RESUMO
OBJECTIVE: To test the hypothesis that low-volume resuscitation with hemoglobin glutamer-200 improves hemodynamic function and tissue oxygenation, whereas arginine vasopressin resuscitation improves blood pressures more than low-volume saline or hemoglobin glutamer infusion but compromises systemic and muscle blood flow and oxygenation. DESIGN: Randomized laboratory investigation. SETTING: University research facility. SUBJECTS: Nineteen dogs. INTERVENTIONS: Dogs were instrumented to determine heart rate; arterial, central venous, pulmonary arterial, and pulmonary arterial occlusion pressures; cardiac output; and quadriceps muscle blood flow and oxygen tension (PMo2). Total and plasma hemoglobin, oxygen content, lactate, pH, standard base excess, and arginine vasopressin levels were determined, and systemic oxygen delivery (Do2I) and extraction ratio were calculated. Measurements were made before and 30 mins following hemorrhage. Dogs were resuscitated over 60 mins with saline (8.5 mL/kg), arginine vasopressin (0.4 IU/kg bolus plus 0.08 IU x kg x min), or 1:1 diluted hemoglobin glutamer-200. Recordings were then repeated. Subsequently, animals received 30 mL/kg shed blood (60 mL x kg x hr), and recordings were repeated immediately and 1 hr later. MEASUREMENTS AND MAIN RESULTS: Hemorrhage ( approximately 52 mL/kg) caused characteristic changes in hemodynamic, hematologic, systemic PMo2, and acid-base variables. Saline resuscitation increased both Do2I and muscle perfusion by 42% and 51%, while arginine vasopressin treatment reduced heart rate by 31% and increased mean arterial pressure by 22% but not cardiac output, Do2I, or muscle blood flow, resulting in a further decrease of PMo2 by 68% and worse metabolic acidosis. Hemoglobin glutamer-200 infusion caused systemic and pulmonary vasoconstriction, however, without deterioration of cardiac output, Do2I, muscle blood flow, or PMo2 despite lack of oxygen content increase. Blood transfusion restored most variables. CONCLUSIONS: Low-volume crystalloid or hemoglobin glutamer-200 resuscitation posthemorrhage may improve (but not restore) macro- and microvascular functions and tissue oxygenation, while arginine vasopressin infusion may only improve blood pressures and result in lower overall systemic perfusion compared with low-volume saline or hemoglobin glutamer-200 treatment and worsening of anaerobic conditions in skeletal muscle.