A comparative evaluation of rotation thromboelastometry and standard coagulation tests in hemodilution-induced coagulation changes after cardiac surgery

BACKGROUND: Coagulopathy after cardiopulmonary bypass (CPB) is caused by multiple perturbations in cellular and humoral elements of coagulation. A timely and comprehensive method to evaluate hemostasis would be helpful in the management of bleeding patients after CPB. The assessment of whole blood coagulation using rotation thromboelastometry (ROTEM) was compared to coagulation tests routinely performed during cardiac surgery. STUDY DESIGN AND METHODS: Blood was obtained from 26 patients undergoing CPB surgery at baseline, at 60 minutes on CPB, at the end of CPB, and on admission to intensive care unit. ROTEM tests (extrinsically activated [EXTEM], intrinsically activated [INTEM], specific clot formation [FIBTEM]), prothrombin time, activated partial thromboplastin time, platelet (PLT) count, fibrinogen, prothrombin level, antithrombin level, and thrombin generation (TG) measurement were performed. RESULTS: We observed strong correlations between FIBTEM-amplitude at 10 minutes (A10) and fibrinogen level (r = 0.87; p < 0.001) and between EXTEM/ INTEM-A10 variables and PLT count (r = 0.72 and 0.67, respectively; p < 0.001). Receiver operating characteristic analysis demonstrated that EXTEM-A10 and INTEM-A10 are predictive of thrombocytopenia below 80 × 10 ⁹/L (area under the curve [AUC], 0.83 and 0.82, respectively), and FIBTEM-A10 was highly predictive of fibrinogen level below 200 mg/dL (AUC, 0.96). There were only weak correlations found between TG peak and clot formation time of EXTEM or INTEM (r = 0.30 and 0.29, respectively; p < 0.05). CONCLUSION: ROTEM variables demonstrated clinically relevant correlations with PLT counts and fibrinogen levels. In particular, decreasing levels of fibrinogen can be quickly determined (<15-20 min) using FIBTEM.