Spirometry is a type of pulmonary function test that measures the amount of air taken in (volume) and exhaled as a function of time.

During a spirometry test, a patient places their mouth over the mouthpiece of the spirometer, takes a deep breath in, and then blows out as forcefully as possible.

Spirometry gives health care professionals two important numbers that may indicate problems with lung function. These are:

• Forced Vital Capacity (FVC) - how much air you can blow out of your lungs

• Forced Expiratory Volume (FEV1) - the amount of air you can blow out in 1 second

Your doctor may use the results of your spirometry to diagnose emphysema or asthma. If you have a lung disease such as asthma, this test can give important information on whether or not medications are working, or if your disease is worsening.