In order to evaluate the importance of red cell O(2) affinity of transfused blood on cardiac performance and adverse effects of transfusion on lung function, a prospective double-blind protocol was used in 27 patients undergoing abdominal aortic aneurysmectomy. Three types of blood were administered: packed red cells (PC), washed red cells (WC) and high 2,3 DPG red cells (2,3 DPG). An average of 4.5 units of blood was used per patient. Transfusion of 2,3 DPG blood resulted in maintenance of in vivo P(50) during surgery and an increase to 31.2 torr after operation (p < 0.001). An intraoperative fall in in vivo P(50) to 23.2 +/- 2.0 torr was observed in patients who were transfused with PC (p < 0.001) and to 25.1 +/- 2.6 torr with WC (p < 0.005). A fall in body temperature averaging 2.2 C intraoperatively was noticed in all three groups. After operation, in vitro P(50) decreased in patients transfused with PC (p < 0.005) and WC (p < 0.005) while it remained unchanged in the high 2,3 DPG group. This was consistent with the decrease of red cell 2,3 DPG in the PC (p < 0.001) and WC groups (p < 0.01) and maintenance in the 2,3 DPG group. Left ventricular stroke work and volume loading Starling type myocardial performance curves were similar for the three groups. Microaggregates measured by Coulter counting and screen filtration pressure were the same for all three products in samples drawn on both sides of the 40 microm transfusion filter. There was no relationship of transfusion volumes or type of blood product to changes in lung function (physiologic shunting, dynamic compliance and pulmonary arterial pressure) in the three groups of patients. The false negative, beta, error of missing a true 25% difference was less than 10%. It is concluded that 2,3 DPG enriched red cells improved oxygen availability, but that a 4.5 unit transfusion of any of the three blood products did not influence lung function or myocardial performance following aneurysmectomy.