Carbon monoxide diffusion capacity (DLCO) has been shown to correlate with:

A. The thickness of the alveolar lining membrane.

B. The permeability of the erythrocyte to carbon dioxide.

C. Pulmonary emboli.

D. Total alveolar-capillary capacity. 

DISCUSSION: The single-breath DLCO is a screening test that has been shown to be decreased in all of the above examples. It is an estimate of the total capacity of the functional alveolar microarchitecture and has been demonstrated to be an independent measure of physiologic capability apart from the FEV 1 and forced ventilatory capacity.