The types of surgery performed and anatomical location of the surgery are major determinants of risk factors in the development of postoperative pulmonary complications. The greatest complications are found with surgery to the thorax and upper abdomen, with additional considerations for resection of the lung for any reason. The types of surgery most commonly associated with complications are discussed. The pulmonary complication rate after surgery to the upper abdomen is as great as 20%, which is significantly more than that of surgery to the lower abdomen. By causing injury to the thoracic muscles, thoracotomy decreases the compliance of the chest wall, reducing the vital capacity and predisposing the patient to alveolar hypoventilation and hypoxemia.