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July 25, 2017 by dailybolusoflr
By: Casey Carr, MD
- 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
- 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
- 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
- Kashuk, et al. “Postinjury Coagulopathy Management”. Annals of Surgery. 2010, April; 251 (4): 604 – 14
- Karon, B. “Why is everyone so excited about thromboelastography?” Clinica Chimica Acta. 2014, May; 436: 143 – 8