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Small Airway Dysfunction in Asthma and COPD: Consequences for Therapy and the Future

Postma DS, van den Berge M.

RDD Europe 2013. Volume 1, 2013: 1-12.

Abstract:

Asthma and COPD are common respiratory diseases with a large personal and worldwide economic impact. It has become clear that small airways can be affected by inflammation and remodeling in both diseases with both similar and different inflammatory patterns. Small airway dysfunction can be present at all severity stages of asthma and this associates with the severity of airway hyperresponsiveness (AHR), the presence of symptoms and, especially, asthma control. These associations are independent of large airway dysfunction, that are often measured by observing changes in FEV1. In COPD, there is suggestive evidence that small airway changes may precede the development of emphysema and are associated with exacerbations and AHR, particularly in centrilobular emphysema. With respect to treatment, ultrafine particle inhaled corticosteroids (ICS) and their combinations with small particle long-acting beta-agonists (LABA) have been shown to be equally or more effective than their large particle equivalents in asthma. In COPD, only a few studies have compared large and small particle size drugs, but the first results are promising. This review is an attempt to raise awareness of small airways disease and to promote studies aimed at assessing the importance of targeting this part of the lung for specific subtypes of asthma and COPD while continuing the development of simple qualitative and quantitative tools for diagnosing small airway dysfunction.