Original Research

Effectiveness of intravenous magnesium sulphate in acute asthma: a retrospective study

Muhammad Saleh Khaskheli1, Rafia Tabassum2, Aijaz Hussain Awan3
1Professor & Chairman, Cell: +92 300 321 1417, E-mail: beesaleh@hotmail.com
2Assistant Professor, +92 306 829 4346, E-mail: rafiatabassum2013@gmail.com
3Consultant Anesthesiologist, Cell: +92 302 322 6500, E-mail: draijazhussainawan@gmail.com

Department of Anesthesiology, SICU & Pain Management Center, Peoples University Of Medical & Health Sciences For Women, Shaheed Benazirabad, Sind, (Pakistan)

Correspondence: Professor Muhammad Saleh Khaskheli, Chairman, Department of Anaesthesiology, SICU & Pain Management Center, Peoples University of Medical & Health Sciences For Women, Shaheed Benazirabad, Sind (Pakistan); Cell: 03003211417; E-mail: beesaleh@hotmail.com


Objective: The recent interest in intravenous magnesium sulphate for using it in many other indications other than control of eclamptic fits lead the researchers to try it as a smooth muscle relaxant in cases of acute bronchial asthma. The results have largely been controversial, so we conducted this study to determine efficacy of intravenous magnesium sulphate in acute asthma based on its terminal outcome.
Methodology: This retrospective study was conducted at Surgical Intensive Care Unit at Peoples University of Medical and Health Sciences for Women, Nawabshah from January 2014-December 2015. We retrospectively reviewed the medical data sheets of all cases of acute asthma admitted during the study period, and extracted the relevant information. All the patients were initially treated with standard therapy for asthma and then given 4ml of 50% MgSO4 (2g) diluted in 250 ml of normal saline intravenously. Outcomes were presented in percentages and frequencies while patient age is presented as mean ± SD.
Results: The mean age of the population was 45.29 ± 20.1 y. We had a female predominance in our population (60.3%). Successfully cured patients were 32.3% whereas those expired were 57.4%. There was not a significant difference between the genders for the outcome (p > 0.05).
Conclusions: We found that intravenous magnesium sulphate is ineffective in successfully management of patients with acute asthma in terms of enhanced survival rate.
Keywords: Magnesium sulphate; Bronchial asthma; Efficacy; Emergency management.
Citation: Khaskheli MS, Tabassum R, Awan AH. Effectiveness of intravenous magnesium sulphate in acute asthma: a retrospective study. Anaesth Pain & Intensive Care 2017;21(4):458462
Received: 02 Feb 2017; Reviewed: 7 Feb & 21 Jul 2017; Corrected: 8 Feb, 31 Mar, 20 Jul 2017; Accepted: 12 Aug 2017


Asthma is a chronic inflammatory disease of the lower airways characterized by respiratory symptoms and variable airway obstruction. Its clinical manifestations include recurrent symptoms, often involving shortness of breath, wheezing, coughing and chest tightness.1 In developed centuries, asthma is prevalent in 4-5% of the population and almost 27% of patients requiring admission.2 It is extremely prevalent with up to 1:10 adults worldwide.3
In addition to general treatment strategy, standard management of asthma include β2-agonists, inhaled anticholinergic agents, short-acting bronchodilators, and corticosteroids.4,5 For patients unresponsive to these initial therapies, magnesium sulfate (MgSO4) may be a treatment option.1,6 It has also been recommended as an adjunct in treating severe asthma with other mainline drugs.7,8 In patients who do not respond to initial treatments and those with severe, life-threatening acute exacerbations, current guidelines are suggestive of using MgSO4 as an adjunct therapy for reducing hospital stay and improving pulmonary functions, while the evidence for using nebulized magnesium is still inconclusive.4,7,9-11 Results have been mixed for several randomized controlled trials (RCTs) using intravenous MgSO4 in acute patients as some studies demonstrate its benefits,12-14 while others do not.2,15,16 Moreover, the studies reporting positive outcomes have shown a benefit predominantly in severe exacerbations as two recent reviews supported its use as an adjunct in severe asthma.2
Intravenous MgSO4 has a high safety profile17 with commonly reported minor side effects including dry mouth, flushing, malaise pain, and numbness at the site of infusion.1,18 Potential drug interactions include potassium-sparing diuretics and glucagon, which when used simultaneously, increase serum magnesium levels. If concomitant use of both drug groups have to be used, commonly reported problems need to be monitored or the later drug withheld temporarily if possible.1,19 Contraindications to the use of MgSO4 include myasthenia gravis, myocardial conditions, AV block and renal failure (creatinine clearance less than 30 ml/min).1,20
There has not been any study from Pakistan on this topic and there is scarce and conflicting data available on it particularly in Asia.9 Therefore, this study was conducted to investigate the efficacy of intravenous magnesium sulphate in acute asthma based on its outcomes.


The study was approved by the institutional ethical committee. We conducted a retrospective review of all cases of acute severe asthma transferred to Surgical Intensive Care Unit at Peoples University of Medical and Health Sciences for Women, Nawabshah over a period of 2 years (January 2014-December 2015), and extracted the relevant information from the medical records. We excluded the poisoning cases, post-operative cases, post-trauma and patients on ventilatory support from the analysis. Variables under consideration were age and outcome (expired, cured, and referred). We, however, did not obtain any information on post-referral state of the patients. These patients were referred to hospitals with better treatment facilities on the request of their family or due to the orders of their treating physician.
Moreover, all the patients were initially managed at the Department of Medicine and then shifted to Surgical Intensive Care Unit. Before the current admission, most patients had a history of asthma and were received treatment with maintenance and/or rescue medications at home. In addition, patients received standard therapy (including nebulized salbutamol and ipratropium bromide, and systematic hydrocortisone) for an asthma exacerbation before receiving treatment with intravenous magnesium sulfate. All the patients were initially treated with standard therapy for asthma and then given intravenous magnesium sulphate i.e. received 4 ml of 50% MgSO4 (2 g) diluted in 250 ml of normal saline and given slowly over 20 min as per the recent recommendations.21 All the patients, after being stable were shifted to the Department of Medicine.
Statistical analysis: The data was recorded and kept on Microsoft Excel 2007 Spreadsheets. We extracted the relevant information and analyzed it on SPSS version 20. Gender and outcomes were presented in percentages and frequencies while age were presented as mean ± SD. Chi square test was used for comparing the outcome between the genders. The significance level was set at p < 0.05. RESULTS A total of 136 patients were enrolled in the study during the study period. There was a female predominance 82 (60.3%) as compared to males, which were 54 (39.7%). The mean age was 45.29 ± 20.1 y. The cured patients were 32.3% whereas those expired were 57.4%. Table 1 shows the demographic variables while Graph 1 shows outcomes based on the gender of the patients. There was not a significant difference between the genders for the outcome; cure rate for males was 25(18.38%) vs. 19(13.87%) (p > 0.05). A total of 78 (57.4%) patients expired despite the use of MgSO4.

Table 1: Demographic variables and outcomes

Variables Data
Age (years) 45.29 ± 20.1

·         Male

·         Female


54 (39.7)

82 (60.3)


·         Cured

·         Expired

·         Referred


44 (32.3%)

78 (57.4%)

14 (10.3%)

Graph 1: The outcome of the patients based upon gender

Effectiveness of intravenous magnesium-Graph-1(13OA)


MgSO4 has been used as an adjunct in managing acute asthma but there is still lack of adequate evidence to support its effectiveness. Most of the studies have been conducted in the West and there is a high gap of research in the Asia-Pacific region.9 The role of MgSO4 in asthma is still unclear, but some studies have helped explain its mode of action. The possible effects of MgSO4 on smooth muscles may include activating sodium-calcium pumps and blocking the entry and release of calcium from the endoplasmic reticulum (ER) which consequently result in decrease in intracellular calcium.22,23 Moreover, MgSO4 inhibits acetylcholine release and depresses excitability of muscle fiber in cholinergic motor nerve terminals, ultimately generating bronchial smooth muscle relaxation.24 Furthermore, calcium and myosin interaction is inhibited by magnesium sulphate resulting into muscle cell relaxation. Magnesium also reduces inflammatory mediators by inhibiting mast cell degranulation and stabilizing T-cells.25 It may also increase the receptor affinity of β2-agonists thereby, increasing their bronchodilator effect.9,26 Lastly, it may directly reduce the severity of asthma by stimulating the synthesis of prostacyclin and nitric oxide.1
We found that 57.4% patients died even after the management of asthma with magnesium sulphate. However, the use of intravenous MgSO4 improved pulmonary function in adults but did not cause any reduction in the rate of hospitalization.27,28 Furthermore, a Cochrane review reported the effectiveness of MgSO4 in the treatment of acute asthma,29 whereas, the recent reviews by Mohammed et al. found that the efficacy of MgSO4 was only marginal on pulmonary function (SMD=0.25, 95% CI= 0.01-0.51).6 Moreover, the most recent review was unable to draw clear conclusions about effectiveness of MgSO4 in adults. However, it was suggested that intravenous MgSO4 seemed to be effective in children.30 This shows that there are mixed results and conclusions about the efficacy of magnesium sulphate in management of acute asthma. We tried a different strategy of finding efficacy of magnesium sulphate as compared to the previous studies; they most often were, randomized controlled trials; but we used an outcome-based retrospective review, concluding that magnesium sulphate was ineffective in asthma management.
Strengths and Limitations: This study is the first one from Pakistan on the role of magnesium sulphate in the management of asthma. However, it has its limitations. The study design for this study was retrospective in which charts of the patients were reviewed. Outcome measures were weak and duration of hospital stay, ventilator support, and post-referral status were not obtained and addressed. Nevertheless, this study expands the previous knowledge base on the use of intravenous magnesium sulphate in asthma management.


We found that intravenous magnesium sulphate is ineffective in managing patients with acute asthma. However, there is still need of some larger studies, primarily the randomized trials and prospective studies, to draw definite conclusions about the role of magnesium sulphate in the management of asthma.

Conflict of interest: None declared by the authors
Author contribution:
MSK – Manuscript editing
RT – Statistical analysis
AHA – Literature search


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