American Board of Internal Medicine (ABIM) Certification Practice Exam

What is the primary cause of ventilator-induced lung injury?

1. High tidal volume and/or plateau pressure

2. Low oxygen levels

3. High respiratory rates

4. Inappropriate ventilator settings

The correct answer is: High tidal volume and/or plateau pressure

The primary cause of ventilator-induced lung injury is high tidal volume and/or plateau pressure. This occurs because mechanical ventilation can lead to barotrauma and volutrauma, which are injuries caused by excess pressure and volume in the lungs, respectively. When high tidal volumes are used, it can distend alveoli beyond their capacity, leading to over-distension, increased airway pressures, and subsequent inflammation and edema in the lung tissue. High plateau pressures can reflect the risk of injury since they indicate that there is significant pressure in the alveoli, which can cause damage to the delicate lung parenchyma. In contrast, low oxygen levels can lead to hypoxia, but they do not directly cause the injury associated with mechanical ventilation itself. High respiratory rates might contribute to inadequate time for gas exchange but are not the primary drivers of lung injury. Inappropriate ventilator settings can vary widely, but it is the volume and pressure specifically that are most directly linked to the pathophysiological mechanisms of ventilator-induced lung injury. Thus, understanding the relationship between tidal volume, plateau pressure, and lung injury is crucial for minimizing risk in patients requiring mechanical ventilation.