Management of Post-Op Bleeding-Exam 2 Flashcards Preview

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Flashcards in Management of Post-Op Bleeding-Exam 2 Deck (116)
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1

What is heparin rebound?

Some heparin may be protein bound and unavailable for reversal. It may become free post-CPB resulting in heparin rebound.

2

What will happen with excess protamine?

bleeding

3

How much of a decrease of circulating factors normally occurs on CPB due to hemodilution?

25-35% decrease; institution depending

4

How much does hypothermia slow enzymatic reaction times?

10 degree C decrease in temp, 50% decrease in enzymatic activity

5

What drives the clotting cascade?

Enzyme driven; enzymatic rxn times slowed during hypothermia

6

What are some sources of post-op bleeding?

Reduced concentration of coag factors
Hyperfibrinolysis
Thrombocytopenia
Impaired plt aggregation
Plt Fragmentation
Loss of membrane receptors

7

What impairs coagulation and increases blood loss after CPB?

Increased inflammation

8

What are some extrinsic factors that can be a source of post-op bleeding?

Residual Heparin/Heparin Rebound
Excessive protamine
Hemodilution
Hypothermia

9

What are some ways to prevent post-op bleeding?

Avoid CPB (off pump procedures)
Improved biocompatibility of foreign surfaces
Alter conduct of bypass
Hemtalogic strategies
Improved surgical technique
Make sure labs are normal pre-op

10

What are some hematologic strategies that can help prevent post-op bleeding?

Harvest whole blood/plasma
PRP

11

What is a major factor in use of blood products and post op bleeding?

Improved surgical technique

12

What drug has a mild fibrinolytic effect? Describe the effect.

Heparin; stimulates release of serum urokinase plasminogen activator (UPA) which induces fibrinolysis

13

CPB activates the breakdown of what?

Fibrinogen and other procoagulant precursors

14

Which is more potent? UPA or TPA?

TPA is more potent that UPA

15

What is the primary activator of fibrinolysis during heart surgery?

Tissue Plasminogen Activator (TPA)

16

When is there a large surge of TPA?

After protamine is given

17

When is the time of greatest thrombin production?

After protamine is given

18

If there was no fibrinolysis (left unchecked by TPA) what would happen?

Could result in large scale clotting or diffuse intravascular coagulation

19

When is thrombin produced?

Throughout CPB

20

When is there a surge of thrombin?

At termination of bypass
After protamine administration

21

What type of protein is thrombin?

Amplifier protein; activates many cell lines

22

What cell lines does thrombin activate?

Inflammation
Coagulation
Fibrinolysis

23

What is metabolically active in sites where heparin cannot reach it?

Thrombin

24

What regulates TPA?

Plasminogen Activator Inhibitor 1 (PAI-1)

25

What releases plasminogen activator inhibitor 1?

Liver and endothelial cells

26

What does PAI-1 bind to as it's exported from endothelial cells?

Binds to TPA; therefore TPA must overcome circulating PAI-1 to initiate fibrinolysis

27

How is PAI-1 a buffer?

It's a buffer to surges of TPA

28

When is PAI-1 released?

in response to inflammatory mediators

29

How does PAI-1 work as a prothrombotic?

Overcomes and suppresses fibrinolytic effect of TPA

30

What makes up a clot?

Thrombin