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Efforts to produce a clinically acceptable hemoglobin solution which could function as a temporary oxygen carrier have evolved through several stages. Beginning with the simple tetramer, we have lowered the affinity state by pyridoxylation and then polymerized the modified tetramer. This new substance, polyhemoglobin, has a normal oxygen capacity and a half-life of 38 hours. Issues of nephrotoxicity and immunocompetence after infusion remain to be defined.

Polymerized pyridoxylated hemoglobin provides a means of obtaining an acellular oxygen carrier that can be infused at a normal hemoglobin concentration, with a normal COP and is stable in vivo. We have also shown that rats can survive a total exchange transfusion with poly SFH-P (Sehgal et al, 1980). It thus become a prime candidate for further in vivo assessment of its oxygen transport characteristics.

In summary, we remain optimistic about the potential value of perfluorochemicals as acellular oxygen carriers. The results of our first patient show that at an FiO2 of 1.0, Fluosol-DA was not necessary. The oxygen content of the plasma alone was adequate, although the FiO2 was at an unsafe level. At the safe FiO2 of 0.6, however, the Fluosol-DA was needed, since the oxygen content of the plasma was inadequate. Fluosol-DA was thus necessary and effective. At an FiO2 = 0.6, the total of the oxygen content of plasma and the oxygen content of Fluosol-DA was adequate. Although these results are encouraging, the temporary nature of this benefit is an important limitation. We hope that the additional data from both our clinical study and the multicenter study will help resolve some of these questions in the future.