FEV1 performance among patients with acute asthma: results from a multicenter clinical trial

Abstract

Objective: To determine the ability of patients seen for acute asthma exacerbations in the emergency department (ED) to perform good-quality FEV(1) measurements.

Methods: Investigators from 20 EDs were trained to perform spirometry testing as part of a clinical trial that included standardized equipment with special software-directed prompts. Spirometry was done on ED arrival and 30 min, 1 h, 2 h, and 4 h later, and during follow-up outpatient visits.

Measurements: Study performance criteria differed from American Thoracic Society (ATS) guidelines because of the population acuity and severity of illness as follows: ability to obtain acceptable FEV(1) measures (defined as two or more efforts with forced expiratory times >/= 2 s and time to peak flow < 120 ms or back-extrapolated volume < 5% of the FVC) and reproducibility criteria (two highest acceptable FEV(1) values within 10% of each other).

Results: Of the 620 patients (age range, 12 to 65 years), > 90% met study acceptability criteria on ED arrival and 74% met study reproducibility criteria. Mean initial FEV(1) was 38% of predicted. Spirometry quality improved over time; by 1 h, 90% of patients met study acceptability and reproducibility criteria. Patients with severe airway obstruction (FEV(1) < 25% of predicted) were initially less likely to meet quality goals, but this improved with time. The site was also an independent predictor of quality.

Conclusion: When staff are well trained and prompt feedback regarding adequacy of efforts is given, modified ATS performance goals for FEV(1) tests can be met from most acutely ill adolescent and adult asthmatics, even within the first hour of evaluation and treatment for an asthma exacerbation.