Topic 12a Blood Surface Interactions

Question 1

% of patients receiving Heparin that develop HIT

Answer 1

2-5% of patients receiving heparin

Causes bleeding

Question 2

% of patients receiving Heparin that develop HITT

Answer 2

0.1-0.2% of patients receiving heparin

Causes thrombosis

Question 3

HIT and HITT mechanisms ?

Answer 3

Heparin binds to PF4 (platelet factor 4) and induces formation of IgG antibodies

Question 4

PF4-IgG complex activates platelets and does what to them ? With HIT and HITT?

Answer 4

Decreases circulating number of platelets
HIT defined as 40-50% decrease
HITT involves decrease AND any evidence of
thrombosis

Question 5

plasma protein adsorption onto surface of ECC amount?

Answer 5

• very quick

* amount adsorbed depends on [protein] & intrinsic surface activity of biomaterial

Question 6

plasma protein adsorption onto surface of ECC correlation?

Answer 6

correlation between physical / chemical

properties of biomaterial and activation of blood are made retrospectively–not possible to predict the response

Question 7

plasma protein adsorption onto surface of ECC depends on what characteristics of the surface?

Answer 7

• wettability
• hydrophilic / hydrophobic ratio
• surface chemistry
• surface electrical properties
• roughness / porosity
• subsurface features
• distribution of functional receptor sites

Question 8

contact activation of blood expose receptor sites on what? (3)

Answer 8

• blood cells
• plasma proteins (factor XII & complement protein 3)
• platelets

Question 9

emboli formation can be caused by what? (5)

Answer 9

*surgery
*blood activation (fibrin emboli, macroaggregates of proteins and, lipoproteins, fat globules)
*homologous blood (if not filtered- fibrin, RBC debris, platelet and leukocyte aggregates)
*crystalloid solutions (debris/dust)
roller pumps (spallation)

Question 10

Increased interstitial fluid formation caused by what?

Answer 10

increased capillary permeability

accumulation proportional to duration of bypass

Question 11

Five protein systems in whole body coagulation?

Answer 11

Contact Activation System
Intrinsic Coagulation
Extrinsic Coagulation
Fibrinolysis
Complement Activation

Question 12

Plasma Contact Activation: Four proteins involved?

Answer 12

factor XII
prekallikrein
high-molecular-weight kininogen (HMWK)
factor XI

Question 13

For factor XII to be absorbed onto foreign surface of ECC - what two things must be present?

Answer 13

prekallikrein & HMWK must be present

Question 14

Once factor XII changes shape it produces what?

Answer 14

active protease factor XIIa and XIIf

Question 15

Factor XIIa cleaves prekallikrein into what?

Answer 15

to kallikrein (strong neutrophil agonist)

Question 16

Factor XIIa Activates factor XI to XIa: what must be present? and what does XIa activate ?

Answer 16

kallikrein & HMWK must be present

factor XIa activates intrinsic coagulation cascade–thrombin production

Question 17

Factor XIIa cleaves HMWK into what?

Answer 17

to bradykinin ( potent vasodilator )

Question 18

Factor XIIa is an agonist of what?

Answer 18

factor XIIa weak neutrophil agonist

Question 19

Intrinsic Coagulation Cascade initiated by what?

Answer 19

Initiated by plasma contact activation

Initiated directly by blood contact with the ECC

Question 20

Extrinsic Coagulation Cascade initiated by what?

Answer 20

Initiated by the expression of tissue factor on

nonvascular cells

Question 21

What are the two forms of tissue factor that are expressed when extrinsic coagulation cascade is initiated?

Answer 21

cell bound tissue factor

soluble plasma tissue factor

Question 22

Binds to and activates factor VII activates what factor?

Answer 22

factor X

Question 23

Thrombin Actions (4)

Answer 23

Production of fibrin from fibrinogen
Cross-linking fibrin
Activating platelets
Stimulating the production of tissue plasminogen activator (tPA) by endothelial cells

Question 24

Compliment system made up of how many proteins ?

Answer 24

30+ proteins–most inactive enzyme precursors

Question 25

Complement Pathway entails 3 paths?

Answer 25

Common Pathway Alternative Pathway Terminal Pathway

Question 26

Alternative Pathway initiated by what two things?

Answer 26

Initiated by C3b (a product of the classical pathway) Initiated by spontaneous activation on a continuous basis Feedback loop for amplification

Question 27

Terminal Pathway does what?

Answer 27

Classical and Alternative merge at the level of C3 convertase production

Question 28

Classical Pathway initiated by what?

Answer 28

Initiated by antigen-antibody complexes

Question 29

End Product-Membrane Attack Complex | Works to prevent / limit damage from invading organism or toxin by what? (7)

Answer 29

``` opsonization lysis agglutination neutralization of viruses chemotaxis activation of mast cells and basophils inflammation ```

Question 30

End Product-Membrane Attack Complex OPSONIZATION does what?

Answer 30

neutrophils & macrophages activated | they engulf bacteria to which antigen-antibody complex is attached

Question 31

End Product-Membrane Attack Complex | LYSIS final product?

Answer 31

final product called lytic complex or terminal complement complex •creates a pore in the cell membrane of bacteria or other invading organisms that allows the influx of ions and water into the cell

Question 32

End Product-Membrane Attack Complex | AGGLUTINATION does what?

Answer 32

complement products change surface of invading organisms | •organisms adhere to each other

Question 33

End Product-Membrane Attack Complex | neutralization of viruses how?

Answer 33

products can attack structures of some | viruses and render them non-virulent

Question 34

C5a causes what of neutrophils | and macrophages?

Answer 34

chemotaxis large number phagocytes migrate to area

Question 35

mast cells and basophils are activated by what?

Answer 35

activated by C3a, C4a, & C5a

Question 36

mast cells and basophils release what?

Answer 36

cells release histamine and other substances | into local fluids

Question 37

mast cells and basophils results in what?

Answer 37

results increased local blood flow & increased leakage of fluid and protein into the tissue

Question 38

inflammation does what to vasomotor tone, cap permeability and cardiac function ?

Answer 38

increased capillary permeability altered vasomotor tone impaired cardiac function