Effect of Hemodilution <i>in vitro</i> and <i>in vivo</i> on the Hemostatic System

Abstract

The aim of the study was to determine experimentally the effect of hemodilution by the 2:1 sterofundin/gelofusine (SG) solution on hemostatic parameters in vitro and in vivo.Material and methods. Experiments were carried out on 75 male Wistar rats weighing 270–380 g and anesthetized with intramuscular tiletamine-zolazepam (40 mg/kg) + xylazine (10 mg/kg). Animals were divided randomly into 4 groups: Group 1 — in vitro 25-percent dilution of carotid blood samples by the SG solution (n=12), Group 2 — in vitro 37.5-percent dilution of similar samples (n=11), Group 3 — in vivo 25-percent dilution (n=10), Group 4 — the controls (n=42) with no dilution. The first stage of the study compared the in vitro dilution groups with the control group and with each other; the second stage compared the in vivo dilution group with the control group. The parameters of low-frequency piezoelectric tromboelastography (LFPTEG), clotting tests and complete blood count were studied to evaluate the effect of hemodilution.Results. At a 25-percent hemodilution with 2:1 CG solution in vitro and in vivo, the hemostatic parameters retained within the reference limits, but a trend to increased intensity of the enzymatic reactions of the coagulation cascade and a significant increase in clot polymerization in vitro due to relative anticoagulant deficiency became evident. In vitro 37.5-percent blood dilution significantly reduced the blood level of fibrinogen and platelet count, inhibited the intensity of the proteolytic stage of coagulation, reduced the clot density at the T3 gelation point, at 5 minutes after reaching it and the maximum amplitude (MA) of the LFPTEG curve, as well as significantly reduced anticoagulant activity of the blood. The observed changes in hemostatic parameters were significantly outside the reference limits, which may affect the interpretation of the experimental results and be clinically important. We found negative correlation between clot density and platelet activity at 25-percent dilution in vivo, whereas at 37.5-percent dilution in vitro an additional positive correlations between platelet count and fibrinogen levels were determined.Conclusion. A 25-percent hemodilution with 2:1 CG solution should be considered «safe» for the in vivo hemostatic system providing minimal effect on the in vitro parameters in the exper-iment.

Keywords

• wistar rats
• dilutional coagulopathy
• low-frequency piezoelectric thromboelastography
• blood coagulation