Advanced Patient Assessment Practice Exam

What is the primary cause of hypoxemia in patients with paradoxical chest movement and decreased breath sounds?

1. Shunt

2. Overall hypoventilation

3. V/Q mismatch

4. Diffusion defect

The correct answer is: Overall hypoventilation

The primary cause of hypoxemia in patients with paradoxical chest movement and decreased breath sounds is overall hypoventilation. In this context, paradoxical chest movement indicates inadequate respiratory mechanics, possibly due to conditions such as respiratory muscle weakness or chest wall abnormalities. When hypoventilation occurs, it leads to insufficient ventilation of the alveoli, preventing adequate oxygenation of the blood. Consequently, this inadequate ventilation causes a retention of carbon dioxide and a failure to expel sufficient oxygen, resulting in hypoxemia. The decrease in breath sounds also suggests that air exchange is compromised, which is consistent with hypoventilation, as there is diminished airflow into the lungs. In this scenario, while shunts, ventilation/perfusion (V/Q) mismatch, and diffusion defects can also lead to hypoxemia, overall hypoventilation directly describes the inadequate breathing mechanics and reduced airflow specific to the symptoms presented.