Ascertainment of Small Airways Dysfunction Using Oscillometry to Better Define Asthma Control and Future Risk: Are We Ready to Implement It in Clinical Practice?

The small airways comprise generations 8 to 23 of the bronchial tree, consist of airways with an internal diameter < 2 mm, and are classically difficult to assess and treat in persistent asthma. Small airways dysfunction (SAD) is integral to the asthma management paradigm because it is associated with poorer symptom control and greater levels of type 2 inflammation, and it has been proposed as a potentially treatable asthma trait. Although identification of SAD based on oscillometry has been found to be clinically useful in managing asthma, very few physicians, including specialists, use this technique as part of standard or adjunct evaluation of lung function to diagnose asthma, grade severity of airway obstruction, ascertain disease control or the risk for future exacerbations, or to make management decisions. To rectify the unrecognized value of oscillometry in the asthma community, a consortium of authors who are investigators with knowledge and experience of oscillometry wished to address the most important clinical questions raised by our colleagues who are considering using this technique, including its clinical utility. In this article, we discuss integral concepts, including applicability of oscillometry as a predictive tool for asthma exacerbations and disease control, adequacy of spirometry and oscillometry in assessing SAD, potential limitations of oscillometry, and treatment options for SAD.