Usefulness of inhaled magnesium sulfate in the coadjuvant management of severe asthma crisis in an emergency department

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Abstract

Rationale

Treatment of severe asthma may be difficult despite the use of several medications including parenteral corticosteroids. Intravenous magnesium sulfate (MgSO4) is one ancillary drug for severe crisis; its inhaled use is controversial.

Objectives

To evaluate the usefulness of inhaled MgSO4 compared to placebo in improving lung function, oxygen saturation, and reducing hospital admission as an adjunct to standard treatment in severe asthma crisis.

Patients and methods

We conducted a placebo-controlled, double-blind clinical trial with asthmatic patients >18 years of age with asthmatic crisis and FEV1 < 60% of predicted (%p). All subjects received 125 mg of IV methylprednisolone followed by nebulization with the combination of albuterol (7.5 mg) and ipratropium bromide (1.5 mg) diluted in 3 ml of isotonic saline solution (as placebo) or 3 ml (333 mg) of MgSO4. After 90 min, subjects with FEV1 < 60%p or SpO2 < 88% or persistent symptoms were admitted to the emergency department (ED).

Results

We included 30 patients per group who were similar at baseline. The MgSO4 group showed higher post-bronchodilator (post-BD) FEV1%p (69 ± 13 vs. 61 ± 12, p < 0.014) and SpO2 (92 ± 4 vs. 88 ± 5%, p < 0.006) than the placebo group. Fewer treated patients were admitted to the ED (5 vs. 13) (p < 0.047), with relative risk (RR) of 0.26 (95% CI 0.079–0.870).

Conclusions

Adding inhaled MgSO4 treatment to standard therapy in severe asthma crisis improves FEV1%p and SpO2 post-BD and reduces the rate of ED admissions.

Introduction

Asthma is an important public health chronic respiratory illness due to its frequency, altered quality of life, and significant health costs along with the impact of severe asthma being able to trigger prolonged hospitalizations and death. Of the total asthma expenditure in the U.S., 25% is attributed to emergency care [1]. Standard treatment for asthma crisis includes short-acting bronchodilator (SAB), β2-agonists and inhaled anticholinergics and corticosteroids, in addition to general management. Intravenous magnesium sulfate (MgSO4) may be added in severe crisis unresponsive to standard treatment [2] but requires special monitoring [3]. MgSO4 produces smooth muscle relaxation, blocking acetylcholine and histamine release, and a reduction in the neutrophil burst [4], leading to improved pulmonary mechanics [5], [6]. Inhaled MgSO4 use is controversial. Studies addressing this subject differ methodologically and are heterogeneous, non-comparable, and with different therapeutic interventions and primary outcomes. Nevertheless, the Global Initiative in National Asthma (GINA) recommendations supported by meta-analysis [7], [8] approve its use during a crisis [2].

The objective of this study was to evaluate the usefulness of inhaled MgSO4 as an adjuvant to the standard treatment (compared with placebo), on spirometry and pulse oximetry in severe asthmatic crisis and to determine whether this effect decreases hospital admissions.

Section snippets

Material and methods

We conducted a randomized, placebo-controlled, double-blind trial to assess the efficacy of standard management adding inhaled MgSO4 compared with the standard treatment plus placebo in patients with severe acute asthma at the National Institute of Respiratory Diseases (INER), a tertiary-care teaching-hospital and national referral center in Mexico City for respiratory disorders. The INER takes care of 1500 patients in asthmatic crisis each year, 2% of whom warrant hospitalization [9]. The

Results

All spirometry tests fulfilled the quality criteria according to ATS–ERS guidelines and were highly reproducible in FEV1, both pre-BD (0.07 ± 0.06 ml) as well as post-BD (0.08 ± 0.07 ml). The study profile is shown in Fig. 2. There were 122 eligible patients, 10 of whom did not wish to participate in the study, and 30 (TG) and 22 (CG) patients had at least one of the exclusion criteria (Fig. 2), leaving 30 patients per group for the final analysis.

In all 60 patients, normal spirometry and normal

Discussion

The study shows that adding inhaled MgSO4 to the standard treatment for severe asthma crisis with a significant impact on quality of life produces a greater improvement in symptoms and lung function determined by post-BD FEV1%p as well as oxygenation (SpO2). Treatment also reduced the risk of emergency hospitalization in a group of patients with severe asthma crisis. Additional treatments for severe asthma crisis are always helpful and MgSO4 may be one of them. GINA recommends its use as

Conclusions

This study suggests that nebulized albuterol and ipratropium bromide diluted with MgSO4 solution improves lung function and oxygen saturation and reduces the rate of ED admissions compared to the standard dilution with isotonic saline.

Acknowledgments

We appreciate the support of Sharon Morey (Scientific Communications) in the translation of the manuscript.

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