RESUMO
OBJECTIVE: To compare survival after exchange transfusion followed by hemorrhage using: 1) the vasoactive, oxygen-carrying, bovine hemoglobin-based blood substitute Oxyglobin (Biopure, 12.9 g hemoglobin/dL); and 2) the hydroxyethyl starch plasma expander Hextend (high molecular weight and low degree of substitution, 6%). DESIGN: Comparison between treatments. SETTING: Laboratory. SUBJECTS: Awake hamster chamber window model. INTERVENTIONS: Fifty percent blood volume exchange transfusion followed by a 60% hemorrhage over 1 hr, followed by 1 hr of observation. Measurement of blood gases, mean arterial blood pressure, functional capillary density, arteriolar and venular diameter, and Po2 tension distribution. MEASUREMENTS AND MAIN RESULTS: Survival with Oxyglobin was 100% and only 50% for the Hextend group. Vasoconstriction was evident in the microcirculation. Mean arterial pressure was higher in the Oxyglobin group. Functional capillary density was significantly reduced, although to a lesser extent by Oxyglobin. There was no difference in microvascular Po2 distribution after 1 hr of shock between groups. CONCLUSIONS: Higher mean arterial pressure during the initial stages of hemorrhage could be due to vasoconstriction in the Oxyglobin group as compared to the Hextend group. It is concluded that the pressor effect due to a vasoactive oxygen carrier may be beneficial in maintaining perfusion in conditions of severe hemodilution followed by hypovolemia.