Pneumothorax is a condition in which which occurs?

• A. Air in the pleural cavity causing the lung to collapse.
• B. Fluid in the pleural space.
• C. Infection of the pleural lining.
• D. Blood in the pleural space.

Answer: (A)

Air in the pleural space causing the lung to collapse. Pneumothorax happens when air leaks into the space between the lung and chest wall, which disrupts the negative pressure that normally keeps the lung expanded. With this pressure balance disturbed, all or part of the lung can deflate, leading to sudden chest pain and shortness of breath in many cases. The other options describe different pleural conditions, not pneumothorax: fluid in the pleural space is a pleural effusion; infection of the pleural lining is pleuritis or empyema; blood in the pleural space is a hemothorax.