Impulse Oscillometry Detected Physiological Abnormalities More Frequently Than Spirometry in Children With Largely Preserved Lung Function

AIM: We compared how well impulse oscillometry (IOS) and spirometry detected small airway dysfunction (SAD) in children with asthma and evaluated associations between IOS abnormalities, asthma control, and asthma severity. METHODS: This observational study comprised 106 children aged 6-18 years with asthma who underwent IOS and spirometry before and after bronchodilator administration. We assessed SAD, bronchodilator responsiveness, asthma control using the Global Initiative for Asthma criteria and asthma severity using the Composite Asthma Severity Index. RESULTS: Most children had mild asthma and preserved spirometry. Spirometry and IOS identified abnormalities suggestive of SAD in 10.4% and 37.7% of patients, respectively, and bronchodilator responsiveness in 12.3% and 20.8%, respectively. IOS abnormalities were not associated with asthma control, while only weak associations were observed between selected IOS parameters and asthma severity. Correlations between oscillometric and spirometric indices were significant but weak. CONCLUSION: IOS detected physiological abnormalities more frequently than spirometry in children with largely preserved lung function. However, these additional abnormalities were not associated with current asthma control and only showed weak associations with asthma severity. IOS should be considered a complementary physiological assessment. Longitudinal studies are needed to establish the clinical relevance and prognostic significance of these findings.