[Hemoglobin solutions: volume replacement or oxygen therapy?].

The development of haemoglobin solutions has progressed significantly in the last 15 years because of a perceived short fall in allogeneic blood within the next decades and increased concern about transmitted infectious diseases. Animal studies have shown that modern highly purified and chemically modified haemoglobin preparations are free of toxic side effects, provide adequate volume replacement and have vasoconstrictive effects that enhance systemic vascular resistance and mean arterial pressures after haemorrhage and in models of nearly complete blood replacement. Microcirculatory effects of haemoglobin-based oxygen carriers are dependent on the respective organ and species in which they are applied and on their degree of purification and chemical modification. Because of different physico-chemical properties in comparison with red cells, haemoglobin solutions provide sufficient tissue oxygenation in areas with critically restricted perfusion even when applied in small doses. First studies in volunteers and patients showed efficacy and tolerability of different newly developed haemoglobin solutions during acute normovolaemic haemodilution and in perioperative blood replacement. However, only little information exists to date in terms of metabolism of haemoglobin preparations and their potential immunogenicity and immunosuppressive side effects. Technical problems with the clinical use of haemoglobin solutions arise because of interference of plasma haemoglobin with routine laboratory tests and oximetry. Future indications for haemoglobin solutions as an oxygen therapeutic allow for application of small doses of such preparations and may help to avoid major technical problems. More clinical studies have to be undertaken to confirm the effectivity and safety of the different haemoglobin solutions and to find out the optimal indications beyond acute preclinical and perioperative blood replacement.