[Importance of the distal airway in COPD].

Chronic obstructive pulmonary disease (COPD) is characterized by inflammation causing airflow obstruction. However, the initial histological lesion of COPD occurs in the respiratory bronchiole and spirometry is unable to detect involvement of this area until the disease is advanced. Major advances have been made in characterizing the inflammatory process in the small airways. However, in clinical practice, a non-invasive marker of small airways involvement, which would allow injury and the effect of treatment to be monitored, is lacking. To date, the combination of bronchodilators and inhaled corticosteroids is recommended for the most severe cases, although the effects of this therapeutic option on the small airways are not well known. New treatments that reach the distal airways and novel techniques to assess the small airways will allow a more complete approach to this disease.