Perioperative volume effect of HES 120/0.7 compared with dextran 70 and Ringer acetate

Hydroxyethyl starch 120 (HES 120/0.7, Plasmafusin) is the smallest medium molecular weight HES preparation used as a plasma substitute for all clinical purposes. We compared the volume and colloid osmotic effect of 6% HES 120 with 6% dextran 70 and Ringer's solution during and after surgery with minimal blood loss. Patients (n = 48) having general anaesthesia were randomly divided into six groups. A thirty-minute bolus infusion was started at the induction of anaesthesia, and thereafter the infusions were continued at two different rates for five hours. The volume of the bolus was 10% and 30% of the calculated volume (CPV) in colloid and Ringer groups, respectively. The constant infusion rates were 2% and 6% of the CPV for the colloids, and 10% and 20% for the two Ringer groups. Blood samples for the measurement of serum proteins and colloid osmotic pressure (COP) were obtained before induction, after the bolus, and thereafter hourly throughout the study. Albumin, prealbumin and total serum protein concentrations were used to calculate relative plasma volumes. After the bolus infusion, plasma volumes increased significantly in all six groups and the increments were sustained throughout the study. At the lower infusion rates of the volume changes of HES and Ringer groups were almost identical and comparable to dextran group up to the third floor. At the higher infusion rates, dextran 70 produced greater plasma volume expansions than HES 120, and the volume effect of Ringer's solution was clearly exceeded by both colloids. The hourly estimated half-lives of dextran were constantly longer compared with HES. With both infusions rates the COPs of dextran and HES groups were higher compared with Ringer groups. There were no differences in COP between the dextran and HES groups. It is concluded, that in this clinical setting the volume effect of 6% dextran 70 exceeds that of the HES 120/0.7, and that both colloids are superior to Ringer's solution.