ABSTRACT
Since the beginning of this century, a few biopolymers have been used as basic materials for volume substitution. Aside from gelatin and dextran, modified starch (hydroxyethyl starch, HES) is currently the first-choice means. Due to special manufacturing processes, different hydroxyethyl starches are now available. They have several different characteristics and produce different clinical effects. These clinical properties depend on the average molecular weight and the distribution of molecular weight as well as on the degree and pattern of substitution. The duration of volume effect, one of the most important parameters for the effectiveness of a volume substitute, depends to a large degree on the substitution. Elimination of HES from serum is delayed by a high degree of substitution and a high C2/C6 ratio of the substitution pattern. The molecular parameters of HES also influence other effects, such as cumulation in various organs and hemostasis. Critical reading of current HES literature shows that many questions still have to be answered. At the same time ways and means of optimizing differential volume substitution therapy and hemodilution therapy are emerging.
