Emphysema can best be described as the ongoing destruction of
the grape-like air sacs (alveoli) that carry out the lung's
basic objective of exchanging oxygen in the atmosphere for
carbon dioxide in the cardiovascular system.
The small air sacs can not completely deflate (remaining over
inflated) and therefore are unable to fill with fresh oxygenated
air for adequate ventilation. Emphysema can not be reversed,
however it is manageable through medications, exercise and good
When the emphysema has been caused by smoking, which makes up
the majority of cases, the very small airways (bronchioles) that
join the alveoli are damaged resulting in their walls lose
As pockets of dead air form in the damaged lung areas, the
ability to exhale is restricted, reducing normal lung function.
Inhalation is not usually impaired in the early stages, but in
the late stages of the disease, oxygen and carbon dioxide levels
are abnormal and breathing becomes labored.
Emphysema patients have typically lost between 50% and 70% of
their lung function by the time symptoms begin to appear.
Experts believe the process leading to emphysema is mostly due
to an imbalance in chemicals that protect the lungs from
infection and damage. Any condition that causes an imbalance in
these substances may trigger emphysema.
Cigarette smoke contains irritants that inflame the air
passages, setting off these biochemical events that damage cells
in the lung, thus increasing the risk both for emphysema and
Because smoking is overwhelmingly the cause of emphysema and
chronic bronchitis, they often develop together and frequently
require similar treatments.
There also is a rare, inherited form of emphysema known as
alpha-1-antitrypsin deficiency, in which both the walls of the
bronchioles and connected alveoli are diseased.