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

Chronic Obstructive Pulmonary Disease Clinical Trial

Official title:

Pathophysiological Mechanisms of Dyspnea and Activity-Limitation in Mild COPD

Clinical Trial Details — Status: Completed

Administrative data

• NCT number: NCT00975403
• Other study ID #: DSS15110
• Status: Completed
• Phase: N/A
• First received: September 10, 2009
• Last updated: December 14, 2012
• Start date: October 2010
• Est. completion date: September 2012

Study information

• Verified date: December 2012
• Source: Queen's University
• Contact: n/a
• Is FDA regulated: No
• Health authority: Canada: Ethics Review Committee
• Study type: Interventional

Clinical Trial 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.

Recruitment information / eligibility

• Status: Completed
• Enrollment: 20
• Est. completion date: September 2012
• Est. primary completion date: September 2012
• Accepts healthy volunteers: Accepts Healthy Volunteers
• Gender: Both
• Age group: 40 Years and older

Eligibility

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.

Study Design

Allocation: Randomized, Intervention Model: Crossover Assignment, Masking: Double Blind (Subject, Investigator, Outcomes Assessor)

Related Conditions & MeSH terms

• Chronic Obstructive Pulmonary Disease
• Lung Diseases
• Lung Diseases, Obstructive
• Pulmonary Disease, Chronic Obstructive

Intervention

Device:
• Dead space breathing
Chemical loading by adding a deadspace (600ml) to the breathing circuit during a single cycle exercise test
• 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

Locations

Country	Name	City	State
Canada	Respiratory Investigation Unit, Kingston General Hospital	Kingston	Ontario

Sponsors (2)

Lead Sponsor	Collaborator
Queen's University	Canadian Lung Association

Country where clinical trial is conducted

Canada, 

Outcome

Type	Measure	Description	Time frame	Safety issue
Primary	Dyspnea intensity measured by the 10-point Borg scale during cycle exercise		Standardized time during exercise	No
Secondary	Cycle exercise endurance time		During exercise testing at study visits	No