Exhaled nitric oxide and exercise-induced bronchoconstriction in young wheezy children: interactions with atopy

The association between exercise-induced bronchoconstriction (EIB) and exhaled nitric oxide (FENO) has not been investigated in young children with atopic or non-atopic wheeze, two different phenotypes of asthma in the early childhood. Steroid naive 3- to 7-yr-old children with recent wheeze (n = 84) and age-matched control subjects without respiratory symptoms (n = 71) underwent exercise challenge test, measurement of FENO and skin prick testing (SPT). EIB was assessed by using impulse oscillometry, and FENO by standard online technique. Although FENO levels were highest in atopic patients with EIB, both atopic and non-atopic wheezy children with EIB showed higher FENO than atopic and non-atopic control subjects, respectively. In atopic wheezy children, a significant relationship between FENO and the severity of EIB was found (r = 0.44, p = 0.0004), and FENO was significantly predictive of EIB. No clear association between FENO and EIB or predictive value was found in non-atopic wheezy children. Both atopic and non-atopic young wheezy children with EIB show increased FENO levels. However, the association between the severity of EIB and FENO is present and FENO significantly predictive of EIB only in atopic subjects, suggesting different interaction between bronchial responsiveness and airway inflammation in non-atopic wheeze.