Croup treatment usually involves a single dose of systemic dexamethasone combined with nebulized epinephrine. However, the optimal dose of l-epinephrine remains unclear. We examined whether a low dose (0.1 mg/kg) was inferior to the conventional dose (0.5 mg/kg) of 1:1000 nebulized l-epinephrine in patients with moderate to severe croup.

This randomized double-blind clinical non-inferiority trial was conducted in three pediatric emergency departments from May 2015 to October 2017. Children 6 months to 5 years old with moderate to severe croup (Westley scale scores 3–11) were eligible. Subjects were randomly assigned to the conventional dose (0.5 mg/kg: maximum 5 mg) or low dose (0.1 mg/kg; maximum 1 mg) group. All subjects received 0.6 mg/kg dexamethasone. Croup scores and other vital signs were measured before and at 30, 60, 90, and 120 min after nebulized l-epinephrine administration. The primary outcome was the change in croup score after 30 min.

The final analysis included 84 patients. The groups did not differ significantly in terms of demographic parameters. At 30 min after treatment with nebulized l-epinephrine, the croup scores in both groups were significantly reduced from the baseline values (p < 0.05) and did not differ between the two groups (p = 0.42). Neither blood pressure nor heart rate differed between the two groups.

Low-dose 1:1000 l-epinephrine was not inferior in croup score reduction to the conventional dose in patients with moderate to severe croup.

Clinical trial No: NCT01664507, KCT0002318.