Beside the necessary volume effect (isoosmotic and isooncotic solution) and the physiological bicarbonate concentration (prevention of dilution acidosis) a possible blood substitute with O2 carrier characteristics should enable an optimal O2 transport: Viscosity as low as possible and shear rate independent (Newtonian behavior), O2 concentration at the given O2 partial pressure at least 6 ml/dl, and mean capillary O2 partial pressure as high as possible. For the judgement of such a blood substitute, the so-called O2 supply index is recommended, i.e., O2 concentration times mean capillary O2 partial pressure divided by viscosity.
