Intravenous magnesium sulfate in acute, life-threatening asthma.

Magnesium, a physiologic calcium antagonist, is known to have a direct effect on calcium uptake in smooth muscle, resulting in smooth muscle relaxation. Studies of magnesium sulfate infusions in patients with mild or moderate-to-severe acute asthma have shown that it may have a significant bronchodilatory effect, similar to that of salbutamol (albuterol). We present the case of a patient with acute severe life-threatening asthma (initially in cardiorespiratory arrest) who responded to an IV infusion of magnesium sulfate after aggressive pharmacologic management failed to result in clinical improvement.