What does FeV1

Pulmonary function test

Depending on the examination method, various parameters of lung function can be measured. The two most important lung function values ​​are probably the vital capacity (VC) and the one-second capacity (FEV1).

Vital capacity (VC)

The vital capacity (VC) is the volume difference that can be measured between maximum inhalation and maximum exhalation. Adults have an average vital capacity of three to five liters. The vital capacity plays a role especially for the diagnosis of diseases in which the lungs shrink, for example at Pulmonary fibrosis or other interstitial lung disease.

In VC, a distinction can be made between what is known as the inspiratory vital capacity (IVC) and the expiratory vital capacity (EVC). IVC is the maximum respiratory volume that can be inhaled again after a complete exhalation. The EVC is the maximum volume that can be exhaled after maximum inhalation.

One-second capacity (FEV1)

Another value of the vital capacity is the so-called forced expiratory volume, which can be exhaled in one second with maximum breathing effort (one-second capacity, FEV1). The FEV1 measures the maximum volume exhaled as quickly as possible within the first second after a complete inhalation with the greatest effort. The one-second capacity is the most important lung function value in lung diseases associated with narrowed bronchi.

The total maximum volume that can be exhaled as quickly as possible after a complete inhalation with the greatest effort is referred to as forced vital capacity for short FVC.

Relative one-second capacity (FEV1 / FVC)

The relative one-second capacity is also known as the Tiffenau index or FEV1 / FVC and describes the proportion of the total maximum exhaled air that can be exhaled in one second (FEV1 as a percentage of vital capacity). This value should be over 75 percent, in older people higher than 70 percent. The value is only meaningful in the case of a slight narrowing of the airways (obstruction), since in the case of severe obstruction the vital capacity also decreases and the result is falsified.