How do you identify respiratory defect by forced expiratory spirogram?

A forced expiratory spirogram can help identify respiratory defects by analyzing the shape and specific measurements of the forced expiratory volume (FEV1) and forced vital capacity (FVC). In obstructive defects, such as Asthma or COPD, the FEV1 is significantly reduced, leading to a decreased FEV1/FVC ratio (typically less than 70%). In restrictive defects, like pulmonary fibrosis, both FEV1 and FVC are reduced, but the FEV1/FVC ratio remains normal or may be increased. Observing these parameters allows clinicians to distinguish between obstructive and restrictive respiratory conditions.