Description

Trauma is the leading cause of death in children. Researchers, starting with Trunkey et al., have described three general time points of mortality after trauma - in the field, early secondary to hemorrhage and late due to infectious complications. Early mortality after trauma is specifically linked to hemorrhage. Trauma-induced coagulopathy is a multifactorial phenomenon present after trauma in both children and adults that can worsen hemorrhage and ultimately lead to increased mortality. Classical laboratory measurements of the coagulation pathway (PT, PTT, INR, fibrinogen, platelet count) have shown derangement after trauma and are correlated with mortality. However, these traditional tests of coagulation function take time to run as they are drawn and sent to a laboratory for evaluation and therefore provide a delayed snapshot of a potentially evolving coagulopathy scenario. Adult trauma centers have increasingly incorporated viscoelastic measures of the coagulation cascade to evaluate for and subsequently treat trauma-induced coagulopathy. One such test is thromboelastography (TEG) which is a whole blood assay that assesses functional clot kinetics and stability. It provides information on how various hemostatic factors, including coagulation factors, platelets, and fibrinogen, contribute to the clot. A 2016 randomized-controlled trial in adult trauma patients who met criteria for the institutions massive transfusion protocol were randomized to transfusion guided by TEG or by conventional measure of coagulopathy. The authors found increased survival in the TEG group as well as less transfusion of platelets and fresh frozen plasma.

TEG assesses the clot rate, clot strength, and clot stability, which then assists the clinician in choosing appropriate blood component therapy. The American College of Surgeons Trauma Quality Improvement Program recommends the use of thromboelastography when patients are at risk for trauma-induced coagulopathy. Visicoeslastic evaluation of the coagulation pathway has become the standard of care in adult trauma patients to provide information on a patient's coagulation status, particularly when the patient is requiring multiple blood products. This allows the physician to deliver a targeted hemostatic resuscitation appropriate for the patient needs in real-time. This can result in a decrease of blood products and quicker reversal of the trauma induced coagulopathy.

Riley Hospital for Children at IU Health has a TEG 5000 machine (Haemonetics Corp.) which performs the coagulation tests needed to help guide the resuscitation of a critical trauma patient. While an improvement over previous tests (such as INR, platelet count, PTT), the TEG 5000 still takes 45-60 minutes to get the results needed to guide fluid/blood resuscitation, making the results outdated as the patient has potentially received multiple units of blood products and/or had additional bleeding during that time. The TEG 5000 machine also has very specific environmental, and preparation needs (i.e. flat surface which is not bumped; controlled pipetting (dropping) of blood products into machine as well as mixing of reagents) that is very difficult to do in a busy trauma bay/emergency department with a critical patient.

The TEG 6s assays are performed in a microfluidic cartridge which only requires a small amount of a patient's blood be transferred to the cartridge for analysis. The vibration frequency of the blood meniscus at which resonance occurs is used to create a clot dynamics tracing. The sample is drawn automatically into the testing chambers rather than requiring manual pipetting, leading to less user variability. This simpler operation provides results in 15-20 minutes, making the test more clinically useful in guiding transfusion therapy during active bleeding.

TEG 6s and TEG 5000 have been evaluated in adult patients with good agreement between the modalities. More specifically, the TEG 6s has been validated in adult trauma patients. However, few pediatric studies exist.