When a lung collapses, air enters the space between the lung and chest wall, known as the pleural space, and creates pressure against the lung. This pressure can cause the lung to partially or fully collapse. A collapsed lung can be caused by a blunt or penetrating chest injury, certain medical procedures, or damage from underlying lung disease. Symptoms of a collapsed lung usually include sudden chest pain and shortness of breath. Treatment for a collapsed lung usually involves inserting a needle or chest tube between the ribs to remove the excess air. In some cases, surgery may be needed to keep the lung inflated.