Abstract: In a separation device for separation of blood into its components, the hematocrit value of the blood to be separated plays a significant role relative to the sedimentation of cellular blood components. Since in blood processing, particularly in the intraoperative area, significant fluctuations of the incoming hematocrit value may occur, for example, due to infused volume expander, irrigation solutions, anticoagulant additives, etc., it is useful for maintenance of a blood separation working with constant values, particularly a constant hematocrit value of the erythrocyte fraction, to take the preset hematocrit value of the blood to be separated into account. According to the invention, the rate of blood flow through the separation device is automatically adjusted as a function of the hematocrit value of the incoming blood.

Abstract: The invention concerns a process and a device for more efficiently obtaining a highly pure fraction of thrombocytes during density centrifugation of blood, which no longer has to be filtered before infusion into a patient for leukocytes contained therein, in order to prevent immunization of the recipient. The invention is based on a two-stage density separation, wherein in a first stage a separation is made between cells and thrombocyte-rich plasma, and the thrombocyte-rich plasma is not separated into a thrombocyte concentrate and thrombocyte-poor plasm until a second stage. During the first separation, the position of the phase boundary is changed cyclically in the first separation stage. Through alternating the phase boundary in the first stage, it becomes possible for the first time in the second stage to obtain highly pure thrombocyte concentrations with minimally low leukocyte contamination from the transferred thrombocyte-rich plasma without loss of efficiency.