COPD is an acronym for the term chronic obstructive pulmonary disease. Chronic obstructive pulmonary dis-ease is a descriptive term rather than a single disease, although it usually is used to refer to emphysema or to chronic obstructive bronchitis.
Technically, COPD refers in a general way to several different lung conditions that demonstrate an abnormality on spirometry, a type of pulmonary function test . The abnormality that characterizes COPD is called obstructive dysfunction. Several different lung conditions typically exhibit the obstructive dysfunction pattern of abnormality on pulmonary function testing. They include emphysema, chronic obstructive bronchi-tis, exacerbated asthma, and bronchiectasis. The two first diseases, in particular, share several features. Both emphysema and chronic obstructive bronchitis are associated with cigarette smoking. Both exhibit obstructive dysfunction on spirometry that does not completely reverse with medication, and thus demonstrate a “fixed” or “irreversible” type of obstructive dysfunction. Both cause respiratory symptoms such as breathlessness or cough. Interestingly, emphysema and chronic obstructive bronchitis frequently co-exist, usually in a current or former cigarette smoker.
Partly because emphysema and chronic obstructive bronchitis appear at first glance to be so similar, physicians have taken to using the term COPD to refer specifically to either emphysema or chronic obstructive bronchitis, or even to a combination of both. The use of COPD as a kind of shorthand for the smoking associated lung diseases, whether emphysema or chronic obstructive bronchitis, has taken hold among medical professionals as well as the general public, despite dis-approval from some linguistic purists.