Emphysema & COPD

The British Thoracic Society guidelines define emphysema as "a permanent destructive enlargement of the air spaces distal to the terminal bronchioles." It is charac­terized by the breakdown of the walls of the alveoli and the capillaries that surround them. As these walls are destroyed, the alveoli form large air pockets. When these air pockets are larger than 1 cm, they are called bullae. The attachments to the alveoli that support the bronchioles and keep them open are also destroyed. As a result, the lungs lose their elasticity and density. Emphysema is not reversible.

One larger alveolar sac has less surface area than 4 or 5 smaller sacs. The reduction in surface area of the alveoli results in less space for the exchange of oxygen and carbon dioxide. The body cannot generate enough oxygen to meet the demands of the tissues or expel the carbon dioxide rapidly enough. Therefore, a person with emphysema experiences dyspnea on exertion.

Exactly what causes the breakdown of the walls of the alveoli is uncertain. One theory focuses on the enzymes secreted by the macrophages and neutrophils as they digest the foreign substance. Researchers suspect that these enzymes (elastolytic proteinases) may also destroy the walls of the alveoli. This is known as the protease-antiprotease theory.

Because only 15% to 25% of smokers develop clinically significant emphysema, researchers also speculate that there are other factors that contribute to the body’s inability to repair the damage caused by the enzymes and the development of emphysema. While it is still not definitively known why so few smokers develop emphysema, researchers have speculated that an individual’s genetic makeup and defense mechanisms may play a role in the determination.

AFTER Empysema clinical changes are;

• the walls of the alveoli break down
• large, thin-walled sacs form
• the alveolar attachments that support the smaller airways are destroyed
• gas exchange is impaired, resulting in dyspnea

In Summary;

• defined as permanent destructive enlargement of the air spaces distal to the terminal bronchioles
• it is characterized by the breakdown of the walls of the alveoli and capillaries surrounding them
• is not reversible
• only 15% to 25% of smokers develop clinically significant emphysema