Alveolar­–capillary reserve during exercise in patients with chronic obstructive pulmonary disease
Mehrdad Behnia,1 Courtney M Wheatley,2 Alberto Avolio,3 Bruce D Johnson2 1Division of Critical Care, Florida Hospital, Orlando, FL, 2Division of Cardiovascular Diseases, Mayo Clinic, Scottsdale, AZ, USA; 3Australian School of Advanced Medicine, Faculty of Medicine and Health Sciences, Macquarie Uni...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
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Dove Medical Press
2017-10-01
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| Series: | International Journal of COPD |
| Subjects: | |
| Online Access: | https://www.dovepress.com/alveolar-capillary-reserve-during-exercise-in-patients-with-chronic-ob-peer-reviewed-article-COPD |
| _version_ | 1811254544053567488 |
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| author | Behnia M Wheatley CM Avolio A Johnson BD |
| author_facet | Behnia M Wheatley CM Avolio A Johnson BD |
| author_sort | Behnia M |
| collection | DOAJ |
| description | Mehrdad Behnia,1 Courtney M Wheatley,2 Alberto Avolio,3 Bruce D Johnson2 1Division of Critical Care, Florida Hospital, Orlando, FL, 2Division of Cardiovascular Diseases, Mayo Clinic, Scottsdale, AZ, USA; 3Australian School of Advanced Medicine, Faculty of Medicine and Health Sciences, Macquarie University, Sydney, NSW, Australia 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, exercise intolerance, lung gas transfer, dyspnea, COPD, diffusion capacity, cardiopulmonary exercise testing |
| first_indexed | 2024-04-12T17:08:58Z |
| format | Article |
| id | doaj.art-36cc86a28f0b49b7a429e5342dcf86ed |
| institution | Directory Open Access Journal |
| issn | 1178-2005 |
| language | English |
| last_indexed | 2024-04-12T17:08:58Z |
| publishDate | 2017-10-01 |
| publisher | Dove Medical Press |
| record_format | Article |
| series | International Journal of COPD |
| spelling | doaj.art-36cc86a28f0b49b7a429e5342dcf86ed2022-12-22T03:23:51ZengDove Medical PressInternational Journal of COPD1178-20052017-10-01Volume 123115312235295Alveolar­–capillary reserve during exercise in patients with chronic obstructive pulmonary diseaseBehnia MWheatley CMAvolio AJohnson BDMehrdad Behnia,1 Courtney M Wheatley,2 Alberto Avolio,3 Bruce D Johnson2 1Division of Critical Care, Florida Hospital, Orlando, FL, 2Division of Cardiovascular Diseases, Mayo Clinic, Scottsdale, AZ, USA; 3Australian School of Advanced Medicine, Faculty of Medicine and Health Sciences, Macquarie University, Sydney, NSW, Australia 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, exercise intolerance, lung gas transfer, dyspnea, COPD, diffusion capacity, cardiopulmonary exercise testinghttps://www.dovepress.com/alveolar-capillary-reserve-during-exercise-in-patients-with-chronic-ob-peer-reviewed-article-COPDAirflow limitationExercise intoleranceLung gas transferDyspneaCOPD |
| spellingShingle | Behnia M Wheatley CM Avolio A Johnson BD Alveolar­–capillary reserve during exercise in patients with chronic obstructive pulmonary disease International Journal of COPD Airflow limitation Exercise intolerance Lung gas transfer Dyspnea COPD |
| 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 shy ndash capillary reserve during exercise in patients with chronic obstructive pulmonary disease |
| topic | Airflow limitation Exercise intolerance Lung gas transfer Dyspnea COPD |
| url | https://www.dovepress.com/alveolar-capillary-reserve-during-exercise-in-patients-with-chronic-ob-peer-reviewed-article-COPD |
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