The usefulness of impulse oscillometry for predicting the severity of bronchiectasis

Abstract Background: Bronchiectasis is a chronic respiratory disease that leads to airway inflammation, destruction, and airflow limitation, which reflects its severity. Impulse oscillometry (IOS) is a non-invasive method that uses sound waves to estimate lung function and airway resistance. The aim of this study was to assess the usefulness of IOS in predicting the severity of bronchiectasis. Methods: We retrospectively reviewed the IOS parameters, clinical characteristics, and results of other examinations in 145 patients diagnosed with bronchiectasis between March 2020 and May 2021. Disease severity was evaluated using the FACED score, and patients were divided into mild and moderate/severe groups. Results: Forty-four patients (30.3%) were in the moderate/severe group, and 101 (69.7%) were in the mild group. The mean predicted forced expiratory volume in one second was 78.0% in the mild group and 54.5% in the moderate/severe group. Patients with moderate/severe bronchiectasis had a higher airway resistance at 5 Hz (R5) (0.53 vs. 0.41, p <0.001), a higher difference between the resistance at 5 and 20 Hz (R5 − R20; 39.85 vs. 26.81, p <0.001), a higher resonant frequency (Fres) (22.52 vs. 17.54, p <0.001), and a higher reactance area (AX) (2.44 vs. 1.06, p <0.001) than patients with mild bronchiectasis. R5 ≥0.43, R20 ≥0.234, R5 − R20 ≥28.3, AX ≥1.02, reactance at 5 Hz (X5) ≤−0.238, and Fres ≥20.88 revealed significant univariable relationships with bronchiectasis severity ( p -values <0.05). Among these, only X5 ≤−0.238 exhibited a significant multivariable relationship with bronchiectasis severity ( p = 0.039). The receiver operating characteristic curve for the severity of bronchiectasis based on IOS parameters exhibited an area under the curve of 0.809. Conclusions: The IOS parameters can effectively reflect airway resistance and elasticity in patients with bronchiectasis and serve as valuable tools for predicting bronchiectasis severity.