The forced vital capacity ("FVC") refers to the volume change of the lung between a full inspiration to total lung capacity and a maximal expiration to residual volume. The measurement is performed during forceful exhalation of at least 6 seconds in duration. The FVC is measured in terms of percentage of predicted. A normal FVC is between 80% - 120% of predicted. Please see the TDP for each Trust for the FVC requirements of the various disease levels.