The in vitro effects of fibrinogen concentrate, factor XIII and fresh frozen plasma on impaired clot formation after 60% dilution.

BACKGROUND: Previous investigations have shown that increasing fibrinogen concentration improves dilution-dependent impairment of clot formation. We conducted an in vitro study to explore whether substitution with fibrin-stabilizing factor XIII (FXIII) combined with fibrinogen promotes further improvement of clot formation, and whether fibrinogen administration as concentrate or fresh frozen plasma (FFP) results in comparable effects. METHODS: Blood from six healthy donors was diluted by 60% using lactated Ringer's solution. Aliquots of diluted blood samples were incubated with two different doses of fibrinogen concentrate, FXIII concentrate, the combination of both, or with two different doses of FFP. Using thrombelastometry (ROTEM) blood samples were analyzed at baseline (undiluted), after dilution and after supplementation. Variables were analyzed for changes from baseline, and effects of fibrinogen concentrate alone or combined with FXIII were compared with effects observed with corresponding FFP doses. RESULTS: After 60% in vitro dilution of blood all ROTEM parameters and global coagulation tests changed significantly. Among the substitutes tested FXIII alone had no effect, the combination with fibrinogen improved coagulation time, alpha angle and fibrinogen/fibrin polymerization significantly more than did small-dose fibrinogen alone. After substituting fibrinogen, median values of all ROTEM variables were within the normal range, thereby showing dose dependency but also significant differences (P = 0.027) from corresponding FFP doses (EXTEM MCF FFP small dose [38 (35, 40.3) mm)], which enabled only coagulation time to be shortened to baseline levels. CONCLUSIONS: Supplementation of fibrinogen restored all ROTEM parameters after dilution. This effect was partially enhanced by adding FXIII and was significantly stronger than for FFP substitution.

The effect of fibrinogen substitution on reversal of dilutional coagulopathy: an in vitro model.

Colloids and crystalloids are usually administered as treatment for hypovolemia in severely injured patients. However, dilution of clotting factors and platelets together with impaired fibrinogen polymerization are associated with fluid therapy and may aggravate hemorrhage, thus worsening final outcome of these patients. We investigated, in an in vitro model, whether the addition of fibrinogen to diluted blood samples can reverse dilutional coagulopathy. Blood from 5 healthy male volunteers was diluted by 60% using lactated Ringer's solution, 4% modified gelatin solution, or 6% hydroxyethyl starch 130/0.4, as well as the combination of lactated Ringer's solution with either of the 2 colloid solutions. Thereafter, aliquots of diluted blood samples were incubated with 3 different concentrations of fibrinogen (0.75, 1.5, and 3.0 mg/mL). Measurements were performed by modified thrombelastography (ROTEM; Pentapharm, Munich, Germany). After 60% dilution, clotting times increased, whereas clot firmness and fibrin polymerization decreased significantly. After administration of fibrinogen, clotting times decreased and clot firmness, as well as fibrin polymerization, increased in all diluted blood samples. The effect of in vitro fibrinogen substitution on ROTEM variables was dependent on the fibrinogen dosage and the type of solution used to dilute the blood samples.