The effects of haemodilution with succinylated gelatin solution on coagulation in vitro as assessed by thromboelastometry and impedance (multiple electrode) aggregometry.

We investigated the in vitro viscoelastic changes of progressive haemodilution with succinylated gelatin (SG) solution compared with normal saline (NS) using rotational thromboelastometry (ROTEM®). Whole blood (WB) samples obtained from 20 healthy volunteers were diluted in vitro with SG solution or NS by 10%, 20% and 40%. Fibrinogen concentration and ROTEM (EXTEM, FIBTEM) variables including coagulation time (CT), clot formation time (CFT), α-angle, and maximum clot firmness (MCF) were measured in the undiluted sample and at each degree of haemodilution. Haemodilution with SG decreased FIBTEM MCF by 34.8% at 20% dilution (SG 20% haemodilution mean 9.1 [standard deviation, SD 2.7] mm versus WB, mean 13.9 [SD 3.4] mm) whereas this was observed only at 40% haemodilution with NS (mean 8.5 [SD 2.7] mm, 38.7% decrease). We found that 40% haemodilution with SG slowed clot formation (EXTEM CFT; SG 40%, mean 179 [SD 39] seconds versus WB mean 87.9 [SD 13.7] seconds; increased CFT by 103%), reduced clot strength by 23.5% (EXTEM MCF; SG 40% mean 47.7 [SD 3.4] mm versus WB mean 62.4 [SD 2.5] mm), and decreased fibrin formation (FIBTEM MCF; SG 40% mean 5.8 [SD 1.6] mm versus WB mean 13.9 [SD 3.4] mm); 58.4% decrease). The platelet contribution to clot strength (EXTEM MCF-FIBTEM MCF) was not changed by SG. We found that haemodilution of more than 20% with SG impaired coagulation greater than that observed with NS haemodilution in this in vitro study. This suggests that at 40% haemodilution with SG, a clinical scenario that could occur during resuscitation of a patient in grade IV haemorrhagic shock, impaired coagulation could occur. Frequent monitoring of coagulation is advised when SG solutions are administered rapidly during volume resuscitation.