Can a 64-year-old female with bronchospasm be given 2 grams of magnesium sulfate (Mg) intravenously?

Magnesium Sulfate for Bronchospasm in a 64-Year-Old Female

Yes, 2 grams of intravenous magnesium sulfate can be safely administered to a 64-year-old female with bronchospasm as an adjunctive treatment when standard therapies have not provided adequate relief.

Indications and Efficacy

• IV magnesium sulfate is recommended for patients with severe bronchospasm that remains severe after 1 hour of intensive conventional treatment (inhaled β2-agonists, anticholinergics, and systemic corticosteroids) 1
• Magnesium causes relaxation of bronchial smooth muscle independent of serum magnesium level, providing a complementary bronchodilator effect to standard treatments 1
• In severe cases of bronchospasm, magnesium sulfate should be considered as part of the secondary management approach 2

Dosing and Administration

• The standard adult dose is 2g administered intravenously over 20 minutes 1, 3
• For IV administration, the solution must be diluted to a concentration of 20% or less prior to administration, commonly using 5% Dextrose Injection or 0.9% Sodium Chloride Injection 3
• The rate of IV injection should generally not exceed 150 mg/minute (1.5 mL of a 10% concentration) 3

Treatment Algorithm

1. First-line treatment should include:

   • Short-acting beta-agonists (SABAs) 2
   • Anticholinergics if needed 2
   • Systemic corticosteroids for significant bronchospasm 2

2. If bronchospasm remains severe after initial treatment:

   • Consider IV magnesium sulfate 2g over 20 minutes 1
   • Continue bronchodilator therapy during magnesium administration 4

3. For persistent bronchospasm:

   • Consider additional therapies such as IV aminophylline 2
   • Prepare for possible intubation if respiratory status deteriorates 2

Safety Considerations

• Monitor for potential adverse effects, which are generally mild and include flushing and light-headedness 1
• Ensure adequate renal function, as magnesium is eliminated solely by the kidneys 3
• Clinical monitoring should include:
  • Presence of patellar reflex (knee jerk) 3
  • Respiratory rate (should remain ≥16 breaths/minute) 3
  • Blood pressure (monitor for hypotension) 3

Precautions

• Use with caution in patients with renal impairment 3
• An injectable calcium salt should be immediately available to counteract potential magnesium toxicity 3
• When administered with CNS depressants, dosages should be adjusted with caution due to additive CNS depressant effects 3
• Use extreme caution in digitalized patients, as serious changes in cardiac conduction may occur if calcium administration becomes necessary 3

Evidence of Effectiveness

• Rapid infusion of IV magnesium sulfate has been shown to dramatically reverse severe bronchospasm and potentially obviate the need for intubation 4
• Multiple studies demonstrate that IV magnesium sulfate can reduce hospital admissions in patients with severe asthma exacerbations 1
• Case reports show successful treatment of bronchospasm in various populations, including pregnant women 5

In this 64-year-old female patient with bronchospasm, 2 grams of IV magnesium sulfate is an appropriate treatment option if standard therapies have not provided adequate relief, with careful monitoring for adverse effects and appropriate administration technique.