A trial of nebulized magnesium sulfate to reverse bronchospasm in asthmatic patients

Magnesium Is a Vital Ion in the Body-It Is Time to Consider Its Supplementation on a Routine Basis

The importance of maintaining proper magnesium intake and total body magnesium content in preserving human health remains underappreciated among medical professionals and laymen. This review aimed to show the importance of hypomagnesemia as a modifiable risk factor for developing disease processes. We searched the PubMed database and Google Scholar using the keywords 'magnesium', 'diabetes', 'cardiovascular disease', 'respiratory disease', 'immune system', 'inflammation', 'autoimmune disease', 'neurology', 'psychiatry', 'cognitive function', 'cancer', and 'vascular calcification'. In multiple contexts of the search terms, all reviews, animal experiments, and human observational data indicated that magnesium deficiency can lead to or contribute to developing many disease states. The conclusions of several in-depth reviews support our working hypothesis that magnesium and its supplementation are often undervalued and underutilized. Although much research has confirmed the importance of proper magnesium supply and tissue levels, simple and inexpensive magnesium supplementation has not yet been sufficiently recognized or promoted.

Review of the role of Magnesium Sulphate in the Management of Asthma patient at A&E Setting

Controversial views exist with regards to the use of intravenous magnesium sulphate in patient with severe asthmatic attack. The benefit of intravenous magnesium sulphate may be masked by the pooling of patients with different pathophysiology. The subsets of patients with severe asthmatic attack who have not responded to nebulised bronchodilator therapy and intravenous steroid therapy may benefit from intravenous magnesium sulphate therapy.

Inhaled magnesium sulfate in the treatment of acute asthma

BACKGROUND

Asthma exacerbations can be frequent and range in severity from mild to life-threatening. 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, the role of inhaled MgSO₄ is less clear.

OBJECTIVES

To determine the efficacy and safety of inhaled MgSO₄ administered in acute asthma.

SPECIFIC AIMS

to quantify the effects of inhaled MgSO₄ I) in addition to combination treatment with inhaled β₂-agonist and ipratropium bromide; ii) in addition to inhaled β₂-agonist; and iii) in comparison to inhaled β₂-agonist.

SEARCH METHODS

We identified randomised controlled trials (RCTs) from the Cochrane Airways Group register of trials and online trials registries in September 2017. We supplemented these with searches of the reference lists of published studies and by contact with trialists.

SELECTION CRITERIA

RCTs including adults or children with acute asthma were eligible for inclusion in the review. We included studies if patients were treated with nebulised MgSO₄ alone or in combination with β₂-agonist or ipratropium bromide or both, and were compared with the same co-intervention alone or inactive control.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trial selection, data extraction and risk of bias. We made efforts to collect missing data from authors. We present results, with their 95% confidence intervals (CIs), as mean differences (MDs) or standardised mean differences (SMDs) for pulmonary function, clinical severity scores and vital signs; and risk ratios (RRs) for hospital admission. We used risk differences (RDs) to analyse adverse events because events were rare.

MAIN RESULTS

Twenty-five trials (43 references) of varying methodological quality were eligible; they included 2907 randomised patients (2777 patients completed). Nine of the 25 included studies involved adults; four included adult and paediatric patients; eight studies enrolled paediatric patients; and in the remaining four studies the age of participants was not stated. The design, definitions, intervention and outcomes were different in all 25 studies; this heterogeneity made direct comparisons difficult. The quality of the evidence presented ranged from high to very low, with most outcomes graded as low or very low. This was largely due to concerns about the methodological quality of the included studies and imprecision in the pooled effect estimates. Inhaled magnesium sulfate in addition to inhaled β₂-agonist and ipratropiumWe included seven studies in this comparison. Although some individual studies reported improvement in lung function indices favouring the intervention group, results were inconsistent overall and the largest study reporting this outcome found no between-group difference at 60 minutes (MD -0.3 % predicted peak expiratory flow rate (PEFR), 95% CI -2.71% to 2.11%). Admissions to hospital at initial presentation may be reduced by the addition of inhaled magnesium sulfate (RR 0.95, 95% CI 0.91 to 1.00; participants = 1308; studies = 4; I² = 52%) but no difference was detected for re-admissions or escalation of care to ITU/HDU. Serious adverse events during admission were rare. There was no difference between groups for all adverse events during admission (RD 0.01, 95% CI -0.03 to 0.05; participants = 1197; studies = 2). Inhaled magnesium sulfate in addition to inhaled β₂-agonistWe included 13 studies in this comparison. Although some individual studies reported improvement in lung function indices favouring the intervention group, none of the pooled results showed a conclusive benefit as measured by FEV1 or PEFR. Pooled results for hospital admission showed a point estimate that favoured the combination of MgSO₄ and β₂-agonist, but the confidence interval includes the possibility of admissions increasing in the intervention group (RR 0.78, 95% CI 0.52 to 1.15; participants = 375; studies = 6; I² = 0%). There were no serious adverse events reported by any of the included studies and no between-group difference for all adverse events (RD -0.01, 95% CI -0.05 to 0.03; participants = 694; studies = 5). Inhaled magnesium sulfate versus inhaled β₂-agonistWe included four studies in this comparison. The evidence for the efficacy of β₂-agonists in acute asthma is well-established and therefore this could be considered a historical comparison. Two studies reported a benefit of β₂-agonist over MgSO₄ alone for PEFR and two studies reported no difference; we did not pool these results. Admissions to hospital were only reported by one small study and events were rare, leading to an uncertain result. No serious adverse events were reported in any of the studies in this comparison; one small study reported mild to moderate adverse events but the result is imprecise.

AUTHORS' CONCLUSIONS

Treatment with nebulised MgSO₄ may result in modest additional benefits for lung function and hospital admission when added to inhaled β₂-agonists and ipratropium bromide, but our confidence in the evidence is low and there remains substantial uncertainty. The recent large, well-designed trials have generally not demonstrated clinically important benefits. Nebulised MgSO₄ does not appear to be associated with an increase in serious adverse events. Individual studies suggest that those with more severe attacks and attacks of shorter duration may experience a greater benefit but further research into subgroups is warranted.Despite including 24 trials in this review update we were unable to pool data for all outcomes of interest and this has limited the strength of the conclusions reached. A core outcomes set for studies in acute asthma is needed. This is particularly important in paediatric studies where measuring lung function at the time of an exacerbation may not be possible. Placebo-controlled trials in patients not responding to standard maximal treatment, including inhaled β₂-agonists and ipratropium bromide and systemic steroids, may help establish if nebulised MgSO₄ has a role in acute asthma. However, the accumulating evidence suggests that a substantial benefit may be unlikely.

The role of magnesium sulfate in the intensive care unit

Magnesium (Mg) has been developed as a drug with various clinical uses. Mg is a key cation in physiological processes, and the homeostasis of this cation is crucial for the normal function of body organs. Magnesium sulfate (MgSO4) is a mineral pharmaceutical preparation of magnesium that is used as a neuroprotective agent. One rationale for the frequent use of MgSO4 in critical care is the high incidence of hypomagnesaemia in intensive care unit (ICU) patients. Correction of hypomagnesaemia along with the neuroprotective properties of MgSO4 has generated a wide application for MgSO4 in ICU.

Lack of efficacy of nebulized magnesium sulfate in treating adult asthma: A meta-analysis of randomized controlled trials

BACKGROUND

Nebulized magnesium sulfate (MgSO₄) has been used to treat asthma, but the efficacy remains controversial. We aimed to comprehensively review the efficacy of nebulized MgSO₄ in treating adult patients with asthma.

METHODS

PubMed, Embase, and Cochrane Library were searched for relevant studies published up to July 18, 2016. Randomized controlled trials (RCTs) were included if adult patients with acute or stable asthma had been treated with nebulized MgSO₄ compared with placebo or another bronchodilator. Standardized mean differences (SMDs), relative risks (RRs) and 95% confidence intervals (CIs) were calculated. Outcomes included pulmonary function, hospital admission and adverse events.

RESULTS

A total of 1386 patients from sixteen trials (1240 acute asthma patients and 146 stable asthma patients) were subjected to meta-analysis. Compared to placebo as normal saline, whether using in acute or stable adult asthma, nebulized MgSO₄ did not significantly improve the respiratory function: SMD 0.39 (95% CI -0.03-0.82, P = 0.07), and 1.48 (95% CI -0.14-3.11, P = 0.07), respectively. Furthermore, nebulized MgSO₄ did not reduce hospital admission in adult patients with acute asthma (RR, 0.72; 95% CI, 0.52-1.00; P = 0.05), although it was not associated with increased adverse events (RR 1.15; 95% CI, 0.88-1.52; P = 0.31).

CONCLUSIONS

Evidence to date suggests that nebulized MgSO₄ has no role in the management of adult patients with acute or stable asthma.

Pediatric acute asthma exacerbations: Evaluation and management from emergency department to intensive care unit

OBJECTIVE

The goal of this report is to review available modalities for assessing and managing acute asthma exacerbations in pediatric patients, including some that are not included in current expert panel guidelines. While it is not our purpose to provide a comprehensive review of the National Asthma Education and Prevention Program (NAEPP) guidelines, we review NAEPP-recommended treatments to provide the full range of treatments available for managing exacerbations with an emphasis on the continuum of care between the ER and ICU.

DATA SOURCES

We searched PubMed using the following search terms in different combinations: asthma, children, pediatric, exacerbation, epidemiology, pathophysiology, guidelines, treatment, management, oxygen, albuterol, β2-agonist, anticholinergic, theophylline, corticosteroid, magnesium, heliox, BiPAP, ventilation, mechanical ventilation, non-invasive mechanical ventilation and respiratory failure. We attempted to weigh the evidence using the hierarchy in which meta-analyses of randomized controlled trials (RCTs) provide the strongest evidence, followed by individual RCTs, followed by observational studies. We also reviewed the NAEPP and Global Initiative for Asthma expert panel guidelines.

RESULTS AND CONCLUSIONS

Asthma is the most common chronic disease of childhood, and acute exacerbations are a significant burden to patients and to public health. Optimal assessment and management of exacerbations, including appropriate escalation of interventions, are essential to minimize morbidity and prevent mortality. While inhaled albuterol and systemic corticosteroids are the mainstay of exacerbation management, escalation may include interventions discussed in this review.

The use of intravenous and inhaled magnesium sulphate in management of children with bronchial asthma

BACKGROUND

Asthma is the most common chronic disease of childhood and the leading cause of childhood morbidity. When uncontrolled, asthma can place significant limits on daily life, and is sometimes fatal. The use of magnesium sulphate (MgSO4) is one of numerous treatment options available during acute severe asthma in children. The efficacy of intravenous, or inhaled MgSO4 has been demonstrated, while little is known about the actual clinical use of either intravenous (IV) or inhaled MgSO4.

OBJECTIVE

To assess the effectiveness of intravenous (IV) and/or inhaled MgSO4 on hospital admissions and pulmonary function in children with asthma. This systematic review assessed the best available evidence for the use of either intravenous or inhaled MgSO4 in children with acute asthma. Magnesium deficiency is a common electrolyte disorder in children with acute severe asthma. Several authors reported that IV magnesium was effective in the treatment of moderate to acute asthma in children but evidence for nebulised magnesium was insufficient. In addition, it is used in severe, progressed cases to prevent respiratory failure and/or admission to the intensive care unit. It has bronchodilating and anti-inflammatory effects and modulates ion transport and influences intracellular calcium concentration. Intravenous MgSO4 therapy helps in achieving earlier improvement in clinical signs and symptoms of asthma, e.g. respiratory function and significantly reduced hospital admission, in children with acute severe asthma. The role of nebulised MgSO4 in asthmatic children requires further investigation.

CONCLUSION

According to the previous studies, the author recommends the use of intravenous MgSO4 as a safe and effective adjunct to conventional bronchodilator therapy in acute severe asthma in children.

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 (MgSO(4)) is one of numerous treatment options available during acute exacerbations. While the efficacy of intravenous MgSO(4) has been demonstrated, little is known of the role of inhaled MgSO(4).

OBJECTIVES

To determine the efficacy of inhaled MgSO(4) administered in acute asthma on pulmonary functions and admission rates.

SPECIFIC AIMS

To quantify the effects of inhaled MgSO(4) i) in addition to inhaled β(2)-agonist, ii) in comparison to inhaled β(2)-agonist alone or iii) in addition to combination treatment with inhaled β(2) -agonist and ipratropium bromide.

SEARCH METHODS

Randomised controlled trials were identified from the Cochrane Airways Group register of trials in September 2012. 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 grey literature and conference proceedings.

SELECTION CRITERIA

Randomised (or pseudo-randomised) controlled trials including adults or children with acute asthma were eligible for inclusion in the review. Studies were included if patients were treated with nebulised MgSO(4) alone or in combination with β(2)-agonist and/or ipratropium bromide and were compared with β(2)-agonist alone or inactive control.

DATA COLLECTION AND ANALYSIS

Trial selection, data extraction and risk of bias were assessed independently by two review authors. Efforts were made to collect missing data from authors. Results are presented as standardised mean differences (SMD) for pulmonary function and risk ratios (RR) for hospital admission; both are displayed with their 95% confidence intervals (CI).

MAIN RESULTS

Sixteen trials (21 references) of unclear and high risk of bias were eligible and included 896 patients who were randomised (838 patients completed). Seven of the 16 included studies involved adults exclusively, three included adults and paediatric patients, four studies enrolled paediatric patients and in the remaining two studies the age of participants was not stated.The design, definitions, intervention and outcomes were different in all 16 studies; this heterogeneity made direct comparisons difficult (see additional tables 1-3).The overall risk of bias among the included studies was variable and this is reflected in the 'Summary of findings' table with most outcomes being judged as only moderate or less.Inhaled magnesium sulfate in addition to inhaled β(2)-agonistThere was no statistically significant improvement in pulmonary function when inhaled MgSO(4) and β(2)-agonist was compared with β(2)-agonist alone (SMD 0.23; 95% CI -0.27 to 0.74; three studies, n = 188); however, there was considerable between study heterogeneity. There was no clear advantage in terms of hospital admissions (RR 0.76 95% CI 0.49, 1.16; four studies, n = 249), and there were no serious adverse events reported.Inhaled magnesium sulfate versus inhaled β(2)-agonistThe results of pulmonary function in three studies that compared inhaled MgSO(4) versus β(2)-agonist were too heterogeneous to combine; however, two of the studies found poorer lung function on MgSO(4). There was no significant difference in terms of hospital admissions in a single small study when MgSO(4) was compared to β(2)-agonist (RR 0.53 95% CI 0.05, 5.31; one study, n = 33), and there were no serious adverse events reported.Inhaled magnesium sulfate in addition to inhaled β(2)-agonist and ipratropiumA further comparison has been included in the 2012 update of this review of MgSO(4) given in addition to inhaled ipratropium and β(2)-agonist therapy (as recommended by the GINA guidelines). However, there is not yet enough data for this outcome to come to any definite conclusions, but both small studies in adults with severe asthma exacerbation found improvements in pulmonary function with additional inhaled MgSO(4).

AUTHORS' CONCLUSIONS

There is currently no good evidence that inhaled MgSO(4) can be used as a substitute for inhaled β(2)-agonists. When used in addition to inhaled β(2)-agonists (with or without inhaled ipratropium), there is currently no overall clear evidence of improved pulmonary function or reduced hospital admissions. However, individual study results from three trials suggest possible improved pulmonary function in those with severe asthma exacerbations (FEV1 less than 50% predicted). Heterogeneity among trials included in this review precludes a more definitive conclusion. Further studies should focus on inhaled MgSO(4) in addition to the current guideline treatment for acute asthma (inhaled β(2) -agonist and ipratropium bromide). As the evidence suggests that the most effective role of nebulised MgSO(4) may be in those with severe acute features and this is where future research should be focused. A set of core outcomes needs to be agreed upon both in adult and paediatric studies to allow improved study comparison in future. 

Nebulized magnesium sulfate in the management of acute exacerbations of asthma

OBJECTIVE

To evaluate the efficacy and safety of nebulized magnesium sulfate in the treatment of acute exacerbations of asthma.

DATA SOURCES

MEDLINE, EMBASE, and PubMed (all to October 2005) were searched using the key words magnesium, magnesium sulfate, magnesium compounds, nebulise, nebulize, vaporise, vaporize, nebulizers and vaporizers, aerosols, asthma, exacerbation, bronchial spasm, and bronchospasm.

STUDY SELECTION AND DATA EXTRACTION

Prospective, randomized, controlled trials that evaluated efficacy and safety endpoints of nebulized magnesium sulfate in the management of acute exacerbations of asthma were included. All studies were evaluated independently by both authors. Efficacy outcomes included pulmonary function, clinical disease severity (as defined by each study), and rate of hospitalization. Safety outcomes were as described by each trial.

DATA SYNTHESIS

Six prospective trials met the study criteria. Nebulized magnesium alone failed to demonstrate any benefit compared with beta(2)-agonists alone at improving pulmonary function. In trials in which nebulized magnesium was used as a vehicle for albuterol, there appear to be additional benefits to albuterol therapy in terms of improvements in pulmonary function in a population with mild-to-moderate asthma. The heterogeneous patient populations, study designs, magnesium doses, and the delivery methods preclude the extrapolation of these results to current clinical practice.

CONCLUSIONS

The studies included in this review fail to clarify the role of nebulized magnesium sulfate; therefore, this therapy cannot be recommended at this time. Future studies evaluating the role of nebulized magnesium as an adjunct therapy to beta(2)-agonist, anticholinergic, and corticosteroid therapy are necessary to determine whether a clinically relevant benefit of this intervention exists.

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.

OBJECTIVES

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

SEARCH STRATEGY

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.

SELECTION CRITERIA

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 beta2-agonist and where compared to beta2-agonist alone or inactive control.

DATA COLLECTION AND ANALYSIS

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).

MAIN 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 non significant improvement in pulmonary function between patients whose treatments included nebulised MgSO4 in addition to beta2-agonist (SMD: 0.23; 95% CI: -0.03 to 0.50; 4 studies). 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 in severe asthmatics the lung function difference was significant (SMD: 0.55; 95% CI: 0.12 to 0.98). Conclusions regarding treatment with nebulised MgSO4 alone are difficult to draw due to lack of studies in this area.

AUTHORS' 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 in patients with severe asthma and there is a trend towards benefit in hospital admission. Heterogeneity between trials included in this review precludes a more definitive conclusion.

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.

OBJECTIVES

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

SEARCH STRATEGY

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.

SELECTION CRITERIA

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.

DATA COLLECTION AND ANALYSIS

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).

MAIN 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.

AUTHORS' 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.

Reduced intracellular Mg concentrations in patients with acute asthma

STUDY OBJECTIVES

To determine the intracellular and extracellular Mg concentrations in patients with acute asthma and their correlation with parameters expressing the disease severity.

PATIENTS

Thirty patients with acute asthma (FEV(1), 56% predicted [SD, 14.5]), 20 patients with stable asthma (FEV(1), 97% predicted [SD, 10]), and 20 healthy subjects (FEV(1), 97% predicted [SD, 8]).

METHODS

Mg concentrations in erythrocytes and plasma were measured four times: at hospital admission, after 2 days, after 5 days, and at hospital discharge. Percentage of predicted FEV(1) and peak expiratory flow rate variability were recorded simultaneously. Similar measurements were carried in all study groups.

RESULTS

Mg concentrations of healthy subjects and patients with stable asthma remained unchanged in both plasma and erythrocytes. Initial Mg content in erythrocytes was significantly lower in patients with acute asthma (1.77 fmmol per cell; 95% confidence interval [CI], 1.71 to 1.83) compared to normal subjects (1.94 fmmol per cell; 95% CI, 1.82 to 2.00) and patients with stable asthma (1.92 fmmol per cell; 95% CI, 1.87 to 1.96) [p < 0.0001], and it increased significantly after the resolution of the exacerbation (from 1.77 fmmol per cell [95% CI, 1.71 to 1.83] at hospital admission to 1.90 fmmol per cell [95% CI, 1.83 to 1.98] at hospital discharge; p < 0.0001). No correlation was observed between parameters of disease severity and the initial values of Mg concentrations in erythrocytes and plasma.

CONCLUSIONS

Acute asthma is associated with lower erythrocyte Mg content while plasma levels remain unchanged. This decrease in intracellular Mg content occurs regardless of the severity of the exacerbation and returns to normal values after control has been achieved.

The pulmonary physician in critical care . 12: Acute severe asthma in the intensive care unit

Most deaths from acute asthma occur outside hospital, but the at-risk patient may be recognised on the basis of prior ICU admission and asthma medication history. Patients who fail to improve significantly in the emergency department should be admitted to an HDU or ICU for observation, monitoring, and treatment. Hypoxia, dehydration, acidosis, and hypokalaemia render the severe acute asthmatic patient vulnerable to cardiac dysrrhythmia and cardiorespiratory arrest. Mechanical ventilation may be required for a small proportion of patients for whom it may be life saving. Aggressive bronchodilator (continuous nebulised beta agonist) and anti-inflammatory therapy must continue throughout the period of mechanical ventilation. Recognised complications of mechanical ventilation include hypotension, barotrauma, and nosocomial pneumonia. Low ventilator respiratory rates, long expiratory times, and small tidal volumes help to prevent hyperinflation. Volatile anaesthetic agents may produce bronchodilation in patients resistant to beta agonists. Fatalities in acute asthmatics admitted to HDU/ICU are rare.

Magnesium as a relaxing factor of airway smooth muscles

In the search for effective treatment of a life-threatening asthma attack, intravenous magnesium infusion has been studied in asthmatic patients because of its potential effect to reverse bronchospasm and improve pulmonary function. To determine whether magnesium sulfate inhibits airway smooth muscle contraction and the possible mechanism of its action, in vitro experiments were performed on rabbit tracheas. Tracheal muscle strips were obtained from 12 rabbits. Initially, the muscle strip was pretreated with a solution containing MgSO4 (concentrations 10(-4) to 2 M) and 85 mM KCl. The response curve of the muscle was recorded. Application of the above solution led to a 40% relaxation at a magnesium concentration of 10(-1) M. The time to peak and to wash-out remained unchanged, and fixed to 66.6 and 123.3 sec, respectively, not influenced by magnesium concentration. On a second phase, the muscle strip was pretreated with KCl alone, and only after a full contractile response was obtained did we add 10(-1) M MgSO4, which led to full relaxation. We follow the same protocol using 10(-4) M acetylcholine (ACH). In this case, simultaneous application of 10(-1) M MgSO4 caused a 55.1% decrease in muscle contraction and a 60% decrease in time to peak. On a second phase, we added magnesium as we did with KCl, but without the same result. Magnesium caused a full relaxation when the constrictor agent was KCl, but a residual contraction was observed when the constrictor was ACH. Based on the knowledge that ACH and KCl cause Ca2+ influx into the cells and subsequent contraction by acting on different Ca2+ channels, we concluded that magnesium inhibits Ca2+ influx by blocking the voltage-dependent calcium channels.

Pharmacologic treatment of the adult hospitalized asthma patient

Acute severe asthma calls for aggressive and early therapy of a multifaceted and all-inclusive approach (Fig. 2). Therapy merely begins in the ED and manifold distinct issues need to find consideration during ongoing hospital care. Currently, beta-agonists, anti-cholinergic agents, and corticosteroids remain the mainstay of therapy. Methylxanthines and magnesium may find consideration in carefully selected patients. Multiple new therapeutic avenues, such as the anti-leukotriene drugs, seem promising and future studies will hopefully extend our armamentarium against life threatening complication of a common disease. Asthma education begun in the hospital may provide the platform for preventing severe acute exacerbations and hospitalization.

Drug therapy approaches in the treatment of acute severe asthma in hospitalised children

Acute severe paediatric asthma remains a serious and debilitating disease throughout the world. The incidence and mortality from asthma continue to increase. Early, effective and aggressive outpatient therapy is essential in reducing symptoms and preventing life-threatening progression. When complications occur or when the disease progresses to incipient respiratory failure, these children need to be managed in a continuous care facility where aggressive and potentially dangerous interventions can be safely instituted to reverse persistent bronchospasm. The primary drugs for acute severe asthma include oxygen, corticosteroids, salbutamol (albuterol) and anticholinergics. Second-line drugs include heliox, magnesium sulfate, ketamine and inhalational anaesthetics. Future therapies may include furosemide, leukotriene modifiers, antihistamines and phosphodiesterase inhibitors. This review attempts to explore the multitude of medications available with emphasis on pharmacology and pathophysiology.

A randomized trial of magnesium in the emergency department treatment of children with asthma

STUDY OBJECTIVE

Magnesium sulfate has been shown to benefit asthmatic children and adults with poor responses to initial beta(2)-agonist therapy in the emergency department. We sought to determine whether the routine early administration of high-dose magnesium would benefit moderate to severely ill children with acute asthma.

METHODS

This was a randomized, double-blind, placebo-controlled trial of 54 children 1 to 18 years of age who presented to the ED of a tertiary care children's hospital with a moderate to severe asthma exacerbation. After receiving a nebulized albuterol treatment (0.15 mg/kg) and methylprednisolone (1 mg/kg), patients were randomly assigned to receive either 75 mg/kg of magnesium sulfate (maximum 2.5 g) or placebo. Thereafter, all patients were treated with frequent nebulized albuterol following a structured protocol. The main outcome was degree of improvement as assessed by Pulmonary Index scores over 120 minutes. Secondary outcomes included hospitalization rates and time required to meet discharge criteria.

RESULTS

The mean change in Pulmonary Index score from baseline to 120 minutes was 2.83 for the magnesium group compared with 2.66 for the placebo group (95% confidence interval -1. 24 to 1.60). Eleven (46%) of 24 magnesium-treated patients were hospitalized compared with 16 (53%) of 30 in the placebo group (95% confidence interval -19% to 34%). There were no statistically significant differences between the groups with respect to time required to meet discharge criteria.

CONCLUSION

The routine administration of high-dose magnesium to moderate to severely ill children with asthma, as an adjunct to initial treatment with albuterol and corticosteroids, was not efficacious.

Assessment of magnesium status in patients with bronchial asthma

To elucidate the contribution of magnesium to bronchial hyperreactivity in patients with stable bronchial asthma, magnesium concentrations in serum (S-Mg), erythrocytes (R-Mg), and lymphocytes (L-Mg) were measured in 25 patients with bronchial asthma (BA group) and 9 age-matched healthy subjects (control group). A parenteral magnesium loading test, a continuous low-dose magnesium infusion of 0.2 mEq/kg over 4 hr, was performed in 10 of 25 asthmatic patients and in the control group. R-Mg was significantly lower in the BA group than in the control group (4.96 +/- 0.47, 6.13 +/- 0.62 mEq/L, p < 0.001, respectively), although S-Mg (2.4 +/- 0.1, 2.4 +/- 0.2 mg/dL) and L-Mg (1.28 +/- 0.26, 1.15 +/- 0.13 microg/mg/protein) were not significantly different between the two groups. Magnesium deficiency in total body stores was revealed in 40% of patients (4/10 patients) and 11% of control subjects (1/9 subjects) by parenteral magnesium loading test. The ratio of magnesium retention to urinary excretion through the parenteral magnesium loading test showed a significant inverse correlation with R-Mg (r = -0.78, p < 0.01). Bronchial reactivity to inhaled methacholine had a significant inverse correlation with R-Mg (r = -0.42, p < 0.05). We conclude that 40% of asthmatic patients demonstrated magnesium deficiency, and that the low magnesium concentration in erythrocytes reflects decreased magnesium stores in patients with bronchial asthma.

Intravenous magnesium as an adjuvant in acute bronchospasm: a meta-analysis

STUDY OBJECTIVE

Although several trials have been published evaluating intravenous magnesium sulfate as treatment for acute bronchospasm, its effectiveness for this indication remains unclear, prompting this meta-analysis.

METHODS

All randomized controlled trials of adjuvant bolus intravenous magnesium sulfate for acute bronchospasm in the emergency department were eligible. Trials were identified using MEDLINE, EMBASE, bibliographies of selected articles, and review of abstracts of 4 scientific societies. Two reviewers abstracted data, one of whom was blinded to author and journal. Because studies used different spirometric outcome measures, effect size was calculated for each study by Hedges' method. The analysis used a fixed-effects model. One-way sensitivity analyses were performed to assess the influence of study quality and to search for publication bias.

RESULTS

Abstracts from 210 articles were reviewed, yielding 40 trials, of which 9 were specific to bolus intravenous magnesium sulfate in the ED, in doses from 1.2 to 2 g, or an equivalent pediatric dose. Combined results across 9 studies including 859 patients showed a posttreatment effect size of 0.162 for patients treated with intravenous magnesium sulfate (95% confidence interval 0.028, 0.297; P =.02). In sensitivity analyses exploring the effects of study quality and publication bias, the summary effect ranged from 0.127 to 0.206. No serious adverse events were reported.

CONCLUSION

Adjuvant bolus intravenous magnesium sulfate in acute bronchospasm appears statistically beneficial in improving spirometric airway function by 16% of a SD. Although the clinical significance of this is uncertain, given the safety of intravenous magnesium sulfate therapy and its relatively low cost, it should be considered, absent contraindications, in patients with moderate to severe acute bronchospasm.

Magnesium sulfate for treating exacerbations of acute asthma in the emergency department

BACKGROUND

Treatment of acute asthma is based on rapid reversal of bronchospasm and arresting airway inflammation. There is some evidence that intravenous magnesium can provide additional bronchodilation when given in conjunction with standard bronchodilating agents and corticosteroids. No systematic review of this literature has been completed on this topic.

OBJECTIVES

To examine the effect of additional intravenous magnesium sulfate in patients with acute asthma managed in the emergency department.

SEARCH STRATEGY

Randomised controlled trials were identified from the Cochrane Airways Review Group register. Bibliographies from included studies, known reviews and texts were searched. Primary authors and content experts were contacted.

SELECTION CRITERIA

Randomised controlled trials or quasi-randomised trials were eligible for inclusion. Studies were included if patients presented with acute asthma and were treated with IV magnesium sulfate vs placebo.

DATA COLLECTION AND ANALYSIS

Data were extracted and methodological quality was assessed independently by two reviewers. Missing data were obtained from authors.

MAIN RESULTS

Seven trials were included (5 adult, 2 pediatric). A total of 665 patients were involved. Patients receiving magnesium sulfate demonstrated non-significant improvements in peak expiratory flow rates when all studies were pooled (weighted mean difference: 29.4 L/min; 95% confidence interval: -3.4 to 62). In studies of people with severe acute asthma, peak expiratory flow rate improved by 52.3 L/min (95% confidence interval: 27 to 77.5). The forced expiratory volume in one second also improved by 9.8 % predicted (95% confidence interval: 3.8 to 15.8). Overall, admission to hospital was not reduced, odds ratio: 0.31 (95% confidence interval: 0.09 to 1.02). In the severe subgroup, admissions were reduced in those receiving magnesium sulfate (odds ratio: 0.10, 95% confidence interval: 0.04 to 0.27). No clinically important changes in vital signs or adverse side effects were reported.

REVIEWER'S CONCLUSIONS

Current evidence does not support routine use of intravenous magnesium sulfate in all patients with acute asthma presenting to the emergency department. Magnesium sulfate appears to be safe and beneficial in patients who present with severe acute asthma.

Effect of different inhaled bronchodilators on recovery from methacholine-induced bronchoconstriction in asthmatic children

Two hundred fourteen children with mild to moderate asthma were studied to determine bronchodilator effects 5 min after administration of five different metered dose inhaler (MDI) aerosol formulations available in our country, and results were compared to placebo. Methacholine bronchial challenge was performed by the tidal breathing method, using increasing concentrations until a fall in forced expired volume in 1 s (FEV(1)) >/=20% was achieved (PC20). Immediately after FEV(1) had fallen 20% or more, children were randomly allocated into 1 of 6 groups to receive: salbutamol 200 microg (S), fenoterol 200 microg (F), salbutamol 200 microg + beclomethasone 100 microg (S + B), fenoterol 200 microg + ipratropium bromide 80 microg (F + IB), salmeterol 50 microg (SM), and placebo (P). The bronchodilator effect was determined by measuring FEV(1) 5 min after inhalation of medications. Nonparametric tests were used for statistical analysis. The six groups were similar in anthropometric and in respiratory characteristics. All five inhaled aerosols containing beta-agonists caused a significant bronchodilator effect as compared to placebo. However, the effect was significantly greater in the groups treated with F or F + IB (P < 0.05) compared to other formulations. We conclude that the five types of aerosols used in this study are able to reverse methacholine-induced bronchoconstriction 5 min after inhalation of a bronchodilator.

Magnesium in the management of asthma: critical review of acute and chronic treatments, and Deutsches Medizinisches Zentrum's (DMZ's) clinical experience at the Dead Sea

The recognition of asthma as an inflammatory disease has led over the past 20 years to a major shift in its pharmacotherapy. The previous emphasis on using relatively short-acting agents for relieving bronchospasms and for removing bronchial mucus has shifted toward long-term strategies with the use of inhaled corticosteroids, which successfully prevent and abolish airway inflammation. Because some of the biological, chemical, and immunological processes that characterize asthma also underly arthritis and other inflammatory diseases, and because many of these conditions have been successfully treated for the past 40 years at the Dead Sea, we were not surprised to realize and record the significant improvement of asthmatic condition after a 4-week stay at the Dead Sea: lung function was improved, the number and severity of attacks was reduced, and the efficacy of beta2-agonist treatments was improved. After reviewing the acute and chronic treatments of asthma in the clinic (including emergency rooms) with magnesium compounds, and the use of such salts as supplementary agents in respiratory diseases, we suggest that the improvement in the asthmatic condition at the Dead Sea may be due to absorption of this element through the skin and via the lungs, and due to its involvement in anti-inflammatory and vasodilatatory processes.

Nebulized glucagon in the treatment of bronchospasm in asthmatic patients

This study sought to determine if nebulized glucagon, a well-known smooth muscle relaxant, is effective in relieving asthmatic bronchospasm. Ten subjects, aged 12 to 26 years, with chronic stable asthma were studied in a pulmonary function laboratory under a randomized double-blind, placebo-controlled, crossover design. Bronchospasm was induced in each subject with progressive doses of nebulized methacholine until forced expiratory volume in 1 second (FEV1) had decreased at least 20% from baseline. Subjects then received either nebulized saline or 2 mg of nebulized glucagon. Spirometry was performed at 5, 15, and 30 minutes after treatment. Subjects then received 2.5 mg of nebulized albuterol and had spirometry 15 and 30 minutes thereafter. Each subject returned for testing with the alternative solution at least 1 week later. Treatment with nebulized glucagon resulted in a 58% +/- 15% improvement in FEV1 15 minutes after treatment compared with 36% +/- 7% after nebulized saline (P < .05). No adverse effects of glucagon treatment occurred. This study suggests that nebulized glucagon reduces methacholine-induced bronchospasm in asthmatic patients.

Alternatives to Standard Status Asthmaticus Therapy

Even with the currently available treatment, morbidity and mortality from asthma continues to rise. Patients with status asthmaticus who do not respond to standard therapy are at risk for respiratory failure and possible mechanical ventilation. Treatment options for refractory status asthmaticus remain limited and alternative and controversial therapies may need to be considered. Alternative therapies include continuous nebulized beta-agonists, ipratropium bromide, intravenous magnesium sulfate, ketamine, or heliox. Morbidity and mortality may be decreased by increased utilization of these alternative therapies. Pharmacists can play a key role in monitoring and recommending new and alternate therapies.

Magnesium attenuates the neutrophil respiratory burst in adult asthmatic patients

INTRODUCTION

IV magnesium (Mg2+) has been proposed as an emergent treatment for acute asthma exacerbations. Recent studies have focused on the effects of Mg2+ on bronchial smooth muscle, yet asthma is primarily an inflammatory disease.

OBJECTIVE

To assess the effects of Mg2+ on the neutrophil respiratory burst of adult patients with asthma.

METHODS

A prospective, blind study of volunteer adult asthmatic patients was performed. The patients' polymorphonuclear neutrophils (PMNs) were isolated, purified, and placed into phosphate-buffered saline with the following test conditions: concentrations of magnesium chloride (MgCl2) added: 0 mmol MgCl2, 1 mmol MgCl2 (low), and 10 mmol MgCl2 (high) both with and without the calcium (Ca2+) ionophore A23187 (0.1 mmol). PMNs were activated using N-formyl-methionyl-leucyl-phenylalanine (fMLP) (10 mumol), and the production of superoxide (O2-) was measured by the spectrophotometric reduction of cytochrome c.

RESULTS

Mg2+ reduced activated PMN O2- production compared with that for no Mg2+ (1.0 +/- 0.1 nmol O2-/5 x 10(5) PMN/min) in both low (-0.52* +/- 0.3 nmol O2-/5 x 10(5) PMN/min) and high (-0.76* +/- 0.3 nmol O2-/5 x 10(5) PMN/min; *p < 0.05) concentrations. The addition of A23187 increased O2- production in both the high (0.53* +/- 0.02 nmol O2-/5 x 10(5) PMN/min) and the low (1.5* +/- 0.6 nmol O2-/5 x 10(5) x 10(5) PMN/min) Mg2+ groups, with no change in the control group (1.2 +/- 0.2 nmol O2-/10(5) PMN/min).

CONCLUSIONS

In clinically relevant concentrations, Mg2+ attenuates the neutrophil respiratory burst in adult asthmatic patients. Mg2+ appears to affect PMNs by interfering with extracellular Ca2+ influx. Mg2+ may have a beneficial anti-inflammatory effect in asthmatic individuals.

Acute asthma

The number of patients presenting to the emergency department with severe acute asthma exacerbations is increasing. Prompt and aggressive therapy often ameliorates the symptoms and decreases the morbidity and mortality associated with this disease. A directed history and physical examination should be performed, often simultaneously with treatment. The use of inhaled beta-adrenergic agents and the early use of corticosteroids will reverse most attacks. In addition, the use of anticholinergic agents may benefit selected patients. Despite aggressive treatment, some patients will require endotracheal intubation. Controlled intubation with proper sedation and paralysis will decrease the associated morbidity. Complications associated with mechanical ventilation may be prevented by decreasing the amount of auto-PEEP by controlled hypoventilation. Asthma, when incompletely or inadequately treated, can be a rapidly fatal disease process. Conservative approaches to patient admission based on strict objective pulmonary function testing should decrease morbidity and mortality.

Treatment of critical status asthmaticus in children

Status asthmaticus is complex in its etiology and pathophysiology and may be associated with significant morbidity and mortality. Although there are many therapeutic options, specific inhaled beta 2-agonists, corticosteroids, and oxygen remain the mainstay of therapy. Several new drugs and some older drugs are being used in management; their exact role in treatment at present, however, relies largely on personal preferences. Innovative methods of providing ventilatory support are also emerging. What is quite clear is the fact that involvement of specialists (pulmonologists and intensivists) early in the course of severe status asthmaticus is needed to ensure optimal management and possibly favorable outcomes.

Magnesium and its therapeutic uses: a review

Magnesium has been reported as an effective medical therapy in an expanding array of conditions. Evidence investigating magnesium's use is presented, with a number of studies suggesting it should be seriously considered in such conditions as ischemic heart disease, cardiac arrhythmias, and asthma. Magnesium balance and metabolism are briefly reviewed, and then various hypotheses are presented that may explain magnesium's physiologic mechanisms of action, most likely involving calcium and potassium flux across cellular membranes in smooth muscle. In a number of the conditions to be discussed, it has been uncertain whether magnesium administration serves the purpose of merely correcting an underlying deficiency state or of utilizing a specific pharmacologic effect of magnesium. Magnesium deficiency is a relatively common condition, and predisposing factors as well as recent methods for assessing total body stores of magnesium are discussed. Physicians should be familiar with the numerous conditions and therapeutics that are risk factors for an underlying magnesium deficiency and in which empiric magnesium replacement should be considered. Guidelines for administration of parenteral magnesium are presented with specific focus on the low risk of adverse effects, as suggested by the large and rapid dosing regimens used in many of the clinical studies discussed here.