Thoracic surgery can result in several common complications, including pneumothorax, atelectasis, pulmonary edema, atrial fibrillation, hemorrhage, respiratory failure, and infection. Pneumothorax involves an abnormal collection of air in the pleural space that causes separation of the lung from the chest wall. Atelectasis is a complete or partial collapse of the lung caused by deflation of the tiny air sacs. Pulmonary edema occurs when excess fluid collects in the lungs, making breathing difficult. [/SUMMARY]