3. Internationales Symposium: „Autologe Transfusion - Von der Euphorie zur Ratio: Praktisches Handeln aus wissenschaftlicher Sicht” (Teil IV)Künstliche Sauerstoffträger: Hämoglobinlösungen - Stand 2004

Abstract

Because of an impending shortfall of allogeneic blood products within the next decades and ongoing problems such as transfusion reactions, immunomodulating side effects and the risk of bacterial, viral and prion transmission associated with relevant costs for testing and storage of banked RBC units which, additionally, suffer from aging processes, the development of alternatives has been intensified during the last 15 years. Modern chemically modified hemoglobin-based oxygen carriers (HBOC) are free of red blood cell membrane remnants eliminating renal toxicity, and they do not possess AB0 antigens which allows transfusion without knowledge of the respective blood group of a patient. Bovine polymerized cell-free hemoglobin can be stored at room temperature for three years. In contrast to the perfluorocarbon solutions, HBOC can be applied at room air oxygen concentrations. Animal experiments have shown that HBOC can compensate for intravascular volume deficits in hemorrhagic shock, including restoration of colloid osmotic pressure and organ perfusion, and deliver oxygen to organs and tissues during nearly complete blood exchange. Chemical modifications of HBOC are able to reduce the vasoconstrictive side-effect of HBOC which is caused by NO scavenging. In spite of vasoconstriction the increased oxygen extraction in presence of HBOC in combination with the plasmatic oxygen transport provides enhanced tissue oxygenation even in post-stenotic tissues. HBOC seem to improve the diffusive oxygen transport at the microcirculatory site thus decreasing tissue damage in acute pancreatitis and the heart and brain after ischemia/reperfusion injury. Clinical studies have shown that the peri-operative use of different HBOC (Hemopure, PolyHeme, Hemolink and HemAssist) can reduce the number of allogeneic RBC units and increase the avoidance rate of allogeneic transfusion in emergency bleeding, vascular, cardiac and non-cardiac surgery. Polymerized HBOC appear to have a lower potential of side effects in comparison to intra-molecularly cross-linked preparations. However, HBOC-201 (Hemopure) is the only substance which has been licensed for the treatment of patients with acute peri-operative anemia in South Africa until now.