LUNG FUNCTION TESTS (PFT)
Pulmonary function tests are a broad range of tests that measure how well the lungs take in and exhale air and how efficiently they transfer oxygen into the blood. They include tests that measure lung size and air flow, such as spirometry and lung volume tests.
Other tests measure how well gases such as oxygen get in and out of your blood. These tests include pulse oximetry and arterial blood gas tests.
Another pulmonary function test, called fractional exhaled nitric oxide (FeNO), measures nitric oxide, which is a marker for inflammation in the lungs.
Spirometry measures the amount and/or speed of air that can be inhaled and exhaled. The information gathered during this test is useful in diagnosing certain types of pulmonary disorders but is most useful when assessing for obstructive lung diseases (especially asthma and chronic obstructive pulmonary disease, COPD).
Lung Volume Tests
Lung volume measurement detects restrictive lung diseases. In this set of diseases, a person cannot inhale a normal volume of air. Restrictive lung diseases may be caused by inflammation or scarring of the lung tissue (interstitial lung disease) or by abnormalities of the muscles or skeleton of the chest wall.
Testing the diffusion capacity (also called the DLCO) permits an estimate of how efficiently the lungs transfer oxygen from the air into the bloodstream.