Physiology

In a normal lung, breathing is an active process that utilizes the diaphragm and muscles of the rib cage. When breathing in (inhaling), the chest cavity expands, which draws air into the lungs, causing them to expand.

Within the normal lung millions of microscopic air sacs called alveoli form the site of gas exchange with the blood. Inhaled oxygen is transferred to the bloodstream while carbon dioxide is carried away. In a healthy lung, the alveoli are elastic and form a dense structure.

Breathing out (exhalation) involves the relaxation of the rib cage and diaphragm muscles. This relaxation causes the chest cavity to shrink. Combined with the natural elasticity of the lungs, this process squeezes air out of the lungs, causing them to empty.

Emphysema is characterized by the destruction of the walls separating the alveoli. This damage is irreversible and results in the alveoli merging into ever larger air sacs. As a result there is less surface area available for the transfer of oxygen and carbon dioxide, resulting in a feeling of breathlessness. The disease also dramatically reduces the natural elasticity of the lung tissue.

During inhalation, air is more easily drawn into the diseased inelastic regions of the lung and cannot easily be exhaled. This results in air being trapped in the diseased lung so it overinflates. Thus, the amount of air reaching healthier lung tissue is reduced and breathing becomes difficult. Hyperinflation also has the effect of crowding out the healthier lung tissue.

While there is no cure for emphysema, a modern, non-surgical treatment called endobronchial lung volume reduction (ELVR) is available in many countries outside the U.S. This treatment has been evaluated in clinical trials and, although not a cure, has been shown to alleviate emphysema symptoms and improve breathing for many patients with emphysema.  Click here to learn more about this treatment option.