The most common lower respiratory infection in the first year of life is bronchiolitis. Treatment of this condition is largely supportive, consisting of supplemental oxygen, intravenous fluids, minimal handling of the infant and, when necessary, mechanical ventilation. The use of bronchodilators in hospitalized infants with bronchiolitis remains controversial, because a number of controlled studies have failed to demonstrate clear benefit. There are theoretic reasons to suppose that epinephrine might be superior to albuterol for treatment, because its combined alpha-adrenergic and beta-adrenergic action may better address the airway edema that typically occurs in patients with bronchiolitis. Wainwright and colleagues performed a randomized, controlled, multicenter trial of nebulized epinephrine in infants hospitalized because of bronchiolitis.

The authors enrolled infants younger than 12 months who were hospitalized for a first episode of wheezing and a clinical diagnosis of bronchiolitis (i.e., history of upper respiratory tract infection and respiratory distress consistent with a clinical diagnosis of bronchiolitis). Exclusion criteria included known cardiac disease, significant respiratory disease (e.g., cystic fibrosis), use of corticosteroids in the previous 24 hours, and use of bronchodilators within four hours of admission. A total of 194 infants were randomized to receive epinephrine (99 patients) or placebo nebulizer solution (95 patients). To minimize treatment variations, each infant was treated according to a clinical pathway specifying when supplemental oxygen, intravenous fluids, and nebulizer therapy were to be used. At the time of admission, there were no significant differences between the groups in regard to demographic variables, duration of wheezing, duration of coryza, need for supplemental oxygen or intravenous fluids, and demonstrated infection with respiratory syncytial virus.

Treatment with epinephrine did not significantly shorten the length of hospital stay or the time until the infant was ready to be discharged compared with placebo. Among sicker infants, who required supplemental oxygen and intravenous fluids, the length of time until they were ready for discharge was significantly longer in those receiving epinephrine. There were no significant differences between epinephrine and placebo treatment in terms of duration of supplemental oxygen use, intensive care unit admission, or need for mechanical ventilation. Changes in respiratory rate, respiratory effort scores, heart rate, and blood pressure were not significant.

The authors conclude that the use of nebulized epinephrine for the treatment of bronchiolitis in infants younger than 12 months does not shorten the length of hospital stay, improve respiratory effort, or decrease the need for supplemental oxygen or intravenous fluids.