Low- and medium-molecular-weight hydroxyethyl starches - Comparison of their effect on blood coagulation

Background: High-molecular-weight hydroxyethyl starch (HES) compromises blo od coagulation more than medium-molecular-weight HES. The authors compared medium molecular weight HES (200 kd [HES200]) and low-molecular-weight HES (70 kd [HES70]). Methods: In a prospective, double-blind, randomized-sequence crossover stud y, 22 male volunteers received 15 ml/kg HES200 and HES70. Blood samples wer e taken before and 5 min, 30 min, 1 h, 2 h, 4 h, 8 h, and 24 h after Infusi on. The following parameters were analyzed at all time points: prothrombin time, activated partial thromboplastin time, fibrinogen, factor VIII, antig enetic and functional von Willebrand factor, platelets, Thrombelastograph(R ) analysis parameters (reaction time, coagulation time, maximum amplitude, angle cu, and clot lysis 30 and 60 min after maximum amplitude), ionized ca lcium, hematocrit, HES plasma concentration, molecular weight (R eight aver age and number average), molar substitution, and polydispersity (weight ave rage/number average). Repeated-measures analysis of variance (P < 0.05) was used to compare the response of the aforementioned parameters to the infus ion of HES70 and HES200. Results: Both HES solutions had a significant impact on all parameters. A s lightly greater compromise with HES200 was found in activated partial throm boplastin time (P = 0.010), factor VIII (P = 0.009), antigenetic von Willeb rand factor (P = 0.041), functional von Willebrand factor (P = 0.026), maxi mum amplitude (P = 0.008), and angle ly (P = 0.003). No difference was esta blished with the other parameters, HES concentration (P < 0.001), weight av erage (P < 0.001), number average (P < 0.001), and polydispersity (P < 0.00 1) were higher with HES200. There was no difference with molar substitution (P = 0.091). Conclusions: Low-molecular-weight hydroxyethyl starch (70 kd) compromises b lood coagulation slightly less than HES200, but it is unclear whether this is clinically relevant.