[Abnormalitis in the distributions of ventilation-perfusion ratios and diffusing capacity-perfusion ratios in three types of chronic obstructive pulmonary disease].
To assess whether diffusion-limited gas exchange plays a significant role in hypoxemia in various types of chronic obstructive pulmonary disease(COPD), we analyzed the distribution of ventilation-perfusion (VA/Q) ratios and of diffusing capacity-perfusion (G/Q) ratios. We compared VA/Q and G/Q distribution in patients with three basic types of COPD: emphysematous changes, bronchiolar involvement, and airway hypersecretion, which were classified based on symptoms and on findings of high-resolution CT. The results were that 1) hypoxemia was not caused by diffusion-limited gas exchange with low G/Q regions in any type of COPD, that 2) hypoxemia was not caused by inhomogeneities in VA/Q distribution, that 3) emphysematous changes and bronchiolar involvement were associated with high and low VA/Q regions, respectively, and that 4) either hypersecretion itself or related airway abnormalities may cause low VA/Q regions to form.
Yamaguchi
K
K
Department of Medicine, School of Medicine, Keio University, Tokyo, Japan.
Mori
M
M
Kawai
A
A
Takasugi
T
T
Koda
E
E
Aoki
T
T
Suzuki
K
K
Miyata
T
T
Nishio
K
K
Suzuki
Y
Y
D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D008173:Lung Diseases, Obstructive / Q000145:classification / Q000000981:diagnostic imaging / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D011653:Pulmonary Diffusing Capacity; D011856:Radiographic Image Enhancement; D014057:Tomography, X-Ray Computed; D014692:Ventilation-Perfusion Ratio