In the United States, the term “COPD” includes two main conditions—emphysema(em-fih-SE-ma) and chronic bronchitis (bron-KI-tis). (Note: The Health Topics article about bronchitis discusses both acute and chronic bronchitis.)
In emphysema, the walls between many of the air sacs are damaged. As a result, the air sacs lose their shape and become floppy. This damage also can destroy the walls of the air sacs, leading to fewer and larger air sacs instead of many tiny ones. If this happens, the amount of gas exchange in the lungs is reduced.
In chronic bronchitis, the lining of the airways is constantly irritated and inflamed. This causes the lining to thicken. Lots of thick mucus forms in the airways, making it hard to breathe.
Most people who have COPD have both emphysema and chronic bronchitis. Thus, the general term “COPD” is more accurate.