ABSTRACT
Chronic obstructive pulmonary disease (COPD) is a highly prevalent pathological condition that causes substantial morbidity and mortality in the adult population (Rabe et al., 2007). COPD is characterized by the presence of a chronic obstruction or limitation of expiratory air¬ow in lungs that is generally progressive and is not fully reversible (Rabe et al., 2007). As COPD progresses, worsening lung in¬ammation and tissue damage in the proximal and peripheral airways, lung parenchyma and pulmonary vasculature are observed. In addition, mucus hypersecretion and ciliary dysfunction lead to cough with sputum, often in the early morning. The air¬ow limitation in COPD patients is usually progressive and is associated with an abnormal in¬ammatory response of lungs to noxious particles and gases. The air¬ow limitation leads to hyperin¬ation, which occurs when air is trapped in lungs after each breath due to an imbalance in the volume of air being inhaled and exhaled (Rabe et al., 2007; Fromer and Cooper, 2008).
