What does a reduced DLCO indicate in the context of restrictive disorders?

• A. Increased lung compliance
• B. Pulmonary vascular disease
• C. Reduced gas exchange capacity
• D. Normal lung function

Answer: (C)

A reduced diffusion capacity for carbon monoxide (DLCO) is a significant indicator in the assessment of restrictive pulmonary disorders. In the context of these conditions, a decrease in DLCO reflects a compromised ability of the lungs to transfer gas from the alveoli into the bloodstream, which is essential for adequate oxygenation.

Restrictive pulmonary disorders, such as pulmonary fibrosis or interstitial lung disease, lead to thickening or scarring of the lung tissue, thereby impairing gas exchange. This results in a decreased surface area available for diffusion, ultimately causing a reduced DLCO. The measurement of DLCO helps clinicians identify the extent to which gas exchange is affected and can assist in the categorization of the lung pathology present.

While pulmonary vascular disease can also lead to a reduced DLCO, it does not specifically reflect the overall gas exchange capacity related to the restrictive process itself. Similarly, increased lung compliance and normal lung function would not lead to a reduction in DLCO; both are indicative of normal or exaggerated lung mechanics rather than impairment in gas exchange, which is a hallmark in restrictive lung diseases.