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Thromboelastography By Mike Poullis

Thromboelastography By Mike Poullis. Measuring Coagulation Status. Why do it? Benefits Need to understand the position of TEG in coagulation assessment. Techniques. Full blood count and Coagulation screen (APTT, PT, and fibrinogen) Whole Blood tests Microaggregation Whole blood analysers

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Thromboelastography By Mike Poullis

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  1. ThromboelastographyByMike Poullis

  2. Measuring Coagulation Status • Why do it? • Benefits • Need to understand the position of TEG in coagulation assessment

  3. Techniques • Full blood count and Coagulation screen (APTT, PT, and fibrinogen) • Whole Blood tests • Microaggregation • Whole blood analysers • Thrombelastography • Purified Platelet tests • Microaggregation • Macroaggregation • Platelet function analysers • Skin bleeding time

  4. Advantages of Techniques • Full blood count and Coagulation screen (APTT, PT, and fibrinogen) • Quick, easy, reproducible, understandable • Whole Blood tests • MAJOR ADVANTAGE IS NO SAMPLE PREPERATION • Microaggregation, Thrombelastography, andWhole blood analysers • Easy • Purified Platelet tests • Microaggregation Easy • Macroaggregation PRECISE DEFECT • Platelet function analysers PRECISE DEFECT • Skin bleeding time • Whole body answer

  5. Limitations of Techniques • Full blood count • Number not function • Coagulation screen (APTT, PT, and fibrinogen) • 20 to 30 minutes, no fibrinolytic assessment • Whole Blood tests • Microaggregation No commercial kit • Thrombelastography ?sensitivity • Purified Platelet tests • YOU HAVE TO PREPARE THE PLATELETS • Microaggregation No commercial kit • Macroaggregation Experienced technician • Platelet function analysers ? • Skin bleeding time • Invasive, not specific

  6. Principles of Thrombelastography Celite (Kaolin) activated Low shear environment resembling sluggish venous flow

  7. Readout

  8. What the numbers/letters mean • R: is a period of time from initiation of the test to the initial fibrin formation • k: time from beginning of clot formation until the amplitude of thromboelastogram reaches 20 mm • alpha angle: The alpha angle represents the acceleration (kinetics) of fibrin build up and cross-linking • MA - Maximum amplitude strength of clot (number function platelets fibrin) • MA60: measures the rate of amplitude reduction 60 min. after MA (stability) of the clot

  9. The Numbers and Letters

  10. Tips and Tricks • Heparinase • Adding c7E3 Fab (ReoPro) to the TEG sample will eliminate platelet function from the thromboelastogram. • Antifibrinolytic agents such as Epsilon-Aminocaproic Acid, Tranexamic acid and Aprotinin

  11. Example 1

  12. Example 1 Answer • Diagnosis:Delayed clot formation; suspect •  heparin effect •  factor deficiency • Treatment: Measure an activated clotting time (ACT) and repeat TEG with Heparinase. •  if ACT prolonged: administer protamine •  repeat TEG with Heparinase: •  if normal: administer protamine •  if abnormal or heparin not utilized in case: administer FFP

  13. Example 2

  14. Example 2 Answer • Diagnosis:Hypercoagulable state. •  Secondary to aggressive replacement of all factors in platelet rich plasma •  Chronic dissection of aortic aneurysms • Treatment: none

  15. Example 3

  16. Example 3 Answer • Diagnosis:Weak Clot Formation • Treatment: FFP, platelets and possible cryoprecipitate. • Adding c7E3 Fab (ReoPro) to the TEG sample will eliminate platelet function from the thromboelastogram. The MA will become a function of fibrinogen activity. • A repeat TEG should be performed post treatment.

  17. Example 4 Heparinase No Heparinase

  18. Example 4 Answer • Diagnosis:Heparin Effect. The top curve represents a TEG with Heparinase (heparin activity eliminated) and the bottom trace is the same sample without Heparinase (an elevated ACT will confirm the diagnosis). • Treatment: Reverse the heparin and repeat the TEG or reverse the heparin and perform an ACT.

  19. Example 5 Heparinase No Heparinase

  20. Example 5 Answer • Diagnosis:Normal Coagulation Profile. This is a TEG from the same patient shown in example 4. The heparin was reversed with protamine. The top curve represents a TEG with Heparinase (heparin activity eliminated) and the bottom trace is the same sample without Heparinase. Since both traces are identical all heparin was reversed by protamine. • Treatment: If there is still bleeding its surgical!

  21. Example 6

  22. Example 6 Answer • Diagnosis:No clot formation •  Very low factor levels •  Heparin effect • Treatment: •  repeat TEG with Heparinase : •  if TEG normal: reverse heparin with protamine •  if TEG abnormal: administer FFP

  23. Example 7

  24. Example 7 Answer • Diagnosis:Poor coagulation and fibrinolysis • Treatment: Administer coagulation factors and antifibrinolytics (Tranexamic Acid or Aprotinin). • The antifibrinolytics can be added to the TEG to pre-evaluate their effectiveness. • Repeat the TEG post treatment.

  25. Example 8

  26. Example 8 Answer • Diagnosis:Technical error in processing TEG or severe coagulopathy (correlate with clinical scenario) • Treatment: Repeat TEG •  if normal: do nothing •  if grossly abnormal and clinical bleeding: administer all products (FFP, platelets, cryoprecipitate) and repeat TEG.

  27. Limitations • Still being evaluated • Paired pre and post operative TEGs • Still do lab tests • Celite and mechanical activation not biochemical • Wythenshaw, and Blackpool have TEG but no communication on experience!

  28. Clinical Common Sense • Use same clinical skills to assess the bleeding patient • On Aspirin, Clopidogrel and Fragmin • IGNORE THE TEG

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