nonspecific pattern and PRISM in PFT


  • nonspecific: reduced FEV1 or FVC and normal FEV/FVC ratio and normal TLC
    • reduced effort: not breathing all the way out. (flow volume curve concave towards end?)
    • early restriction: FVC smaller but RV the same
    • early obstruction: small airway disease, FVC smaller and RV increased. FEV/FVC has not started to fall yet.
  • PRISM: preserved ratio impaired spirometry. This is when the TLC is not measured

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Footnotes

  1. ERS ATS technical standard on interpretive strategies for routine lung function tests