Lung volume reduction surgery (LVRS) is performed to alleviate the dyspnea of patients with emphysema and improve performance in the activities of daily living. Removing diseased and functionless lung may improve the function of remaining, less diseased lung by (1) increasing elastic recoil pressure, thereby increasing expiratory airflow rates, (2) decreasing the degree of hyperinflation resulting in improved diaphragm and chest wall mechanics, and (3) decreasing inhomogeneity resulting in decreased work of breathing and improved alveolar gas exchange. The guidelines used for patient assessment were (1) airflow limitation with a forced expiratory volume in 1 second (FEV1) less than 35%, (2) hyperinflation and air trapping with total lung capacity more than 125% and respiratory volume more than 250% predicted, and (3) regional heterogeneity of the emphysematous process providing target areas for resection. We sought to exclude patients with the following: (1) obliteration of the pleural space by previous disease or surgery, (2) severe structural abnormalities of the thoracic cage, (3) PaCo2 greater than 55 mm Hg. (4) mean pulmonary artery pressure greater than 35 mm Hg. (5) predominant airway disease such as asthma, bronchiectasis, or chronic bronchitis with persistent excessive purulent secretions, (6) significant coexisting disease, and (7) maintenance corticosteroid therapy in excess of 10 mg prednisone per day. The assessment process continues to be evaluated by analysis of patient outcome.