Exercise-induced bronchoconstriction diagnosis in asthmatic children: comparison of treadmill running and eucapnic voluntary hyperventilation challenges.

ABSTRACT

BACKGROUND: Exercise-induced bronchoconstriction (EIB) occurs in up to 90% of young people with asthma and can be diagnosed using serial measurements of forced expiratory volume in 1 second (FEV1) after standardized exercise, usually treadmill running (TR). Eucapnic voluntary hyperventilation (EVH) is a guideline-recommended alternative challenge for EIB diagnosis. The 2 methods have not been compared for EIB diagnosis in this population. OBJECTIVE: To compare 2 methods of EIB diagnosis in children and adolescents with asthma. METHODS: Thirty-four children 8 to 18 years of age attending the allergy clinic of the Hospital das Clínicas (Recife, Brazil) from September through December 2013 were examined. All underwent a basal FEV1 determination followed by TR for 8 minutes or EVH for 6 minutes on consecutive days. The first challenge was chosen at random. Serial FEV1 determinations were obtained at 3, 5, 7, 10, 15, and 30 minutes after the challenge and the test result was considered positive if at least 2 consecutive FEV1 measurements decreased at least 10% below the basal value. RESULTS: Thirteen patients responded to the 2 challenges, 6 only after TR and 4 exclusively after EVH (agreement 71%, κ = 0.41). The 95% limits of agreement of FEV1 decreasing after the challenges were widely spread (mean 0.1%, limits 19.8% to -19.6%). CONCLUSION: The 2 tests cannot be used interchangeably and the reproducibility of the FEV1 response to the EVH challenge has to be properly evaluated to better understand its role in EIB diagnosis.