Spirometry is a pulmonary function test that measures the volume of air that can be inspired and expired as a function of time. The primary signal measured in spirometry may be volume or flow.
Maximum expiratory flow-volume curves are measured before and after bronchodilator administration to test for reversibility of airflow limitation or to assist in diagnosing Asthma versus COPD.
A spirometry test may also be conducted as part of a bronchial challenge test, used to determine bronchial hyper-responsiveness to either rigorous exercise, inhalation of cold/dry air, or with a pharmaceutical agent such as mannitol.
An indication of maximum inspiratory capacity and performance can also be measured to assess the degree of fixed or variable airway obstruction.
The measurements from spirometry are valuable as a screening tool for respiratory health however spirometry alone cannot lead to a diagnosis.