Theoretical analysis of effects of blood substitute affinity and cooperativity on organ oxygen transport

Hemoglobin-based O-2 carriers (HBOCs), which are developed as an alternative to blood transfusion, provide O-2 delivery. At present, there is no model to predict the O-2 transport for a red blood cellHBOC mixture on a whole organ basis. On the basis of the first principles of mass balance, a model of O-2 transport for an organ was derived to calculate venous PO2 (Pv(o2)) for a given inlet arterial PO2 (Pa-o2), blood flow, and oxygen consumption. The model was validated by using several in vivo animal studies on HBOC administration for a wide range of HBOC oxygen-binding parameters and predicted Pv(o2) for various Pa-o2 in the same species. The model was also used to predict the effect of HBOC affinity and cooperativity on Pv(o2) for humans. The results indicate that Pv(o2) can be increased at a constant blood flow-to-oxygen consumption ratio by reducing the affinity of HBOC for normoxia and mild hypoxia; however, a high-affinity HBOC would be more efficient in maintaining higher Pvo(2) for severe hypoxia (Pa-o2 < 40 Torr).