Aerosolized metaproterenol in the treatment of asthmatics with severe airflow obstruction. Comparison of two delivery methods.

The bronchodilator response to metaproterenol delivered by metered-dose inhaler (MDI) with a spacer device (Aerochamber [A]) and by jet nebulizer was studied in 44 asthmatic patients who presented to the emergency department with acute severe (FEV1 less than 50 percent predicted) airflow obstruction. The delivery method was randomized, double-blinded and placebo controlled. The A group received one puff of metaproterenol every five minutes for a total of three puffs (1.95 mg). The jet nebulizer group received 15 mg of metaproterenol by continuous nebulization over ten minutes. Only about 2.75 mg of the original 15 mg delivered by jet nebulizer was calculated to be available for inhalation due to the inefficiencies of the delivery system. The mean percentage of improvement in FVC and FEV1 in the A group was 33.5 and 49.0 percent, respectively. The mean percentage of improvement in FVC and FEV1 in the jet nebulizer group was 22.8 and 33.0 percent, respectively. There was no significant difference in the mean percentage of improvement values between the two groups. We were unable to demonstrate a difference in bronchodilator response to metaproterenol delivered by MDI-A and jet nebulizer in emergency department asthmatics with acute severe airflow obstruction.