Effects of Inhaled Corticosteroids in Chronic Obstructive Pulmonary Disease (COPD)

Overview

Human and animal studies have shown that inhaled corticosteroids (ICS) decrease airway blood flow . This effect is immediate (within 30 minutes), transient (lasting 90 minutes), and in animal studies independent of gene expression. In COPD patients, decrease in bronchial blood flow may also decrease mucosal edema, airway resistance and improve small airway function. If such an effect exists, then we should be able to measure improvements in airway conductance and reduce lung hyperinflation, which would have salutary effects on dyspnea and exercise endurance. To our knowledge, no study has examined the immediate effect of ICS on small airway function in COPD. The purpose of this study is to examine the effects of nebulized Pulmicort on small airway function (spirometry, plethysmographic lung volumes, airways resistance, closing volume, partial flow-volume loop analysis) and exercise endurance in patients with moderate to severe COPD. HYPOTHESIS 1. Nebulized ICS will immediately improve airway function compared with placebo (nebulized saline). 2. Enhanced lung emptying and reduced operating lung volumes during rest and exercise following ICS therapy will translate acutely into clinically important reductions in exertional dyspnea and improvements in exercise endurance.

This will be a single site, pilot, randomized, double-blinded, placebo-controlled, cross-over study that will be conducted at this centre. Subjects will be required to complete four (4) visits to the laboratory over a one-month period. At Visit 1, subjects who meet all study inclusion and exclusion criteria, will have a full set of pulmonary function tests (PFT) done and complete a symptom-limited incremental cycle exercise test. At Visit 2, subjects will have a partial set of pulmonary function tests (PFT) done and complete a symptom-limited constant load cycle exercise test. On the third and fourth visit subjects will be randomized to treatment with either nebulized saline or nebulized Pulmicort® in a double blinded, cross-over design, subsequent to which they will have their PFT's and symptom limited constant load exercise testing done.