What effect does pulmonary fibrosis have on diffusion capacity?

Pulmonary fibrosis is characterized by the thickening and stiffening of lung tissue due to scarring, which impairs the ability of the lungs to transfer oxygen and carbon dioxide between the alveoli and the bloodstream. As a result, the diffusion capacity of the lungs is adversely affected.

In conditions like pulmonary fibrosis, the surface area available for gas exchange is reduced due to the fibrosis process, leading to a decrease in the diffusion of gases. The changes in the blood-gas barrier that occur with scarring and inflammation mean that the efficiency with which oxygen and carbon dioxide can diffuse across this barrier into and out of the bloodstream is compromised.

Consequently, the diffusion capacity—often assessed using tests such as the DLCO (diffusing capacity of the lungs for carbon monoxide)—is decreased in individuals with pulmonary fibrosis. This decrease indicates that less gas is able to be exchanged, confirming that pulmonary fibrosis negatively impacts diffusion capacity.