INCREASED HEMORRHAGIC RISK AFTER REPEATED INFUSION OF HIGHLY SUBSTITUTED MEDIUM MOLECULAR-WEIGHT HYDROXYETHYL STARCH

Infusion of large volumes of high molecular weight hydroxyethyl, starc h (HES) has been known to lead to coagulation disorders. Medium molecu lar weight starch is considered a safe alternative, even after repeate d administration. In 10 patients with cerebrovascular diseases, a 10-d ay hemodilution was carried out using 10 % HES 200/0.62. Initially, a loading dose of 500 mi was administered once over 45-60 min, followed by 500 mi maintenance dose per day for 10 days. Its high intravscular molecular weight (120,000 D) showed that cleavage of the starch is slo wed due to the higher degree of substitution. The continuous increase of HES-serum concentration to 27.7 mg/ml gave evidence of a cumulation of poorly degradable molecules. Although this caused a prolonged volu me effect, plasma viscosity and erythrocyte aggregation were influence d in an unfavourable way. The negative effects were most evident in th eir influence on the coagulation system. Under therapy, a significant 42.8 % increase (p < 0.01) in activated partial thromboplastin time oc curred. Factor VIII:C, von Willebrand ristocetin co-factor and von Wil lebrand factor antigen dropped during the therapy below the hemostasio logical limit of 30 % (p < 0.01, and in some patients below 10 %. A hi gh degree of substitution, particularly after repeated infusion, leads to a cumulation of large molecules that are difficult to break down a nd which unfavourably affect rheological and hemostasiological paramet ers.