Pulmonary Function Tests (PFTs) are tests used to evaluate how well the lungs are working. Spirometry is a particular type of PFT done in the office to evaluate and follow the progress of respiratory disorders such as asthma.
Spirometry is performed by having a patient inhale a breath as deeply as possible, then exhale into the spirometer as hard and as long as possible. This simple process gives the physician very important insight into the health of the lungs and airways. Patients with asthma have a reduced ability to empty their lungs due to constriction of the airways, so repeating spirometry after asthma treatments can help determine the effectiveness of the therapy.