A new concept in autologous blood transfusion

Preserved erythrocytes have a maximum shelf life of 50 days. Cryopreservation with HES could result in unlimited storage stability with long-term availability of autologous blood. In vitro and in animals the therapeutic efficacy of HES-cryopreserved erythrocytes has been proven. This study deals with erythrocytes after repeated cryopreservation. Blood from 10 donors was cryopreserved; in each case the samples A, B and C were stored in LN2. Preserves A were examined after one single freezing/thawing-procedure, B after two and C after three procedures. The erythrocytes were analysed by morphological and biophysical means. Therefore the degree of hemolysis in hypotonic salt-solutions was measured; from that the survival rate (Sst.), the erythrocyte fragility (p50) and the homogeneity of the erythrocyte-population (tan (p50)) were determined. Nearly 90% of the erythrocytes survived the first freezing-thrawing-cycle, 72% the second and 59% the third (fig. 2). In A only normocytes were seen, in C echinocytes and acanthocytes sporadically (fig. 3–6). the membrane flexibility was normal. The p50 and tan (p50) – values worsened. Repeated freezing results in a loss of number and quality of the preserved erythrocytes. But after removing the products of hemolysis transfusion of erythrocytes, which have been frozen twice, can be seen as save! This means a useful possibility for the preservation of autologous blood of high-risk patients in cardiac surgery, either in order to satisfy an expected need for transfusion or to form a reserve without an exact date for its use.