DLCO

Overview
DLCO stands for the Diffusing capacity of the Lung for Carbon Monoxide, the test used to determine this parameter. DLCO is the extent to which oxygen passes from the air sacs of the lungs into the blood. It was introduced in 1909.

Mechanism of test
The DLCO Test

This test involves measuring the partial pressure difference between inspired and expired carbon monoxide. It relies on the strong affinity and large absorption capacity of erythrocytes for carbon monoxide and thus demonstrates gas uptake by the capillaries that is less dependent on cardiac output.

Factors reducing DLCO
DLCO can be reduced by the following:


 * 1) Hindrance in the alveolar wall. e.g. fibrosis, alveolitis, vasculitis
 * 2) Decrease of total lung area, e.g. emphysema.
 * 3) Uneven spread of air in lungs, e.g. emphysema.
 * 4) Cardiac insufficiency
 * 5) Hemoglobin decrease in blood
 * 6) Pulmonary hypertension

Factors increasing dlco include polycythaemia and increased pulmonary blood volume as occurs in exercise.