How does emphysema affect gas exchange?

Emphysema impairs gas exchange by damaging the alveoli, reducing the surface area available for oxygen and carbon dioxide exchange.

Emphysema is a chronic lung condition that is part of a group of diseases known as chronic obstructive pulmonary disease (COPD). It is characterised by the destruction of the walls of the alveoli, the tiny air sacs in the lungs where gas exchange occurs. This damage results in fewer, larger alveoli, which significantly reduces the surface area available for gas exchange.

The process of gas exchange in the lungs involves the diffusion of oxygen from the air in the alveoli into the blood in the surrounding capillaries, and the diffusion of carbon dioxide from the blood into the alveoli, from where it can be exhaled. This process relies on a large surface area and a thin barrier between the air and the blood for efficient diffusion. In emphysema, not only is the surface area reduced, but the walls of the alveoli can become thickened and inflamed, further impeding gas exchange.

Furthermore, the loss of elasticity in the alveoli means they are less able to recoil and push out stale air, leading to air trapping. This means that fresh air containing oxygen cannot fully reach the alveoli, reducing the amount of oxygen that can be absorbed into the blood. At the same time, the trapped air retains carbon dioxide, which can then re-enter the bloodstream, leading to higher levels of carbon dioxide in the blood.

The overall effect of these changes is that people with emphysema often experience shortness of breath and have lower levels of oxygen in their blood, which can lead to fatigue and other health problems. They may also have higher levels of carbon dioxide in their blood, which can cause symptoms such as confusion and unconsciousness in severe cases. The damage caused by emphysema is irreversible, but treatments can help to manage the symptoms and slow the progression of the disease.