Pneumothorax is defined as what?

• A. Accumulation of blood in the pleural cavity
• B. Inflammation of the lung tissue
• C. Accumulation of air or gas in the pleural cavity resulting in partial or complete collapse of the lung
• D. Fluid in the alveolar spaces

Answer: (C)

Pneumothorax happens when air or gas gets into the pleural space, the little gap between the lung and chest wall. That air disrupts the negative pressure that normally keeps the lung expanded. With the pleural space filled with air, the lung can’t stay fully inflated and may collapse partially or completely. This can occur suddenly, from trauma or a medical procedure, or spontaneously in some individuals.

The other descriptions aren’t pneumothorax: blood in the pleural space is a hemothorax; inflammation of lung tissue points to pneumonia or pneumonitis; and fluid in the alveolar spaces refers to conditions like pulmonary edema, not air in the pleural space.