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Alveolar–capillary reserve during exercise in patients with chronic obstructive pulmonary disease
BACKGROUND: Factors limiting exercise in patients with COPD are complex. With evidence for accelerated pulmonary vascular aging, destruction of alveolar–capillary bed, and hypoxic pulmonary vasoconstriction, the ability to functionally expand surface area during exercise may become a primary limitat...
Autores principales: | , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
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Dove Medical Press
2017
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5661445/ https://www.ncbi.nlm.nih.gov/pubmed/29123389 http://dx.doi.org/10.2147/COPD.S142523 |
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author | Behnia, Mehrdad Wheatley, Courtney M Avolio, Alberto Johnson, Bruce D |
author_facet | Behnia, Mehrdad Wheatley, Courtney M Avolio, Alberto Johnson, Bruce D |
author_sort | Behnia, Mehrdad |
collection | PubMed |
description | BACKGROUND: Factors limiting exercise in patients with COPD are complex. With evidence for accelerated pulmonary vascular aging, destruction of alveolar–capillary bed, and hypoxic pulmonary vasoconstriction, the ability to functionally expand surface area during exercise may become a primary limitation. PURPOSE: To quantify measures of alveolar–capillary recruitment during exercise and the relationship to exercise capacity in a cohort of COPD patients. METHODS: Thirty-two subjects gave consent (53% male, with mean ± standard deviation age 66±9 years, smoking 35±29 pack-years, and Global Initiative for Chronic Obstructive Lung Disease (GOLD) classification of 0–4: 2.3±0.8), filled out the St George’s Respiratory Questionnaire (SGRQ) to measure quality of life, had a complete blood count drawn, and underwent spirometry. The intrabreath (IB) technique for lung diffusing capacity for carbon monoxide (IBDLCO) and pulmonary blood flow (IBQc, at rest) was also performed. Subsequently, they completed a cycle ergometry test to exhaustion with measures of oxygen saturation and expired gases. RESULTS: Baseline average measures were 44±21 for SGRQ score and 58±11 for FEV(1)/FVC. Peak oxygen consumption (VO(2)) was 11.4±3.1 mL/kg/min (49% predicted). The mean resting IBDLCO was 9.7±5.4 mL/min/mmHg and IBQc was 4.7±0.9 L/min. At the first workload, heart rate (HR) increased to 92±11 bpm, VO(2) was 8.3±1.4 mL/kg/min, and IBDLCO and IBQc increased by 46% and 43%, respectively, compared to resting values (p,0.01). The IBDLCO/Qc ratio averaged 2.0±1.1 at rest and remained constant during exercise with marked variation across subjects (range: 0.8–4.8). Ventilatory efficiency plateaued at 37±5 during exercise, partial pressure of mix expired CO(2)/partial pressure of end tidal CO(2) ratio ranged from 0.63 to 0.67, while a noninvasive index of pulmonary capacitance, O(2) pulse × PetCO(2) (GxCap) rose to 138%. The exercise IBDLCO/Qc ratio was related to O(2) pulse (VO(2)/HR, r=0.58, p<0.01), and subjects with the highest exercise IBDLCO/Qc ratio or the greatest rise from rest had the highest peak VO(2) values (r=0.65 and 0.51, respectively, p<0.05). Of the noninvasive gas exchange measures of pulmonary vascular function, GxCap was most closely associated with DLCO, DLCO/Qc, and VO(2) peak. CONCLUSION: COPD patients who can expand gas exchange surface area as assessed with DLCO during exercise relative to pulmonary blood flow have a more preserved exercise capacity. |
format | Online Article Text |
id | pubmed-5661445 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2017 |
publisher | Dove Medical Press |
record_format | MEDLINE/PubMed |
spelling | pubmed-56614452017-11-09 Alveolar–capillary reserve during exercise in patients with chronic obstructive pulmonary disease Behnia, Mehrdad Wheatley, Courtney M Avolio, Alberto Johnson, Bruce D Int J Chron Obstruct Pulmon Dis Original Research BACKGROUND: Factors limiting exercise in patients with COPD are complex. With evidence for accelerated pulmonary vascular aging, destruction of alveolar–capillary bed, and hypoxic pulmonary vasoconstriction, the ability to functionally expand surface area during exercise may become a primary limitation. PURPOSE: To quantify measures of alveolar–capillary recruitment during exercise and the relationship to exercise capacity in a cohort of COPD patients. METHODS: Thirty-two subjects gave consent (53% male, with mean ± standard deviation age 66±9 years, smoking 35±29 pack-years, and Global Initiative for Chronic Obstructive Lung Disease (GOLD) classification of 0–4: 2.3±0.8), filled out the St George’s Respiratory Questionnaire (SGRQ) to measure quality of life, had a complete blood count drawn, and underwent spirometry. The intrabreath (IB) technique for lung diffusing capacity for carbon monoxide (IBDLCO) and pulmonary blood flow (IBQc, at rest) was also performed. Subsequently, they completed a cycle ergometry test to exhaustion with measures of oxygen saturation and expired gases. RESULTS: Baseline average measures were 44±21 for SGRQ score and 58±11 for FEV(1)/FVC. Peak oxygen consumption (VO(2)) was 11.4±3.1 mL/kg/min (49% predicted). The mean resting IBDLCO was 9.7±5.4 mL/min/mmHg and IBQc was 4.7±0.9 L/min. At the first workload, heart rate (HR) increased to 92±11 bpm, VO(2) was 8.3±1.4 mL/kg/min, and IBDLCO and IBQc increased by 46% and 43%, respectively, compared to resting values (p,0.01). The IBDLCO/Qc ratio averaged 2.0±1.1 at rest and remained constant during exercise with marked variation across subjects (range: 0.8–4.8). Ventilatory efficiency plateaued at 37±5 during exercise, partial pressure of mix expired CO(2)/partial pressure of end tidal CO(2) ratio ranged from 0.63 to 0.67, while a noninvasive index of pulmonary capacitance, O(2) pulse × PetCO(2) (GxCap) rose to 138%. The exercise IBDLCO/Qc ratio was related to O(2) pulse (VO(2)/HR, r=0.58, p<0.01), and subjects with the highest exercise IBDLCO/Qc ratio or the greatest rise from rest had the highest peak VO(2) values (r=0.65 and 0.51, respectively, p<0.05). Of the noninvasive gas exchange measures of pulmonary vascular function, GxCap was most closely associated with DLCO, DLCO/Qc, and VO(2) peak. CONCLUSION: COPD patients who can expand gas exchange surface area as assessed with DLCO during exercise relative to pulmonary blood flow have a more preserved exercise capacity. Dove Medical Press 2017-10-24 /pmc/articles/PMC5661445/ /pubmed/29123389 http://dx.doi.org/10.2147/COPD.S142523 Text en © 2017 Behnia et al. This work is published and licensed by Dove Medical Press Limited The full terms of this license are available at https://www.dovepress.com/terms.php and incorporate the Creative Commons Attribution – Non Commercial (unported, v3.0) License (http://creativecommons.org/licenses/by-nc/3.0/). By accessing the work you hereby accept the Terms. Non-commercial uses of the work are permitted without any further permission from Dove Medical Press Limited, provided the work is properly attributed. |
spellingShingle | Original Research Behnia, Mehrdad Wheatley, Courtney M Avolio, Alberto Johnson, Bruce D Alveolar–capillary reserve during exercise in patients with chronic obstructive pulmonary disease |
title | Alveolar–capillary reserve during exercise in patients with chronic obstructive pulmonary disease |
title_full | Alveolar–capillary reserve during exercise in patients with chronic obstructive pulmonary disease |
title_fullStr | Alveolar–capillary reserve during exercise in patients with chronic obstructive pulmonary disease |
title_full_unstemmed | Alveolar–capillary reserve during exercise in patients with chronic obstructive pulmonary disease |
title_short | Alveolar–capillary reserve during exercise in patients with chronic obstructive pulmonary disease |
title_sort | alveolar–capillary reserve during exercise in patients with chronic obstructive pulmonary disease |
topic | Original Research |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5661445/ https://www.ncbi.nlm.nih.gov/pubmed/29123389 http://dx.doi.org/10.2147/COPD.S142523 |
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