Inhaled magnesium sulfate in the treatment of acute asthma.
BACKGROUND
Asthma exacerbations can be frequent and range in severity from relatively mild to status asthmaticus. The use of magnesium sulfate (MgSO4) is one of numerous treatment options available during acute exacerbations. While the efficacy of intravenous MgSO4 has been demonstrated, little is known about inhaled MgSO4.


OBJECTIVE
To examine the efficacy of inhaled MgSO4 in the treatment asthma exacerbations.


METHODS
Randomised controlled trials were identified from the Cochrane Airways Group "Asthma and Wheez*" register. These trials were supplemented with trials found in the reference list of published studies, studies found using extensive electronic search techniques, as well as a review of the gray literature and conference proceedings.


METHODS
Randomised (or pseudo-randomised) controlled trials were eligible for inclusion. Studies were included if patients were treated with nebulised MgSO4 alone or in combination with beta(2)-agonist and where compared to beta2-agonist alone or inactive control.


METHODS
Trial selection, data extraction and methodological quality were assessed by two independent reviewers. Efforts were made to collect missing data from authors. Results from fixed effects models are presented as standardized mean differences (SMD) for pulmonary functions and relative risks (RR) for hospital admission; both are displayed with their 95% confidence intervals (95% CI).


RESULTS
Six trials involving 296 patients were included. Four studies compared nebulised MgSO4 with beta2-agonist to beta2-agonist and two studies compared MgSO4 to beta2-agonist alone. Three studies enrolled only adults and 2 enrolled exclusively pediatric patients; three of the studies enrolled severe asthmatics. Overall, there was a significant difference in pulmonary function between patients whose treatments included nebulised MgSO4 in addition to beta2-agonist (SMD: 0.30; 95% CI: 0.03 to 0.56; 4 studies); however, hospitalizations were similar between the groups (RR: 0.69; 95% CI: 0.42 to 1.12; 3 studies). Subgroup analyses did not demonstrate significant differences in lung function improvement between adults and children, but were significantly different between severe and mild to moderate asthmatics (SMD: 0.69; 95% CI 0.13 to 1.25). Conclusions regarding treatment with nebulised MgSO4 alone are difficult to draw due to lack of studies in this area.


CONCLUSIONS
Nebulised inhaled magnesium sulfate in addition to beta2-agonist in the treatment of an acute asthma exacerbation, appears to have benefits with respect to improved pulmonary function and there is a trend towards benefit in hospital admission. The benefit is significantly greater in more severe asthma exacerbations. Heterogeneity between trials included in this review precludes a more definitive conclusion.
Blitz
M
M
Division of General Surgery, University of Alberta, W.C. Mackenzie Centre, 8440-112 Street, Edmonton, Alberta, Canada, T6G 2B7. moblitz@shaw.ca
Blitz
S
S
Beasely
R
R
Diner
B M
BM
Hughes
R
R
Knopp
J A
JA
Rowe
B H
BH
D000208:Acute Disease; D000280:Administration, Inhalation; D000318:Adrenergic beta-Agonists / Q000008:administration & dosage*; D000328:Adult; D018927:Anti-Asthmatic Agents / Q000008:administration & dosage*; D001249:Asthma / Q000188:drug therapy*; D002648:Child; D006760:Hospitalization; D006801:Humans; D008278:Magnesium Sulfate / Q000008:administration & dosage*; D016032:Randomized Controlled Trials as Topic
D000318:Adrenergic beta-Agonists; D018927:Anti-Asthmatic Agents; D008278:Magnesium Sulfate