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COPD is an obstructive airway disorder characterized by a slowly progressive and irreversible decrease in FEV1 (1, 2, 7). FEV1 decreases are caused by a narrowing of airway lumen diameters that develops as a result of varying perturbations in both airway and interstitial lung tissue. Airway abnormalities consist of increased wall thickening, intraluminal mucus accumulation, smooth muscle hypertrophy, and small airway lining fluid changes. Additional early lesions include inflammatory cell infiltration and goblet cell metaplasia. The tissue component of emphysema is defined anatomically as the permanent destructive enlargement of airspaces distal to the terminal bronchioles with a concomitant loss of alveolar attachments (7). Emphysema is recognized in vivo by a decreased diffusing capacity (DLCO) and reduced lung parenchymal density on chest radiograph and high-resolution computerized tomography …