In a study published in the Journal of Cardiothoracic and Vascular Anesthesia, researchers described the first ROTEM sigma-based algorithm for the treatment of coagulopathic bleeding and reported optimal values of ROTEM sigma (TEM International Inc) parameters.

Preliminary normal ranges for parameters of ROTEM sigma are different from the well established ROTEM delta parameters. Therefore, the investigators compared standard laboratory tests with ROTEM sigma parameters. The goal was to determine the optimal sensitivity and specificity for critical values of standard laboratory tests to detect specific hemostatic deficiencies and to establish cutoff values for the development of a treatment algorithm.

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Blood samples from 14 healthy volunteers and 35 patients with various hemostatic disorders (such as isolated factor deficiencies, von Willebrand disease, thrombocytopenia, and the like) were obtained in order to compare standard laboratory tests with ROTEM sigma parameters.

Correlation coefficients were calculated between values for standard laboratory tests and ROTEM parameters. The investigators used receiver operator characteristics to define the values of ROTEM parameters that best predicted defined thresholds for plasma fibrinogen level, platelet count, prothrombin time, and activated partial thromboplastin time.

ROTEM sigma offers 2 cartridges for different clinical situations: the “complete” cartridge, which contains test cells for intrinsic pathway activation (INTEM), extrinsic pathway activation (EXTEM), extrinsic pathway activation with platelet inhibition (FIBTEM), and extrinsic pathway activation with inhibition of fibrinolysis (APTEM); and the “complete + hep” cartridge, which contains test cells for INTEM, EXTEM, and FIBTEM as well as a cell for intrinsic activation with inhibition of heparin (HEPTEM). A parameter to describe platelet contribution to clot firmness (PLTEM) was also calculated by subtracting FIBTEM amplitude from EXTEM amplitude. Amplitudes within tests were calculated at 5 minutes (A5), 10 minutes (A10), and 30 minutes (A30).

A fibrinogen level below 1.5 g/L could be identified with 100% sensitivity and 77.5% specificity using a combination of FIBTEM A5 of 12 mm or lower and EXTEM A5 of 44 mm or lower. For a platelet count below 50 × 109/L, PLTEM A5 of 16 mm or below had sensitivity and specificity of 100% and 96.4%, respectively. The parameter of EXTEM coagulation time of more than 80 seconds had sensitivity and specificity of 25.0% and 100%, respectively, for a prothrombin time below 80%. The parameter of INTEM coagulation time of more than 204 seconds had sensitivity and specificity of 75.0% and 97.4%, respectively, for activated partial thromboplastin time greater than 37 seconds and 100% and 80.0%, respectively, for an activated partial thromboplastin time greater than 55 seconds.

Researchers described the algorithm as using “parameters with optimal sensitivity and specificity for critical values of standard laboratory tests calculated from a heterogenous group of healthy donors and patients” and noted that further research is warranted to improve the clinical utility of this algorithm.

Reference

1.      Scala E, Coutaz C, Gomez F, Alberio L, Marcucci C. Comparison of ROTEM sigma to standard laboratory tests and development of an algorithm for the management of coagulopathic bleeding in a tertiary center [published online November 4, 2019]. J Cardiothorac Vasc Anesth. doi:10.1053/j.jvca.2019.10.016