In PFT, what do restrictive ventilatory defects typically show?

Restrictive ventilatory defects are characterized by a reduced lung volume, specifically a decrease in forced vital capacity (FVC). This reduction occurs due to various conditions that restrict lung expansion, such as interstitial lung disease, pleural disease, or neuromuscular disorders. In these situations, the FEV1 (forced expiratory volume in one second) may also be decreased, but the FEV1/FVC ratio tends to remain normal or may be increased because both FEV1 and FVC are reduced, with the decrease in FVC often being more pronounced than that of FEV1.

This results in an FEV1/FVC ratio that remains unchanged or improves, pointing towards a restrictive pattern rather than an obstructive one. The understanding of this pattern is crucial for accurate interpretation of pulmonary function tests and the diagnosis of restrictive disorders. In contrast, a normal or increased FEV1/FVC ratio associated with a decreased FVC correctly identifies it as a restrictive defect.