Effects of inhaled metaproterenol and atropine on the pulmonary mechanics of infants with bronchopulmonary dysplasia.

We evaluated the individual and combined effects of an inhaled beta-adrenergic agent (metaproterenol) and an inhaled anticholinergic agent (atropine) on the pulmonary function of infants with bronchopulmonary dysplasia. In this randomized, double-blind study we studied 15 infants at a mean postnatal age of 15.8 weeks (range 4-28 weeks). On 4 successive days, pulmonary function tests were measured before and after a single treatment with one of the following four aerosols: placebo, metaproterenol, atropine, and combined metaproterenol and atropine. Following treatment with metaproterenol, atropine, and combined metaproterenol and atropine, airway resistance and maximal expiratory flow at functional residual capacity improved significantly when compared with baseline. Pulmonary function values returned toward baseline by 3 hours after the treatments. We found no significant differences between the effects of metaproterenol and atropine and were unable to show any synergy of the two agents.