What is Fev1?
FEV1 stands for first expiratory volume in the first second, the maximum amount of air a person can expel in one second of forceful exhalation. FEV 1 is used in spirometry, the most common of pulmonary function tests which measures the volume and flow of inhalation and exhalation. This test is used for assessing conditions like asthma, cystic fibrosis, pulmonary fibrosis and chronic obstructive pulmonary disease.
After a patient forcefully exhales for one second, it is then converted into a percentage of the control volume and flow, which is the normal volume and flow for most healthy people based on height weight and race. FEV1 then serves as the marker for the level of obstruction in the lungs. FEV1 that is 80% of the predicted means the person has normal airflow, FEV1 of 60-79% means the person has a mild obstruction, 40-59% means that there is moderate obstruction while less than 40% indicates a severe obstruction.
FEV1 is also measured in conjunction with FVC which stands for forced vital capacity. FEV1/FVC indicates the ration of FEV1 to FVC and in normal healthy adults this should fall between 75% and 80%.