Chest
Volume 107, Issue 6, June 1995, Pages 1576-1581
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Clinical Investigations: Asthma
Intravenous Magnesium Sulfate as an Adjunct in the Treatment of Acute Asthma

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Study objective

This study was conducted to determine whether intravenous magnesium sulfate (MgSO4), when used as part of a standardized treatment protocol, can improve pulmonary function and decrease admission rate in patients presenting to the emergency department with exacerbations of asthma.

Design

In this randomized double-blind placebo-controlled study, patients with acute asthma were treated with inhaled β-agonists at regular intervals and intravenous (IV) steroids. At 30 min after entry, patients received either 2 g IV MgSO4 or IV placebo. Patients were monitored for up to 4 h with regular measurements of pulmonary function. Patients who were discharged from the emergency department were contacted at 1 day and 7 days for follow-up.

Setting

Emergency departments of a university-affiliated, voluntary hospital and municipal hospital.

Participants

Asthmatics aged 18 to 65 years during acute exacerbation with FEV1 less than 75% predicted both before and after a single albuterol treatment.

Interventions

Patients were given 2 g of MgSO4 or placebo as an adjunct to standardized emergency department procedure for acute asthma.

Measurements and results

One hundred thirty-five patients were studied. Hospital admission rates were 35.3% for placebo-treated group and 25.4% for the magnesium-treated group (p=0.21). FEV1 measured at 120 min was 56% predicted for the placebo-treated group and 55% predicted for the magnesium-treated group. (p=0.92) For subgroup analysis, patients were divided into “severe” (baseline FEV1 <25% predicted on presentation) or “moderate” (baseline FEV1, 25 to 75% predicted on presentation). For the severe group, admission rates were 78.6% (11/14) for the placebo-treated group and 33.3% (7/21) for the magnesium-treated group (p=0.009). For the moderate patients, admission rates were 22.4% (11/49) for the placebo-treated group and 22.2% (10/25) for the magnesium-treated group (p=0.98). There was no significant improvement in FEV1 in the moderate group for magnesium-treated patients. However, in the severe group, there was a significant improvement in FEV1 at 120 min and 240 min (p=0.014 and 0.026, respectively).

Conclusion

Intravenous MgSO4 decreased admission rate and improved FEV1 in patients with acute severe asthma but did not cause significant improvement in patients with moderate asthma.

Section snippets

Patient Selection

Patients aged 18 to 65 years presenting with acute asthma to the ED of two teaching hospitals (Long Island Jewish Medical Center and Queens Hospital Center), between August 1990 and December 1991, were considered for the study. Asthma was defined by the criteria set out by the American Thoracic Society.14 Patients were excluded if they had a history of congestive heart failure, diabetes mellitus, angina, chronic renal insufficiency, temperature >38° C, pneumonia, or if pregnant. Patients

Results

One hundred forty-nine patients originally were randomized into the study; however, 135 were included in the final statistical analysis. Among the 14 patients who were excluded, 12 were enrolled more than once, 1 had irreversible airway disease, and 1 had congestive heart failure. Four patients were included as an intent to treat analysis because the study protocol was violated. Violations include 1 patient who received epinephrine, 1 patient who received theophylline, 1 patient with subsequent

Discussion

This study failed to demonstrate significant benefit from the use of 2 g of IV MgSO4 as an adjunct to a standardized treatment protocol for asthma in a diverse group of asthmatics. However, it does demonstrate significant improvement in the subgroup of patients presenting to the ED with severe airway obstruction. Improvement was demonstrated by a decrease in hospital admission rate and an increase in FEV1. We did not demonstrate benefit from MgSO4 in patients with more moderate airway

Conclusion

In summary, our data indicate that when 2 g of MgSO4 is given as an adjunct to standardized asthma therapy, there is no improvement in pulmonary function or admission rates in patients presenting to the ED. However, when patients with severe asthma are analyzed separately, there is a significant improvement in FEV1 and hospital admission rate when magnesium is received. Thus, confirming these results in the most severe patients would support the routine use of MgSO4 in patients with severe

ACKNOWLEDGMENTS

We would like to express special consideration to Pamela Arsove, MD, FACEP, for her contribution in the design and implementation of the study. We would also like to express our appreciation to Rich Thailer, PA, for computer work; Bernadette Belcastro and Denise Foti, for secretarial work; Neal Richmond, MD, and Dawn Williamson, MD, for patient recruitment; and Michael Borenstein, PhD, and Ruth Bernstein Hyman, PhD, for statistical analysis.

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    Considering the efficacy from the included RCTs in the Rowe et al. meta-analysis [2] evaluating the adult population, 2 g (1.2 g) IV MgSO4 reduced hospital admissions in severe acute asthma [16,17], while the results regarding the pulmonary function tests are contradictory (Table 2) [16–19]. Bloch et al. [16] reported no difference in hospital admissions after 2 g IV MgSO4 vs placebo, in patients with mild to moderate acute asthma (Table 2). All patients received SABA and some received CS (those who had < 40% of predicted FEV1 or those who had received oral prednisone within 6 months).

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    RevMan software (version 5.1) was used for all statistical analyses. After reviewed by two independent reviewers, our searches generated 194 reports prior to October 18, 2011, of which 25 studies (16 intravenous, 9 nebulized)4,7–30 met the inclusion criteria. The flow of identified studies through the selection process is shown in Fig. 1.

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Supported in part by the Nina Weisman Pulmonary Research Fund.

revision accepted November 16.

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