Emphysema is frequently preceded (leaded) by chronic bronchitis. As a result of long standing irritation or infection of breathing (bronchial) tubes there is swelling of bronchial walls and increased mucus production. This blocks the airways and as a result air is trapped in the tiny air sacs.

Eventually, the walls of the air sac stretch out and become stiff and break down. Because of loss of elasticity (destruction of elastin) the air sacs are unable to completely deflate and are unable to fill with fresh air for adequate ventilation.

The damage to the alveolar wall is caused due to an imbalance between two proteins in the lungs:

  • Elastase which breaks down elastin
  • Alpha-1-antitrypsin (AAT) which inhibits elastase

The damage to the alveolar walls becomes worse over time affecting the exchange of oxygen and carbon dioxide in the lungs, causing shortness of breath.