Intensive Care Medicine (ICM) Practice Exam

What condition is indicated by a collapsed left lung on a chest X-ray?

1. Atypical pneumonia

2. Community-acquired pneumonia

3. Pleural effusion

4. Pneumothorax

The correct answer is: Pneumothorax

The presence of a collapsed left lung, or left lung collapse, suggests the occurrence of a pneumothorax. In this condition, air enters the pleural space, leading to lung collapse due to a loss of negative pressure that typically keeps the lung expanded against the chest wall. On a chest X-ray, a pneumothorax can be identified by a visual absence of vascular markings beyond a certain point in the lung field and the presence of a visceral pleural line, indicating that the lung has retracted. Pneumothorax can be spontaneous or traumatic and may lead to significant respiratory distress and hypoxemia. Thus, it is critical to accurately recognize it through imaging for appropriate intervention, such as needle decompression or chest tube insertion, to allow the lung to re-expand. Differentiating it from conditions like atypical pneumonia or community-acquired pneumonia is crucial, as these typically do not cause lung collapse but rather lead to infiltration or consolidation of lung tissue on X-ray. Pleural effusions may also present with a significant finding on X-ray but would show fluid levels in the pleural space, not an air-filled space as seen in pneumothorax. Therefore, the collapsed left lung in this scenario appropriately indicates pneumoth