Spirometry: basic concepts.

Spirometry is a pulmonary function test that allows screening, diagnosis and monitoring of respiratory diseases. This is a simple, non-invasive test that is easy to perform. By quantifying the respiratory volumes and flows, such as forced vital capacity (FVC) or forced expiratory volume in six seconds (FEV6), forced expiratory volume in the first second (FEV1), and the relationship between these parameters (FEV1/FVC or FEV1/FEV6 ratio), obstruction can be detected with high sensitivity and specificity; likewise, it is possible to classify the severity and response to the bronchodilator. This article presents indications, contraindications, and basic concepts for the interpretation of spirometry.