Inuvair® is a novel fixed combination product used in the treatment of asthma and under clinical development for the treatment of COPD. Thanks to the extrafine particle size, it is able to target the whole bronchial tree, including the small airways and hence, is expected to act in these airways and it may thus be beneficial in COPD in that sense. In COPD, its action on the small airways is not directly demonstrated thus far. By way of contrast, dear evidence is present that treatment with bronchodilators alone does not beneficially alter small airway function. The study hypothesis states that the effects of inhaled corticosteroids or ICS/LABA combinations on small airway is present and can be objectivated.