Abstract
Background: Pharmacokinetic properties of hydroxyethyl starch (HES) depend on its molecular structure. However, various medium molecular weight HES preparations with different molar substitution (MS) are used in haemodilution (HD) with identical dosage recommendations.
Objective: HES 200/0.5 and HES 200/0.62 respectively were compared with respect to their quantitative and qualitative parameters when used in hypervolemic haemodilution.
Materials and Methods: 20 patients who suffered from acute middle cerebral artery infarction were randomly assigned to hypervolemic haemodilution with either HES 200/0.5 or HES 200/0.62. Using infusion pumps, a dosage of 500ml HES/24h was administered over a period of five days. Blood samples were drawn daily and analyzed with respect to molecular weight fractions, erythrocyte aggregation and plasma Viscosity. Clinical examinations using Mathew Scale were performed on days 1, 3 and 5.
Results: 120 hours following initial HD, significantly lower HES plasma levels (p < 0.01) and plasma viscosity (p < 0.05) were measured in the HES 200/0.5 group. Erythrocyte aggregation was also found to be less pronounced in this group, however, not to a statistically significant extent.
Conclusion: “Steady state” infusion with HES 200/0.62 was followed by a higher accumulation of molecules compared to HES 200/0.5 leading to higher plasma viscosity and erythrocyte aggregation. Lower MS might thus have a more favourable influence on microcirculation. These findings, however, did not reflect statistically significant differences in clinical parameters in any HD group.
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