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Updated: Jul 1, 2026
Conducting Respiratory Oscillometry in an Outpatient Setting
Published on: April 8, 2022
Impulse oscillometry with quantitative computed tomography provides additional clinical information beyond spirometry
Gyuri Kim1, Hyonsoo Joo2, Hyeon-Kyoung Koo3
1School of Mechanical Engineering & Research Institute of Engineering Design & Technology (IEDT), Kyungpook National University, Daegu, Republic of Korea.
Background:
Conventional spirometric indices such as forced expiratory volume in 1 second (FEV1), forced vital capacity (FVC), and its ratio, FEV1/FVC, are commonly used to assess functional alterations in lungs. Quantitative computed tomography (qCT) and impulse oscillometry (IOS) provide additional insights on the traditional metrics. This study aims to investigate the interrelationship among spirometric, oscillometric, and qCT measures in subjects with varying pulmonary function.
Methods:
Sixty-four subjects with variable pulmonary functions were recruited and stratified into four sub-groups (G1-G4) based on spirometric severity defined by FVC and FEV1/FVC. The qCTs at full inspiration and normal expiration enable image registration-based metrics, including the determinant of the Jacobian (Jacobian), the anisotropic deformation index (ADI), and functional small airway disease (fSAD%). We also obtained IOS metrics to measure reactance (X5 through X20), resonant frequency (fres) and reactance area (AX) for respective subjects.
Results:
IOS-based reactances at 10 and 15 Hz (X10 and X15) were significantly more negative in groups with reduced FVC (G2 and 4) than in those with preserved FVC (G1 and 3), whereas resistances did not differ significantly between the sub-groups. The Jacobian and ADI were predominantly decreased in Groups 2 and 4 with FVC<80%. fSAD% was predominantly increased in Groups 3 and 4 with FEV1/FVC<70%. In particular, the X10 was most significantly correlated with Jacobian in the left and right lower lobes.
Conclusion:
The IOS-based reactances with low frequency were significantly associated with spirometry-pulmonary function and CT-based parenchymal lung function metrics. This finding suggests that a combined approach using IOS and CT can provide a better understanding of parenchymal alterations than spirometry alone.
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