Definition
obstructive lung disease characterized by abnormal permanent enlargement of the air spaces distal to the terminal bronchioles, accompanied by destruction of their walls without significant fibrosis. Destruction of alveolar septa results in a loss of elastic recoil and impair gas exchange across the alveolar septa (decrease the surface area for gas exchange).

Normally proteases secreted by inflammatory cells are inactivated by proteases inhibitors particularly by alpha 1 antitrypsin

If proteases are not inactivated, they can destroy the lung tissue

Emphysema is caused by imbalance in the activity of proteases and protease inhibitors

Congenital lack of protease inhibitors is an important cause of excess protease activity

chronic: progressively worsening dyspnea and chronic cough and fatigue and even weight loss.

acute: during acute exacerbation (triggered by URI), patients have sudden onset severe dyspnea, wheezing, and/or severe cough.