Some patients with life-threatening asthma do not respond to inhaled selective beta-adrenergic agents and subsequently advance to respiratory failure. Although epinephrine has no advantage to these inhaled agents in mild to moderate asthma, intravenous epinephrine may have some usefulness in life-threatening situations. Intravenous administration provides rapid onset of action, reliable dose titration, and the ability to immediately stop administration if adverse effects are noted. Smith and associates conducted a retrospective chart review to study the effects of intravenous epinephrine use in two large hospital emergency departments.

Intravenous epinephrine was used at the discretion of the attending physician, usually when other therapies, including inhaled beta agonists and intravenous or oral steroids, failed or when an already at-risk patient had altered mental status or decreased respirations. All patients requiring intravenous epinephrine were admitted to the intensive care unit. During the eight-year study, 27 patients met the inclusion criteria, with most receiving an intravenous loading dose between 50 mcg and 1 mg of a 1:10,000 solution (mean, 200 mcg) of epinephrine. About one half received a continuous infusion of intravenous epinephrine ranging between 3 to 20 mcg per min, with most receiving 1 mg over an hour.

No major adverse events resulting from epinephrine administration were noted, and none of the study patients died while hospitalized. One patient had chest pain that eventually resolved without any sequelae. The only arrhythmia noted in the study group was sinus tachycardia. There was no evidence of ischemia or increase in cardiac enzymes. No patient had any neurologic deficit resulting specifically from the epinephrine administration. There were no significant, untreatable blood pressure changes. No other adverse effects were noted.

The authors conclude that administration of intravenous epinephrine to patients with life-threatening asthma did not cause hypotension, acute cardiac or cerebral ischemia, or increased mortality. Most changes in vital signs were caused by intubation, not by epinephrine administration. A prospective trial of intravenous epinephrine in patients with life-threatening asthma would be useful to further define the efficacy and safety of this treatment step.