooth muscle but studies have shown conflicting results on its efficacy in acute asthma, although its use is recommended in national and international guidelines.
Aims: To determine if intravenous MgSO(4), when used as an adjunct to standard therapy, improves the outcome in acute asthma.
Methods: A double blind, randomised placebo controlled trial comparing 1.2g MgSO(4) with standard therapy in adult patients with acute asthma. Patients had a PEF <or=75% predicted and all were treated with oxygen, nebulised salbutamol and ipratropium, and IV hydrocortisone. They then received 1.2g IV MgSO(4) or placebo. Outcome measures were % predicted PEF at 60 min and hospital admission rates.
Results: One hundred and twenty nine patients were studied. Placebo and active treatment groups were well matched at baseline. MgSO(4) had no benefit with regards hospital admission rates or % predicted PEF at 60 min (p=0.48) for the whole group, or for subgroups of life-threatening (p=0.85), severe (p=0.63) and moderate (p=0.67) acute asthma.
Conclusion: This study did not show additional benefit from 1.2g IV MgSO(4) when given as an adjunct to standard therapy for acute asthma.