Exhaled Nitric Oxide and Exercise-Induced Bronchospasm Assessed by FEV₁, FEF_{25 − 75%} in Childhood Asthma

Abstract

The relationship between exhaled nitric oxide (eNO) and bronchial hyperresponsiveness (BHR) should be clarified. The aim of this study was to determine the relationship between eNO and exercise-induced bronchospasm (EIB) by estimation of the each lung parameter in asthmatic children who performed a bicycle ergometer exercise test. Twenty children with asthma were recruited. eNO concentration was examined by the recommended online method. To evaluate BHR, an exercise stress test was performed on a bicycle ergometer. The mean baseline eNO value was significantly correlated with the mean maximum % fall in forced expiratory volume in 1 second (FEV₁), forced expiratory flow between 25% and 75% (FEF25-75%) after exercise (r = 0.53, r = 0.65, respectively). eNO in the EIB-positive group was significantly higher than that in the EIB-negative group by assessing FEV₁, FEF_25−75% (p < 0.005, p = 0.005). We demonstrated that the most important lung parameter assessed the occurrence of EIB by a bicycle ergometer exercise test was not only FEV₁ but FEF_25−75%, which significantly correlated with eNO. This suggests that not only FEV₁ but FEF_25−75% can be used to evaluate the correlations between BHR (EIB) and airway inflammation (eNO) in asthmatic children. A low eNO is useful for a negative predictor for EIB.

Keywords:

• bicycle ergometer exercise test
• bronchial hyperresponsiveness
• childhood asthma
• exercise-induced bronchospasm
• exhaled nitric oxide