Cargando…

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...

Descripción completa

Detalles Bibliográficos
Autores principales: Behnia, Mehrdad, Wheatley, Courtney M, Avolio, Alberto, Johnson, Bruce D
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Dove Medical Press 2017
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
_version_ 1783274480629448704
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
work_keys_str_mv AT behniamehrdad alveolarcapillaryreserveduringexerciseinpatientswithchronicobstructivepulmonarydisease
AT wheatleycourtneym alveolarcapillaryreserveduringexerciseinpatientswithchronicobstructivepulmonarydisease
AT avolioalberto alveolarcapillaryreserveduringexerciseinpatientswithchronicobstructivepulmonarydisease
AT johnsonbruced alveolarcapillaryreserveduringexerciseinpatientswithchronicobstructivepulmonarydisease