Small Airways Disease in Patients With COPD: A Question-and-Answer Approach for Everyday Clinical Practice

Small airways are recognized as the main site of disease progression and airflow limitation in patients with COPD. Whereas conventional lung function testing, for example spirometry, is nonspecific to small airways disease (SAD), the advent and wider availability of techniques sensitive to SAD, such as oscillometry, has improved our understanding of the clinical importance of small airways dysfunction. Despite this progress, a gap between the recent advances in knowledge of SAD and its implementation in daily clinical practice remains. We aimed to answer key questions that would allow practitioners (eg, family doctors, internists, pulmonologists) to introduce oscillometry into their clinical practice.

COPD pathogenesis is characterized by SAD, with an increasing prevalence with more advanced disease. Evaluation of small airways dysfunction with sensitive techniques (eg, oscillometry, nitrogen washout) contributes to early disease detection and plays a significant role in almost every aspect of disease assessment, including confirmation of diagnosis, functional severity grading, and monitoring of lung function decline. Moreover, small airways dysfunction shows equivalent or even better correlation with patient-reported outcomes, including symptoms, quality of life, and exacerbations, compared with conventional lung function testing. This suggests a role for small airways assessment as a treatable trait in COPD to target and monitor therapeutic interventions.

Accumulating evidence and recent advances have delineated the role of small airways assessment in COPD and warrant its implementation in the management plan of patients with COPD in daily clinical practice.