EMPHYSEMA

Emphysema is a long-term, progressive disease of the lung(s) and occurs when the alveolar walls are destroyed along with the capillary blood vessels that run within them. This lessens the total area within the lung where blood and air can come together, limiting the potential for oxygen and carbon dioxide transfer.





In early emphysema, there is associated inflammation of the small airways or bronchioles that limits the amount of air that can flow to the alveoli. In more severe emphysema, there is also loss of elasticity in the alveolar walls that have not been destroyed. When the patient breathes out, the alveoli and small airways collapse. This makes it hard for air to get out of the lungs and makes it even harder for new air to enter.

As more of the lung is destroyed and the lung cannot maintain oxygen concentrations in the bloodstream, the body compensates by gradually increasing the breathing rate. After a while, even hyperventilation (hyper=more + ventilation=breathing) cannot maintain adequate oxygen levels, and the arteries in the lung begin to constrict or narrow. The heart has to work harder to push blood into these narrower blood vessels, causing the blood pressure in the lung arteries to increase (pulmonary hypertension). Over time, the extra work requirement causes the heart muscle to enlarge (hypertrophy) and can cause heart failure.