Intravenous magnesium sulphate provides no additive benefit to standard management in acute asthma

Background: Treatment of acute asthma is based on rapid reversal of bronchospasm and airway inflammation. Magnesium sulphate (MgSO4) 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 MgSO4, when used as an adjunct to standard therapy, improves the outcome in acute asthma. Methods: A double blind, randomised placebo controlled trial comparing 1.2 9 MgSO4 with standard therapy in adult patients with acute asthma. Patients had a PEF <= 75% predicted and all were treated with oxygen, nebulised salbutamol and ipratropium, and IV hydrocortisone. They then received 1.2g IV MgSO4 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. MgSO4 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 MgSO4 when given as an adjunct to standard therapy for acute asthma. (C) 2007 Elsevier Ltd. All rights reserved.