Coagulation & Transfusion

Question 1

List 6 functions of platelets:

Answer 1

1. hemostasis
2. inflammatory pathways
3. Immunity & anaphylaxis
4. Tumour growth and metastasis
5. Angiogenesis
6. Endotherlial interactions and maintenance

Question 2

Why do petechiaes occur in thrombocytopenia?

Answer 2

Lack of platelets de-stabiilises vascular endothelial cadherin bonds and disrupts the tight junctions causing rbc to be able to leak out.

Question 3

What do alpha granules in PLT contain?

Answer 3

Adhesions: Factor XIII, PAF, P-selectin, vWF

Question 4

What do dense granules contain?

Answer 4

ATP, ADP, serotonin, Ca, phosphate

Question 5

Name the 4 major platelet receptor classes and an example or 2 from each:

Answer 5

1. G-protein coupled receptors e.g. P2Y12 <-> ADP, TXA2, PAR 1 <-> thrombin
2. Leucine-rich repeat receptors e.g. GPIb-IX-V <-> vWF, collagen, P-selectin, TLRs interact with inflammatory pathways
3. Immunoglobulin superfamily receptors e.g. GPVI <-> collagen, laminin (enhanced by vWF)
4. Integrins, alpha2beta1 <-> collagen and alpha2b, betal3 <-> fibrinogen, vWF, fibrin

Question 6

List the pro-coagulant roles of thrombin (4)

Answer 6

1. PLT activation to initiate coagulation cascade via PAR1 and 4
2. Feedsback to Facter XI to amplify coagulation and make more thrombin
3. Cleaves fibrinogen to fibrin + crosslinks fibrin with factor XIII to form a stable clot
4. Thrombin activable fibrinolysis inhibitor (TAFI), downregulates fibronolysis

Question 7

List the anitcoagulant roles of thrombin:

Answer 7

1. binds thrombomodulin and activates protein C, that together with Protein S, inactivate factors V and VIII
2. Thrombin makes fibrin which triggers fibrinolysis, also activates tPA

Question 8

List the 4 stages of the cell-based model:

Answer 8

1. Initiation
2. Amplification
3. Propagation
4. Termination

Question 9

Name the 3 stage model of platelet activation:

Answer 9

1. Initiaition
2. Extension
3. Stabilisation

Question 10

Name 3 ways HES are implicated in PLT dysfunction:

Answer 10

1. Binding of colloidal molecule to integrin alpha2b,beta3 or GPIb inhibit conformational change, preventing PLT aggregation and adhesion
2. Interferes with VIII/vWF complex formation -> accelerated elimination
3. Slow degradable HES: interferes with intracellular PLT signalling

Question 11

TRACS recommends PCR screening on top of serological testing for donors for which 4 canine pathogens as a minimum?

Answer 11

Leishmania
Erlichia canis
Anaplasma
Babesia

Question 12

In which canine patients does TRACS recommend fresher RBC?

Answer 12

IMHA, sepsis

Question 13

What % of hemolysis is acceptable for transfusion?

Answer 13

<1%

Question 14

In filter size for transfusions:

Answer 14

170-260micron

Question 15

Acceptable delivery of blood in cats:

Answer 15

18micron microaggregate filter + syringe driver

Question 16

what is in cryoprecipitate?

Answer 16

Fibrinogen, fibronectin
FVIII
vWF

Question 17

what is in cryopoor?

Answer 17

Albumin, globulin
Antithrombin, protein C/S
Factors: II, VII, IX, X, XI, XII