The ROTEM sigma whole blood viscoelastic test uses different technology than the former delta model. Existing ROTEM based algorithms use cutoff values based on the delta model, and cannot be applied to the sigma model. The authors tested sensitivity and specificity of ROTEM sigma parameters to detect specific hemostatic deficiencies and established cutoff values with the aim of developing a treatment algorithm.
Prospective observational evaluation of diagnostic accuracy.
This study was performed in a tertiary center.
Blood samples for standard laboratory tests (SLTs) and ROTEM sigma analysis were obtained from 14 healthy volunteers and 35 patients showing various hemostatic disorders (isolated factor deficiencies, von Willebrand's disease, thrombocytopenia, hypofibrinogenemia, hyperfibrinogenemia, and patients undergoing cardiac surgery).
Correlation coefficients were calculated between SLTs and ROTEM parameters in the extrinsic pathway activation, intrinsic pathway activation, and extrinsic pathway activation with platelet inhibition tests. Receiver operator characteristics defined the values of ROTEM parameters, which best predict plasma fibrinogen level measured by Clauss method <1.5 g/L and <2.0 g/L, platelet < 50 × 10 ⁹ /L and < 100 × 10 ⁹ /L, prothrombin time (PT) <80% and activated partial thromboplastin time (aPTT) >37 seconds and 1.5 times the upper normal limit.
The combination of FIBTEM A5 ≤12 mm and EXTEM A5 ≤44 mm identified a fibrinogen level <1.5 g/L with 100% sensitivity and 77.5% specificity. PLTEM describes the platelet contribution to clot firmness and is calculated as EXTEM - FIBTEM. PLTEM A5 ≤16 mm sensitivity and specificity were 100% and 96.4% for a platelet count < 50 × 10 ⁹ /L. EXTEM coagulation time (CT) >80 seconds had a 25.0% sensitivity and a 100% specificity for a PT <80%. The INTEM CT >204 seconds showed a sensitivity of 75.0% and a specificity of 97.4% for an aPTT >37 and a sensitivity of 100% and a specificity of 80.0% for an aPTT >55 seconds.
The authors present the first ROTEM sigma-based algorithm for the treatment of coagulopathic bleeding. The algorithm uses parameters with optimal sensitivity and specificity for critical values of SLTs determined from a heterogenous group of donors.