In vitro Influence of Fibrinogen and Factor XIII on Viscoelastic Characteristics of Clot Formation under Hypothermia and Acidosis

Abstract

platelets and coagulant proteins such as fibrinogen. Furthermore, fibrinogen is affected by dilutional coagulopathy. It is the first coagulation factor that decreases in trauma associated dilution coagulopathy [6,7]. Intensified blood loss during coagulopathy can occur when fibrinogen deficiency is combined with reduced levels of FXIII, a transglutaminase that improves clot firmness by crosslinking of fibrin monomers [8,9]. Previous studies showed an improvement of platelet function as well as overall clot firmness during hypothermia and acidosis by administration of fibrinogen [10,11] and suggested a higher survival rate in an animal model [12]. An effect of additional administration of FXIII under such circumstances has not been examined to date. Thus we tested fibrinogen and FXIII in a model of hypothermia and acidosis on viscoelastic effects on clot formation in vitro as assessed by rotation thromboelastometry. Materials and MethodsThe study was approved by the local ethic committee and was conducted according to the Helsinki Declarations and European Unions Convention on Human Rights and Biomedicine. 10 healthy volunteers were included into the study after oral and written informed consent. All volunteers were free of coagulation affecting medication or bleeding disorders.Blood samples were drawn from a cubital vein using an 18 gauge cannula. The first 5 ml were discarded. 21 ml were collected into 7 citrated tubes (Sarstedt AG & Co, Nümbrecht, Germany). Fibrinogen and FXIII levels were determined in the local standard laboratory (Fibrinogen: Dade ® Thrombin Reagent FXIII: Berichrom ® FXIII; both Siemens Healthcare Diagnostics, Marburg, Germany; both measured on a SYSMEX CS-2100i, SYSMEX GmbH, Norderstedt, Germany). Samples for rotation thromboelastometry were prepared according to a protocol which is displayed in table 1.