We compared the effects of progressive in vitro hemodilution (30% and 60%) on blood coagulation in 80 patients receiving one of two different 6% hydroxyethyl starch (HES) solutions using thrombelastography (TEG). The newly developed solution has a mean molecular weight of 130 kD and a degree of substitution, defined as the average number of hydroxyethyl groups per glucose moiety, of 0.4 (HES 130/0.4); the conventional solution has a mean molecular weight of 200 kD and a degree of substitution of 0.5 (HES 200/0.5). Both HES solutions significantly compromised blood coagulation, as seen by an increase in reaction time and coagulation time and a decrease in angle alpha, maximal amplitude, and coagulation index (all P < 0.05). There was no difference between HES 130/0.4 and HES 200/0.5 diluted blood (P > 0.05 for all TEG variables). When analyzing the intrinsic HES effect by taking hemodilution with 0.9% saline into account, progressive hemodilution with both HES solutions resulted in an increasing clot lysis (P < 0.05 after 60 min). Again, there was no difference between HES 130/0.4 and HES 200/0.5 diluted blood. We conclude that HES 130/ 0.4 and HES 200/0.5 compromise blood coagulation to the same degree.
Implications: Progressive in vitro hemodilution using hydroxyethyl starch (HES) compromises blood coagulation. We observed similar effects of a new HES solution with a mean molecular weight of 130 kD and a degree of substitution of 0.4 (HES 130/0.4), compared with the conventional HES 200/0.5.