Pulmonary Gas Exchange Abnormalities in Patients With Mild COPD

Study Overview
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Brief Summary
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People with mild chronic obstructive pulmonary disease (COPD) can have significant physiological abnormalities and breathing inefficiency which become more pronounced during the stress of exercise, leading to intolerable breathing discomfort (dyspnea). To better understand the mechanisms of respiratory symptoms and exercise limitation in mild COPD, we will examine detailed lung function tests and other important measurements during rest and exercise in people with mild COPD compared with healthy non-smokers. This will be the first study to uncover the fundamental causes of breathing inefficiency and the related shortness of breath during physical exertion in patients with mild COPD. We hope to demonstrate that one simple measurement during exercise [the relation (ratio) between the total amount of air breathed (ventilation) and the amount of carbon dioxide breathed out] gives meaningful information about the extent of damage to the small airways and blood vessels in mild COPD and the overall gas exchanging function of the lungs, without the need for an arterial blood sample. This is a case-controlled observational study not involving an intervention. Participants will complete 2 visits approximately 1 week apart, each conducted at the same time of day. Visit 1 will consiste of screening for iligibility, symptom and activity assessments, pulmonary function tests and an incremental cycle cardiopulmonary exercise test (CPET) for familiarization purposes. Visit 2 will include spirometry followed by an incremental cycle CPET with detailed measures of ventilatory, gas exchange, sensory-perceptual and arterial blood gas responses.

Official Title
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Pulmonary Gas Exchange Abnormalities in Patients With Mild COPD

Conditions
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COPD

Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Stable symptomatic patients with GOLD grade 1B mild COPD; at least 50 years of age; a cigarette smoking history ≥20 pack-years; a Baseline Dyspnea Index focal score ≤9; post-bronchodilator forced expiratory volume in 1 second (FEV1) ≥80 %predicted and an FEV1/forced vital capacity (FVC) ratio <0.7 and < lower limit of normal. Exclusion Criteria: clinically significant comorbidities; contraindications to exercise testing; history/clinical evidence of asthma; body mass index <18.5 or >30 kg/m2; use of supplemental oxygen.

Ages Eligible for Study
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Minimum Age: 50 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Mild COPD<br>Symptomatic smokers with mild COPD | |
| Healthy Control<br>Non-smokers, matched to mild COPD group for age (at least 50 years) and gender | |

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| ventilatory equivalent for carbon dioxide (VE/VCO2) | Exercise will consist of a symptom-limited incremental test on a cycle ergometer | Measured at its nadir during an exercise test. Participants will be followed for the amount of time taken to complete 2 study visits, an expected average duration between 1 and 2 weeks. | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| dead space to tidal volume ratio (VD/VT) |  | Measured at standardized work rates during exercise | 
| arterial blood gas measurements | Measurements will include arterial oxygen tension (PaO2), arterial carbon dioxide tension (PaCO2), pH, hydrogen ion (H+), plasma bicarbonate (HCO3-) and lactate. | Measured at standardized work rates during exercise | 
| dyspnea intensity measured using the modified 10-point Borg scale |  | Measured at standardized work rates during exercise | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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exercise