Vital organ tissue oxygenation after serial normovolemic exchange transfusion with HBOC-201 in anesthetized swine

This study determined the effects of serial, normovolemic, stepwise exchange transfusions with either 6% human serum albumin (HSA) or the hemoglobin-based oxygen carrier, HBOC-201, on tissue oxygenation of the heart, brain, and kidney in intact anaesthetized pigs. Exchange transfusions to 10%, 30%, and 50% of the pigs' total blood volume were completed at a withdrawal rate of 1.0 mL·kg(-1)·min(-1) followed by an infusion rate of 0.5 mL·kg(-1)·min(-1) of HBOC-201 or iso-oncotically matched 6% HSA. Measurements included invasive systemic hemodynamic (blood pressures, left ventricular end-diastolic pressure), hematolic (hemoglobin, hematocrit, methemoglobin), acid-base (pH, PCO2), and biochemistry (serum lactate) measurements. Brain and kidney tissue oxygenation (tPO2) was determined by electron paramagnetic resonance and heart tPO2 by O2 sensitive fiberoptic probe. The main results demonstrated that tPO2 after HBOC-201 remained stable despite significant decreases in hematocrit and changing hemodynamics. In vivo tPO2 measurements (heart tPO2 average ≥22 mmHg, brain tPO2 average ≥8 mmHg, and kidney tPO2 average ≥10 mmHg) were maintained in all groups at all times. Blood pressures were 20 to 30 mmHg higher after HBOC-201 compared with HSA controls. Heart rate and left ventricular end-diastolic pressure were not different among treatment groups. In conclusion, the administration of HBOC-201 maintained tPO2 in three vital organs after profound hemodilution.