Which statement best describes typical pulmonary function test results in CHF with pulmonary edema?

• A. Normal volumes and capacities
• B. Increased DLCO
• C. Reduced volumes and capacities with a normal FEV1/FVC ratio
• D. Decreased DLCO

Answer: (C)

In heart failure with pulmonary edema, the buildup of fluid in the interstitial and alveolar spaces makes the lungs stiffer and less compliant. That stiffness reduces the overall lung volumes, so measures like total lung capacity and vital capacity drop. Because the restrictive effect lowers both FEV1 and FVC more or less in parallel, the ratio of FEV1 to FVC stays normal or near normal. This combination—lower volumes with a preserved FEV1/FVC ratio—fits the typical pattern seen in CHF with edema rather than an obstructive process, where the ratio would be reduced.

DLCO can be affected in edema because the diffusion pathway is thickened and capillary blood volume may be reduced, so diffusion capacity may decrease, but the defining pattern for this scenario is the reduced volumes with a normal FEV1/FVC ratio. The other descriptions either imply normal volumes, an increased diffusion capacity, or focus solely on diffusion without addressing the volume changes seen with edema.