Characterization of a Modified, Stroma-Free Hemoglobin Solution as an Oxygen-Carrying Plasma Substitute

A new infusion solution prepared from stroma-free, crosslinked and pyridoxalated hemoglobin is described. The characteristics of which have been adapted to the functions of native, intra-erythrocyte hemoglobin. The solution contains 8.5 per cent weight per volume of glutardialdehyde modified hemoglobin with a mean molecular weight (Mn) of 200,000 Dalton. The non-crosslinked fraction constitutes 15 per cent of the total hemoglobin. The p50 of 27 torr at pH 7.4 (plasma pH) corresponds to the value for the intra-erythrocyte hemoglobin at pH 7.25. The oncotic pressure is adjusted to 28 torr by the addition of 2.5 per cent weight per volume of human albumin. The methemoglobin content is less than 5 per cent of the total hemoglobin and remains constant for one year. The relative viscosity of the 8.5 per cent hemoglobin solution is 3.0 and, thus, is lower than the viscosity of blood. The intravascular half-life was determined in chimpanzees as about 16 hours. On the basis of available data, this hemoglobin solution may be suitable for clinical use as oxygen carrying plasma substitute.