The TEG (Thromboelastogram)
Editor’s Note:
Recently we began employing the TEG routinely for all of our open-heart procedures. Now I am relatively familiar with the concept, having discussed and written about it before. However there is an array of numbers and categories that come with the TEG analysis that I wasn’t certain about, so to clear it up in my own head- decided I needed to do a little more research into the process and interpretation of the TEG results. So bear with me if this is purely an academic exercise for most of you- for me, I want to make it and keep it simple 🙂
The Thromboelastogram
The thromboelastogram is a whole blood clot test that was invented in the late 1940s but which has recently gained popularity because of its use in hepatic transplantation and cardiac surgery. The test is simple and essentially examines whole blood clot strength over time. The TEG assesses clot function from the time of initial clot formation through the acceleration phase, clot strengthening phase, retraction phase, until eventual lysis. In summary it examines the entire life cycle of a clot in a rather gross manner and does not isolate the subsegments of procoagulant precursors and their individual inputs into clot dynamics. It’s primary function is to examine clot strength. The two most important variables impacting on clot strength are the fibrinogen concentration and the overall platelet activity (function and number). The TEG answers four essential questions regarding clot formation:
1: Does the clot initiate in the normal time?
2: Does the clot grow normally?
3: Does it reach normal strength?
4: Does the clot hold together or does it undergo early lysis?
If the answer to all four questions is that the clot behaves normally, then there is no implication that the patient will have coagulopathic bleeding, regardless of the platelet count, Pt or aPTT. Sole reliance on the TEG as a definitive assay of platelet dysfunction should be avoided. The TEG, the platelet count, and fibrinogen concentration form a very useful battery. The TEG will detect some platelet function abnormalities. It is less sensitive to aspirin-induced platelet function changes than the bleeding time.
Discussion
Graphic Interpretation
Defining the Reported Lab Values
Editor’s Note:
Waiting for the lab to give me normal values, and measurement units…
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TEG Split Pt Citrated:
TEG Split Pt Citrated w Hep:
TEG R Time Citrated:
TEG R Time Citrated w Hep:
TEG R-SP Citrated:
TEG R-SP Citrated w Hep:
TEG K Time Citrated:
TEG K Time Citrated w Hep:
TEG Alpha Angle Citrated:
TEG Alpha Angle Citrated w Hep:
TEG Max Amplitude Citrated:
TEG Max Amplitude Citrated w Hep:
TEG G CL Str Citrated:
TEG G CL Str Citrated w Hep:
TEG % Lysis 30 min Citrated
TEG % Lysis 30 min Citrated w Hep:
TEG Net G ADP
TEG Path Interpretation
Plt % Inhibition (AA)
Plt % Inhibition (ADP)
References
