Mathematical, Physical, and Computational Principles of Rotational Thromboelastometry

Rotational thromboelastometry (ROTEM) is a viscoelastic assay used to evaluate whole blood coagulation dynamics in clinical settings. Despite its utility, commercial ROTEM analyzers operate as proprietary systems, obscuring the mechanical and computational algorithms that translate clot formation into viscoelastic amplitude. This opacity limits mechanistic research and educational applications. We present a transparent, open-source computational framework that models the biochemical and mechanical principles of rotational thromboelastometry. A reduced-order ordinary differential equation (ODE) system was developed to simulate thrombin generation, fibrin polymerization, fibrinolysis, and platelet activation. Biochemical states were mapped to viscoelastic amplitude using an additive Clot Elasticity (CE) transformation, incorporating a fibrin scaffold gate to ensure biomechanical fidelity during lysis. The model was integrated numerically using a stiff solver (LSODA) with strict mass conservation tolerances. Simulated assays (EXTEM, FIBTEM, APTEM) were calibrated against clinical reference ranges and validated phenotypically. The framework accurately reproduces normal clotting times and maximum clot firmness. Perturbations of initial state variables successfully simulate hypofibrinogenemia, thrombocytopenia, and the lethal hyperfibrinolytic phenotype. The APTEM assay simulation correctly reverses hyperfibrinolytic decay via plasmin inhibition. This monograph and its computational implementation provide a mathematically rigorous, open-source laboratory for investigating viscoelastic coagulation testing.Disclaimer: This document is a preprint. It has not yet been peer-reviewed by a scientific journal and should be regarded as an independent, open-source computational framework. The mathematical models and clinical simulations presented herein are intended for educational and research purposes only and are not a substitute for professional clinical judgment or proprietary medical device software.