Spirometry

Pulmonary Function Testing (PFT) is a broad term to describe several tests.  It requires specification by the prescribing physician for the individual components:

  • Spirometry- FEV1 and FVC.
    • FEV1 is the forced expiratory volume in 1 second.   A normal person would be able to expire 80% of their forced vital capacity in 1 second.  Individuals with obstruction will have a reduced FEV1 volume.  Forced vital capacity is the volume an individual can expire in 6-8 seconds.  An FEV1/FVC ratio <0.70 signifies obstruction.
  • Lung volumes- TLC, RV, ERV.
    • At Temple this is measured by body plethysmography.  RV and TLC are normal if values are between 80-120%.  RV and TLC percentages >120% signify gas trapping and hyperinflation, respectively.  Percentages <80% signify restriction.
  • Diffusion capacity- DLCO, DLCO/VA
    • Diffusion capacity is measured through inhalation of carbon monoxide.  DLCO/VA will correct for the patients alveolar volume.
  • Methacholine challenge
    • Increasing amounts of methacholine will be given to a patient to see if it will cause a reduction in FEV1.  FEV1 drop of 20% will lead to immediate discontinuation of the test.  Patients cannot take their bronchodilator the day of the test.
  • 6 minute walk test