Abstract
BackgroundHaemodilution and hypothermia induce coagulopathy separately, but their combined effect on coagulation has not been widely studied. Fibrinogen concentrate can correct dilutional coagulopathy and has an additional effect when combined with factor XIII concentrate. However, their effect on dilutional coagulopathy concomitant with hypothermia has not been studied previously. Free oscillation rheometry – FOR (Reorox®) – is a novel viscoelastic haemostatic assay that has not been studied in this context before.MethodsBlood from 10 healthy volunteers was diluted by 33% with hydroxyethyl starch or Ringer’s acetate solutions. Effects of fibrinogen added in vitro with and without factor XIII were studied at 33°C and 37°C. Coagulation velocity (coagulation time) and clot strength (elasticity) were assessed with FOR. Coagulation was initiated in vitro with thromboplastin alone, or thromboplastin plus a platelet inhibitor.ResultsHydroxyethyl starch increased the coagulation time and decreased clot strength significantly more than Ringer’s acetate solution, both in the presence and absence of a platelet inhibitor. There was a significant interaction between haemodilution with hydroxyethyl starch and hypothermia, resulting in increased coagulation time. After addition of fibrinogen, coagulation time shortened and elasticity increased, with the exception of fibrinogen-dependent clot strength (i.e., elasticity in the presence of a platelet inhibitor) after hydroxyethyl starch haemodilution. Factor XIII had an additional effect with fibrinogen on fibrinogen-dependent clot strength in blood diluted with Ringer’s acetate solution. Hypothermia did not influence any of the coagulation factor effects.ConclusionsBoth haemodilution and mild hypothermia impaired coagulation. Coagulopathy was more pronounced after haemodilution with hydroxyethyl starch than with Ringer’s acetate. Addition of fibrinogen with factor XIII was unable to reverse hydroxyethyl starch induced clot instability, but improved coagulation in blood diluted with Ringer’s acetate solution. Fibrinogen improved coagulation irrespective of hypothermia.
Highlights
Exsanguination is the second most common cause of death in major trauma after central nervous system (CNS) injury [1,2]
The aim of our study was to investigate hypothermiaand haemodilution-induced coagulopathy measured with free oscillation rheometry, and to what extent this coagulopathy could be reversed with fibrinogen concentrate, combined with or without factor XIII (FXIII)
Our study was performed in blood from healthy volunteers, whereas trauma patients may exhibit a wide range of coagulopathies. In conclusion, this in vitro study shows that hypothermia at 33°C combined with 33% haemodilution, especially with hydroxyethyl starch in saline (HES), interact to impair coagulation variables measured with free oscillation rheometry (FOR)
Summary
Exsanguination is the second most common cause of death in major trauma after central nervous system (CNS) injury [1,2]. To maintain an adequate circulatory blood volume and oxygen carrying capacity, traumatic and surgical haemorrhages are generally initially compensated for by administrating a combination of Fibrinogen is the first coagulation factor to reach critical levels in major haemorrhage [7] and fibrinogen concentrate should be given in active bleeding when plasma levels reach 1.5 to 2.0 g/l [8]. This increases clot stability after haemodilution [9,10], reduces bleeding [11,12,13] and may improve survival [14,15]. Free oscillation rheometry – FOR (ReoroxW) – is a novel viscoelastic haemostatic assay that has not been studied in this context before
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