Analysis of Thromboelastography, PT, APTT and Fibrinogen in Intraosseous and Venous Samples : An Experimental Study

Background:Laboratory analysis of coagulation is often important in emergencies. If vascular access is challenging,intraosseous catheterization may be necessary for treatment. We studied the analysis of coagulation parameters inintraosseous aspirate during stable conditions and after major haemorrhage in a porcine model.Methods:Ten anesthetized pigs received central venous and intraosseous catheters and samples were taken foranalysis of thromboelastography (TEG), prothrombin time (PT), activated partial thromboplastin time (APTT) andfibrinogen concentration. Analyses were repeated after removal of 50 % of the calculated blood volume andresuscitation with crystalloid. Intraosseous and venous values were compared.Results:Bleeding and resuscitation resulted in haemodilution and hypotension. Median TEG reaction time wasshorter in intraosseous than in venous samples before (1.6 vs 4.6 min) and after (1.6 vs 4.7 min) haemodilution.Median maximal amplitude was smaller in intraosseous samples at baseline (68.3 vs 76.4 mm). No major differenceswere demonstrated for the other TEG parameters. The intraosseous samples often coagulated in vitro, makinganalysis of PT, APTT and fibrinogen difficult. After haemodilution, TEG maximal amplitude andα-angle, andfibrinogen concentration, were decreased and PT increased.Discussion:The intraosseous samples were clinically hypercoagulable and the TEG demonstrated a shortenedreaction time. The reason for this may hypothetically be found in the composition of the IO aspirate or in thesampling technique. After 50 % haemorrhage and haemodilution, a clinically relevant decrease in fibrinogenconcentration and a lower TEG maximal amplitude were observed.Conclusions:Although the sample is small, these data indicate that intraosseous samples are hypercoagulable,which may limit their usefulness for coagulation studies. Major haemodilution only moderately affected the studied parameters