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

The safety and scientific validity of this study is the responsibility of the study sponsor and investigators. Listing a study does not mean it has been evaluated by the U.S. Federal Government. Read our disclaimer for details. Identifier: NCT00975403
Recruitment Status : Completed
First Posted : September 11, 2009
Last Update Posted : December 17, 2012
Canadian Lung Association
Information provided by (Responsible Party):
Dr. Denis O'Donnell, Queen's University

Brief Summary:

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 or disease Intervention/treatment Phase
Chronic Obstructive Pulmonary Disease Device: Dead space breathing Device: Room air breathing Not Applicable

Study Type : Interventional  (Clinical Trial)
Actual Enrollment : 20 participants
Allocation: Randomized
Intervention Model: Crossover Assignment
Masking: Triple (Participant, Investigator, Outcomes Assessor)
Official Title: Pathophysiological Mechanisms of Dyspnea and Activity-Limitation in Mild COPD
Study Start Date : October 2010
Actual Primary Completion Date : September 2012
Actual Study Completion Date : September 2012

Resource links provided by the National Library of Medicine

U.S. FDA Resources

Arm Intervention/treatment
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

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

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

Information from the National Library of Medicine

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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.

Information from the National Library of Medicine

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.

Please refer to this study by its identifier (NCT number): 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

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
First Posted: September 11, 2009    Key Record Dates
Last Update Posted: December 17, 2012
Last Verified: December 2012

Keywords provided by Dr. Denis O'Donnell, 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