The ATS and ERS define COPD as
a preventable and treatable disease state
characterized by airflow limitation that
is not fully reversible (1). The airflow
limitation is usually progressive and
associated with a chronic inflammatory
response of the lungs to noxious particles
or gases. Cigarette smoking is the most
common risk factor (4), but others are
increasingly being recognized (e.g., biomass
fuels, a1-antitrypsin deficiency). Dyspnea
and exacerbations are the most prominent
respiratory manifestations of COPD. In
most patients, COPD represents the
pulmonary component of a chronic
multimorbidity.