ABSTRACT
BACKGROUND: Exercise-induced bronchoconstriction (EIB), which describes acute airway narrowing that occurs as a result of exercise, is associated with eosinophilic airway inflammation, bronchial hyperresponsiveness. The forced expiratory volume in one second (FEV₁) is the most commonly used spirometric test in the diagnosis of EIB in exercise challenge in asthma. Other parameters such as forced expiratory flow at 50% of the vital capacity (FEF(50%)) and peak expiratory flow (PEF) are used less often in the diagnosis of EIB. OBJECTIVE: The purpose of this study is to evaluate the association of FEV₁ and FEF(50%), PEF parameters, blood eosinophil counts in EIB in children with mild asthma. METHODS: Sixty-seven children (male: 39, female: 28) with mild asthma were included in this study. Pulmonary functions were assessed before and at 1, 5, 10, 15, and 20 minutes after exercise. The values of spirometric FEV₁, FEF50(%), PEF, and blood eosinophil counts were evaluated in EIB in children with mild asthma. RESULTS: There was a positive correlation between FEV₁ with FEF(50%) and PEF values (p < 0.05; FEF(50%), r=0.68; PEF, r=0.65). Also, a positive correlation was found between blood eosinophil counts and the values of spirometric FEV₁, FEF(50%), and PEF (p < 0.05; FEV₁, r=0.54; FEF(50%), r=0.42; PEF, r=0.26). In addition to these correlations, in the exercise negative group for FEV₁, the FEF(50%) and PEF values decreased more than the cutoff values in 3, and 2 patients, respectively. CONCLUSION: According to the presented study, eosinophil may play a major role in the severity of EIB in mild asthma. FEF(50%) and PEF values can decrease in response to exercise without changes in FEV₁ in mild asthmatic patients.