Quantification of Both Platelet Count and Fibrinogen Concentration Using Maximal Clot Firmness of Thromboelastometry during Liver Transplantation

Background Rotation thromboelastometry (ROTEM®) is increasingly used in liver transplantation (LT). Of the ROTEM® parameters, maximum clot firmness (MCF) of EXTEM (MCF_EXT) and INTEM (MCF_INT) are influenced by both platelet count (PLT) and fibrinogen concentration (FIB), whereas MCF of FIBTEM (MCF_FIB) is solely influenced by FIB. We aimed to determine whether using MCFs of thromboelastometry could reliably predict both PLT and FIB and to evaluate their relations in patients with thrombocytopenia and hypofibrinogenemia during LT. Methods A total of 4100 retrospective ROTEM® assays with simultaneous standard laboratory tests performed during LT were analyzed in 295 patients. The optimal cut-off values of PLT and FIB according to the ROTEM® transfusion guideline were determined by area under the curve (AUC) of receiver operating characteristic (ROC) curve analysis. Results MCF_EXT and MCF_INT showed good correlation with platelet count (r = 0.79 and 0.80, respectively, P <.001) and with fibrinogen concentration (r = 0.67 and 0.66, respectively, P <.001). MCF_FIB and fibrinogen concentration were highly correlated (r = 0.84, P <.001). Additionally, PLT and FIB were calculated mathematically: PLT (/μL) = 14827 + 3.93 (MCF_EXT)^2.5; FIB (mg/dL) = 63 + 0.00082 (MCF_EXT)^3.0; FIB (mg/dL) = 29 + 13.3 MCF_FIB. MCF_EXT <35 mm predicted PLT of 43 × 10³/μL (AUC = 0.89) and FIB of 91 mg/dL (AUC = 0.78), whereas MCF_EXT <45 mm predicted PLT of 52 × 10³/μL (AUC = 0.89) and FIB of 121 mg/dL (AUC = 0.86), MCF_FIB <8 mm predicted FIB of 128 mg/dL (AUC = 0.94). MCF_INT showed almost the same cut-off values as MCF_EXT. Conclusions Both PLT and FIB can be reliably quantified by MCFs of thromboelastometry, reducing the needs for additional laboratory tests to know values of thrombocytopenia and hypofibrinogenemia in patients undergoing LT.