AACN ECCO Pulmonary Practice Exam

A reduced FEV1/FVC ratio typically indicates obstructive lung disease. In obstructive diseases such as asthma, chronic bronchitis, and emphysema, there is a significant reduction in the forced expiratory volume in one second (FEV1) relative to the forced vital capacity (FVC). This occurs because these conditions cause narrowing of the airways, making it difficult for patients to exhale air quickly, which leads to a decreased FEV1 while the FVC may remain relatively preserved.

In contrast, a normal FEV1/FVC ratio indicates that lung function is within normal limits, and a reduced ratio does not signify restrictive lung disease, which is characterized by a proportional decrease in both FEV1 and FVC. Therefore, in the context of chronic lung diseases, when the FEV1/FVC ratio is reduced, it points specifically towards an obstructive pattern, highlighting the need to differentiate between the types of lung disease for appropriate diagnosis and management.