Which condition decreases the diffusing capacity of the lung for carbon monoxide (DLCO)?
Answer and explanation
Correct answer: A. Emphysema
- Step 1: DLCO falls when the alveolar-capillary surface is lost. Step 2. Emphysema destroys alveolar walls and capillaries. Answer: emphysema. Why not the others: polycythemia and alveolar hemorrhage add hemoglobin to bind CO and raise DLCO, and early heart failure can raise it through capillary engorgement.
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