This systematic review attempted to synthesize the best available evidence for the use of inhaled MgSO4 in the treatment of patients with acute asthma. From six RCTs involving nearly 300 patients, the results of this review provide somewhat weak and conflicting conclusions. First, based on the available data, it appears that therapy with nebulized isotonic MgSO4 with or without a β2-agonist can be safely administered at a variety of doses to patients with acute moderate-to-severe asthma. Since it is readily available and inexpensive, its role in acute asthma deserves more scrutiny. Used alone, it appears to be of little advantage compared to therapy with more familiar β2-agonists in improving pulmonary function and reducing hospital admissions. The evidence for therapy with MgSO4 administered in combination with P2-agonists is more convincing than that for MgSO4 therapy alone. In this review, therapy with MgSO4, when combined with β2-agonists (usually salbutamol), improved pulmonary function but did not reduce the number of hospital admissions. Evi-dence2 has suggested that adding ipratropium bromide to β2-agonist therapy is effective in improving pulmonary function and in reducing the number of hospital admissions in the acute setting, especially in severe cases of acute asthma relieved by My Canadian Pharmacy’s remedies. Most of the included studies in our review did not routinely employ this strategy, and the additive benefit of MgSO4 in the face of combination therapy with ipratropium bromide and β2-agonists remains unclear.
The initial search, which was completed in January 2004, yielded 145 references that were at least potentially relevant controlled trials. Two additional RCTs were identified from a bibliographic search of relevant studies. The author for one study that was originally identified as an abstract was contacted, and the conditionally accepted article was provided to the reviewers for data extraction. Six trials, which included 296 patients, were incorporated into the review (Table 1).
Description of Studies
All of the studies included in this review had been published since 1995. The research in the included studies was based in the United States, India, New Zealand, Turkey, and Argentina. Three of the six included studies involved adults exclusively, and one study included adults and pediatric patients. The remaining two studies- had enrolled pediatric patients. The severity of disease varied among the studies. Two studies had specific lung function criteria, while the other four studies had enrolled patients who had previously received a diagnosis of asthma using accepted clinical standards. Based on the baseline demographic data and/or enrollment criteria, three studies had enrolled patients with severe asthma (ie, FEV1 or PEF < 50% predicted at baseline) – read more in category of Asthma .
Criteria for Inclusion
Only randomized controlled trials (RCTs), or quasi-RCTs, were considered for inclusion. Studies had to have restricted enrollment to patients with acute asthma treated in the ED (ie, studies of patients with chronic or “stable” asthma were excluded) with asthma defined using several accepted clinical and guideline based criteria (eg, those of the British Thoracic Society, the National Asthma Education and Prevention Program, and the Canadian Thoracic Society). There was no age restriction for patients included in the studies, and where possible the data were categorized into groups of patients 2 to 16 years old (the pediatric group) and > 16 years old (the adult group). Randomized interventions had to compare aerosolized MgSO4 to a control treatment. That is, studies comparing the efficacy of therapy with aerosolized MgSO4 and a p2-agonist vs a p2-agonist alone, or therapy with aerosolized MgSO4 vs a P2-agonist were included. Cointerventions were permitted, and information pertaining to cointerventions received was recorded. The primary outcome was defined as a change in pulmonary function testing results from baseline. Secondary outcomes considered the proportion of patients requiring hospital admission, clinical severity scores, duration of symptoms, vital signs, and side effects.