Lung split function test and pneumonectomy. A lower limit for operability.

Regional 133Xe ventilation/perfusion studies were used to predict residual lung function after pulmonary resections. The accuracy of the method was good as checked by postoperative spirometry in 11 patients. In 25 patients with impaired lung function and pulmonary cancer, who were consecutively selected for surgery, the predicted postoperative maximal breathing capacities (MBC) ranged from 17 to 41 l/min-1 m-2. No patients became permanent pulmonary invalids. One patient died from myocardial infarction, 7 had transient pulmonary insufficiency and 17 patients survived operation without complications. Perfusion studies alone proved as reliable as perfusion/ventilation studies.