Fractional exhaled nitric oxide (FENO), lung function and airway hyperresponsiveness in naive atopic asthmatic children

Background. Measurement of fractional exhaled nitric oxide (FENO) is a noninvasive, simple, well-tolerated, and reproducible marker of airway inflammation. Asthmatic children with normal respiratory function could be affected by airway inflammation. The aim of this study was to assess the correlation between FENO and bronchial hyperesponsiveness (BHR) to methacholine, and between FENO and lung function in atopic children with intermittent asthma. Methods. Thirty-seven children (21 male), aged 7.2-14.4 years (median: 10.9 years), suffering from mild intermittent atopic asthma with a physician-diagnosed history of wheezing and/or chest tightness were studied. None had taken anti-asthmatic therapy for at least three months before the study. No child had symptoms of respiratory tract infection in the month before the study. All subjects underwent FENO measurement, pulmonary function testing and the methacholine provocation tests. Results. The mean percentages of FEV1 and FEF25-27 were 91.9 +/- 10.5 and 88.3 +/- 11.8, respectively. The mean FENO was 62.2 +/- 39.2 ppb and PC20 methacholine was 0.93 mg/ml +/- 0.54. Significant correlations were identified between FENO and FEV1 (p < 0.0059, r = 0.468) and between FENO and FEF25-75 (p < 0.0098, r = 0.439). There was no correlation between FENO and logPC20 (p = 0.14). Conclusions. A single FENO measurement is probably of scarce prognostic and predictive value and it is not surprising to find discordance with BHR. We suggest that FENO measurement could represent a good marker of airway inflammation also in naive atopic children with intermittent asthma. Repeated measurements over time are probably necessary to understand better the clinical implications of the data obtained in this study.