Restrictive Lung Disease - Diagnosis

Diagnosis

In restrictive lung disease, 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, FEV1 is reduced while FVC remains stable, consequentially depicting a lower FEV1/FVC ratio.

One definition requires a total lung capacity which is 80% or less of the expected value.