SYSTEMIC HEMODYNAMIC AND HEPATIC MICROVASCULAR RESPONSES TO A 33-PERCENT BLOOD-VOLUME EXCHANGE WITH WHOLE-BLOOD, STROMA-FREE HEMOGLOBIN, AND OXYPOLYHEMOGLOBIN SOLUTIONS

Little is known about the microvascular effects of blood replacement s olutions. This study was undertaken to develop an animal model suitabl e for studies of the microcirculatory effects of such solutions and to investigate microvascular responses to isovolemic transfusion with st roma-free hemoglobin (SFH), whole donor blood, or a new potential bloo d substitute solution containing oxypolyhemoglobin (OPH) as an oxygen carrier. Hamster livers were exposed and the microcirculation studied using intravital epifluorescent video microscopy. 33% blood volume rep lacement with SFH elevated systemic blood pressure by 25 Torr. Accompa nying this increase in pressure was a 36% decrease in sinusoidal blood flow velocity and a 10% decrease in terminal hepatic venular diameter s. Terminal portal venular diameters did not change. Decrease in liver sinusoidal perfusion was not due to neutrophil mediated injury, as my eloperoxidase activity in jejunum, liver, kidney, and lung remained un changed. The reduction in perfusion was likely due to systemic vasocon striction produced by SFH. In contrast, transfusion with whole blood d id not change any of the measured parameters showing the excellent sta bility of the model. OPH transfused animals exhibited only a small 10 Torr transient increase in MAP 15 min post-transfusion. By 30 min MAP returned to the pre-infusion value. No significant changes were observ ed in either venular diameters or sinusoidal velocities in this group of animals. These results demonstrate suitability of this model for st udies of the microcirculatory and hemodynamic effects of blood replace ment solutions. Furthermore, OPH solution produced only minor transien t disturbances in microvascular and systemic parameters.