Utility of portable spirometry in a pediatric emergency department in children with acute exacerbation of asthma.

OBJECTIVES: The primary purpose of this study was to determine if portable spirometers can be successfully used in an emergency department (ED) in children with an acute exacerbation of asthma. The secondary purpose of this study was to determine if a validated clinical asthma score (CAS) correlates with the spirometry results in children with an acute exacerbation of asthma.

METHODS: Children between the ages of 6 and 17 years who presented to an urban free-standing children's hospital ED with an acute exacerbation of asthma were enrolled in our study. On arrival, the CAS was recorded and then portable spirometry was performed. Attempts were continued until acceptable and reproducible flow loop measurements were obtained or until the patient was unable to perform further attempts. Outcomes included success at spirometry and correlation of spirometry with the CAS.

RESULTS: A total of 101 patients were enrolled in this study. Of those patients, only 35 (35%) were able to successfully perform portable spirometry. Successful spirometry attempts were associated with older age (10.4 vs. 8.9, p = .01), lower respiratory rates (24.8 vs. 30.2, p = .001), lower heart rates (110 vs. 124, p = .004), and lower CASs (8.4 vs. 9.7, p = .001). Increasing asthma severity correlated with a decreased likelihood of successfully obtaining a useful forced expiratory volume in 1 second (FEV(1)) measurement (p = .013). Compared with cases of mild asthma, a patient with moderate asthma is 33% less likely to be able to perform spirometry, and a patient with severe asthma 93% less likely to perform spirometry. The CAS correlated poorly with the more objective measure of FEV(1)% predicted in those with mild asthma.

CONCLUSION: Many children are incapable of using portable spirometry for the evaluation of acute exacerbations of asthma in the ED. The clinical asthma scoring system demonstrated poor correlation with portable spirometry measurements in terms of severity classification.