Concentration of Blood in the Extracorporeal Circuit Using Ultrafiltration

During cardiopulmonary bypass (CPB) the concentration of blood components is controlled by fluid administration and diuresis. However, diuresis is not always adequate and at the end of CPB the diluted pump blood, unless processed by expensive and cumbersome RBC saving techniques, is usually discarded. To control “diuresis” during CPB and to concentrate all blood components of the diluted pump blood post CPB, we evaluated ultrafiltration as a technique to extract plasma water from the extracorporeal circuit in 17 patients. At the end of each case, the blood left in the CPB circuit was circulated through a hollow fiber dialyzer (TriEx-3, Extracorporeal). At a transmembrane pressure of 430 torr, plasma water was extracted at 29 cc/min. Extracting plasma water decreased the initial pump volume by 50% causing the initial concentration of blood components to increase as follows: hemoglobin 80%, platelets 53%, fibrinogen 79%, total protein 75%, and plasma hemoglobin 294%. Following concentration, the high activated partial thromboplastin, prothrombin and thrombin times obtained for the pump blood decreased towards normal. There were no clinically significant changes in the plasma concentration of electrolytes. The concentrated blood was transfused to the patient within 2 hours of collection without any adverse effects. As compared to the increase in hemoglobin, the smaller increase in platelets and larger increase in plasma hemoglobin indicates that the dialyser caused some platelet loss and red blood cell damage. However, the concentrated blood did provide whole blood for the patient without the risks associated with donor blood