Objective: To evaluate clinical and pulmonary function measurements taken in the first fifteen minutes of the assessment of acute asthma in the emergency room and used for prognostic purposes. Methods: A prospective cohort study involving consecutive patients with acute asthma. Only patients who were between the ages of 12 and 55 and presented peak expiratory flow rates < or = 50% of predicted were included. Evaluations were performed upon admission, then again at 15 minutes and 4 hours after the initiation of treatment. Treatment included albuterol and ipratropium delivered by metered-dose inhaler with a spacer, together with 100 mg of intravenous hydrocortisone. Favorable outcomes were defined as peak expiratory flow > or = 50% of predicted after 4 hours of treatment, and unfavorable outcomes were defined as peak expiratory flow < 50% after 4 hours of treatment. Results: Favorable outcomes were seen in 27 patients, and unfavorable outcomes were seen in 24 patients. In the multivariate analysis, peak expiratory flow as percentage of predicted was identified as the variable with the highest predictive value. A peak expiratory flow > or = 40% after 15 minutes of treatment showed significant power in predicting a favorable outcome (sensitivity = 0.74, specificity = 1.00, and positive predictive value = 1.00). A peak expiratory flow < 30% after 15 minutes of treatment was predictive of a poor outcome (sensitivity = 0.54, specificity = 0.93, and positive predictive value = 0.87). Conclusion: Our results suggest that measuring peak expiratory flow after 15 minutes of management in the emergency room is a useful tool for predicting outcomes in cases of acute asthma.

Keywords: Asthma; Acute disease; Respiratory mechanics; Prognosis; Emergency Service, Hospital; Cohort studies