Certified Respiratory Therapist Practice Exam

What condition is most consistent with a patient showing low FEV1% and high TLC and RV values?

1. Chronic bronchitis

2. Pulmonary fibrosis

3. Pneumonia

4. Pulmonary emphysema

The correct answer is: Pulmonary emphysema

In respiratory physiology, a low FEV1% (Forced Expiratory Volume in 1 second as a percentage of Forced Vital Capacity) indicates an obstructive pattern of lung disease. A high TLC (Total Lung Capacity) and RV (Residual Volume) suggest that the lungs are hyperinflated, which is a hallmark of conditions involving airflow obstruction and air trapping. In the case of pulmonary emphysema, this condition is characterized by the destruction of the alveolar walls, leading to decreased elastic recoil of the lungs. As a result, patients struggle to exhale air fully, causing not only a reduction in FEV1 but also an increase in RV due to trapped air. The high TLC reflects the overall lung volume increase due to air trapping and the inability to fully exhale. Chronic bronchitis is also an obstructive lung disease with low FEV1%, but it typically does not present with as high a TLC or RV as seen in emphysema. In pulmonary fibrosis, the classic pattern is restrictive lung disease, leading to decreased lung volumes overall, rather than hyperinflation. Pneumonia would not be consistent with a chronic state of low FEV1% and high lung volumes; rather, it often presents with normal or increased