forced expiratory volume

(medicine) During the performance of a forced vital capacity measurement, the volume of exhaled gas over a specific time interval.

The volume of air that a person with fully inflated lungs can breathe out in one second. The forced expiratory volume (FEV) is used in the diagnosis of respiratory conditions such as asthma. A low FEV indicates difficulty in breathing, which usually restricts the ability to exercise. People who can expel less than 75 per cent of their vital capacity (the maximum volume which can be breathed out from fully inflated lungs) are generally advised to consult a doctor. See also exercise-induced asthma.

The volume of air that can be forcibly expelled in a fixed time period after full inspiration.

The volume of air forcibly exhaled in the first second after maximal inhalation. The FEV_1.0 is a measure of the expiratory power of the lungs. It is reduced by asthma and decreases with age. See also exercise-induced asthma.