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