Effects of Bronchodilation on CT Parameters Reflecting Airways Remodelling, and Pulmonary Emphysema Extent: Comparisons Between CT Scans Obtained Before and After Bronchodilation and Relationships With Pulmonary Function Tests.

Patients : COPD patients aged 40 years or more, with a smoking history of > 10 pack-years (PY) and a post-bronchodilator forced expiratory volume in one second to vital capacity ratio (FEV1/VC) < 0.7 will be included. Exclusion criteria are: COPD exacerbation or respiratory infection in the 4 weeks before the begin of the study, concomitant pulmonary disease (tuberculosis, significant bronchiectasis, lung cancer), pulmonary resection, active malignancy or malignancy of any organ system within the past 5 years.

Procedures:

At Visit 1, after obtaining the written informed consent of the patient, medical history, smoking status and patient's treatment will be collected. They will be asked to discontinue bronchodilator therapies as follows, such that pulmonary function tests (PFT) and CT scan will be initially evaluated in a medication wash-out period at Visit 2:

• Short acting a2 agonists and anticholinergics: 8 wash-out
• Long acting a2 agonists: 12h wash-out
• Long acting anticholinergics: 48h wash-out
• Theophylline preparations: 48h wash-out
• Antileucotrienes: 48h wash-out

At visit 2, PFT will be performed, including vital capacity (VC), forced vital capacity (FVC), functional residual capacity (FRC), total lung capacity (TLC), residual volume (RV), forced expiratory volume in one second (FEV1), diffusion lung capacity for carbon monoxide (DLCO), and alveolar volume (VA) measurements (either in absolute values and percentage of predicted values). A first CT scan will be performed using the following technique: