Thromboelastography (TEG)

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July 25, 2017 by dailybolusoflr

By: Casey Carr, MD


Introduction
  • Thromboelastography (TEG) is an assay that measures the visco-elastic properties of whole blood clot.
  • TEG allows the assessment of platelet functioning and the strength of clot formation.
  • Useful because many patients have medication or disease processes that change platelets ability to initiate coagulation
  • aPTT and PT are only sensitive in relatively large changes in clotting factor concentrations and many times lack the sensitivity to detect early coagulation changes.
  • Can guide blood product choice during transfusion after massive hemorrhage
  • However, a recent Cochrane Review found that there was limited evidence to endorse the efficacy of thromboelastography guided transfusion when compared to current transfusion practices

How to interpret
  • Reaction time (R): reflects adequacy of coagulation factors (similar to PT/PTT)
  • Kinetics (K) and alpha (angle): demonstrate clot kinetics and time taken to reach certain level of clot strength and are determined by thrombin generation and fibrinogen concentration
  • Maximum amplitude (MA): reflects maximum clot strength, a function of platelet activity
  • Lysis30 or Lysis 60: percent decrease in clot area after 30/60 minutes; shows presence of fibrinolysis

Summary

  • R reflects changes in clotting factor deficiencies, K/angle corresponds to fibrinogen deficiencies, MA corresponds to platelet dysfunction, and Lysis30/60 reflects the presence of fibrinolysis

Proposed Transfusion Protocols
  • Increased R – Transfuse FFP
  • Increased alpha – Transfuse cryoprecipitate
  • Decreased MA – Transfuse platelets

References

  1. Hunt H, et al. “Thromboelastography (TEG) and rotational thromboelastometry (ROTEM) for trauma induced coagulopathy in adult trauma patients with bleeding”. Cochrane Database Systematic Review. 2015, February
  2. Kashuk, et al. “Postinjury Coagulopathy Management”. Annals of Surgery. 2010, April; 251 (4): 604 – 14
  3. Karon, B. “Why is everyone so excited about thromboelastography?” Clinica Chimica Acta. 2014, May; 436: 143 – 8

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