Definition
Pneumothorax is an abnormal collection of air or gas in the pleural space. Pressure in the pleural space becomes greater than pressure in the lungs, causing the affected lung to collapse partially or completely.
Hemopneumothorax: Occurs if both air and blood are present in the pleural space
Hemothorax: Collection of blood in the pleural space (Figure 1)
Tension pneumothorax: Air enters the pleural space on inspiration and does not escape on exhalation, causing the mediastinum to shift toward the unaffected lung