Which symptom set best matches pneumothorax?

• A. Sudden chest pain with dyspnea and subcutaneous emphysema
• B. Coughing fits with a "whooping" sound and fever
• C. Barrel chest, pursed-lip breathing, cyanosis, and dyspnea on exertion
• D. High fever, drooling, stridor, and tripod position in a child

Answer: (A)

Pneumothorax happens when air enters the pleural space and separates the lung from the chest wall, causing the lung to partially or completely collapse. The most characteristic presentation is a sudden onset of sharp, often pleuritic chest pain accompanied by shortness of breath. Air escaping into the tissues can track under the skin, producing subcutaneous emphysema that may be felt as a crackling sensation or seen as crepitus in the chest wall or neck. This combination of abrupt chest pain, dyspnea, and possible subcutaneous emphysema lines up best with pneumothorax.

The other symptom clusters point to different conditions: whooping cough shows paroxysmal coughing with a distinctive sound and fever; COPD-related symptoms include a barrel chest with pursed-lip breathing and dyspnea on exertion; a child with high fever, drooling, stridor, and a tripod stance suggests an upper airway infection like epiglottitis or croup.