Letters to the Editor: Letters & Announcements
Scharbert and Kozek-Langenecker's (1) comments about our recent in vitro study (2) on the influence of different hydroxyethylstarch (HES) preparations on coagulation are correct in stating that both techniques we used to assess coagulation effects of a new balanced HES preparation may depend upon platelet count. Although low platelet count (e.g., with 50% hemodilution) may have influenced our results, this occurred in both groups! This study was not designed to measure the influence of platelet number on these in vitro coagulation monitoring techniques, but to compare two HES solutions. If there would be an error induced by low platelet count, this would have been similar in both groups.
Schabert and Kozek-Langenecker comment that in vitro studies do not always reflect the in vivo situation. They are definitely correct that some important factors are missing in in vitro studies (e.g., the endothelium). Nevertheless, there are several studies (3,4), that have been accepted in peer reviewed journals that are very similar to our study. Whether our findings can be translated to the clinical setting remains to be elucidated in large clinical studies in patients in whom varying amounts of this balanced HES preparation is administered.
Joachim Boldt, MD, PhD
Michael Wolf, MD
Andinet Mengistu, MD
Department of Anesthesiology and Intensive Care Medicine
Klinikum der Stadt Ludwigshafen
1. Scharbert G, Kozek-Langenecker S. Limitations of in vitro experiments on hydroxyethyl starch solutions. Anesth Analg 2007;105:885
2. Boldt J, Wolf M, Mengistu A. A new plasma-adapted hydroxyethylstarch preparation: in vitro coagulation studies using thrombelastography and whole blood aggregometry. Anesth Analg 2007;104:425–30
3. Fries D, Innerhofer P, Klingler A, Berresheim U, Mittermayr M, Calatzis A, Schobersberger W. The effect of the combined administration of colloids and lactated Ringer's solution on the coagulation system: an in vitro study using thrombelastograph coagulation analysis (ROTEG). Anesth Analg 2002;94:1280–7
4. Petroianu GA, Maleck WH, Koetter KP, Liu J, Schmitt A. Effect of in vitro hemodilution with hydroxyethyl starch and dextran on the activity of plasma clotting factors. Crit Care Med 2003;31:250–4