PULMONARY-HYPERTENSION AND SYSTEMIC VASOCONSTRICTION MAY OFFSET THE BENEFITS OF ACELLULAR HEMOGLOBIN BLOOD SUBSTITUTES

Objective: We tested the hypothesis that the pharmacologic properties of a small volume of alpha alpha-cross-linked hemoglobin (alpha alpha Hb) could effectively resuscitate pigs subjected to hemorrhage, Method s: Fourteen pigs hemorrhaged to a mean arterial pressure (MAP) of 40 m m Hg for 60 minutes were treated with a 4-mL/kg 2-minute infusion of 1 0 g/dL alpha alpha Hb or 7 g/dL human serum albumin, an oncotically ma tched control solution, Results: The removal of blood (17 +/- 1.5 mL/k g) caused the typical physiologic responses to hemorrhagic hypovolemia , Infusion of alpha alpha Hb restored mean arterial pressure and coron ary perfusion pressure, but cardiac output and mixed venous O-2 satura tion did not improve significantly, Pulmonary arterial pressure and pu lmonary vascular resistance increased markedly and were higher than ba seline levels after alpha alpha Hb. Infusion of human serum albumin pr oduced only minor hemodynamic changes, Brain blood flow did improve to baseline values after alpha alpha Hb, but was the only tissue to do s o, In the human serum albumin group, superior mesenteric artery blood flow recovered to baseline values, whereas brain blood flow did not, B lood flows to other tissues were similar in both groups, Conclusion: S mall-volume infusion of alpha alpha Hb restored mean arterial pressure and brain blood flow, but pulmonary hypertension and low peripheral p erfusion may offset benefits for trauma patients.