Chronic obstructive pulmonary disease (COPD) is a progressive
syndrome of expiratory airflow limitation caused by
chronic inflammation of the airways and lung parenchyma.
The airway inflammatory response in COPD is initiated by
smoking in the overwhelming majority of cases, and chronic
exposure to cigarette smoke initiates a series of events that
causes damage to central airways, peripheral airways, and terminal
airspaces, leading to physiologic and clinical abnormalities.
Although COPD shares some clinical features with asthma,
another prevalent airway inflammatory disease, there are
distinct differences in the phenotypic characteristics of airway
inflammation between COPD and asthma.