What is the patient preparation for lung volume determination in pulmonary function testing?

Updated: May 14, 2020
  • Author: Kevin McCarthy, RPFT; Chief Editor: Nader Kamangar, MD, FACP, FCCP, FCCM  more...
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Use of supplemental oxygen just prior to a nitrogen washout test may cause underestimation of FRC unless the initial exhaled nitrogen is considered in the calculations. Supplemental oxygen should be discontinued for at least 10 minutes before starting a nitrogen washout test. Duplicate measurements of FRC by either gas dilution technique should be delayed until a posttest interval is equivalent to 1.5 times the equilibration time to eliminate the effects of residual oxygen or helium.

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