Pneumothorax is a collapsed lung that is caused by excessive air that leaks into the empty space between the lung and chest cavity wall. The air can push against the lung and collapse a portion or all of the lung. Pneumothorax can be caused by a chest injury, medical procedures or damage from a lung disease. Symptoms may include sudden chest pain, shortness of breath and lightheadedness. In some cases, Pneumothorax can be life threatening and may require immediate medical attention. Treatment usually includes the insertion of a flexible tube between the lung and cavity wall to remove the excess air. In less severe cases, the lung may repair itself without medical treatment.