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THROMBOELASTOGRAPHY 
VISHNU AMBAREESH
• In surgery we have to manage 
patients with a bleeding 
diathesis in the preoperative, 
intraoperative or 
postoperative...
• Complex surgical procedures 
including cardiac and liver surgery 
are associated with a potential for 
significant perio...
• inherent risks of the use of 
homologous blood and blood 
products, and allied to the scarcity of 
these resources, make...
• A variety of coagulation tests are used to 
assess whole blood coagulation.
COAGULATION MONITORING 
Conventional tests 
•Tests of coagulation 
*Platelets 
• number 
• function 
*Clotting studies 
• ...
• Each of these tests measures a 
different aspect of the clotting 
process, but even in combination 
they do not provide ...
• Besides evaluation of platelet 
function remains insensitive and 
time consuming. The platelet 
count provides only a 
q...
• At present the treatment of postoperative 
bleeding remains empirical because of the 
perceived need for immediate corre...
What we need? 
an effective and convenient means of 
monitoring whole blood coagulation 
which evaluates the elastic prope...
THROMBOELASTOGRAPHY
• First developed by Dr. Hellmut Hartet at 
University of Heidelberg, School of Medicine 
in 1948 as a method to assess gl...
WHAT IS THROMBOELASTOGRAPHY 
Functional Description 
• Thromboelastography monitors the 
thrombodynamic properties of bloo...
• The strength and stability of the clot 
provide information about the ability of 
the clot to perform the work of 
haemo...
• In classical thrombelastography, a small 
sample of blood (typically 0.36 ml) is placed 
into a cuvette (cup) which is r...
• The patterns of changes in strength 
and elasticity in the clot provide 
information about how well the 
blood can perfo...
THROMBOELASTOGRAPHY 
Basic Principles 
• Heated (37C) oscillating cup 
• Pin suspended from torsion 
wire into blood 
• De...
THROMBOELASTOGRAPHY 
Basic Principles 
• Electrical signal amplified to 
create TEG trace 
• Result displayed graphically ...
THROMBOELASTOGRAPHY 
Refinements to Technique 
• TEG accelerants / activators / modifiers 
• Celite / Kaolin / TF accelera...
THROMBOELASTOGRAPHY 
The “r” time 
r time 
•represents period of time of 
latency from start of test to 
initial fibrin fo...
THROMBOELASTOGRAPHY 
What affects the “r” time? 
•r time  by 
• Factor deficiency 
• Anti-coagulation 
• Severe 
hypofibr...
THROMBOELASTOGRAPHY 
The “k” time 
k time 
•represents time taken to 
achieve a certain level of clot 
strength (where r t...
THROMBOELASTOGRAPHY 
What affects the “k” time? 
•k time  by 
• Factor deficiency 
• Thrombocytopenia 
• Thrombocytopathy...
THROMBOELASTOGRAPHY 
The “” angle 
 angle 
•Measures the rapidity of 
fibrin build-up and cross-linking 
(clot strengthe...
THROMBOELASTOGRAPHY 
What affects the “” angle? 
• Angle  by 
• Hypercoagulable 
state 
• Angle  by 
• Hypofibrinogen...
THROMBOELASTOGRAPHY 
The “maximum amplitude” (MA) 
Maximum amplitude 
•MA is a direct function of the 
maximum dynamic pro...
THROMBOELASTOGRAPHY 
What affects the “MA” ? 
•MA  by 
• Hypercoagulable 
state 
•MA  by 
• Thrombocytopenia 
• Thromboc...
THROMBOELASTOGRAPHY 
Fibrinolysis 
•LY30 
•measures % decrease 
in amplitude 30 minutes 
post-MA 
•gives measure of 
degre...
THROMBOELASTOGRAPHY 
Other measurements of Fibrinolysis 
•A30 (A60) 
• amplitude at 30 (60) mins 
post-MA 
•EPL 
•earliest...
THROMBOELASTOGRAPHY 
What measurements are affected by 
fibrinolysis? 
•Fibrinolysis leads to: 
•  LY30 /  LY60 
•  EPL...
THROMBOELATOGRAPHY 
Quantitative analysis 
• Clot formation 
– Clotting factors - r, k times 
• Clot kinetics 
– Clotting ...
THROMBOELATOGRAPHY 
Qualitative analysis
TEG v CONVENTIONAL STUDIES 
• Conventional tests 
• test various parts of 
coag cascade, but in 
isolation 
• out of touch...
Advantages of TEG over conventional 
coagulation monitoring 
• It is dynamic, giving information on entire 
coagulation pr...
ROTEM 
• Rotational thromboelastography uses a 
modification of TEG, signal of the pin is 
transmitted using an optical de...
• In ROTEM the sensor shaft rotates rather tha 
the cup 
• avoids limitations of traditional instruments 
esp. susceptibil...
SONOCLOT 
• Sonoclot incorporates a very sensitive 
visco-elastic detection system which is 
very sensitive to the changes...
• PRINCIPLE 
measures the changing impedence to 
movement imposed by the developing clot on 
a small probe vibrating at an...
THANK YOU!!!!
Thromboelastography
Thromboelastography
Thromboelastography
Thromboelastography
Thromboelastography
Thromboelastography
Thromboelastography
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Thromboelastography

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THROMBOELASTOGRAPHY

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Thromboelastography

  1. 1. THROMBOELASTOGRAPHY VISHNU AMBAREESH
  2. 2. • In surgery we have to manage patients with a bleeding diathesis in the preoperative, intraoperative or postoperative period.
  3. 3. • Complex surgical procedures including cardiac and liver surgery are associated with a potential for significant perioperative blood loss and the development of post operative bleeding disorders.
  4. 4. • inherent risks of the use of homologous blood and blood products, and allied to the scarcity of these resources, make it important that treatment with blood products is based on scientific evidence of need.
  5. 5. • A variety of coagulation tests are used to assess whole blood coagulation.
  6. 6. COAGULATION MONITORING Conventional tests •Tests of coagulation *Platelets • number • function *Clotting studies • PT • APTT *Fibrinogen levels •Tests of fibrinolysis * degradation products
  7. 7. • Each of these tests measures a different aspect of the clotting process, but even in combination they do not provide a complete picture of the status of the coagulation system
  8. 8. • Besides evaluation of platelet function remains insensitive and time consuming. The platelet count provides only a quantitative, not qualitative index of platelet status.
  9. 9. • At present the treatment of postoperative bleeding remains empirical because of the perceived need for immediate correction of the haemostatic defect and lack of readily available measures of all phases of clot formation and breakdown , including the strength of the clot • FFP and platelets often given with little scientific basis.
  10. 10. What we need? an effective and convenient means of monitoring whole blood coagulation which evaluates the elastic properties of whole blood and provides a global assessment of heamostatic function.
  11. 11. THROMBOELASTOGRAPHY
  12. 12. • First developed by Dr. Hellmut Hartet at University of Heidelberg, School of Medicine in 1948 as a method to assess global haemostatic function from a single blood sample; this was the original thromboelastography
  13. 13. WHAT IS THROMBOELASTOGRAPHY Functional Description • Thromboelastography monitors the thrombodynamic properties of blood as it is induced to clot under a low shear environment resembling sluggish venous flow. The patterns of change in shear-elasticity enable the determination of the kinetics of clot formation and growth as well as the strength and stability of the formed clot.
  14. 14. • The strength and stability of the clot provide information about the ability of the clot to perform the work of haemostasis, while the kinetics determine the adequacy of quantitative factors available to clot formation
  15. 15. • In classical thrombelastography, a small sample of blood (typically 0.36 ml) is placed into a cuvette (cup) which is rotated gently through 4º 45´ (cycle time 6/min) to imitate sluggish venous flow and activate coagulation. When a sensor shaft is inserted into the sample a clot forms between the cup and the sensor. The speed and strength of clot formation is measured in various ways (now usually by computer)
  16. 16. • The patterns of changes in strength and elasticity in the clot provide information about how well the blood can perform hemostasis (the halting of blood flow), and how well or poorly different factors are contributing to clot formation.
  17. 17. THROMBOELASTOGRAPHY Basic Principles • Heated (37C) oscillating cup • Pin suspended from torsion wire into blood • Development of fibrin strands “couple” motion of cup to pin • “Coupling” directly proportional to clot strength •  tension in wire detected by EM transducer
  18. 18. THROMBOELASTOGRAPHY Basic Principles • Electrical signal amplified to create TEG trace • Result displayed graphically on pen & ink printer or computer screen • Deflection of trace increases as clot strength increases & decreases as clot strength decreases
  19. 19. THROMBOELASTOGRAPHY Refinements to Technique • TEG accelerants / activators / modifiers • Celite / Kaolin / TF accelerates initial coagulation • Reopro (abciximab) blocks platelet component of coagulation • Platelet mapping reagents modify TEG to allow analysis of Aspirin / Clopidigrol effects • Heparinase cups • Reverse residual heparin in sample • Use of paired plain / heparinase cups allows identification of inadequate heparin reversal or sample contamination
  20. 20. THROMBOELASTOGRAPHY The “r” time r time •represents period of time of latency from start of test to initial fibrin formation •in effect is main part of TEG’s representation of standard”clotting studies” •normal range • 15 - 23 mins (native blood) • 5 - 7 mins (kaolin-activated)
  21. 21. THROMBOELASTOGRAPHY What affects the “r” time? •r time  by • Factor deficiency • Anti-coagulation • Severe hypofibrinogenaemia • Severe thrombocytopenia •r time  by • Hypercoagulability syndromes
  22. 22. THROMBOELASTOGRAPHY The “k” time k time •represents time taken to achieve a certain level of clot strength (where r time = time zero ) - equates to amplitude 20 mm •normal range • 5 - 10 mins (native blood) • 1 - 3 mins (kaolin-activated)
  23. 23. THROMBOELASTOGRAPHY What affects the “k” time? •k time  by • Factor deficiency • Thrombocytopenia • Thrombocytopathy • Hypofibrinogenaemia •k time  by • Hypercoagulabili ty state
  24. 24. THROMBOELASTOGRAPHY The “” angle  angle •Measures the rapidity of fibrin build-up and cross-linking (clot strengthening) •assesses rate of clot formation •normal range • 22 - 38 (native blood) • 53 - 67(kaolin-activated)
  25. 25. THROMBOELASTOGRAPHY What affects the “” angle? • Angle  by • Hypercoagulable state • Angle  by • Hypofibrinogenemia • Thrombocytopenia
  26. 26. THROMBOELASTOGRAPHY The “maximum amplitude” (MA) Maximum amplitude •MA is a direct function of the maximum dynamic properties of fibrin and platelet bonding via GPIIb/IIIa and represents the ultimate strength of the fibrin clot •Correlates to platelet function • 80% platelets • 20% fibrinogen •normal range • 47 – 58 mm (native blood) • 59 - 68 mm (kaolin-activated)
  27. 27. THROMBOELASTOGRAPHY What affects the “MA” ? •MA  by • Hypercoagulable state •MA  by • Thrombocytopenia • Thrombocytopathy • Hypofibrinogenemia
  28. 28. THROMBOELASTOGRAPHY Fibrinolysis •LY30 •measures % decrease in amplitude 30 minutes post-MA •gives measure of degree of fibrinolysis •normal range • < 7.5% (native blood) • < 7.5% (celite-activated) •LY60 • 60 minute post- MA data
  29. 29. THROMBOELASTOGRAPHY Other measurements of Fibrinolysis •A30 (A60) • amplitude at 30 (60) mins post-MA •EPL •earliest indicator of abnormal lysis •represents “computer prediction” of 30 min lysis based on interrogation of actual rate of diminution of trace amplitude commencing 30 secs post-MA •early EPL>LY30 (30 min EPL=LY30) •normal EPL < 15%
  30. 30. THROMBOELASTOGRAPHY What measurements are affected by fibrinolysis? •Fibrinolysis leads to: •  LY30 /  LY60 •  EPL •  A30 /  A60
  31. 31. THROMBOELATOGRAPHY Quantitative analysis • Clot formation – Clotting factors - r, k times • Clot kinetics – Clotting factors - r, k times – Platelets - MA • Clot strength / stability – Platelets - MA – Fibrinogen - Reopro-mod MA • Clot resolution – Fibrinolysis - LY30/60; EPL A30/60
  32. 32. THROMBOELATOGRAPHY Qualitative analysis
  33. 33. TEG v CONVENTIONAL STUDIES • Conventional tests • test various parts of coag cascade, but in isolation • out of touch with current thoughts on coagulation • plasma tests may not be accurate reflection of what actually happens in patient • difficult to assess platelet function • static tests • take time to complete  best guess or delay treatment • TEG • global functional assessment of coagulation / fibrinolysis • more in touch with current coagulation concepts • use actual cellular surfaces to monitor coagulation • gives assessment of platelet function • dynamic tests • rapid results  rapid monitoring of intervention
  34. 34. Advantages of TEG over conventional coagulation monitoring • It is dynamic, giving information on entire coagulation process, rather than on isolated part • It gives information on areas which it is normally difficult to study easily – fibrinolysis and platelet function in particular • Near-patient testing means results are rapid facilitating appropriate intervention • It is cost effective compared to conventional tests
  35. 35. ROTEM • Rotational thromboelastography uses a modification of TEG, signal of the pin is transmitted using an optical detecter instead a torsion wire. • Movement orginates from pin and not the cup • Uses an electronic pippette which improves reproducibility and performance
  36. 36. • In ROTEM the sensor shaft rotates rather tha the cup • avoids limitations of traditional instruments esp. susceptibility to mechanical shocks and vibrations. • However TEG is rated as the best compromise between usability, usefulness and cost as compared to ROTEM
  37. 37. SONOCLOT • Sonoclot incorporates a very sensitive visco-elastic detection system which is very sensitive to the changes in the developing clot. It gives more detailed information as compared to Thromboelastograph
  38. 38. • PRINCIPLE measures the changing impedence to movement imposed by the developing clot on a small probe vibrating at an ultrasonic frequency in a coagulating blood sample.
  39. 39. THANK YOU!!!!

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