Ascertainment of small airway 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 <2mm, and are classically difficult to assess and treat in persistent asthma. Small airways dysfunction (SAD) is integral to the asthma management paradigm as it is associated with poorer symptom control, greater levels of type 2 inflammation, and has been proposed as a potential treatable asthma trait. Although identification of SAD by 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; as well as treatment options for SAD.