TY - JOUR
T1 - Transfer coefficients better reflect emphysematous changes than carbon monoxide diffusing capacity in obstructive lung diseases
AU - Shimizu, Kaoruko
AU - Konno, Satoshi
AU - Makita, Hironi
AU - Kimura, Hirokazu
AU - Kimura, Hiroki
AU - Suzuki, Masaru
AU - Nishimura, Masaharu
N1 - Funding Information:
The Hokkaido-based Investigative Cohort Analysis for Refractory Asthma (Hi-CARAT) Study was supported by the Ministry of Education, Science, Culture, and Sports of Japan scientific Research Grants 21390253 and 24249049 (M. Nishimura), the Japan Allergy Foundation, AstraZeneca K.K., KYORIN Pharmaceutical, and a grant to the Respiratory Failure Research Group from the Ministry of Health, Labor, and Welfare, Japan. The Hokkaido COPD cohort study is supported by a scientific research grant to the Hokkaido COPD Cohort Study from the Ministry of Education, Science, Culture and Sports of Japan (17390239 and 2139053 to M. Nishimura), Nippon Boehringer Ingelheim, Pfizer, and a grant to the Respiratory Failure Research Group from the Ministry of Health, Labor, and Welfare, Japan.
Publisher Copyright:
Copyright © 2018 American Physiological Society. All rights reserved.
PY - 2018/7
Y1 - 2018/7
N2 - 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 (%CSA5) 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 %CSA5 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.
AB - 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 (%CSA5) 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 %CSA5 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.
KW - Carbon monoxide diffusion capacity
KW - Emphysema
KW - Small vessels in the lungs
KW - Transfer coefficients
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U2 - 10.1152/japplphysiol.01062.2017
DO - 10.1152/japplphysiol.01062.2017
M3 - Article
C2 - 29648520
AN - SCOPUS:85051082964
SN - 8750-7587
VL - 125
SP - 183
EP - 189
JO - Journal of Applied Physiology
JF - Journal of Applied Physiology
IS - 1
ER -