TEG: Evidence for its Use in the Emergency Department

By Emerson Posadas, MD, MBA (PGY-3)

Thromboelastography (TEG) is a tool that measures in real-time clot development, stability, and dissolution.  It not only measures the coagulation cascade, but also shows the interaction of platelets in clot formation. It is a dynamic measurement, that has in recent years, become more readily available in the emergency department. This blog will review the evidence behind its use in the Emergency Department in the setting of shock in both trauma and medical patients. 

First, we must review the basics of TEG and its interpretation. Keep in mind that TEG does not necessarily correlate with traditional coagulation measurements such as INR, PT/PTT, and total platelets. The general method of TEG involves measuring the physical properties of the clot by spinning whole blood in a cup with an electrical transducer. The strength of clot formation affects the rotation of the cup, which then generates data that is visualized in real time. There are several different tests available, some of which can measure fibrinogen and others that take into account whether the patient is on heparin. 
 
What may be difficult for many people first trying to interpret TEG results is that they are presented as not only values but also graphically. As emergency physicians, we have been trained to look at numbers and discrete ranges. Analyzing graphical data on the fly is a skillset many of us have not used in quite some time, if ever. What’s important to note, is that approximate normal ranges are also given; in the event one does not want to interpret the graphical data. Below is a very basic interpretation of the different values:

In broad terms, what are the indications for TEG? In general, TEG should not be ordered as a screening exam, but should only be used when a physician is considering an intervention, be it transfusing a patient or performing an invasive procedure.  It can also be used to guide resuscitation, especially in the massive transfusion setting.1
 
The utility of TEG in guiding massive transfusions protocols, especially in the setting of trauma, is well studied.2 Since the PROPPR trial in 2015, 1:1:1 of FFTP:PLT:PRBC has been a mainstay for trauma resuscitation as it showed that more patients achieved hemostasis and fewer deaths due to exsanguination at 24 hours.3 However, transfusions of any type of blood product do pose serious risks. TEG-directed resuscitation has been explored as a tool that allows physicians to target specific coagulation parameters, with the idea that often less is more. In 2016, a randomized control trial compared TEG-directed resuscitation versus conventional coagulation assays in the trauma setting. In this study, with a sample size of 111, they found that TEG-guided massive transfusion protocols improved survival compared to those guided by conventional coagulation assays. TEG-directed resuscitation also resulted in less blood products being used.4 However, it is important to note prior to this study the recommendation from a Cochrane systemic review in 2015 stated that there was no evidence on the accuracy of TEG for trauma induced coagulopathy, and strongly suggest that at present these tests should only be used for research.5 Further complicating the issue, studies have since been published either in favor or against TEG-guided management. 
 
While controversy still exists in the trauma setting, there is even less clear evidence for the use of TEG-directed resuscitation in medical coagulopathies.  There is some evidence for its use in post-partum hemorrhage, bleeding cirrhotic patients, GI bleeds, and severe epistaxis. However, currently many published articles regarding its use outside of the trauma setting are for very specific patient populations and/or case reports. In a recent randomized control trial, TEG-guided blood resuscitation was compared with conventional coagulation assays for patients with cirrhosis with nonvariceal bleeding. The study showed a significantly lower use of blood components in the TEG-guided resuscitation with similar mortality between the two groups.6 Within OBGYN, TEG has been studied for its use in guiding management of severe postpartum hemorrhage.7 The use of TEG to identify coagulation abnormalities in adult patients with sepsis has also been studied, but its exact applications have yet to be established. 8More studies need to be conducted to better understand the efficacy for its use in the emergency department.
 
In summary, TEG-directed resuscitation has been more established in the trauma setting but remains controversial. Studies have only recently started regarding its use in the bleeding medical patient, many of which are not conducted in the emergency department setting. Regardless, TEG-directed therapy seems promising and should at least be considered by emergency department physicians for any patient with serious bleeding that may require transfusion. 
 
 

1. da Luz LT, Nascimento B, Rizoli S. Thrombelastography (TEG(R)): practical considerations on its clinical use in trauma resuscitation. Scand J Trauma Resusc Emerg Med. 2013;21:29. 
2. Howley IW, Haut ER, Jacobs L, Morrison JJ, Scalea TM. Is thromboelastography (TEG)-based resuscitation better than empirical 1:1 transfusion? Trauma Surg Acute Care Open.2018;3(1):e000140. 
3. Holcomb JB, Tilley BC, Baraniuk S, et al. Transfusion of plasma, platelets, and red blood cells in a 1:1:1 vs a 1:1:2 ratio and mortality in patients with severe trauma: the PROPPR randomized clinical trial.JAMA. 2015;313(5):471-482. 
4. Gonzalez E, Moore EE, Moore HB, et al. Goal-directed Hemostatic Resuscitation of Trauma-induced Coagulopathy: A Pragmatic Randomized Clinical Trial Comparing a Viscoelastic Assay to Conventional Coagulation Assays. Ann Surg. 2016;263(6):1051-1059.
5. Hunt H, Stanworth S, Curry N, et al. Thromboelastography (TEG) and rotational thromboelastometry (ROTEM) for trauma induced coagulopathy in adult trauma patients with bleeding. Cochrane Database Syst Rev. 2015(2):CD010438. 
6. Kumar M, Ahmad J, Maiwall R, et al. Thromboelastography-Guided Blood Component Use in Patients With Cirrhosis With Nonvariceal Bleeding: A Randomized Controlled Trial. Hepatology. 2019. 
7. Jackson DL, DeLoughery TG. Postpartum Hemorrhage: Management of Massive Transfusion. Obstet Gynecol Surv. 2018;73(7):418-422. 
8. Muller MC, Meijers JC, Vroom MB, Juffermans NP. Utility of thromboelastography and/or thromboelastometry in adults with sepsis: a systematic review. Crit Care. 2014;18(1):R30.