Plasma volume expansion with solutions of hemoglobin, albumin, and Ringer lactate in sheep

We have measured plasma volume expansion (Evans blue and hematocrit changes ) and hemodynamic responses in conscious hemorrhaged and normovolemic splen ectomized sheep after a 30-min infusion of either 20 ml/kg of diaspirin cro ss-linked hemoglobin (DCLHb), 20 ml/kg of human albumin (Alb), or 60 ml/kg of a solution of Ringer lactate (RL). All regimens expanded blood volume an d increased blood pressure and cardiac output after hemorrhage. However, on ly 15 +/- 3% of the infused volume of RL was evident as intravascular expan sion 10-min postinfusion, compared with 67 +/- 16% and 139 +/- 139% for Alb and DCLHb, respectively. DCLHb infusions were associated with higher blood pressures and lower cardiac outputs compared with RL and Alb infusions, bu t the increased oxygen content of blood with DCLHb resulted in systemic del ivery of oxygen similar to that of the other infusions. These differences i n hemodynamics and vascular volume continued for 6 h, and at 24 h vascular volume and all hemodynamics were similar in all three groups. The better vo lume expansion with DCLHb may be due to greater mobilization of endogenous interstitial protein or reduced transcapillary loss as total intravascular endogenous plasma protein increased after infusion of DCLHb, whereas there was an apparent loss of endogenous intravascular protein after infusions of Alb and RL. Vasoconstriction by DCLHb is one mechanism that could lower bl ood-to-tissue transport of fluid and protein. In addition to its oxygen-car rying capacity and vasoactivity, DCLHb is associated with volume expansion properties out of proportion to its colloid osmotic pressure.