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Thromboelastography-Final-Presentation.pptx
1. Thromboelastography (TEG) and Rotational
Thromboelastometry (ROTEM): Applications in Anesthesia
Copyright 2019. Jamie Cieslak and Amy Selmer. All Rights Reserved.
2. Disclosure Statement
We have no financial relationships with any commercial interest related to
the content of this activity.
We will not discuss off-label use during our presentation.
3. Learner Outcomes
Describe how Thromboelastography (TEG) and Rotational
Thromboelastometry (ROTEM) tests provide clinically useful information
on clot formation and dissolution.
Understand TEG and ROTEM results.
Identify evidence pertaining to patient outcomes utilizing TEG and ROTEM
compared to traditional coagulation studies.
4. Background
1818: First successful blood transfusion for postpartum
hemorrhage
1900: Human blood groups, A, B and O discovered
1939-1940: The Rh blood group recognized as the cause
behind most transfusion reactions
1940: The US government establishes a blood collection
program
1943: First cell salvage autotransfusion device developed
5. Problem
11.3 million units of PRBCs transfused in 2015
Median cost per unit:
– Non-leukocyte reduced PRBCs = $204
– Single apheresis platelet unit = $524
– Fresh frozen plasma = $52
Bacterial contamination
Anaphylaxis – 1:20,000 to 1:50,000
Acute hemolytic transfusion reaction – 1:76,000
Sepsis – 1:50,000 for platelets; 1:5,000,000 for PRBCs
17. Cardiac Surgery
Both TEG and ROTEM decreased overall transfusions
Newer generations of viscoelastic tests:
– Reduced surgical re-exploration rate
– Reduced use of fresh frozen plasma and platelet concentrates
Inconclusive data on clinical outcomes
18. Trauma
Trauma Induced Coagulopathy (TIC)
– High morbidity and mortality
TEG/ROTEM guided protocols for massive transfusion
– No national consensus for protocols
– Decreased morbidity and mortality
19. Obstetrics
Postpartum hemorrhage
– TEG/ROTEM protocols decreased plasma and platelet transfusions
Neuraxial anesthesia
– Unknown if viscoelastic tests can predict risk for epidural hematoma
20. Liver Transplant
TEG/ROTEM guided protocols for transfusion
– Significantly decreased overall number of transfusions
intraoperatively
Postoperative patient outcomes
– Not enough studies to comment
21. Conclusion
TEG and ROTEM are forms of whole blood point-of-care tests that
analyze clot formation and degradation in real time
Cardiac surgery has been the most studied specialty utilizing these
tests
Viscoelastic guided transfusion protocols decrease overall number
of transfusions
Patient outcome data continues to be an area of evolving research
22. References
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Akay OM. The double hazard of bleeding and thrombosis in hemostasis from a clinical point of view: A global assessment by rotational thromboelastometry(ROTEM). Clinical and Applied
Thrombosis/hemostasis. 2018; 24(6):850-858. doi: 10.1177/1076029618772336.
Branco BC, Inaba K, Ives C, et al. Thromboelastogramevaluation of the impact of hypercoagulability in trauma patients. Shock. 2014;41(3):200-207. doi:10.1097/SHK.0000000000000109.
Clevenger B, Mallett SV. Transfusion and coagulation management in liver transplantation. World journal of gastroenterology. 2014;20(20):6146-6158. doi:10.3748/wjg.v20.i20.6146.
Cohen J, Scorer T, Wright Z, et al. A prospective evaluation of thromboelastometry (ROTEM) to identify acute traumatic coagulopathy and predict massive transfusion in military trauma
patients in Afghanistan. Transfusion. 2019;59(S2):1601-07. doi: 10.1111/trf.15176.
Collins PW, Cannings-John R, Bruynseels D, et al. Viscoelastometric-guided early fibrinogen concentrate replacement during postpartum haemorrhage: OBS2, a double-blind randomized
controlled trial. Br J Anaesth. 2017;119:411-421. doi:10.1093/bja/aex181.
Corredor C, Wasowicz M, Karkouti K, et al. The role of point-of-care platelet function testing in predicting postoperative bleeding following cardiac surgery: a systematic review and meta-
analysis. Anaesthesia. 2015;70(6):715-731. doi:10.1111/anae.13083.
Curry NS, Davenport R, Pavord S, et al. The use of viscoelastic haemostatic assays in the management of major bleeding: a British Society for Haematology Guideline. British journal of
haematology. 2018;182(6):789-806. doi:10.1111/bjh.15524.
Da Luz LT, Nascimento B, Shankarakutty AK, et al. Effect of thromboelastography(TEG®) and rotational thromboelastometry(ROTEM®) on diagnosis of coagulopathy, transfusion guidance and
mortality in trauma: descriptive systematic review. Critical Care. 2014;18(5):518. doi:10.1186/s13054-014-0518-9.
Davies JR, Fernando R, Hallworth SP. Hemostatic function in healthy pregnant and preeclamptic women: an assessment using the platelet function analyzer (PFA-100) and
thromboelastography. Anesth Analg. 2007;104:416-420. doi:10.1213/01.ane.0000253510.00213.05.
Davis JPE, Northup PG, Caldwell SH, et al. Viscoelastic testing in liver disease. Annals of hepatology. 2018;17(2):205-213. doi:10.5604/01.3001.0010.8635.
23. References
Donohue CI, Mallett SV. Reducing transfusion requirements in liver transplantation. World journal of transplantation. 2015;5(4):165-182. doi:10.5500/wjt.v5.i4.165.
Gonzalez E, Moore EE, Moore HB. Management of trauma-induced coagulopathy with thrombelastography. Critical care clinics. 2017;33(1):119-34. doi:10.1016/j.ccc.2016.09.002.
Gorlinger K, Dirkmann D, Meller-BeiBenhirtz H, et al. Thromboelastometry-based perioperative coagulation management in visceral surgery and liver transplantation: experience of 10 years
and 1105LTX. Liver Transpl. 2010;16:S86.
Gorlinger K, Fries D, Dirkmann D, et al. Reduction of fresh frozen plasma requirements by perioperative point-of-care coagulation management with early calculated goal-directed therapy.
Transfusion medicine and hemotherapy:offizielles Organ der Deutschen Gesellschaft für Transfusionsmedizin und Immunhämatologie. 2012;39(2):104-113.
Gorlinger K, Perez-Ferrer A, Dirkmann D, et al. The role of evidence-based algorithms for rotational thromboelastometry-guided bleeding management. Korean journal of anesthesiology.
2019. doi:10.4097/kja.19169.
Hawkins RB, Raymond SL, Hartjes T, et al. Review: The perioperative use of thromboelastography for liver transplant patients. Transplantation proceedings. 2018;50(10):3552-3558.
doi:10.1016/j.transproceed.2018.07.032.
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 of Systematic Reviews. 2015;2. doi: 10.1002/14651858.CD010438.pub2.
Kozek-Langenecker SA, Afshari A, Albaladejo P, et al. Management of severe perioperative bleeding: guidelines from the European Society of Anaesthesiology. European journal of
Anaesthesiology. 2013;30(6):270-382. doi:10.1097/EJA.0b013e32835f4d5b.
Mallaiah S, Barclay P, Harrod I, et al. Introduction of an algorithm for ROTEM-guided fibrinogen concentrate administration in major obstetric haemorrhage. Anaesthesia. 2015;70:166-175.
doi:10.1111/anae.12859.
24. References
Nakayama Y, Nakajima Y, Tanaka K, et al. Thromboelastometry-guided intraoperative haemostatic management reduces bleeding and red cell transfusion after paediatric cardiac surgery.
British Journal of Anesthesia. 2015;114(1):91-102. doi:10.1093/bja/aeu339.
Othman M, Han K, Elbatarny M, et al. The use of viscoelastic hemostatic tests in pregnancy and puerperium: review of the current evidence - communication from the women's health SSC of
the ISTH. Journal of thrombosis and haemostasis:JTH. 2019;17(7):1184-1189. doi:10.1111/jth.14461.
Peng HT, Nascimento B, Tien H, et al. A comparative study of viscoelastic hemostatic assays and conventional coagulation tests in trauma patients receiving fibrinogen concentrate. Clinica
chimica acta; international journal of clinical chemistry. 2019;495:253-62. doi: 10.1016/j.cca.2019.04.066.
Serraino GF, Murphy GJ. Routine use of viscoelastic blood tests for diagnosis and treatment of coagulopathic bleeding in cardiac surgery: updated systematic review and meta-analysis. British
Journal of Anaesthesia. 2017;118(6):823-833. doi:10.1093/bja/aex100.
Smart L, Mumtaz K, Scharpf D, et al. Rotational thromboelastometry or conventional coagulation tests in liver transplantation: comparing blood loss, transfusions, and cost. Annals of
hepatology. 2017;16(6):916-923. doi:10.5604/01.3001.0010.5283.
Snegovskikh D, Souza D, Walton Z, et al. Point-of-care viscoelastic testing improves the outcome of pregnancies complicated by severe postpartum hemorrhage. Journal of clinical anesthesia.
2018;44:50-56. doi:10.1016/j.jclinane.2017.10.003.
Solomon C, Collis RE, Collins PW, et al. Haemostatic monitoring during postpartum haemorrhage and implications for management. Br J Anaesth. 2012;109:851-863. doi:10.1093/bja/aes361.
Trzebicki J, Flakiewicz E, Kosieradzki M, et al. The use of thromboelastography in the assessment of hemostasis during orthotopic liver transplantation reduces the demand for blood products.
Ann Transplant. 2010;15(3):19-24.
Wikkelsø A, Wetterslev J, Møller AM, et al. Thromboelastography(TEG) or thromboelastometry(ROTEM) to monitor haemostatic treatment versus usual care in adults or children with
bleeding. The Cochrane Database of Systematic Reviews. 2016;(8).doi: 10.1002/14651858.CD007871.pub3.
Now, let’s discuss how a clot is formed.
Hemostasis is commonly described as occurring in three steps (although all three steps are occurring simultaneously).
The first step is vasospasm where at the location of injury, endothelial cells secrete signals for the smooth muscles to contract. This helps temporarily minimize blood loss from the area of injury.
Second is Platelet plug formation. This occurs in three phases
Platelet adhesion - von willebrand factor helps bind platelets to exposed collagen.
Platelet activation- platelets secrete chemicals to attract more platelets and further increase vasoconstriction (ADP, serotonin, thromboxane A2)
Platelet aggregation- platelets clump together to form the platelet plug.
This plug however is not very strong so there is an additional step to strengthen this temporary plug: coagulation with clotting factors
The third step is clot formation which occurs via the coagulation cascade. This ultimately creates a fibrin mesh that surrounds the platelet plug and stabilizes the clot.
This process involves a system of checks and balances with positive and negative feedback loops.
Endogenous anticoagulants are present in the blood to provide negative feedback and prevent clot overgrowth (some examples include: Active protein C, Antithrombin, Tissue factor pathway inhibitor)
The Fibrinolytic system is also active in the blood. This system creates plasmin which cuts fibrin strands to break down clots.
Traditional coagulation studies (such as PT, PTT and INR) are performed on centrifuged plasma fractions and only look at isolated portions of the coagulation cascade.
They do not provide information on interactions among coagulation factors and blood components important for the clinical evaluation of hemostatic disorders.
Platelet count and fibrinogen levels only provide the number of factors present but do not comment on the function of those components.
PT and PTT were originally designed to evaluate clotting factor deficiencies and are not good predictors of bleeding when looking at a clinical picture of an acquired coagulopathy.
In addition, traditional coagulation studies are not able to detect when a patient is in a hypercoagulable state.
Thromboelastography (TEG) and Rotational Thromboelastometry (ROTEM) are point of care viscoelastic tests that utilize whole blood to measure global clot formation and dissolution.
The systems work by using a sensor pin which is placed in a cup of whole blood and either the cup or pin rotates (depending on which system you are using).
As a clot forms between the walls of the cup and the sensor pin, the resistance created by the clot against the rotation of the system is translated into a graph in real time.
We can then interpret this graph into clinically useful data.
Whereas traditional coagulation tests can take 45-60 minutes for results however, TEG and ROTEM provide clinically useful data in 15-20 minutes.
This is what ROTEM results will look like. Each of the boxes in this photo is a different assay (or cup of blood) being run by the ROTEM system.
Different reagents are added to each sample in order to activate different coagulation pathways.
EXTEM: looks at the extrinsic pathway
INTEM: looks at the intrinsic pathway
FIBTEM: evaluates the contribution of fibrinogen to clot formation
HEPTEM: Reverses heparin in the blood sample to assess coagulation without the influence of heparin
There is also another assay not pictured here called the APTEM which evaluates fibrinolysis.
Now I’m going to talk about how to interpret a ROTEM but just as a general DISCLAIMER: There are many variations to ROTEM guided transfusion algorithms in terms of the order of products to be transfused and cutoff values for transfusion triggers.
These vary widely between institutions and there is currently no national standard so I am going to describe an approach that we found frequently in the literature.
Overall, there are three important variables to consider:
”HOW FAST” is the clot forming? This is based on the Clotting time which is the green line here in the photo. (Time to form 2mm clot)
For the EXTEM assay we want the clotting time < 100 seconds
For the INTEM assay we want the clotting time < 250 seconds
IF Prolonged the patient may benefit from FFP, Prothrombin complex concentrate or heparin reversal depending on HEPTEM result
The next variable to consider is
”HOW STRONG” is the clot that is forming? That is indicated by the A10 which is the amplitude (mm) of the clot at 10 minutes (post CT)
EXTEM and INTEM A10 values should be > 40 mm
IF < 40 mm the patient could need platelets, but you have to also look at the FIBTEM A10 to see if the problem is fibrinogen
FIBTEM A10 should be > 9-10 mm
IF < 9-10 mm the patient likely needs Cryoprecipitate or fibrinogen concentrate
“FOR HOW LONG” is the clot sticking around? This is the “maximal lysis” which reports the reduction of clot firmness in relation to the maximum clot firmness (MCF)
IF maximal lysis is > 15% within one hour this indicates hyperfibrinolysis and the patient could benefit from an anti-fibrinolytic such as TXA
We are going to look at an example here of a bleeding patient in the OR:
First we are going to look at HOW FAST the clot is forming: Clotting time EXTEM is < 100 seconds, CT INTEM < 250 seconds - good there
Next, HOW STRONG: Want the A10 for EXTEM and INTEM > 40 mm however it is < 40mm - not good.
Still need to assess fibrinogen function by looking at the A10 FIBTEM which we want > 9-10mm – good
FOR HOW LONG is the clot sticking around? this would be indicated by the Maximal lysis %, however this sample does not have a value reported yet, the sample likely need more time to run before the machine will report this value.
Either this patient has low platelets or their platelets are not functioning properly. Since they are actively bleeding, this patient would benefit from a platelet transfusion.
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That was a lot of information all at once. But this method is a fun and easy way to give you an idea of where the problem lies just by glancing at the graph.
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Postpartum hemorrhage is the leading cause of maternal morbidity and mortality worldwide, and fibrinogen plays a very important role in the development of postpartum hemorrhage.
Studies indicate that declining fibrinogen function is detected within 5-10 minutes utilizing viscoelastic tests over traditional coagulation studies which can take 30-60 minutes for results.
Treatment of postpartum hemorrhage utilizing TEG/ROTEM- guided transfusion protocols decreased overall number of transfusions, particularly fresh frozen plasma and platelets.
It is important to note that cutoff values for algorithms in the parturient population are different due to the physiologic impact of pregnancy on coagulation, and many of these algorithms have not been formally validated in the literature.
The European Society of Anesthesiology recommends these tests for monitoring and management of postpartum hemorrhage in their guidelines with a weak recommendation due to the low-quality level of evidence currently available (only been a few prospective cohort studies and no RCTs).
When considering neuraxial anesthesia in patients with questionable coagulation status such as preeclampsia or idiopathic thrombocytopenia, it is unknown if viscoelastic tests can predict risk for epidural hematoma.
Overall, there have not been many studies in this field and there is a need for large, high powered, multicenter studies in order to comment on clinical outcomes.
Orthotopic liver transplantation is an ideal application for viscoelastic tests because traditional coagulation tests offer misleading information in patients with liver disease.
There is a large consensus that patients with stable liver disease have normal coagulation due to a balanced reduction in pro and anticoagulants.
For example, platelet count is often low in patients with liver disease however function is frequently preserved with increased levels of von Willebrand factor which helps promote platelet adhesion.
For these reasons, INR, PT and aPTT are poor predictors of intraoperative bleeding during liver transplant.
Although the patient in liver failure may have a compensated system of coagulation, they are highly vulnerable to decompensation when placed under stress.
Individualized treatment with blood products is particularly critical in the liver transplant population as massive transfusion (> 6 u PRBCs) is an independent predictor for increased morbidity and mortality.
In several studies, the use of TEG/ROTEM-guided transfusion decreased overall number of transfusions significantly
Some studies cited up to a 90% reduction in FFP use after implementation however these results should be cautiously interpreted because they were compared to data from much older procedures.
Overall not enough evidence to comment on postoperative patient outcomes utilizing TEG/ROTEM guided protocols for transfusion.
