What is COPD?

COPD is an acronym for the term chronic obstructive
pulmonary disease. Chronic obstructive pulmonary disease
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 bronchitis,
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 disapproval
from some linguistic purists.