Which condition involves air in the pleural space causing the lung to collapse?

• A. Pneumothorax
• B. Open Pneumothorax
• C. Pulmonary Contusion
• D. Occlusive Dressing

Answer: (A)

Air in the pleural space disrupts the lung’s negative pressure that normally keeps it inflated. When air collects there, intrapleural pressure rises toward atmospheric pressure, and the lung can no longer stay expanded, leading to collapse. That describes pneumothorax. A chest wound can allow air to enter and contribute to this condition, but the defining idea is that air in the pleural space causes the lung to collapse. Pulmonary contusion is simply bruising of lung tissue with bleeding, not air in the pleural space, so it doesn’t cause the lung to collapse in the same way. An occlusive dressing relates to sealing chest wounds and is not itself the mechanism behind a lung collapse due to air in the pleural space.