of patients attending our Emergency Department (ED) with acute asthma has increased from 3300 patient/year in 1980 to 15364 in 2003. Short acting bronchodilators (albuterol/ipratropium) administered in wet nebulizations, a resource consuming procedure, were our main initial treatment in 2002. To improve treatment goals, we switched the method of bronchodilator delivery to metered dose inhalers (MDI) in 2003. The purpose of this study is to evaluate the impact of this change in the bronchodilator delivery system. We compared 90 patients with acute asthma treated with MDIs in December 2003 with a similar number treated with wet nebulizers in December 2002 matched for sex, age, height, and FEV1 on admission. Treated with MDIs resulted in significant reduction of length of stay in the ED (median 3 vs 4 hs--quartiles 2-4.75 vs. 1-6 hs, p = 0.01) and an increase in the number of discharges in the first 2 hours of treatment (48 vs. 31% p = 0.03). Overall, patients in the MDI's group received 87% of the scheduled bronchodilator doses, while patients in the wet nebulizer's group received only 37% of the prescribed doses. Although there was a trend towards better FEV1 at discharge in the MDI's group, the difference was not statistically significant (78% +/- 17% vs. 73% + 17% p = 0.09). Percentage of patients finally discharged from the ED was similar in both groups (96 vs 94%). Patients treated with bronchodilators delivered by MDI improved faster and had better fulfillment of treatment standards.