How does KCO help distinguish restrictive from emphysematous disease?

In restrictive disease (fibrosis), DLCO falls but KCO is preserved or elevated (good alveolar function per unit volume). In emphysema, both DLCO and KCO fall, reflecting loss of alveolar surface area and capillary bed.

What are normal KCO values?

Normal KCO is 80–120% predicted for age, sex, and height. KCO 120% predicted may indicate extrapulmonary restriction or single-lung transplant physiology.

KCO — Carbon Monoxide Transfer Coefficient

Calculate and interpret the KCO (DLCO/VA, carbon monoxide transfer coefficient per unit alveolar volume) to distinguish intrinsic lung disease from reduced lung volume in diffusion impairment.

Use the full interactive calculator below, or

KCO — Carbon Monoxide Transfer Coefficient

Frequently Asked Questions

How does KCO help distinguish restrictive from emphysematous disease?

What are normal KCO values?