Emphysema

Airways of the lung with emphysema

People with COPD often have emphysema, whose hallmark symptom is shortness of breath. Smoking is the primary cause of emphysema.

Emphysema refers to the destruction of the air sacs (alveoli). This is the portion of the lung involved in the transfer of oxygen into the blood stream. This results in fewer air sacs, but the air sacs are larger because destruction of the air sac walls has caused multiple air sacs to merge.

These large, irregular shaped air sacs have poor gas exchange capabilities (oxygen and carbon dioxide). This means that the air sacs are not able to transfer oxygen into the bloodstream as well as healthy air sacs. Furthermore, like a rubber party balloon that has been blown up and deflated many times, the emphysematous air sacs loose their elasticity (ability to stretch and shrink with breathing). This results in "stale" air becoming trapped in the air sacs. Over time, this causes the air sacs, and the lungs, to become even bigger (hyperinflation). Hyperinflated lungs do not function as well as normal lungs.

This information has been approved by Russell Bowler, MD, PhD (March 2006).