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Klinik für Anästhesiologie und Intensivtherapie Friedrich-Schiller-Universität Jena D-07740 Jena, Germany
To the Editor:
Knutson et al. (1) did not describe the hetastarch preparation used adequately. The average molecular weight, distribution of molecular weight, and the degree and pattern (C2/C6 ratio) of the substitution of hydroxyethyl starch (HES) can influence hemostasis. Treib et al. (2) investigated the effect of different HES preparations in patients suffering from vasospasm after subarachnoid hemorrhage during a 10-day intravascular volume therapy. When using a HES with an average molecular weight of 200.000, the substitution of 0.5 and a C2/C6 ratio of 6 did not lead to significant reductions in factor VIII:C or von-Willebrand-Ristocetin-Cofactor; yet, a preparation with the same average molecular weight, a degree of substitution of 0.62, and an higher C2/C6 ratio (10) caused profound reductions. In Europe, a large variety of HES solutions are available (70.000/0.5; 130.000/0.4; 200.000/0.5 [with different C2/C6 ratios ranging from 6 to 13]; 200.000/0.62; 450.000), dominated by the medium molecular weight, easily degradable HES (200.000/0.5). Thus, European colleagues may find it hard to decide whether their current practice is to be challenged by the data provided by Knutson et al. (1).
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Department of Anesthesiology Mayo Clinic Rochester, MN 55901
In Response:
I would like to thank Dr. Huettemann for his thoughtful letter to the editor. As noted by Treib et al. (1), there is only one type of hydroxyethyl starch available in the United States, whereas several hydroxyethyl starch preparations are widely used in Europe. The results of our study should only be applied to the preparation used in the United States (Hespan®, Abbott Laboratories, North Chicago, IL; average molecular weight 450,000 daltons, substitution of 0.7) or similar European preparations, because they induce a greater degree of anticoagulation than the smaller, more easily degraded hydroxyethyl starch preparations (1). Furthermore, as the anticoagulant effects of hydroxyethyl starch may potentiate the known coagulopathic state induced by cardiopulmonary bypass and exacerbate bleeding, the results of our study can only be applied to patients undergoing cardiopulmonary bypass.
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