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Understanding the contribution of native tracheobronchial structure to lung function: CT assessment of airway morphology in never smokers

BACKGROUND: Computed tomographic (CT) airway lumen narrowing is associated with lower lung function. Although volumetric CT measures of airways (wall volume [WV] and lumen volume [LV]) compared to cross sectional measures can more accurately reflect bronchial morphology, data of their use in never s...

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Autores principales: Diaz, Alejandro A, Rahaghi, Farbod N, Ross, James C, Harmouche, Rola, Tschirren, Juerg, San José Estépar, Raul, Washko, George R
Formato: Online Artículo Texto
Lenguaje:English
Publicado: BioMed Central 2015
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4335784/
https://www.ncbi.nlm.nih.gov/pubmed/25848985
http://dx.doi.org/10.1186/s12931-015-0181-y
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author Diaz, Alejandro A
Rahaghi, Farbod N
Ross, James C
Harmouche, Rola
Tschirren, Juerg
San José Estépar, Raul
Washko, George R
author_facet Diaz, Alejandro A
Rahaghi, Farbod N
Ross, James C
Harmouche, Rola
Tschirren, Juerg
San José Estépar, Raul
Washko, George R
author_sort Diaz, Alejandro A
collection PubMed
description BACKGROUND: Computed tomographic (CT) airway lumen narrowing is associated with lower lung function. Although volumetric CT measures of airways (wall volume [WV] and lumen volume [LV]) compared to cross sectional measures can more accurately reflect bronchial morphology, data of their use in never smokers is scarce. We hypothesize that native tracheobronchial tree morphology as assessed by volumetric CT metrics play a significant role in determining lung function in normal subjects. We aimed to assess the relationships between airway size, the projected branching generation number (BGN) to reach airways of <2mm lumen diameter –the site for airflow obstruction in smokers- and measures of lung function including forced expiratory volume in 1 second (FEV(1)) and forced expiratory flow between 25% and 75% of vital capacity (FEF 25–75). METHODS: We assessed WV and LV of segmental and subsegmental airways from six bronchial paths as well as lung volume on CT scans from 106 never smokers. We calculated the lumen area ratio of the subsegmental to segmental airways and estimated the projected BGN to reach a <2mm-lumen-diameter airway assuming a dichotomized tracheobronchial tree model. Regression analysis was used to assess the relationships between airway size, BGN, FEF 25–75, and FEV(1). RESULTS: We found that in models adjusted for demographics, LV and WV of segmental and subsegmental airways were directly related to FEV(1) (P <0.05 for all the models). In adjusted models for age, sex, race, LV and lung volume or height, the projected BGN was directly associated with FEF 25–75 and FEV(1) (P = 0.001) where subjects with lower FEV(1) had fewer calculated branch generations between the subsegmental bronchus and small airways. There was no association between airway lumen area ratio and lung volume. CONCLUSION: We conclude that in never smokers, those with smaller central airways had lower airflow and those with lower airflow had less parallel airway pathways independent of lung size. These findings suggest that variability in the structure of the tracheobronchial tree may influence the risk of developing clinically relevant smoking related airway obstruction. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s12931-015-0181-y) contains supplementary material, which is available to authorized users.
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spelling pubmed-43357842015-02-21 Understanding the contribution of native tracheobronchial structure to lung function: CT assessment of airway morphology in never smokers Diaz, Alejandro A Rahaghi, Farbod N Ross, James C Harmouche, Rola Tschirren, Juerg San José Estépar, Raul Washko, George R Respir Res Research BACKGROUND: Computed tomographic (CT) airway lumen narrowing is associated with lower lung function. Although volumetric CT measures of airways (wall volume [WV] and lumen volume [LV]) compared to cross sectional measures can more accurately reflect bronchial morphology, data of their use in never smokers is scarce. We hypothesize that native tracheobronchial tree morphology as assessed by volumetric CT metrics play a significant role in determining lung function in normal subjects. We aimed to assess the relationships between airway size, the projected branching generation number (BGN) to reach airways of <2mm lumen diameter –the site for airflow obstruction in smokers- and measures of lung function including forced expiratory volume in 1 second (FEV(1)) and forced expiratory flow between 25% and 75% of vital capacity (FEF 25–75). METHODS: We assessed WV and LV of segmental and subsegmental airways from six bronchial paths as well as lung volume on CT scans from 106 never smokers. We calculated the lumen area ratio of the subsegmental to segmental airways and estimated the projected BGN to reach a <2mm-lumen-diameter airway assuming a dichotomized tracheobronchial tree model. Regression analysis was used to assess the relationships between airway size, BGN, FEF 25–75, and FEV(1). RESULTS: We found that in models adjusted for demographics, LV and WV of segmental and subsegmental airways were directly related to FEV(1) (P <0.05 for all the models). In adjusted models for age, sex, race, LV and lung volume or height, the projected BGN was directly associated with FEF 25–75 and FEV(1) (P = 0.001) where subjects with lower FEV(1) had fewer calculated branch generations between the subsegmental bronchus and small airways. There was no association between airway lumen area ratio and lung volume. CONCLUSION: We conclude that in never smokers, those with smaller central airways had lower airflow and those with lower airflow had less parallel airway pathways independent of lung size. These findings suggest that variability in the structure of the tracheobronchial tree may influence the risk of developing clinically relevant smoking related airway obstruction. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s12931-015-0181-y) contains supplementary material, which is available to authorized users. BioMed Central 2015-02-14 2015 /pmc/articles/PMC4335784/ /pubmed/25848985 http://dx.doi.org/10.1186/s12931-015-0181-y Text en © Diaz et al.; licensee BioMed Central. 2015 This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.
spellingShingle Research
Diaz, Alejandro A
Rahaghi, Farbod N
Ross, James C
Harmouche, Rola
Tschirren, Juerg
San José Estépar, Raul
Washko, George R
Understanding the contribution of native tracheobronchial structure to lung function: CT assessment of airway morphology in never smokers
title Understanding the contribution of native tracheobronchial structure to lung function: CT assessment of airway morphology in never smokers
title_full Understanding the contribution of native tracheobronchial structure to lung function: CT assessment of airway morphology in never smokers
title_fullStr Understanding the contribution of native tracheobronchial structure to lung function: CT assessment of airway morphology in never smokers
title_full_unstemmed Understanding the contribution of native tracheobronchial structure to lung function: CT assessment of airway morphology in never smokers
title_short Understanding the contribution of native tracheobronchial structure to lung function: CT assessment of airway morphology in never smokers
title_sort understanding the contribution of native tracheobronchial structure to lung function: ct assessment of airway morphology in never smokers
topic Research
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4335784/
https://www.ncbi.nlm.nih.gov/pubmed/25848985
http://dx.doi.org/10.1186/s12931-015-0181-y
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