American Board of Surgery Qualifying Exam (ABS QE) Practice Test

Which lung condition is characterized by decreased TLC, RV, and FVC?

1. Obstructive lung disease

2. Restrictive lung disease

3. Bacterial lung disease

4. Viral lung disease

The correct answer is: Restrictive lung disease

In lung conditions, understanding the various measurements of lung function, such as Total Lung Capacity (TLC), Residual Volume (RV), and Forced Vital Capacity (FVC), is crucial. A decrease in these values characterizes restrictive lung disease. Restrictive lung diseases lead to a reduction in lung volumes due to stiffness in the lungs or chest wall, which limits expansion. This can be caused by a variety of factors, including interstitial lung disease, pneumonia, or conditions affecting the pleura or thoracic wall such as obesity hypoventilation syndrome. In restrictive conditions, both the volume of air that can be forcibly exhaled (FVC) and the overall capacity of the lungs (TLC) are diminished. Additionally, RV may also be reduced as the lungs can't inflate completely, leading to less air being trapped after expiration. In contrast, obstructive lung diseases, such as asthma and COPD, typically present with increased RV and decreased FVC, so they do not align with the decreased values mentioned. Bacterial and viral lung diseases can lead to respiratory symptoms, but their primary characteristics do not involve a standard pattern of lung volume changes seen in restrictive diseases. Thus, the characteristic decrease in TLC, RV, and FVC clearly signifies restrictive