Which finding is typical in pulmonary function tests (PFT) for restrictive disorders?

• A. FEV1/FVC ratio less than 70%
• B. Normal or >90% FEV1/FVC ratio
• C. Increased lung capacity
• D. Peak flow rates exceeding predicted values

Answer: (B)

In the context of restrictive pulmonary disorders, the pulmonary function tests (PFTs) demonstrate a characteristic finding of a normal or even increased FEV1/FVC ratio, typically greater than 90%. In restrictive lung disease, there is a reduction in lung expansion leading to decreased total lung capacity (TLC), but the FEV1 and FVC values are reduced proportionally. As a result, the FEV1/FVC ratio remains normal or may even increase, distinguishing it from obstructive disorders where this ratio is notably decreased.

This characteristic is essential because it highlights the nature of restrictive disorders, where the problem lies primarily in the lung's ability to expand rather than in airway obstruction, which is the main issue in obstructive diseases. Understanding these patterns can help in accurately diagnosing and differentiating between various types of pulmonary diseases.

In contrast, other options would indicate different pathophysiological conditions or patterns. For instance, an FEV1/FVC ratio less than 70% is typically seen in obstructive disorders. Increased lung capacity contradicts the definition of restrictive disorders, and peak flow rates exceeding predicted values would not fit the expected outcomes of restrictive lung function, where airway resistance isn't the primary issue.