Affiliation:
1. Department of Respiratory Medicine, Hokkaido University, Sapporo, Japan
Abstract
The overlap between asthma and chronic obstructive pulmonary disease (COPD) has attracted the interest of pulmonary physicians; thus, measurement of carbon monoxide diffusion capacity (DLco) and/or transfer coefficients (Kco, DLco/VA) may become valuable in clinical settings. How these parameters behave in chronic obstructive lung diseases is poorly understood. We predicted that Kco might more accurately reflect emphysematous changes in the lungs than DLco. We examined DLco and Kco in nonsmokers and smokers with asthma and investigated their relationships with forced expiratory volume in 1 s (%FEV1) by group. We then selected nonsmokers (As-NS) and smokers with asthma (As-Sm) in both groups and those with COPD while controlling for the degree of airflow limitation across groups. Emphysema volumes [%lung attenuation volume (%LAV)] and percentage of cross-sectional area of small pulmonary vessels <5 mm2 (%CSA<5) were measured by computed tomography. In As-NS, %Kco was significantly higher when FEV1% was reduced, but such a correlation was not seen in As-Sm. %Kco successfully differentiated among the three groups when airflow limitation levels were matched. However, %DLc, was significantly reduced only in patients with COPD. Both %LAV and %CSA<5 were better correlated with %Kco than with %DLco. There was discordance between %DLCO and %Kco in As-Sm, which was not seen in As-NS. Overall, %Kco better reflects emphysematous changes in obstructive lung diseases than %DLco. NEW & NOTEWORTHY Despite differing behaviors of %Kco and %DLco in several diseases, the characteristics of these parameters have not been fully examined in smokers with asthma. Here, we demonstrated that %Kco is a more sensitive parameter of pathophysiology, better reflecting emphysematous changes in chronic obstructive lung diseases overall, compared with %DLco. Thus, more precise interpretations of %DLco and %Kco may provide clues for understanding the pathophysiology of obstructive lung diseases.
Funder
tha Ministory of Education, Science, Culture and Sports of Japan
Japan Allergy Fundation
AstraZeneca
Kyorin Phermathutical Co. Ltd.
the Ministory of Health, Labor and Welfare of Japan
Boehringer Ingelheim (Boehringer Ingelheim Pharmaceuticals)
Pfizer
GlaxoSmithKline (GSK)
Novartis
Publisher
American Physiological Society
Subject
Physiology (medical),Physiology
Cited by
11 articles.
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