From the Guidelines
The recommended dose of magnesium sulfate for pediatric asthma management is 25-75 mg/kg (maximum 2 grams) administered as a single intravenous infusion over 20 minutes. This dosing is based on the study by Silverman et al. 1, which demonstrated the efficacy of IV magnesium sulphate in the treatment of acute severe asthma. Although the study was conducted in adults, the dosing can be extrapolated to pediatric patients. Magnesium sulfate works as a smooth muscle relaxant, helping to dilate constricted airways by blocking calcium uptake. It should be administered in a monitored setting due to potential side effects including hypotension, flushing, and respiratory depression.
The medication should be diluted appropriately before administration, typically in normal saline or dextrose solution. Clinical improvement is usually observed within 30-60 minutes if the treatment is effective. Magnesium sulfate is generally considered a second-line or adjunctive therapy after standard treatments (inhaled beta-agonists, anticholinergics, and systemic corticosteroids) have been initiated. Continuous cardiac monitoring is recommended during administration due to the potential for cardiac effects. Key factors to consider when deciding to administer magnesium sulfate include the severity of the asthma exacerbation, the patient's response to initial bronchodilator therapy, and the presence of any contraindications to magnesium sulfate use.
Some key points to consider when administering magnesium sulfate include:
- Monitoring for signs of magnesium toxicity, such as respiratory depression, cardiac arrest, and decreased reflexes
- Avoiding administration in patients with renal insufficiency or those taking medications that interact with magnesium
- Using caution in patients with cardiac conduction abnormalities or those taking cardiac medications
- Ensuring adequate hydration and electrolyte balance during and after administration.
From the Research
Magnesium Sulfate Dosing for Pediatric Asthma Management
- The recommended dose of magnesium sulfate for pediatric asthma management varies across studies, but most studies suggest a dose range of 25-50 mg/kg/h or a single dose of 40-50 mg/kg 2, 3, 4, 5.
- A study published in 2021 found that a continuous infusion of magnesium sulfate at a dose of 50 mg/kg/h for 4 hours was well tolerated and led to improved respiratory status in children with severe acute asthma 3.
- Another study published in 2020 found that a single dose of 40-50 mg/kg of intravenous magnesium sulfate improved lung function parameters in children with acute asthma 4.
- A study published in 1997 found that a dose of 0.2 ml/kg of 50% magnesium sulfate as an intravenous infusion over 35 minutes was effective in improving clinical signs and symptoms of asthma in children with acute severe asthma not responding to conventional therapy 5.
- However, a study published in 2020 found that larger doses of magnesium sulfate (>27 mg/kg) were associated with an increased need for escalation in therapy, including invasive or non-invasive mechanical ventilation or adjunctive therapy 6.
Key Findings
- Magnesium sulfate is a calcium antagonist that inhibits bronchial smooth muscle contraction, promoting bronchodilation 2.
- Intravenous magnesium sulfate has been shown to be effective in reducing the need for mechanical ventilation support in children with acute severe asthma 2.
- The use of magnesium sulfate in continuous infusion has been found to be well tolerated and effective in improving respiratory status in children with severe acute asthma 3.
- The optimal dose of magnesium sulfate for pediatric asthma management is still unclear, and further studies are needed to determine the most effective and safe dose range 4, 5, 6.