Hydroxyethyl starch (HES), a widely used plasma volume expander, has been associated with platelet dysfunction and inhibition of coagulation. Six% HES (Molecular weight 670 kd, molar substitution 0.75) is a plasma volume expander in a physiologically balanced medium of electrolytes, lactate and glucose. The aim of this study is to evaluate the effect of 6% HES (670/0.75) on hemostasis during acute normovolemic hemodilution (ANH).

Eighteen healthy adult male patients scheduled for spine surgery were enrolled in this study. Before general anesthesia, patients underwent ANH with 20 ml/kg of 6% HES (670/0.75). Hemoglobin, platelet count, plasma fibrinogen concentration, factor VII activity, prothrombin time (PT), activated partial thromboplastin time (aPTT) and thromboelastography (TEG) were measured before and 120 minutes after the completion of ANH.

Hb, Hct, platelet, plasma fibrinogen concentration and factor VII activity decreased significantly (P < 0.05) after ANH. Compared with pre-ANH values, only maximal amplitude decreased significantly (P = 0.001) among post-ANH thromboelastographic parameters.

Except maximal amplitude, significant difference were not observed in CI (Coagulation Index) which represents general coagulation state and other thromboelastographic parameters between pre and post ANH. ANH with 20 ml/kg of 6% HES (670/0.75) didn't cause impairment of TEG parameters.