Prevention of Excess Hemolysis During Cardiopulmonary Bypass by the Use of Mannitol

tracorporeal eirculation has been ob-served in about three of every 100 unselected cases.1, 2 The occurrence of hemoglobinuria, jaundice and indirect bilirubinemia suggested to us that hemolysis in excess of that normally expected might be contributing significantly to this problem. All of the cases in one series' uinderwen-it operations involving the aortic valve that required extracorporeal eirculatorv suipport exceeding two hours. Although pump hemolysis was investigated extenisively during the early phase of open-heart surgery,3 reappraisal was deemed im-portant in light of recent improvements in operative technique4 which have led to the use of longer periods of cardiopulmonary by-pass. It was during this reappraisal that a correlation between plasma hemoglobin con-centration and renal shutdown was docu-mented. ' This was considered of sufficient importance for us to undertake a systematic plan to reduce plasma hemoglobin concentra-tion. Attempts to decrease red cell trauma by changing blood collectioni techniques and/or containers were unsuccessful. More recently, the production of an osmotic diuresis during the time of bypass has giveu promising results. Methods Ten ml. of heparinized blood was drawn into siliconized syringes. Samples were taken either from the patients ' indwelling venous catheters or, at 15-minute intervals, from the heart-lung ma-chine, depending on the stage of the operation. After 15 minutes of centrifugation, the plasm