Purpose: Magnesium sulfate is thought to be an effective bronchodilator when administered intravenously to patients with acute severe asthma, and it can be safely administered via inhalation to patients with stable asthma. Our goal was to determine if isotonic magnesium sulfate could be used as a vehicle for nebulized salbutamol for patients with acute asthma.
Methods: We enrolled 35 patients with acute asthma in a randomized, double-blind, controlled trial. After measurement of peak expiratory flow, patients received 2.5 mg salbutamol plus either 3 mL normal saline solution (n = 16) or isotonic magnesium sulfate (n = 19) through a jet nebulizer. Peak flow was reassessed 10 and 20 minutes after treatment.
Results: Peak flow at baseline was similar in the two groups. Ten minutes after baseline, the mean (+/- SD) percentage increase in peak flow was greater in the magnesium sulfate-salbutamol group (61% +/- 45%) than in the normal saline-salbutamol group (31% +/- 28%; difference = 30%; 95% confidence interval [CI] for the difference: 3% to 56%; P = 0.03). At 20 minutes, the percentage increase in peak flow was 57% greater in the magnesium sulfate group (95% CI: 4% to 110%, P = 0.04). There was a significant inverse correlation between baseline peak flow (percent of predicted) and the percentage increase in peak flow at 20 minutes in the magnesium sulfate group (r = -0.82, P <0.0001), but not in the saline group (r = -0.12, P = 0.67).
Conclusion: In patients with acute asthma, isotonic magnesium sulfate, as a vehicle for nebulized salbutamol, increased the peak flow response to treatment in comparison with salbutamol plus normal saline.