Résumé
Poor asthma control and recurrent exacerbations have been shown to be a phenotypic counterpart of asthma with predominantly small-airway involvement.1 Biomarkers are not always accurate in asthmatic patients, especially in serum, because compartmentalization can occur between the blood and airways. Blood eosinophil counts do not represent an overall view of airway inflammation, and exhaled nitric oxide measurements at different flow rates (fraction of exhaled nitric oxide [Feno] and alveolar nitric oxide [Calvno]) have been developed and validated to reflect more accurately proximal and distal airway inflammation.2Club cell secretory protein (CCSP) serum concentration has been shown to be associated with chronic obstructive pulmonary disease, bronchiolitis obliterans syndrome, and sarcoidosis, which are all predominantly diseases involving the small airways. Ranges of CCSP concentrations in healthy subjects, reproducibility, and relationships between serum and airway levels are known and can be used as potential surrogate markers. Our aim was to assess small-airway disease in asthmatic patients and to find a related biomarker. We used a dynamic assessment of gas trapping using computed tomographic (CT) imaging of the chest during methacholine challenge as a marker of small-airway disease.