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Pathophysiological Mechanisms of Dyspnea and Activity-limitation in Mild Chronic Obstructive Pulmonary Disease (COPD)

This study has been completed.
Canadian Lung Association
Information provided by (Responsible Party):
Dr. Denis O'Donnell, Queen's University Identifier:
First received: September 10, 2009
Last updated: December 14, 2012
Last verified: December 2012

Chronic obstructive pulmonary disease (COPD) is a growing cause of death, disability and health care costs in Canada. Nevertheless, COPD remains largely under-diagnosed and under-treated, particularly in its early stages. Patients with mild COPD have variable respiratory symptoms and often go unrecognized by their caregivers. Recent studies indicate that even smokers with near normal breathing test results can have extensive small airway disease/dysfunction at rest, which becomes more pronounced during the stress of exercise thus leading to unpleasant breathing difficulty. This study seeks to better understand the nature and causes of breathing discomfort and activity limitation in a group of patients with mild COPD. The investigators will compare detailed tests of small airway function and conduct an evaluation of several key physiological parameters during the stress of exercise in patients with mild COPD and in healthy, age-matched, non-smoking control subjects. The investigators will also compare detailed physiological responses to exercise under conditions of chemical loading and mechanical unloading of the respiratory system in patients with mild COPD.

The proposed study will be the first to systematically test the hypothesis that pathophysiological abnormalities in ventilatory demand, pulmonary gas exchange, small airway function, dynamic ventilatory mechanics and respiratory muscle function contribute significantly to exertional dyspnea and activity-limitation in patients with mild COPD. This study will be the first to determine if these abnormalities can be manipulated.

Condition Intervention
Chronic Obstructive Pulmonary Disease
Device: Dead space breathing
Device: Room air breathing

Study Type: Interventional
Study Design: Allocation: Randomized
Intervention Model: Crossover Assignment
Masking: Double Blind (Subject, Investigator, Outcomes Assessor)
Official Title: Pathophysiological Mechanisms of Dyspnea and Activity-Limitation in Mild COPD

Resource links provided by NLM:

Further study details as provided by Queen's University:

Primary Outcome Measures:
  • Dyspnea intensity measured by the 10-point Borg scale during cycle exercise [ Time Frame: Standardized time during exercise ]

Secondary Outcome Measures:
  • Cycle exercise endurance time [ Time Frame: During exercise testing at study visits ]

Enrollment: 20
Study Start Date: October 2010
Study Completion Date: September 2012
Primary Completion Date: September 2012 (Final data collection date for primary outcome measure)
Arms Assigned Interventions
Experimental: Dead space breathing Device: Dead space breathing
Chemical loading by adding a deadspace (600ml) to the breathing circuit during a single cycle exercise test
Sham Comparator: Room air breathing Device: Room air breathing
Sham comparator (vs deadspace) during a single cycle exercise test will entail breathing room air on the same circuit without the rebreathe valves


Ages Eligible for Study:   40 Years and older   (Adult, Senior)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   Yes

Inclusion Criteria:

  • Post-bronchodilator forced expiratory volume in 1 sec (FEV1) ≥ 80%predicted and a FEV1/forced vital capacity (FVC) ratio < 0.70;
  • Clinically stable as defined by no changes in medication dosage or frequency of administration with no exacerbations or hospitalizations in the preceding 6 weeks;
  • A cigarette smoking history ≥ 20 pack-yrs;
  • Body mass index between 18.5 and 30 kg/m2;
  • Able to perform all study procedures and provide informed consent.

Exclusion Criteria:

  • A diffusing capacity of the lung for carbon monoxide (DLCO) < 40 %predicted;
  • Presence of active cardiopulmonary disease (or comorbidities) other than COPD that could contribute to dyspnea and exercise limitation;
  • Clinical diagnosis of sleep disordered breathing;
  • History or clinical evidence of asthma;
  • Presence of important contraindications to clinical exercise testing, including inability to exercise because of neuromuscular or musculoskeletal disease(s);
  • Use of daytime oxygen or exercise-induced arterial oxygen desaturation to <80% on room air.
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Please refer to this study by its identifier: NCT00975403

Canada, Ontario
Respiratory Investigation Unit, Kingston General Hospital
Kingston, Ontario, Canada, K7L 2V7
Sponsors and Collaborators
Queen's University
Canadian Lung Association
Principal Investigator: Denis E O'Donnell, MD, FRCPC Queen's University and Kingston General Hospital
  More Information

Publications automatically indexed to this study by Identifier (NCT Number):
Responsible Party: Dr. Denis O'Donnell, Principal Investigator, Queen's University Identifier: NCT00975403     History of Changes
Other Study ID Numbers: DSS15110
Study First Received: September 10, 2009
Last Updated: December 14, 2012

Keywords provided by Queen's University:
mild COPD
respiratory mechanics

Additional relevant MeSH terms:
Lung Diseases
Lung Diseases, Obstructive
Pulmonary Disease, Chronic Obstructive
Respiratory Tract Diseases
Respiration Disorders
Signs and Symptoms, Respiratory
Signs and Symptoms processed this record on March 27, 2017