In the described patient with thoracic injuries and chest tube, the pulmonary function disturbance is best described as a disturbance in:

• A. Ventilation-perfusion mismatch
• B. Compliance
• C. Diffusion capacity
• D. Airway resistance

Answer: (B)

The main idea is how easily the lungs and chest wall can expand during breathing, which is called compliance. Thoracic injuries, especially with a chest tube, tend to make the chest wall and the lungs stiffer and less distensible. Rib fractures, pain guarding, and pleural injury reduce the ability of the chest to expand for a given pressure, so the same inspiratory effort yields less change in volume. That means increased work of breathing and reduced tidal volume, even if the air is able to re-expand the lung after the chest tube decompresses the pleural space.

Ventilation-perfusion mismatch, diffusion capacity, and airway resistance can be affected in trauma, but the characteristic disturbance here is decreased respiratory system compliance due to chest wall and lung stiffness, making it the best description of the impairment.