In<unk> , both forced expiratory volume in one second (FEV1) and forced vital capacity (FVC) are reduced, however, the decline in FVC is more than that of FEV1, resulting in a higher than 80% FEV1/FVC ratio. In obstructive lung disease however, the FEV1/FVC is less than 0.7, indicating that FEV1 is significantly reduced when compared to the total expired volume. This indicates that the FVC is also reduced, but not by the same ratio as FEV1. One definition requires a total lung capacity which is 80% or less of the expected value.
Restrictive lung disease
Obstructive lung disease
Alveolar lung disease
Reactive airway disease
Pulmonary heart disease
Interstitial lung disease
Asthma
Radiation-induced lung injury