Spirometry A physiological test called spirometry gauges a person's capacity to breathe in and out in relation to time.Forced vital capacity (FVC), forced expiratory volume expelled in the first second (FEV1), and the FEV1/FVC ratio are the primary outcomes of spirometry.A diagnostic test for a number of common respiratory conditions, including asthma and chronic obstructive pulmonary disease (COPD), is spirometry.It is also helpful in tracking how different respiratory conditions are developing.