Hydroxyethyl starch (HES) solutions compromise blood coagulation. Low molecular weight, low-substituted HES products, and electrolyte-balanced solutions might reduce this effect. We compared the effects of in vitro haemodilution on blood coagulation with a balanced 6% HES 130/0.42 solution (HES(BAL)), a saline-based 6% HES 130/0.4 solution (HES(SAL)), a balanced lactated Ringer's solution (RL) and a saline-based 4% gelatin solution (GEL). Blood was obtained from 10 healthy male volunteers and diluted with the test solutions by 33% and 66%. Quality of clot formation was measured using two viscoelastic coagulation tests: SONOCLOT and activated rotation thromboelastometry ROTEM. Of 16 parameters measured by the viscoelastic devices, we found three statistically significant differences compared with baseline for RL, but 11 for GEL, 10 for HES(SAL), and 11 for HES(BAL) in the 33% haemodilution group (P=0.01). Comparing the different solutions, we observed a significant difference between crystalloids and colloids but none between GEL and HES. In the 66% dilution group, effects on blood coagulation were increased when compared with the 33% dilution group. We found no differences in coagulation impairment between balanced and non-balanced HES products and no differences in the detection of impaired blood coagulation due to haemodilution between the two viscoelastic coagulation tests. Both ROTEM and SONOCLOT are sensitive tests for the detection of impaired blood coagulation due to haemodilution. There are fewer effects on blood coagulation using crystalloids compared with colloids. The effects of GEL and HES are similar. There is no difference between balanced HES 130/0.42 and non-balanced HES 130/0.4.
