Small airway dysfunction in asthma based on oscillometry

Dear Editor, Small airway dysfunction (SAD) has long been an issue in the pathophysiology and management of asthma. The large ATLANTIS study revealed that the difference between respiratory system resistance at 5 Hz and 20 Hz (R5-R20), respiratory system reactance at 5 Hz (*5), and low-frequency reactance area (AX) were all strong contributors to SAD and were associated with control, severity, exacerbations, and quality of life in asthma. However, since the study was based on the reference values of western countries by using Impulse Oscillometry (IOS) with greater reactance values than MostGraph, the significance of SAD in Japanese asthma patients is unknown. In this study, we assessed the clinical characteristics of such patients with SAD based on the Japanese reference values of MostGraph.