PHARMACOKINETICS AND ONCOTIC EFFECT OF HIGH-DOSE HYDROXYETHYL STARCH DURING SURGERY COMPARED TO APPLICATION OF 5-PERCENT ALBUMIN

Objective: Medium-molecular hydroxyethyl starch (HES) is an effective and save colloid for blood substitution up to 20 ml/kg body weight. Li ttle is known about oncotic effects, when used above this dosage. Thes e are important questions to be answered in order to replace expensive albumin application in doses above 20 ml/kg. Design: Controlled, pros pective and randomized study. Setting: Operating room of an university hospital. Patients: 40 patients with extensive urological surgery. In terventions: We treated blood loss in accordance with a blood substitu tion scheme using colloids, red cells, fresh frozen plasma, and platel ets. The HES group received 6% HES 200 0.5 and the ALB group 5% albumi n as exclusive colloid. We determined oncotic function and characteris tics of the plasmatic HES fraction before surgery, after application o f 1,000 ml, 2,000 ml and 3,000 ml of colloid, and at the end of surger y. Results: We administered a total median amount of 2,700 ml of HES ( HES group), and 2,000 ml of albumin (ALB group), which resulted in a s ignificant difference in total serum protein of 34.4 g/l (HES) vs. 56. 5 g/l (ALB) (p < 0.01) but comparable oncotic function and colloidosmo tic pressure (COP) of 18.0 mmHg (HES) vs. 18.8 mmHg (ALB) at the end o f surgery. The plasmatic HES fraction was characterized by a HES conce ntration of 6.9 g/l and an average numeric molecular weight of (median ) 51,800 Da (25-75% quantiles: 42,000-63,000 Da) and showed marked int erindividual va;iability of the HES-related oncotic effect during all points of measurement Conclusions: In a dosage above 20 ml/kg 6% HES 2 00 0.5 is able to maintain oncotic function and therefore to replace 5 % albumin during therapy of blood loss. However, the oncotic effect re vealed polydisperse expression so that our results cannot be transferr ed on high-dose administration of other HES preparations without furth er evaluations.