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Shimizu K, Kimura H, Tanabe N, Chubachi S, Sato S, Suzuki M, Tanimura K, Iijima H, Oguma A, Ito YM, Wakazono N, Takimoto-Sato M, Matsumoto-Sasaki M, Abe Y, Takei N, Makita H, Nishimura M, Konno S. Relationships of computed tomography-based small vessel indices of the lungs with ventilation heterogeneity and high transfer coefficients in non-smokers with asthma. Front Physiol 2023; 14:1137603. [PMID: 36935740 PMCID: PMC10014854 DOI: 10.3389/fphys.2023.1137603] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2023] [Accepted: 02/17/2023] [Indexed: 03/05/2023] Open
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 <5 mm2 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.
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Affiliation(s)
- Kaoruko Shimizu
- Department of Respiratory Medicine, Faculty of Medicine, Hokkaido University, Sapporo, Japan
- *Correspondence: Kaoruko Shimizu,
| | - Hirokazu Kimura
- Department of Respiratory Medicine, Faculty of Medicine, Hokkaido University, Sapporo, Japan
| | - Naoya Tanabe
- Department of Respiratory Medicine, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Shotaro Chubachi
- Department of Medicine, Division of Pulmonary Medicine, Keio University School of Medicine, Tokyo, Japan
| | - Susumu Sato
- Department of Respiratory Medicine, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Masaru Suzuki
- Department of Respiratory Medicine, Faculty of Medicine, Hokkaido University, Sapporo, Japan
| | - Kazuya Tanimura
- Department of Respiratory Medicine, Nara Medical University, Kashihara, Japan
| | - Hiroaki Iijima
- Department of Respiratory Medicine, Tsukuba Medical Center Hospital, Tsukuba, Japan
| | - Akira Oguma
- Department of Respiratory Medicine, Faculty of Medicine, Hokkaido University, Sapporo, Japan
| | - Yoichi M. Ito
- Data Science Center, Promotion Unit, Institute of Health Science Innovation for Medical Care, Hokkaido University Hospital, Sapporo, Japan
| | - Nobuyasu Wakazono
- Department of Respiratory Medicine, Faculty of Medicine, Hokkaido University, Sapporo, Japan
| | - Michiko Takimoto-Sato
- Department of Respiratory Medicine, Faculty of Medicine, Hokkaido University, Sapporo, Japan
| | | | - Yuki Abe
- Department of Respiratory Medicine, Faculty of Medicine, Hokkaido University, Sapporo, Japan
| | - Nozomu Takei
- Department of Respiratory Medicine, Faculty of Medicine, Hokkaido University, Sapporo, Japan
| | - Hironi Makita
- Department of Respiratory Medicine, Faculty of Medicine, Hokkaido University, Sapporo, Japan
- Hokkaido Medical Research Institute for Respiratory Diseases, Sapporo, Japan
| | - Masaharu Nishimura
- Department of Respiratory Medicine, Faculty of Medicine, Hokkaido University, Sapporo, Japan
- Hokkaido Medical Research Institute for Respiratory Diseases, Sapporo, Japan
| | - Satoshi Konno
- Department of Respiratory Medicine, Faculty of Medicine, Hokkaido University, Sapporo, Japan
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