The effect of in vitro hemodilution with gelatin, dextran, hydroxyethyl starch, or Ringer's solution on Thrombelastograph (R)

To determine the effects of progressive in vitro hemodilution with various plasma substitutes on whole blood coagulation, blood was obtained from six healthy volunteers. The Thrombelastograph(R) (TEG; Haemoscope Corp., Morton Grove, IL) variables of reaction time, coagulation time, maximum amplitude , and growth angle were determined. The following plasma substitutes were t ested: two gelatin solutions (4% gelatin polysuccinate and 5.5% oxypolygela tin); two dextrans (10% dextran 40 and 6% dextran 60); and five hydroxyethy l starch (HES) preparations (6% HES 70/0.5-0.55, 3% HES 200/0.5, 6% HES 200 /0.5, 10% HES 200/0.5, and 6% HES 450/0.7). Ringer's solution was also test ed to assist analyzing the intrinsic effect of colloid molecules on blood c oagulation. The dilution ratios of citrated blood volume to plasma substitu te volume were 10:2, 10:4, and 10:10. Blood coagulation was affected by pla sma substitutes when the dilution ratios of citrated blood volume to colloi d solution volume were 10:4 and 10:10. TEG variables did not change signifi cantly after ill vitro hemodilution with lactated Ringer's solution. The te sted gelatin solutions showed less intrinsic effect on blood coagulation th an other plasma substitutes. All HES preparations showed similar intrinsic effects as 6% dextran 60. The plasma substitute of 10% dextran 40 had the s trongest effect on coagulation. Coagulation time was the most markedly affe cted TEG variable. Blood coagulation may be compromised when the dilution r atio of blood volume to colloid solution volume is >10.4. Whereas gelatin s olutions have less intrinsic effect on blood coagulation, 10% dextran 40 ha s the strongest effect on coagulation. Implications: Blood coagulation may be compromised when the dilution ratio of blood volume to colloid solution volume is >10.4. Whereas gelatin solutions have less intrinsic effect on bl ood coagulation than hydroxyethyl starch or dextran, 10% dextran 40 has the strongest effect on coagulation.