QUEENSLAND, AUSTRALIA—Acute viral bronchiolitis in infants is usually self-limiting, and thus care is generally supportive, consisting of supplemental oxygen and the use of intravenous fluids and ventilatory support when needed. Although bronchodilators are also often used, their efficacy is questionable. For example, a Cochrane review of bronchodilator use in bronchiolitis reported short-term improvement in clinical scores but not in oxygenation or rates of hospitalization.[1]

Recently, researchers conducted a multicenter, randomized, placebo-controlled trial to study nebulized epinephrine’s effect on length of hospital stay in 194 infants with bronchiolitis. They found that nebulized epinephrine had no clinical effect.[2]

Infants 12 months or younger with bronchiolitis who were admitted to one of four Queensland, Australia, hospitals between April 2000 and September 2001 were eligible for inclusion. Of these, 194 were randomized to receive three doses of nebulized epinephrine (n = 99) or placebo (n = 95) every four hours within 24 hours of hospital admission. Respiratory rate, oxygen saturation, and respiratory effort were used to calculate a disease severity score. Primary outcomes were length of hospital stay and time until the child was deemed ready for discharge. Secondary outcomes were changes in clinical scores after nebulizer therapy and duration of supplemental oxygen use.

The need for supplemental oxygen was the greatest determinant of disease severity and length of hospital stay. Among infants who required oxygen and intravenous fluids, the time until ready for discharge was significantly longer in the treatment group than in the placebo group. Among the other infants, no between-group difference in these parameters was found. There was also no significant between-group difference in the change in respiratory effort from before to 60 minutes after treatment, nor was there any significant difference in the response to epinephrine between the study hospitals.

A history of asthma, eczema, or hay fever in a first-degree relative did not affect the response to epinephrine. According to the authors, this indicates that bronchodilators are not effective in acute bronchiolitis—even when the child is at risk for asthma.

In response to studies showing short-term improvements in bronchiolitis after bronchodilator use, the authors wrote, “We thought that if nebulized epinephrine resulted in any significant clinical improvement, albeit transient, it should be apparent from our observations before and after the administration of the three doses over the nine hours of repeated observations. No consistent statistically significant change in the respiratory rate or respiratory-effort score was found.”

—Gale Jurasek