Alveolar-Capillary reserve during exercise in patients with chronic obstructive pulmonary disease

Mehrdad Behnia, Courtney M. Wheatley, Alberto Avolio, Bruce David Johnson

Research output: Contribution to journalArticle

3 Citations (Scopus)

Abstract

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 FEV1/FVC. Peak oxygen consumption (VO2) 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, VO2 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 CO2/partial pressure of end tidal CO2 ratio ranged from 0.63 to 0.67, while a noninvasive index of pulmonary capacitance, O2 pulse × PetCO2 (GxCap) rose to 138%. The exercise IBDLCO/Qc ratio was related to O2 pulse (VO2/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 VO2 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 VO2 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.

Original languageEnglish (US)
Pages (from-to)3115-3122
Number of pages8
JournalInternational Journal of COPD
Volume12
DOIs
StatePublished - Oct 24 2017

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Chronic Obstructive Pulmonary Disease
Exercise
Lung
Partial Pressure
Blood Vessels
Heart Rate
Gases
Pulmonary Gas Exchange
Lung Volume Measurements
Ergometry
Aptitude
Blood Cell Count
Spirometry
Carbon Monoxide
Vasoconstriction
Workload
Oxygen Consumption
Smoking
Quality of Life
Oxygen

Keywords

  • Airflow limitation
  • Cardiopulmonary exercise testing
  • COPD
  • Diffusion capacity
  • Dyspnea
  • Exercise intolerance
  • Lung gas transfer

ASJC Scopus subject areas

  • Pulmonary and Respiratory Medicine
  • Health Policy
  • Public Health, Environmental and Occupational Health

Cite this

Alveolar-Capillary reserve during exercise in patients with chronic obstructive pulmonary disease. / Behnia, Mehrdad; Wheatley, Courtney M.; Avolio, Alberto; Johnson, Bruce David.

In: International Journal of COPD, Vol. 12, 24.10.2017, p. 3115-3122.

Research output: Contribution to journalArticle

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title = "Alveolar-Capillary reserve during exercise in patients with chronic obstructive pulmonary disease",
abstract = "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 FEV1/FVC. Peak oxygen consumption (VO2) 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, VO2 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 CO2/partial pressure of end tidal CO2 ratio ranged from 0.63 to 0.67, while a noninvasive index of pulmonary capacitance, O2 pulse × PetCO2 (GxCap) rose to 138{\%}. The exercise IBDLCO/Qc ratio was related to O2 pulse (VO2/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 VO2 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 VO2 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.",
keywords = "Airflow limitation, Cardiopulmonary exercise testing, COPD, Diffusion capacity, Dyspnea, Exercise intolerance, Lung gas transfer",
author = "Mehrdad Behnia and Wheatley, {Courtney M.} and Alberto Avolio and Johnson, {Bruce David}",
year = "2017",
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AU - Behnia, Mehrdad

AU - Wheatley, Courtney M.

AU - Avolio, Alberto

AU - Johnson, Bruce David

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Y1 - 2017/10/24

N2 - 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 FEV1/FVC. Peak oxygen consumption (VO2) 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, VO2 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 CO2/partial pressure of end tidal CO2 ratio ranged from 0.63 to 0.67, while a noninvasive index of pulmonary capacitance, O2 pulse × PetCO2 (GxCap) rose to 138%. The exercise IBDLCO/Qc ratio was related to O2 pulse (VO2/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 VO2 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 VO2 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.

AB - 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 FEV1/FVC. Peak oxygen consumption (VO2) 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, VO2 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 CO2/partial pressure of end tidal CO2 ratio ranged from 0.63 to 0.67, while a noninvasive index of pulmonary capacitance, O2 pulse × PetCO2 (GxCap) rose to 138%. The exercise IBDLCO/Qc ratio was related to O2 pulse (VO2/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 VO2 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 VO2 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.

KW - Airflow limitation

KW - Cardiopulmonary exercise testing

KW - COPD

KW - Diffusion capacity

KW - Dyspnea

KW - Exercise intolerance

KW - Lung gas transfer

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