Comparison of Whole Blood Fibrin-Based Clot Tests in Thrombelastoraphy and Thromboelastometry

BACKGROUND: Fibrin-based clot firmness is measured as maximum amplitude (MA) in the functional fibrinogen (FF) thrombelastographic assay and maximum clot firmness (MCF) in the FIBTEM thromboelastonnetric assay. Differences between the assays/devices may be clinically significant. Our objective was to compare clot firmness parameters through standard (FE on a thrombelastography device [TEG (R)]; FIBTEM on a thromboelastometry device [ROTEM (R)]) and crossover (FE on ROTEM (R); FIBTEM on TEG (R)) analyses. METHODS: Whole-blood samples from healthy volunteers were subjected to thrombelastography and thromboelastometry analyses. Samples were investigated native and following stepwise dilution with sodium chloride solution (20%, 40%, and 60% dilution). Samples were also assessed after in vitro addition of medications (heparin, protamine, tranexamic acid) and 50% dilution with hydroxyethyl starch, gelatin, sodium chloride, and albumin. RESULTS: FE produced higher values than FIBTEM, regardless of the device, and TEG (R) produced higher values than ROTEM (R), regardless of the assay. With all added medications except heparin 400 U/kg bodyweight, FE MA remained significantly higher (P < 0.05) than FIBTEM MCF, which was largely unchanged. FF MA was significantly reduced (P = 0.04) by high-dose heparin and partially restored with protamine. Fifty percent dilution with hydroxyethyl starch, albumin, and gelatin decreased FIBTEM MCF and FE MA by >50%. CONCLUSIONS: These results demonstrate differences when measuring fibrin-based clotting via the FE and FIBTEM assays on the TEG (R) and ROTEM (R) devices. Point-of-care targeted correction of fibrin-based clotting may be influenced by the assay and device used. For the FF assay, data are lacking. (Anesth Analg 2012;114:721-30)