Practical application of point-of-care coagulation testing to guide treatment decisions in trauma
Despite remarkable advances in knowledge, the etiology of trauma-induced coagulopathy (TIC) is still not fully understood. Recent concepts suggest an “endogenous” TIC primarily driven by shock-associated hypoperfusion in combination with tissue trauma, which activates the protein C pathway, resulting in anticoagulation, hypofibrinogenemia, hyperfibrinolysis (HF), and platelet dysfunction.7,8 In addition, “exogenous” factors such as consumption of coagulation proteins, in particular fibrinogen, and dilution of the remaining coagulation factors, accompanied by other potentiating effects, such as acidosis, hypothermia, and electrolyte disturbance, further contribute to TIC.9 Importantly, TIC is not uniform but varies with pattern of injury and in type during the course of treatment, underscoring the potential importance of point-of-care (POC) testing that can rapidly provide information on an actual individual patient’s coagulation status.10
Conventional plasma-based coagulation testing, such as prothrombin time (PT) or international normalized ratio (INR), and activated partial thromboplastin time (aPTT) fail to fully assess the clotting process. SCTs were designed to evaluate anticoagulation therapy rather than coagulopathy in major trauma.11 In fact, none of the conventional coagulation tests was developed to predict bleeding or to guide coagulation in the surgical setting.11–14 Moreover, a substantial amount of precious time transpires before the results of standard coagulation assessments become available, with a median turnaround time for these tests to be completed at a central laboratory ranging from 78 minutes to 88 minutes.15,16
Viscoelastic tests (VETs), most commonly thrombelastography (TEG, Haemoscope-Haemonetics, Niles, IL) and rotational thromboelastometry (TEM, Tem Systems Inc., Durham, NC), provide a valuable alternative or an adjunct to SCT in the setting of bleeding in the emergency department. VETs yield rapid, POC assessment of whole-blood coagulation in a variety of conditions in which conventional testing may not be sensitive.12,15,17,18 Unlike SCT, VETs provide a rapid and dynamic bedside assessment of the initiation and kinetics of clot formation, maximum clot firmness (MCF), and clot breakdown.12,17,18 VETs can characterize the range of acute coagulopathies present in patients with traumatic injury, identify the presence and type of coagulopathy at an early stage, and, in turn, reveal the most appropriate treatment options for these patients.19–23
This review examines the TEG and TEM devices, assesses the efficacy of each device in the trauma setting, and discusses the practical benefits and limitations of these devices in achieving rapid reversal of coagulopathy.