How does barometric pressure affect diffusing capacity of lung for carbon monoxide (DLCO) testing?

Updated: May 14, 2020
  • Author: Kevin McCarthy, RPFT; Chief Editor: Nader Kamangar, MD, FACP, FCCP, FCCM  more...
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The current recommendation is to correct the measured DLCO for barometric pressure. As barometric pressure falls, so does the partial pressure of inspired oxygen (PIO2) and DLCO increases. The typical variation in DLCO expected from atmospheric pressure fluctuation at a given altitude is +1.5%. Laboratories at higher altitude can produce higher values; the expected change is approximately 0.5% for each 100-meter increase in altitude. This adjustment can only be made if the barometric pressure is made or updated in the measuring system on a daily basis.

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