by Pablo V. Romero MD , PhD
Functional diagnosis usually begins by identifying ventilatory dysfunction through forced spirometry. Forced spirometry is the simplest and most consolidated test of pulmonary function, and so it is very useful for an initial approximation to evaluation of the ventilatory status of the lung and respiratory system. Forced spirometry has three main parameters: Forced Vital Capacity (FVC), Forced Expiratory Volume in one second (FEV1) and the percent ratio between both (FEV1%FVC). FVC is the maximal volume that can be exhaled forcibly after a maximal deep inspiration; FEV1 is defined as the amount of gas that can be exhaled in one second after a maximal inspiration and during a maximal forced expiratory maneuver.