What is the typical VEV1 value in obstructive lung diseases compared to predicted values?

• A. Higher than predicted value
• B. Equal to predicted value
• C. Lower than predicted value
• D. Variable and unpredictable

Answer: (C)

In obstructive lung diseases, the typical value for forced expiratory volume in one second (FEV1) is lower than the predicted value for healthy individuals. This reduction is linked to the impaired airflow, which is a hallmark of obstructive conditions such as asthma, chronic obstructive pulmonary disease (COPD), and bronchiectasis.

The obstruction in the airways makes it more difficult for patients to exhale forcefully and completely, resulting in a decreased FEV1. To quantify this, pulmonary function tests are performed, comparing an individual's FEV1 value to the predicted value derived from normative data based on age, height, sex, and ethnicity. When an individual's FEV1 is significantly lower than what is predicted, it indicates the presence and severity of obstruction in the airways.

Understanding the implications of reduced FEV1 is critical in managing obstructive lung diseases, as it helps guide treatment decisions and evaluate the effectiveness of interventions over time.