Asthma Testing
Asthma is typically diagnosed using two tests. Learn more about how the test is performed and what it reveals.

• Pulmonary Function Test - This test measures the amount of air that can be taken in with a deep breath and how quickly it can be expelled from the lungs by a forceful exhalation.
• Spirometry Test - Tests the fuction of the lungs. It determines how much air a person can exhale, how fast a person can exhale and how much air a person can inhale.

Pulmonary Function Test (PFT)
PFTs are a broad range of tests. They measure how well the lungs take inand exhale air and how efficiently they transfer oxygen into the blood.

Spirometry measures how well the lungs exhale. The information gathered during this test is useful in diagnosing certain types of lung disorders, but is most useful when assessing for obstructive lung diseases (especially asthma and chronic obstructive pulmonary disease [COPD]).

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.

Spirometry
Spirometry is a powerful tool that can be used to detect, follow and manage patients with lung disorders.

Technology advancements have made spirometry much more reliable and relatively simple to incorporate into a routine office visit. However, interpreting spirometry results can be challenging because the quality of the test is largely dependent on patient effort and cooperation and the interpreter's knowledge of appropriate reference values. A simplified and stepwise method is key to interpreting spirometry. The first step is determining the validity of the test. Next, the determination of an obstructive or restrictive ventilatory pattern is made. If a ventilatory pattern is identified, its severity is graded. In some patients, additional tests such as static lung volumes, diffusing capacity of the lung for carbon monoxide and bronchodilator challenge testing are needed. The tests can further define lung processes but require more sophisticated equipment and expertise only in a pulmonary function laboratory.