Carbon monoxide diffusion capacity is decreased in all, except:: (A) Emphysema, (B) Primary pulmonary hypertension, (C) Alveolar haemorrhage, (D) Infiltrative lung disease
Answer is C. Flows remain normal, as does the diffusion capacity of the lung for carbon monoxide (DlCO), unless obstructive sleep apnea (which often accompanies obesity) and associated chronic intermittent hypoxemia have induced pulmonary arterial hypertension,in which case DLCO may be low.