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- Title
Relationships of computed tomography-based small vessel indices of the lungs with ventilation heterogeneity and high transfer coefficients in non-smokers with asthma.
- Authors
Kaoruko Shimizu; Hirokazu Kimura; Naoya Tanabe; Shotaro Chubachi; Susumu Sato; Masaru Suzuki; Kazuya Tanimura; Hiroaki Iijima; Akira Oguma; Yoichi M. Ito; Nobuyasu Wakazono; Michiko Takimoto-Sato; Machiko Matsumoto-Sasaki; Yuki Abe; Nozomu Takei; Hironi Makita; Masaharu Nishimura; Satoshi Konno; Hi-CARAT investigators
- Abstract
Background: The mechanism of high transfer coefficients of the lungs for carbon monoxide (Kco) in non-smokers with asthma is explained by the redistribution of blood flow to the area with preserved ventilation, to match the ventilation perfusion. Objectives: To examine whether ventilation heterogeneity, assessed by pulmonary function tests, is associated with computed tomography (CT)-based vascular indices and Kco in patients with asthma. Methods: Participants were enrolled from the Hokkaido-based Investigative Cohort Analysis for Refractory Asthma (Hi-CARAT) study that included a prospective asthmatic cohort. Pulmonary function tests including Kco, using single breath methods; total lung capacity (TLC), using multiple breath methods; and CT, were performed on the same day. The ratio of the lung volume assessed using single breath methods (alveolar volume; VA) to that using multiple breath methods (TLC) was calculated as an index of ventilation heterogeneity. The volume of the pulmonary small vessels <5mm2 in the whole lung (BV5 volume), and number of BV5 at a theoretical surface area of the lungs from the plural surface (BV5 number) were evaluated using chest CT images. Results: The low VA/TLC group (the lowest quartile) had significantly lower BV5 number, BV5 volume, higher BV5 volume/BV5 number, and higher Kco compared to the high VA/TLC group (the highest quartile) in 117 non-smokers, but not in 67 smokers. Multivariable analysis showed that low VA/TLC was associated with low BV5 number, after adjusting for age, sex, weight, lung volume on CT, and CT emphysema index in non-smokers (not in smokers). Conclusion: Ventilation heterogeneity may be associated with low BV5 number and high Kco in non-smokers (not in smokers). Future studies need to determine the dynamic regional system in ventilation, perfusion, and diffusion in asthma.
- Subjects
VENTILATION; NON-smokers; LUNGS; PULMONARY function tests; COMPUTED tomography
- Publication
Frontiers in Physiology, 2023, Vol 14, p1
- ISSN
1664-042X
- Publication type
Article
- DOI
10.3389/fphys.2023.1137603