Flashcards in Thromboelastography (TEGs) Deck (25)
C.I. is a measure of what? What is a normal range? What does it mean if the patient is above or below this range?
C.I. = coagulation index, measures coagulation. -3 to 3. 3 = hypercoagulable.
What is R?
the time of latency from the time the blood was placed in the TEG analyzer to the initial fibrin formation
What is alpha?
Measures the rapidity of fibrin build-up and cross-linking (the speed of clot strengthening)
What is K?
A measure of the rapidity to reach a certain level of clot strengthening.
What is MA?
Maximum Amplitude. Represents the ultimate strength of the fibrin clot. Affected by platelet number and function and, to a lesser extent, by fibrinogen level.
What is LY30?
Measures the rate of amplitude reduction 30 minutes after MA. Gives an indication of the stability of the clot.
What does an elongated R value generally mean?
It takes longer for the first fibrin strand to form. Corrected by administering FFP.
What factors do K and alpha depend upon?
fibrinogen, which determines the rate of clot buildup; factor XIII, which enables cross-linking; and, to a lesser extent, by platelets.
TEG shows an elongated K and reduced alpha. What does this mean?
Low fibrinogen level (factor XIII is rarely difficient). Can be corrected by administering CRYO, which has both.
What does a small MA value represent? How can it be corrected?
Thrombocytopenia or platelet dysfunction and can be corrected by administering platelets.
What does LY30 greater than 7.5% represent? How can it be corrected?
Hyperfibrinolysis and may be corrected by administering antifibrinolytic drugs such as Amicar®, tranexamic acid or aprotinin.
What TEG parameters would be affected by mechanical bleeding?
Nothing. TEG would be normal.
What is the end result of activation of coagulation proteins?
Formation of fibrin strands, which interact with activated platelets to create a fibrin-platelet bonded complex that = clots.
What is the difference between a CI reading of 3.0 when EPL (estimated percent lysis) is greater than 15%?
3.0 = secondary fibronolysis
A patient is bleeding with TEG reading that has an abnormally long R value. What category of bleeding disorders should you investigate?
Enymatic pathway abnormalities.
(Coagulation factor deficiency/dysfunction or anticoagulant presence)
What effect would you expect in a patient wth an abnormally long R value?
Slow clot formation due to slow or insufficient thrombin generation (may be due to presence of heparin)
How do we test for residual heparin using a TEG?
Run blood samples with two cups simultaneously: K = clear cup, kaolin activated, KH - blue cup, kaolin with heparinase
If the R value for the K cup > KH cup, presence of heparin is suggested
A patient is bleeding with a teg reading that only has one abnormal value - a low angle (a).
What is the probable cause and effect of this reading?
Cause: low fibrinogen levels
Effect: slow clot ofrmation
What are some causes of fibrinogen deficiency?
-Liver disease or congestion
-Disseminated intravascular coagulation (DIC) in hypOcoagulable stage
-OBGYN complications such as placental rupture
Common treatments for fibrinogen deficiency
cyroprecipitate or ffp
What are signs in a TEG reading of platelet deficiencies?
-Pt is bleeding
-TEG has an abnormally low MA value
-May see elongated R or low angle (a) values
What effect does low platelet count have on patients?
Clot strength is insufficient to stop vascular bleeding
What are some causes of low platelet counts?
-Bone marrow disorders (leukemia)
-Trauma with significant blood loss or blood salvage
-Cardiac valve dysfunction (regurgitation)
-Consumption and/or sequestration
-Platelet antibodies - HITT
What are some mechanisms of platelet dysfunction?
>Activation - inhibition or dysfunction of platelet receptors
>Adhesion - inhibition or dysfunction of GPIb receptor preventing adhesion of platelet to endothelium
>Aggregation - inhibition or dysfunction of GPIIb/IIIa receptors preventing development of a platelet plug
>Secretion - inhibition or dysfunction of secretory pathways resulting in reduced platelet activation
>Procoagulant activity - reduction of thrombin generation on platelet surface