LAUSR

Airways diseases account for most of the burden of respiratory diseases. In Australia, the burden of chronic respiratory diseases is the 3rd highest behind mental and musculoskeletal diseases. Despite the contrasting pathophysiologic mechanisms underlying asthma, COPD, and bronchiolitis, they all have abnormal structure and function of the peripheral (or small) airways. Peripheral airway dysfunction is fundamental to early COPD and is a strong determinant of symptoms, exacerbations and the development of irreversible airflow obstruction in asthma (Hogg et al., 2004; Burgel, 2011). Bronchiolitis following lung transplantation is purely a disease of the peripheral airways. Despite the obvious importance and clinical relevance of peripheral airway function, it has only been able to be measured meaningfully in the last decade thanks to advances in technology that have enabled sophisticated testing methods to be freely available (Petousi et al., 2019; Usmani et al., 2021). Thus, it is now time to make the “leap forward” in managing airways diseases, and to go beyond inhaled corticosteroids and long-acting bronchodilators. Asthma and COPD are not singular diagnoses and as such their management necessitates a personalised medicine approach. This approach has been embraced in most medical specialties that facilitate better assessment of a patient’s disease processes, allowing logical management and improved outcomes. Together with inflammatory phenotyping, physiological phenotyping must now be considered. The tools are accessible and the clinical significance of measurements has increasingly been acknowledged. Comprehensive phenotyping is critical if new treatments beyond inhaled therapy are to be realised, as stated emphatically by the Lancet Commissioners on COPD (Stolz et al., 2022). The papers in this series demonstrate how physiological information complements spirometry, lung volumes and diffusing capacity measurements, and inflammometry. Exhaled gas washout, imaging and oscillometry as measures of lung function have been very well studied. Although oscillometry is somewhat daunting to understand initially, users should soon appreciate the fact that it is a tidal volume breathing test that is sensitive to widespread and heterogeneous peripheral airway narrowing and closure. Ynuk Bossé (2022) describes the underlying principles of oscillometry and how it can be adapted to measure volume-dependent changes, i.e. closing volumes and airway distensibility, that will provide further phenotypic information in airways diseases. Fu et al. demonstrate the use of oscillometry in lung transplant recipients to detect allograft dysfunction earlier, a common OPEN ACCESS