THE VALUE OF PULMONARY FUNCTION STUDIES IN THE ASSESSMENT OF PATIENTS FOR CARDIAC SURGERY.

Preoperative pulmonary function, intracardiac pressures and degree of dyspnea were related to the incidence of postoperative respiratory insufficiency in 102 adult patients who underwent cardiac surgery. The purpose was to seek a reliable method of prognosticating the risk of postoperative respiratory insufficiency, especially after the use of cardiopulmonary bypass. When the heart-lung pump was used, 24 of 30 patients with a vital capacity less than 80% of the predicted normal developed respiratory insufficiency, whereas only eight of 41 patients with a normal vital capacity had this complication. In 26 patients where the vital capacity and gas diffusion were both normal, only three developed postoperative respiratory insufficiency. Other single or combined pulmonary function abnormalities, including tests of the mechanics of breathing, were of no greater value in predicting the postoperative course. The degree of dyspnea and the level of intracardiac pressures, although sometimes helpful, were often misleading.