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I & M 441 > Thromboelastography (TEGs) > Flashcards

Thromboelastography (TEGs) Flashcards

1
Q

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?

A

C.I. = coagulation index, measures coagulation. -3 to 3. 3 = hypercoagulable.

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2
Q

What is R?

A

the time of latency from the time the blood was placed in the TEG analyzer to the initial fibrin formation

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3
Q

What is alpha?

A

Measures the rapidity of fibrin build-up and cross-linking (the speed of clot strengthening)

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4
Q

What is K?

A

A measure of the rapidity to reach a certain level of clot strengthening.

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5
Q

What is MA?

A

Maximum Amplitude. Represents the ultimate strength of the fibrin clot. Affected by platelet number and function and, to a lesser extent, by fibrinogen level.

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6
Q

What is LY30?

A

Measures the rate of amplitude reduction 30 minutes after MA. Gives an indication of the stability of the clot.

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7
Q

What does an elongated R value generally mean?

A

It takes longer for the first fibrin strand to form. Corrected by administering FFP.

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8
Q

What factors do K and alpha depend upon?

A

fibrinogen, which determines the rate of clot buildup; factor XIII, which enables cross-linking; and, to a lesser extent, by platelets.

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9
Q

TEG shows an elongated K and reduced alpha. What does this mean?

A

Low fibrinogen level (factor XIII is rarely difficient). Can be corrected by administering CRYO, which has both.

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10
Q

What does a small MA value represent? How can it be corrected?

A

Thrombocytopenia or platelet dysfunction and can be corrected by administering platelets.

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11
Q

What does LY30 greater than 7.5% represent? How can it be corrected?

A

Hyperfibrinolysis and may be corrected by administering antifibrinolytic drugs such as Amicar®, tranexamic acid or aprotinin.

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12
Q

What TEG parameters would be affected by mechanical bleeding?

A

Nothing. TEG would be normal.

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13
Q

What is the end result of activation of coagulation proteins?

A

Formation of fibrin strands, which interact with activated platelets to create a fibrin-platelet bonded complex that = clots.

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14
Q

What is the difference between a CI reading of 3.0 when EPL (estimated percent lysis) is greater than 15%?

A

3.0 = secondary fibronolysis

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15
Q

A patient is bleeding with TEG reading that has an abnormally long R value. What category of bleeding disorders should you investigate?

A

Enymatic pathway abnormalities.

Coagulation factor deficiency/dysfunction or anticoagulant presence

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16
Q

What effect would you expect in a patient wth an abnormally long R value?

A

Slow clot formation due to slow or insufficient thrombin generation (may be due to presence of heparin)

17
Q

How do we test for residual heparin using a TEG?

A

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

18
Q

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?

A

Cause: low fibrinogen levels

Effect: slow clot ofrmation

19
Q

What are some causes of fibrinogen deficiency?

A
  • Liver disease or congestion
  • Disseminated intravascular coagulation (DIC) in hypOcoagulable stage
  • OBGYN complications such as placental rupture
  • Hemodilution
  • Excessive consumption
20
Q

Common treatments for fibrinogen deficiency

A

cyroprecipitate or ffp

21
Q

What are signs in a TEG reading of platelet deficiencies?

A
  • Pt is bleeding
  • TEG has an abnormally low MA value
  • May see elongated R or low angle (a) values
22
Q

What effect does low platelet count have on patients?

A

Clot strength is insufficient to stop vascular bleeding

23
Q

What are some causes of low platelet counts?

A
  • Bone marrow disorders (leukemia)
  • Chemotherapy
  • Congenital disorders
  • Lupus
  • Trauma with significant blood loss or blood salvage
  • Hemodilution
  • Cardiac valve dysfunction (regurgitation)
  • Consumption and/or sequestration
  • Platelet antibodies - HITT
24
Q

What are some mechanisms of platelet dysfunction?

A

> 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

25
Q

What are some causes of platelet dysfunction?

A
  • Cardiopulmonary bypass
  • Antiplatelet therapies
  • Platelet antibodies
  • Congenital disorders
  • Liver disease
  • Uremia
  • Consumption

I & M 441 (13 decks)

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