Regional ventilation distribution in emphysema and non-emphysema regions affects diffusion capacity in COPD H. Shima (Kyoto, Japan), N. Tanabe (Kyoto, Japan), T. Oguma (Kyoto, Japan), S. Kozawa (Kyoto, Japan), T. Kubo (Kyoto, Japan), K. Togashi (Kyoto, Japan), A. Sato (Kyoto, Japan), S. Sato (Kyoto, Japan), T. Hirai (Kyoto, Japan)
Source: Virtual Congress 2020 – Phenotypes of obstructive diseases
Session: Phenotypes of obstructive diseases Session type: E-poster sessionNumber: 1248
Disease area: Airway diseasesAbstract Background: Impaired lung diffusion capacity is an important prognostic factor that can be assessed as transfer coefficients of carbon monoxide (Kco) on pulmonary function test in COPD. While Kco is closely associated with emphysema severity in the whole lung, it is unclear whether Kco is affected by regional ventilation distribution in emphysema and non-emphysematous region. By using inspiratory and expiratory CT, this study tested a hypothesis that a relative increase in regional ventilation in emphysematous regions compared to that in non-emphysematous regions may be associated with a reduction in Kco in COPD.
Methods: Non-rigid registration of inspiratory and expiratory CT scans was performed to calculate a volume change percentage for each voxel from expiration to inspiration in 80 stable COPD subjects. Emphysema was defined as low attenuation voxels less than -950 HU on inspiratory CT and emphysema severity in the whole lung was assessed as low attenuation volume percent (LAV%). Volume change percentage was averaged for emphysema and non-emphysematous region, separately. Emphysema ventilation ratio (EVR) was defined as a ratio of the mean volume change percentage in emphysema to that in non-emphysematous region.
Results: Kco was significantly associated with LAV% (R=-0.74, p<0.001) and EVR (R=-0.28, p =0.01). In multivariate regression analysis, the increase in EVR was significantly associated with decreased Kco independent of LAV%.
Conclusion: Regional ventilation shift from non-emphysematous to emphysematous regions might be associated with impaired diffusion capacity independent of the whole lung emphysema severity in COPD.
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H. Shima (Kyoto, Japan), N. Tanabe (Kyoto, Japan), T. Oguma (Kyoto, Japan), S. Kozawa (Kyoto, Japan), T. Kubo (Kyoto, Japan), K. Togashi (Kyoto, Japan), A. Sato (Kyoto, Japan), S. Sato (Kyoto, Japan), T. Hirai (Kyoto, Japan). Regional ventilation distribution in emphysema and non-emphysema regions affects diffusion capacity in COPD. 1248
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