DLCO: adjust for lung volume, standardised reporting and interpretation

Douglas C. Johnson
  • European Respiratory Journal, August 2017, European Respiratory Society (ERS)
  • DOI: 10.1183/13993003.00940-2017

DLCO and KCO - Should adjust predicted values for lung volume, and standardize reporting

What is it about?

DLCO and KCO are very dependent on lung volume, so adjusting predicted DLCO and KCO for lung volume is essential. This reviews how to make those adjustments, and recommends how to report DLCO, including the effect of lung volume, Hb, and other factors that effect predicted DLCO

Why is it important?

Since DLCO and KCO change significantly with lung volume, it is important to adjust predicted values for lung volume to evaluate the lung's ability for gas exchange. Is a low DLCO due to low lung volume or abnormal gas exchange? Does a "normal" KCO reflect normal gas exchange, or very abnormal gas exchange since it should be much "above normal" due to low lung volume?


Dr Douglas Johnson
baystate medical center

KCO more than DLCO is misunderstood, with many patients with significant interstitial lung disease with low lung volumes having a "normal KCO or DLCO/VA". However, a patient with lung volume 50% of predicted should have a DLCO 80% predicted and KCO 160% of predicted. A KCO of 100% predicted is much below the expected 160% for such a patient. Adjusting predicted KCO and DLCO for lung volume (KACO and DACO) yields a much better evaluation of the lung's ability for gas exchange.

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The following have contributed to this page: Dr Douglas Johnson

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