FEV1, Forced Expiratory Volume, represents the volume of air, in litres, exhaled during the first second of a forceful exhalation. It is one of the most significant lung function parameters.
This test can be performed via a spirometer. You must breath as forcefully and fast as possible into the mouthpiece of the spirometer. The “normal” value for FEV1 differs from person to person, since it is based on age, height, race, gender, and life quality. Therefore, the predicted FEV1 value for everyone is different. A lower than predicted FEV1 value can be associated with obstructive lung diseases such as asthma and chronic obstructive pulmonary diseases.
The FEV1/FVC ratio is also significant in terms of distinguishing obstructive and restrictive lung diseases.