Blood conservation in cardiac operations. Cell separation versus hemofiltration.

The effects of hemoconcentration performed during and after extracorporeal circulation by either centrifugation (cell separation group, n = 20) or hemofiltration (n = 20) were investigated in 40 patients undergoing elective aorta-coronary bypass grafting. Interest was focused on the quality of the blood concentrated from the blood remaining in the extracorporeal circuit and on the reaction of the patients after retransfusion of the concentrated products. Hemofiltration was easy to perform and produced whole blood quicker than the cell separation technique. Coagulation studies revealed no significant differences in heparin concentration, levels of fibrinogen and antithrombin III, or platelet counts. Various coagulation parameters tended to normalize completely and more quickly after hemofiltration than after centrifugation. None of the patients had severe bleeding postoperatively. Free hemoglobin levels were not affected by hemofiltration; elastase concentration was higher only immediately after retransfusion of the concentrated blood, with no effect on organ function. We conclude that both methods were effective means of hemoconcentration during extracorporeal circulation and in salvaging the diluted pump blood after extracorporeal circulation. Loss of plasma fraction is an important disadvantage in the centrifugation technique, which can be avoided by hemofiltration; derangement in colloid osmotic pressure and coagulation parameters was less pronounced after hemofiltration. Costs were lower, as well. Therefore, when a high volume of cardioplegic solution and two-stage cannulation are used, hemofiltration seems to be the method of choice for blood conservation during cardiac operations.