What is the effect of a diffuse capacity decrease in pulmonary function tests?

A decrease in diffuse capacity, particularly measured by the diffusing capacity of the lungs for carbon monoxide (DLCO), is commonly associated with emphysema. Emphysema, a type of chronic obstructive pulmonary disease (COPD), involves the destruction of the alveoli, where gas exchange occurs. This destruction leads to a reduced surface area for gas exchange, which in turn lowers the DLCO value. As a result, individuals with emphysema often exhibit a decreased capacity to transfer gases from the alveoli into the bloodstream, indicating an impairment in lung function specifically related to emphysema.

While other conditions may also affect diffuse capacity, the association with emphysema is particularly strong due to the underlying pathology involving alveolar damage and loss of elastic recoil, making this the most relevant choice in this context.