Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

ECVECC Board Exam > Transfusion/Coagulation > Flashcards

Transfusion/Coagulation Flashcards

1
Q

What is oxyhemoglobin blood product made up of?

A

13 g/dl of polymerized bovine hemoglobin in LRS

  • Bovine hemoglobin depends on chloride instead of 2-3 DPG to determine oxygen affinity → great oxygen transport ability in the body
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are P50 in dogs and cats?

A

Dogs: 31.5 mmHg

Cats: 35.6 mmHg

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Is oxyhemoglobin isoosmotic or hyperosmotic? hyperoncotic or normooncotic?

A

Isoosmotic (300 mOsm/L)
Hyperoncotic (COP = 43 mmHg)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What are common complications/side effects for oxyhemoglobin administration? Why?

A

Hypertension - nitric oxide scanvenging effect leads to vasoconstriction
Volume overload - hyperoncotic & vasoconstriction
Transient Yellow-orange color skin and urine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is the dose for oxyhemoglobin administration and what is the half-life?

A

10-30 ml/kg
18-43 hr

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is the formula for albumin deficit?

A

Albumin deficit (g) = 10 x [Desired albumin - patient albumin] x body weight x 0.3

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What are in frozen plasma?

A

Albumin, fibrinogen, globulin, Factor 2, 7, 9, 10,11, 12

Mainly lacking factor 5, 8

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What are in cryoprecipitate?

A

von Willbrand factor, Factor 8, 13, fibrinogen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What are in cryo-poor plasma?

A

albumin, vit-K dependent factor, globulin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is the FFP volume required to raise albumin by 0.5 g/dL

A

20-25 ml/kg

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is the canine albumin dose required to raise albumin by 0.5 g/dL?

A

450 mg/kg

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

True or False: Platelets contains nucleus.

A

False

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

List 7 structures in the platelet.

A

1) Actin
2) Myosin
3) Fibrin-stabilizing factors (fXIII)
4) Prostaglandins
5) Mitochondria → can form ATP and ADP
6) Endoplasmic reticulum
7) Golgi apparatus
8) Growth factors
9) Thrombosthesnin
10) 𝜶 granules
11) Dense granules
12) Lysosomal granules

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What are in platelet 𝜶 granules (10) and dense granules (6)?

A

𝜶 granules:
- Fibrinogen
- von Willbrand factors
- P-selectin
- Factor V, VIII
- Thrombospondin
- Glycoprotein IIb/IIIa
- Platelet factor 4
- Insulin like growth factor
- Platelet derived growth factor
- Vascular endothelium growth factor

Dense granules:
- Ca2+, Mg2+, phosphate
- ATP, ADP
- Histamine
- Serotonin
- Polyphosphate
- Catecholamines

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What the structure in the endothelium that store the vWF?

A

Weibel-Palade bodies

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What composes the extrinsic tenase complex?

A

Tissue factor (fIII), factor VIIa, calcium

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What composes the intrinsic tenase complex?

A

Factor VIIIa, Factor IXa, phospholipid, calcium

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What composes the prothrombinase complex?

A

Factor Xa, Factor Va

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What are the 7 G protein-coupled receptors on the platelet and what do them bind to?

A

ADP (P2Y1, P2Y12)
Thrombin (PAR1, PAR4)
Thromboxane (TP)
Epinephrine (𝜷2 receptors)
Serotonin (5-HT2A)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What are the two integrins receptors and what do they bind to?

A

Integrin 𝜶2𝜷1 → collagen
Integrin 𝜶II2𝜷3 (GP IIbIIIa) → fibrinogen

  • inside-out and outside-in activation
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What dose GPIb/IX/V receptors bind to?

A

vVF, P-selectin, collagen

  • a member of the leucine-rich receptor class
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What is GPVI activated by?

A

collagen

  • Immunoglobulin superfamily receptors
  • activates integrins via inside-out signalling
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What is glenzocimab?

A

Monoclonal antibody against GPVI receptor (experimental)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Where does the thrombopoietin mainly synthesized?

A

Liver

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

What is the threshold of platelet count when we can see clinical bleeding?

A

25000-50000/ul

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

List 4 tick-borne diseases that can cause thrombocytopenia.

A

Ehrlichiosis
Babesiosis
Rocky Mountain Spotted Fever (Rickettsia rickettsii)
Anaplasmosis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

What are the three proposed mechanisms of drugs causing immune-mediated destruction of platelets and an example for each one of them?

A

1) hapten-dependent antibody formation: drugs bind covalently with the platelet membrane proteins → antibody production
- Penicillin, cephalosporins

2) drugs induce antibodies to bind to platelet membrane proteins in the presence of drugs (e.g. GPIIbIIIa)
- quinine, vancomycin, sulfonamides, rifampin, fluoroquinolones

3) drugs induce antibodies to bind to platelet membrane proteins without the presence of drugs
- sulfonamides

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

List 5 drugs that can cause bone narrow suppression.

A

1) Chemotherapeutic drug
2) Methimazole
3) Phenobarbitals
4) Penicillins
5) Azathioprine
6) Estrogen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

What is the MOA of using vincristine to treat ITP?

A

1) stimulate thrombopoiesis
2) accelerate fragmentation of megakaryocytes
3) impairment of the phagocytosis of platelets by macrophages
4) interference with antiplatelet antibody formation and binding

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

True or False: lyophilized platelets have shorter half-life than PRP.

A

True

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

Define platelet concentrate

A

Plt concentrates are derived from centrifugation of whole blood or by apheresis. They are stored at room temperature with constant mixing and they last 5-7 days.
If they are refrigerated they can last for 14 days, but they have lower survival post transfusion while maintaining good haemostatic function.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

How long can lyophylised or cryopreserved platelets be kept for?

A

3y

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

According to the European guidelines, when is prophylactic transfusion of platelets indicated?

A

Prophylactic transfusions are indicated by the European guidelines by plt count thresholds of 10 x109 in critically ill patients

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

Are platelet transfusions indicated for the reversal of anti-platelet agents?

A

No evidence supporting improved outcomes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

Findings of PROPPR trial regarding platelet transfusion

A

PROPPR trial showed that early (<6h) platelet administration was associated with improved hemostasis and decreased mortality.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

What is the max platelet increase when giving one unit of fresh whole blood derived PRP (80K/uL)/10kg ?

A

40K/uL

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

True or False: Extrinsic thrombocytopathies are more common than intrinsic thrombocytopathies in small animals.

A

False

Intrinsic is more common!

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

Side effects of platelet transfusions

A

SIDE EFFECTS:
* Thrombosis (especially in thrombotic thrombocytopennic purpura and other microvascular thrombotic disorders)
* Infection (TRIM)
* Pulmonary events (TRALI, TACO)
* Impaired neurological recovery (in brain haemorrhage)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

What is the most common extrinsic thrombocytopathy?

A

von Willebrand’s disease

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

List 3 places where von Willebrand factors are stored.

A

1) Platelet 𝜶 granules
2) Weibel-Palade bodies in the endothelial cells (richest!)
3) plasma (bind with fVIII)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

Describe three types of VWD in dogs

A

Type I: quantitative reduction of von Willebrand factors
Type II: qualitative reduction of von Willebrand factors
Type III: absolute lack of von Willebrand factors

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

What is normal BMBT in dogs and cats?

A

< 3 min

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
42
Q

List 4 differential for prolonged BMBT.

A

1) vWD
2) Thrombocytopenia
3) Thrombocytopathia
4) Vascular wall abnormalities

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
43
Q

List two treatments for vWD.

A

1) Cryoprecipitate (1 unit/10kg)
2) DDAVP (Desmopressin acetate)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
44
Q

What is the MOA of DDAVP administration in vWD?

A

Stimulate endothelial V2 receptors to release intracellular von Willebrand factors.

  • Type I has the best response compared to Type II and Type III
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
45
Q

For vWD patient that needs surgery, when should you give DDAVP, the dose and how long does it last?

A

Give 1 ug/kg SC/IV 30min - 1hr before surgery
Last about 2 hours

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
46
Q

How to perform clot retraction assay? What does it used for?

A

Clot retraction is determined by the placement of 5 ml of whole blood into a sterile glass tube (without any anticoagulant). A wooden applicator is inserted into the tube and blood. The tube then is sealed with plastic paraffin film before incubation at 37°C. The assessment of clot formation and clot retraction is noted over 8 to 24 hours. Within 2 to 4 hours a normal clot retracts markedly.
* Used in patient with normal platelet count

Abnormal result → thrombocytopathia, low fibrinogen or coagulopathy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
47
Q

What is the breed that can have idiopathic asymptomatic macrothrombocytopenia?

A

Cavalier King Charles Spaniels (CKCS)

  • mutation in β1-tubulin
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
48
Q

List 3 causes of acquired vWD.

A

1) Immune-mediated disease
2) Hypothyroidism
3) Hydroxyethyl starch administration
4) High shear stress (e.g. mitral regurgitation, aortic stenosis)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
49
Q

What is the proposed major cause of uremia causing bleeding?

A

*defects in vWD structure (sort of acquired type II vWd)
*defective intracellular Ca++ mobilisation –> defective plt degranulation
* storage pool deficiency in dense and alpha granules

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
50
Q

What is Virchow’s triad?

A

It describes the three factors that predispose a patient to vascular thormbosis.

Endothelial injury
Hypercoagulability
Blood stasis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
51
Q

How many deoxygenated Hb need to be present in the vessels for the cyanosis to be clinically appreciable?

A

5 g/dL

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
52
Q

“Serious bleeding concerns arise when there are ___ platelets or less per high-power field.”

What is the number in the blank?

A

3

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
53
Q

What are the two heavy metal that can induce hemolysis?

A

Zinc, copper

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
54
Q

List 5 substances that can cause methemoglobinemia.

A

1) Acetaminophen
2) Nitrates
3) Skunk musk
4) Nitrites
5) topical benzocaine formulations
6) hydroxycarbamide
7) phenazopyridine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
55
Q

List 5 RBC’s self-protective mechanisms for oxidative injury.

A

1) superoxide dismutase
2) catalase
3) glutathion peroxidase
4) glutathion
5) metHb reductase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
56
Q

Why is feline Hb more susceptible to oxidative injury?

A

Because feline Hb has 8 SH-group (sulfhydryl) on the globin part; dogs’ only have 4.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
57
Q

True or False: Heinz bodies can be seen in normal feline erythrocytes.

A

True

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
58
Q

What are the three major components of glutathione?

A

Glutamic acid
Cysteine
Glycine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
59
Q

What is the process of vitamin K dependent coagulation factors systhesis called?

A

𝛄-carboxylation (vitamin K is the cofactor)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
60
Q

There are two ADP receptors on the platelets, what are their functions?

A

P2Y1: platelet shape change and mild aggregation
P2Y12: activation of intergrin and platelet granule release, induction of thromboxane production

** Both ADP receptors need to be activated for full ADP-induced platelet aggregation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
61
Q

True or False: Clopidogrel is a prodrug and require hepatic cytochrome p450 system transformation to be effective.

A

True

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
62
Q

True or False: Is clopidogrel irreversible or reversible antagonist when it binds to P2Y12 ADP receptors?

A

Irreversible antagonist

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
63
Q

What is the MOA of aspirin in anti-platelet aggregation?

A

It irreversibly blocks COX-1 in the platelets → inhibit thromboxane (TXA2) production → inhibit TXA2 induced platelet aggregation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
64
Q

What is the MOA of Abciximab?

A

Non-competitive GPIIbIIIa inhibitor → inhibit fibrinogen induced platelet aggregation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
65
Q

What is extrinsic factor pathway also called? What about intrinsic factor pathway?

A

Extrinsic factor pathway: tissue factor pathway
Intrinsic factor pathway: contact activation pathway

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
66
Q

Where are the tissue factor located?

A

Extravascular cells
Monocytes, macrophages, neoplastic cells, microparticles released from endothelial cells, platelets

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
67
Q

List 10 functions of thrombin.

A

1) Platelet activation
2) Convert fibrinogen to fibrin
3) Activate FXI & FV (11 & 5)
4) Release FVIII from von Willebrand factors
5) Activate FVIII (8)
5) Activate thrombin-activatable fibrinolysis inhibitor (TAFI)
6) Induce inflammation
7) Combine with thrombomodulin → activate protein C
8) Increase endothelial cell microparticle release
9) Activate fXIII (13)
10) Activate protein C (alone, slow)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
68
Q

What is INR and what is it used for?

A

It is an abbreviation of International Normalized Ratio. It is a type of calculation based on PT result, and is used to monitor patients’ on anticoagulant.

INR = [Patient PT/Control PT]^ISI

*ISI = international sensitivity index; the relative strength of the thromboplastin reagent

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
69
Q

Why is the benefit of INR compared to PT test result? What is normal INR?

A

INR takes into account of the variation of different machines, different reagents used and sensitivity difference in the TF activators.

Normal INR: ≤ 1.1

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
70
Q

Why at the beginning of warfarin treatment, patient may be in hypercoagulable state instead of hypocoagulable state?

A

Because warfarin also inhibit the activation of protein C and protein S, both of which are anticoagulant.

  • Sometimes patients can be treated with heparin at the first few days of warfarin therapy
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
71
Q

When a patient is on vitamin K anticoagulant, what is the therapeutic range for INR?

A

2.0 - 4.0

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
72
Q

What coagulation factors can unfractionated heparin inhibit?

A

Factor II, X
Factor IX, XI, XII

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
73
Q

Which one is highly protein bound, UFH or LMWH?

A

UFH

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
74
Q

Which one can bind to endothelial cells and possible platelets or other plasma proteins, UFH or LMWH?

A

UFH

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
75
Q

What are the elimination of UFH and LMWH, respectively?

A

UFH
- saturable pathway: cleared by reticuloendothelial system and endothelial cells
- non-saturable pathway: excreted via kidneys

LMWH
- mainly excreted via kidneys

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
76
Q

What are the half-life of UFH and LMWH, respectively?

A

UFH: 60-90 min
LMWH: 3-6 hours

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
77
Q

Which test do you used to monitor UFH? PT or aPTT?

A

aPTT

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
78
Q

Why are old clots more resistant to thrombolysis?

A

Because of more extensive fibrin polymerization

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
79
Q

Where is the urokinase or urokinase plasminogen activator produced?

A

renal tubular epithelium

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
80
Q

What is the most common complication from thrombolytic therapy in cats?

A

Reperfusion injury

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
81
Q

What is the MOA of EACA and TXA?

A

Both drugs **reversibly **bind to lysine-binding site on the plasminogen → inhibit plasminogen to bind to fibrin → inhibit plasminogen activation → inhibit fibrinolysis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
82
Q

What does plasmin bind to?

A

Fibrin
Fibrinogen
TPA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
83
Q

True or False: Is estrogen prothrombotic or antithrombotic?

A

Prothrombotic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
84
Q

Which one is more potent, TXA or EACA?

A

TXA is 6-10x more potent than EACA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
85
Q

How are TXA and EACA metabolized?

A

Mainly excreted via kidneys

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
86
Q

What is the half-life for TXA and EACA?

A

TXA: 1-2 hours
EACA: 2-3 hours

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
87
Q

Side effects of EACA and TXA

A

EACA can induce myonecrosis
TXA vomiting and seizure (glycin receptor)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
88
Q

What is fibrinolytic shutdown?

A

Inflammatory cytokines (post-op) induce large amount of PAI - stop physiologic fibrinolysis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
89
Q

What is the main difference between vasopressin and desmopressin?

A

In Desmopressin, the L-arginine is switched to D-arginine → no effect on V1 receptor (vasoconstriction) but more effective on V2 (antidiuretic & release vWF and fVIII from endothelium)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
90
Q

Which coagulation factor is hemophilia A lacking? What about hemophilia B and C?

A

hemophilia A: fVIII (8)
hemophilia B: fIX (9)
hemophilia C: fXII (11)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
91
Q

Which amino acid composes the 2/3 of protamine?

A

arginine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
92
Q

List 5 adverse effects of protamine.

A

1) Hypotension
2) Anaphylaxis reaction
3) Pulmonary hypertension
4) Delayed noncardiogenic pulmonary edema
5) Paradoxical bleeding (e.g. thrombocytopenia, thrombocytopathia, heparin-rebound effect)

  • Heparin-rebound effect: protein-bound heparin that is incompletely bound by protamine. After the protamine-heparin complexes are cleared from the circulation, remaining protein-bound heparin dissociates slowly and binds to antithrombin to produce an anticoagulant effect
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
93
Q

Can protamine reverse any type of heparin? why?

A

No, it is much more efficient in reversing unfractionated heparin as it prefers long chains.
It can only reverse 60% of LMWH.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
94
Q

What is the proposed mechanism for conjugated estrogen in hemostasis?

A

Increased vWF, fVII and fXII

  • Often used in uremic patients
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
95
Q

What is the difference of the thrombus components between arterial and venous thrombus?

A

Arterial thrombus
- White clot; platelets + fibrins

Venous thrombus
- Red clot; fibrins + red blood cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
96
Q

When a patient is on UFH therapy, what is the common target range?

A

1.5 - 2.5x prolongation of aPTT

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
97
Q

What is the 5P rules in FATE?

A

Pallor (i.e. purple or pale toes)
Polar (i.e. cold extremities)
Pulselessness
Paralysis
Pain

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
98
Q

What are the two factors are associated with better prognosis in FATE?

A

Presence of motor function
Only one limb is affected

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
99
Q

List 7 causes of aortic thrombosis in dogs.

A

1) Neoplasia
2) Hyperadrenocorticism
3) PLN
4) PLE
5) Hypothyroidism
6) IMHA
7) Infective endocarditis

35% cryptogenic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
100
Q

What is the pathophysiology of heparin-induced thrombocytopenia

A
  • Non-immunogenic: direct interaction between heparin and platelets causing platelets clumping or sequestration
  • Immunogenic: Heparin bids to platelet factor 4 (released from alpha granules) → becomes immunogenic and cause release of IgG targeting at heparin-PF4 complex → The heparin–PF4–IgG multimolecular immune complex activates platelets via their FcγIIa receptors → release of prothrombotic platelet‐derived microparticles, platelet consumption, thrombocytopenia

*Thrombosis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
101
Q

True or False: Both tPA and uPA requires the presence of fibrin to activate plasminogen.

A

False

uPA does not require the presence of fibrin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
102
Q

Describe the difference between fibrin degradation products (FDPs) and D-dimers.

A

Fibrin degradation products (FDPs): degradation of fibrin, fibrinogen and cross-linked fibrin

D-dimers: degradation of fibrin that are cross-linked by fXIII

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
103
Q

What are the two plasma proteins that can inhibit plasmin function?

A

𝜶-2-antiplasmin
𝜶-2-macroglobin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
104
Q

What are the two inhibitors for plasminogen activators?

A

Plasminogen activator inhibitor-1 (PAI-1)
Protease nexin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
105
Q

What are the two activators for TAFI?

A

Thrombin-thrombomodulin complex
Plasmin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
106
Q

How does TAFI inhibit fibrinolysis?

A

It eliminates carboxyl-terminal lysine residues from fibrin → reduces the ability of plasminogen to bind fibrin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
107
Q

True or False: Primary hyperfibrinolysis can be seen in chronic liver failure secondary to increased concentrations of tPA.

A

True

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
108
Q

List 4 substances that can induce endothelial PAI-1 release.

A

LPS
IL-1
TNF-𝜶
TGH-𝜷

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
109
Q

True or False: Increase D-Dimer level indicates hyperfibrinolysis.

A

False

Increase D-Dimer can be a result of increase fibrinolysis or increase thrombosis → cannot identify hypo or hyper-fibrinolysis!

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
110
Q

In ROTEM, there are two assays called INTEM, EXTEM, and APTEM, which are used to evaluate intrinsic and extrinsic pathways, as well as the effect of hyperfibrinolysis on other assays, respectively. What are the activators/inhibitors for them?

A

INTEM: ellagic acid
EXTEM: tissue factor
APTEM: aprotinin

111
Q

If a young cat has prolonged aPTT but is otherwise normal on PE without clinical evidence of bleeding, what is the congenital disease that should be on the differential list?

A

Factor XII deficiency (Hageman trait)

112
Q

What is the dose for DDAVP to treat vWD?

A

1-4 mcg/kg SC

113
Q

What is the proposed mechanism of hyperfibrinolysis in dogs with acute liver failure?

A

1) Decreased hepatic clearance of tPA
2) Decreased levels of PAI-1, 𝜶-2-antiplasmin, and TAFI.

114
Q

True or False: Bleeding diathesis can be seen in about 1/3 of Angiostrongylus vasorum infection.

A

True

bleeding tendency due to vWf deficiency, thrombocytopenia, DIC and hyperfibrinolysis (67% of dogs)

Hyperfibrinolysis might be due to the mechanical activity of worms in vessels eliciting production of TPA and plasmin (demonstrated in Dirofilaria)

115
Q

Where is streptokinase derived from?

A

𝜷-hemolytic streptococci

116
Q

What is the difference between traumatic induced coagulopathy (TIC) and acute traumatic coagulopathy (ATC)?

A

TIC: ATC + resuscitation-associated coagulopathy (RAC)

ATC: endogenous coagulation abnormality

117
Q

What are the two characteristics of acute traumatic coagulopathy?

A

Hypocoagulable state
Hyperfibrinolysis

118
Q

What are the four main contributors to resuscitation-associated coagulopathy?

A

Lethal diamond
* Hypothermia
* Metabolic acidosis
* Hemodilution coagulopathy
* Hypocalcemia

119
Q

Explain the pathophysiology of acute traumatic coagulopathy (or acute coagulopathy of trauma shock).

A

During severe trauma, there is lots of catecholamine release & extensive endothelial damage → extensive activation of coagulation cascade; extensive release of thrombomodulin → many thrombins are formed; clotting factors and platelets are consumed → eventually hypocoagulable state

enhanced thrombomodulin-thrombin-proteinC pathway: Injury = massive release of thrombin = binding to thrombomodulin = massive activation of protein C

Hyperfibrinolytic DIC phenotype: trauma = tissue injury = massive release of thrombin = massive activation of TPA = hyperfibrinolysis. However upon resusciation rebound synthesis of PAI»>TPA = hypercoagulable pattern after the first 24h.

120
Q

ATC requires two conditions to be present, what are they?

A

Severe tissue damage
Hypoperfusion

121
Q

In veterinary medicine when is ATC suspected?

A
  1. recent history of severe trauma
  2. hypoperfusion, hypothermia, shock, bleeding
  3. PT > 50% prolonged or TEG with MA decreased by more than 40%
122
Q

Where is PAI produced?

A

Many different types of cells

123
Q

Where is tPA stored in the endothelium?

A

Weibel-Palade bodies!

124
Q

When should you do a cross match in dogs and cats?

A

Dogs: if patient has a transfusion more than 3 days ago (recent evidence supports 24h)

Cats: always do a crossmatch due to possible anti-mik antibodies

125
Q

True or False: Crossmatch can prevent all the transfusion reactions.

A

False

It can only prevent acute hemolytic transfusion reaction.

126
Q

What are the components for CPDA?

A

Citrate
Phosphate
Dextrose
Adenine

127
Q

What is Optisol solution and what is the function?

A

Optisol solution contains adenine, dextrose, NaCl and mannitol. It is a RBC additive solution that can provide RBCs nutrition and prolong the storage life. It needs to be used with anticoagulant (usually CPD).

128
Q

How much blood can dogs and cats donate each time?

A

Dog: 20 ml/kg
Cat: 10 ml/kg

129
Q

Define major and minor crossmatch.

A

Major crossmatch: Donor’s RBCs + Recipient’s plasma

Minor crossmatch: Recipient’s RBCs + Donor’s plasma

130
Q

True or False: A blood have the genotype a/a or a/b; only homozygous b/b cats express the type B antigen on their RBCs.

A

True

  • That’s why type B is so rare!
131
Q

For a type AB cat that needs RBC transfusion, which type of the pRBC should be given if AB blood is not available.

A

Type A

132
Q

True or False: A dog that was previously given a compatible transfusion from a donor dog may become incompatible with blood from the same donor 1 to 2 weeks later.

A

True

133
Q

True or False: A dog that was previously given a compatible transfusion from a donor dog may become incompatible with blood from the same donor 1 to 2 weeks later.

A

True

134
Q

What is the weight limit for dog and cat donors and what are the maximum blood volume (in ml) for donation?

A

Dog: 23kg; 450ml
Cat: 4kg; 40ml

135
Q

Why acepromazine is not recommended for blood donor sedation?

A

1) Cause hypotension (due to 𝛼1 antagonism)
2) Interfere with platelet function (due to 5-HT2 antagonism)

136
Q

What is open collection system and what is closed collection system?

A

Open collection system: the blood can be in contact with the environment and increase the risk of contamination
- needle + Three-way stopcock + syringe + blood bag

Closed collection system: the blood is not exposed to the environment at any time point during the collection or separation into blood components.
- commercial blood bag with needle

137
Q

What is the diameter of the microfilter pores?

A

170 um

138
Q

According to the blood bank standard, after pRBC transfusion, how many percentage of RBC should survive after 24 hours (if there is no bleeding or hemolysis)?

A

70-80%

139
Q

How many ml of PRP can be made from 1 unit of FWB? What about platelet concentrate?

A

PRP: 200ml
PC: 50ml

  • 1 unit FWB = 450ml
140
Q

One unit PRP can increase how many platelet in a 30kg dog?

A

10K/uL

141
Q

What is the common dose for cryoprecipitate? What about cryo-poor?

A

cryoprecipitate: 1-2 ml/kg
cryo-poor: 6-10 ml/kg

142
Q

List 5 adverse effects that can be caused by hemoglobin.

A

1) NO scavenging → vasoconstriction
2) Increase oxidative stress and cause oxidative injury
3) Pro-inflammatory
4) Endothelial damage
5) Increase risk of AKI
6) Increase pulmonary arterial pressure

143
Q

What is the FDA standard if a blood product is considered “Leukoreduced?”

A

No more than 5 x 10^6 of leukocytes should be present per unit of human pRBC

144
Q

What are the two mechanisms of leukoreduction?

A

1) Mechanical filtration
2) Cell adhesion (to the filter)

145
Q

During leukoreduction, how many ml of blood can be lost from the filter and tubing?

A

about 51-52 ml

146
Q

There are two type of leukoreduction - pre-storage and post-storage leukoreduction. Which one is superior? Why?

A

Pre-storage leukoreduction is superior

It reduces the accumulation of the metabolites produced by WBCs and platelets

147
Q

What are the three types of storage lesions? List 3 examples for each.

A

1) Biochemical changes
- Decreased ATP
- Increased potassium
- Decreased 2,3-DPG
- Dysfunction of NO
- Accumulation of ammonia
- Oxidative injury
- Accumulation of cell free hemoglobin

2) Biomechanical changes
- Decreased RBC deformability (spectrin and ankrin degradation)
- Accumulation of microparticles
- RBC shape changes
- Adhesion to endothelial cells

3) Immunological changes
- Leukocyte contamination
- Transfusion-related immunomodulation

148
Q

Explain why there may be decreased ATP in RBCs during storage?

A

Erythrocytes do not have mitochondria → they generate ATP via anaerobic glycolysis → generate pyruvate, hydrogen ion → accumulate of hydrogen ions inhibit PFK function (key enzyme in glycolysis) → decrease ATP

149
Q

Are microparticles pro-inflammatory or anti-inflammatory?

A

Pro-inflammatory and also pro-thrombotic

150
Q

What are the 4 definitions of massive transfusion?

A

1) Receive 1 whole blood volume within 24 hours
2) Receive half of the blood volume within 3-4 hours
3) Receive 1.5 times of the blood volume regardless of time
4) Receive blood at 1.5 ml/kg/min for 20 minutes

151
Q

List 3 common electrolytes imbalances associated with massive transfusion.

A

1) Hypocalcemia
2) Hypomagnesemia
3) Hyperkalemia

152
Q

What is the recommended transfusion ratio for plasma: platelet: RBC?

A

1:1:1

153
Q

List 3 complications associated with massive transfusion besides electrolyte abnormalities.

A

1) Hypothermia
2) Metabolic acidosis
3) Coagulopathy
4) Immunosuppression
5) TRALI

154
Q

List 5 substances that are in Weibel-Palate bodies.

A

1) vWf
2) fVIII
3) tPA
4) P-selectin
5) IL-8

155
Q

What is the function of ADAMTS13?

A

It is a von Willebrand factor-cleaving protease. It cleaves vWf into smaller multimers → preventing accumulation of ultra large multimers of vWf which can lead to diffuse microvascular thrombosis

156
Q

What are the three mechanisms of decreased AT in critical illness?

A

1) consumption
2) eliminated by neutrophil elastase
3) decrease production (negative acute phase protein)

157
Q

List 5 places that TFPI can be found.

A

Endothelial cells
Platelets
Mononuclear cells
Fibroblasts
Vascular smooth muscles

158
Q

List 5 causes of hypofibrinogenemia

A

1) Hemodilution
2) Hepatic dysfunction
3) DIC
4) Sepsis
5) After thrombolytic therapy

159
Q

What does thrombin time test?

A

It tests functional fibrinogen, via measure of the time taken for a standardized thrombin solution to convert fibrinogen to fibrin

160
Q

True or False: Dal is a special RBC antigen than only presents in Dalmatian.

A

False

Dal is present in most dogs but is lacking in some Dalmatians.

161
Q

What is the phenotypes for canine universal donor?

A

DEA 1.1, 1.2, 3, 5, and 7 negative but positive for DEA 4

162
Q

True or False: Cats should always receive type-specific plasma.

A

True

163
Q

According to the 2014 guidelines for viscoelastic test, how long should the blood sample to be held at room temperature for prior to testing for TEG/ROTEM?

A

30 min

Longer → hypercoagulable

164
Q

What is the difference between the TEG and ROTEM in terms of the relationship of the pin and the cup?

A

TEG: cup oscillates around the stationary pin

ROTEM: Pin oscillates while the cup is stationary

165
Q

What activators can be added to the TEG test? Which pathway does it stimulate?

A

All the samples need to add calcium

Kaolin: stimulate intrinsic pathway
Tissue factor: stimulate extrinsic pathway
T-PA: used to assess fibrinolysis

166
Q

What are the four assays in ROTEM?

A

INREM
- Activator: ellagic acid
EXTEM
- Activator: tissue factor
FibTEM
- Activator: tissue factor
- Modification: cytochalasin D is added to inhibit the platelet contribution to the clot → assess fibrinogen
ApTEM
- Activator: tissue factor
- Modification: aprotinin is added to inhibit fibirnolysis → assess the impact of hyperfibrinolysis

167
Q

How does Sonoclot work and what does it test?

A

it involves a vertically oscillating probe immersed in a cuvette of whole blood in which glass beads activate coagulation.

It tests ACT, clot rate, and platelet function

168
Q

What is ACT comparable to?

A

aPTT

Both test the intrinsic and common pathway

169
Q

What is the parameter to assess the rate of clot formation in TEG? What about in ROTEM?

A

TEG: K
ROTEM: Clot forming time (CFT)

Time to get a clot 20mm

170
Q

What is the parameter to assess the time it takes to initiate the fibrin formation in TEG? What about in ROTEM and VCM?

A

TEG: R
ROTEM: Clot time (CT)
VCM: Clot time (CT)

Time to get a clot of 2mm

171
Q

Does the higher or lower lysis index in VCM mean increase fibrinolysis?

A

Lower (more residual clot being lysed)

172
Q

How does VCM work?

A

Small portable machine
Blood clots between two moving glass plates and increased resistance between plates gives trace

173
Q

True or False: According to the CURATIVE guidelines, antithrombotic administration should be considered as a routine treatment in dogs with Cushing’s disease.

A

False

Unless other risk factor exists

174
Q

What are the two conditions in dogs and one condition in cats that warrant routine antithrombotic administration?

A

Dogs: IMHA, PLN
Cat: Cardiac disease

  • For canine pancreatitis, only acute necrotizing pancreatitis is indicated
175
Q

What are the three conditions that are considered high risk for thrombosis

A

1) Dogs with IMHA or PLN
2) Cats with cardiomyopathy and associated risk factors (history of ATE, LA enlargement, spontaneous echo contrast, reduced LA appendage flow velocity)
3) Dogs or cats with > 1 disease/risk factor for thrombosis (e.g. pancreatitis with sepsis)

176
Q

Which blood clot have higher composition of platelets, arterial clot or venous clot?

A

Arterial clot

177
Q

List an example for arterial clot and venous clot, respectively.

A

Arterial clot: ATE from HCM

Venous clot: IMHA, PLN, PTE

178
Q

According to the CURATIVE guidelines, which anticoagulant is superior, LMWH or UFH?

A

LMWH in both dogs and cats
(positive safety profile, reliable bioavailability)

179
Q

According to the CURATIVE guidelines, which anticoagulant is superior, direct Xa inhibitor or UFH?

A

Direct Xa inhibitor in both dogs and cats
(efficacy, reliable pharmacokinetics, ease of oral dosing)

180
Q

According to the CURATIVE guidelines, which anticoagulant is superior, direct Xa inhibitor or LMWH?

A

Either one is reasonable

181
Q

According to the CURATIVE guidelines, is the combination of antiplatelet with anticoagulant outweigh the anticoagulant alone?

A

Dog: aspirin/clopidogrel in addition to LMWH or individually adjusted UFH therapy may be considered in dogs at high risk of VTE

Cat: insufficient data; combination therapy may be considered where there is a high risk of thrombosis

182
Q

According to the CURATIVE guidelines, what is the recommended loading dose and daily dose of clopidogrel in dogs and cats?

A

Dog:
- Loading dose: 4-10 mg/kg
- Daily dose: 1.1-3 mg/kg q24h

Cat:
- Loading dose: 37.5mg
- Daily dose: 18.75mg q24h

183
Q

What are the recommended UFH IV and SC doses in dogs?

A

IV
- 100 U/kg IV
- CRI 480-900 U/kg/24hr

SC
- 150-300 U/kg SC q6h

184
Q

What is the recommended UFH dose in cats?

A

250 U/kg SC q6h

185
Q

What is the recommended dose of rivaroxaban in dogs and cats?

A

Dog: 1-2 mg/kg/d PO
Cat: 0.5-1 mg/kg/d PO

186
Q

What is the recommended monitoring modality for dogs and cats on UFH treatment?

A

Dog: Anti-Xa activity (target: 0.35-0.7 U/ml)
Cat: insufficient data

187
Q

According to the CURATIVE guidelines, what is the recommended monitoring modality for dogs and cats on LMWH treatment?

A

insufficient evidence to make strong recommendations for therapeutic monitoring

  • targeting anti-Xa levels of 0.5–1.0 U/mL 2–4 hours postdose can be considered (dog)
188
Q

True or False: According to the CURATIVE guidelines, antithrombotic treatment should not be discontinued prior to invasive procedure in patients with high risk of thrombus formation.

A

True

  • Doesn’t matter anti-platelet or heparin
189
Q

According to the CURATIVE guidelines, if a previous arterial blood clot has resolved, should you discontinue the antithrombotic therapy?

A
  • If underlying causative conditions have resolved → d/c
  • Unknown or unsolved underlying cause → continue
190
Q

According to the CURATIVE guidelines, if a previous venous blood clot has resolved, should you discontinue the antithrombotic therapy?

A
  • If underlying causative conditions have resolved → d/c
    o Unknown or unsolved underlying cause → continue
191
Q

What is the recommendation in the CURATIVE guidelines regarding the weaning of UFH, LMWH and direct-Xa inhibitor?

A

UFH: need to wean (from IV to SC)
* “rebound” hypercoagulation phenomenon following discontinuation of heparin therapy may be observed

LMWH: no need to wean
direct-Xa inhibitor: weaning is recommended

192
Q

What are the two formulas to calculate the required pRBC for transfusion?

A

1) Volume (ml) = PCV rise desired % x body weight x 1.5

2) Volume (ml) = Body weight x blood volume x (Desired PCV - Patient PCV)/Donor PCV

*Blood volume: dog 90 ml/kg; cat 60 ml/kg

193
Q

Under normal condition, which phospholipids are inside and which are outside the membrane?

Phosphatyldserine (PS)
Phosphatidylethanolamine (PE)
Phosphatidylcholine (PC)
Sphingomyelin
Sugar-linked sphingolipids

A

Outside: Phosphatidylcholine (PC), Sphingomyelin, Sugar-linked sphingolipids

Inside: PS, PE

194
Q

What are the functions of flippase, floppase and scramblase

A

The functions of flippase and floppase are to maintain the resting state
- Flippase: flip PS in
- Floppase: flip PC out

The function of scramblase is to facilitate the activation state
- Scramblase: transpot PS, PE out

195
Q

List 4 substances/conditions that can stimulate microparticle formation.

A

1) cytokines (e.g. TNF-𝜶)
2) thrombin
3) hypoxia
4) shear stress

196
Q

List 8 endogenous anticoagulant.

A

1) Heparan sulfate proteoglycans
2) NO
3) Tissue factor pathway inhibitor
4) Thrombomodulin
5) Protein C & Protein S
6) Prostacyclin
7) Physical barrier
8) Ecto-adenosine diphosphatase
9) Antithrombin

197
Q

Name three functions of Protein C-protein S complex.

A

1) Cleaves fV and fVIII
2) Inhibits PAI-1
3) Shut down thrombin formation
4) Inhibit TAFI

198
Q

Which coagulation factor is the only one that is routinely circulating in the blood in active forms?

A

fVII (about 1% is active form)

199
Q

True or False: In the initiation phase of the cell-based model, fXa is only functional at the surface of the TF-bearing cells, while fIXa can dissociate to the distant cells.

A

True

fXa will be degraded by TFPI and AT once it leaves the cell surface

200
Q

What are the three coagulation factors thrombin activates during amplification phase?

A

fV, fVIII, fXI

5,8,11

201
Q

What is the difference in terms of the components in cryoprecipitate and cryo-poor plasma?

A

Cryoprecipitate
- Fibrinogen, vWf, fVIII,fXIII, fibronectin

Cryo-poor plasm
- Vitamin K dependent factors, albumin

202
Q

What are the special structures on the vitamin K dependent coagulation factors?

A

Glutamic acid (Gla)

  • Need 𝛄-carboxylation to be able to bind to membrane surface
203
Q

What are the two substances that can induce TFPI release?

A

1) Heparin
2) Activated platelets

204
Q

Describe how TFPI interfere with the coagulation pathway?

A

TFPI has three domains - K1, K2, and K3.

  • The K1 domain then binds to fVII-TF complex (irreversible, need Ca).
  • The K2 domain binds to fXa and inhibit it (reversible, no Ca needed).
  • K3 domain binds to protein S
205
Q

True or False: AT can inhibit coagulation factors 2, 7, 9, 10, 11, 12

A

True

AT can inhibit 2, 9, 10, 11, 12 without heparin (slow)
AT NEEDS heparin to inactivate factor 7

206
Q

What are the three other factors needed for activated protein C to work?

A

Protein S
Calcium
Phospholipid

207
Q

What are the four functional binding sites on thrombin (B-chain)

A

1) Sodium binding site
2) Active site
3) Exosite I
4) Exosite II

208
Q

When Na binds to the thrombin sodium binding site, does it make the thrombin procoagulant or anti-coagulant?

A

Procoagulant

209
Q

What does thrombin exosite I and exosite II bind to? What does it make thrombin become, more procoagulant or anti-coagulant?

A

Exosite I: hirudin (from leech!), fibrinogen
Exosite II: heparin, thrombomodulin, AT

Anticoagulant

210
Q

Explain the cell-based model.

A
211
Q

Why protein C and AT/heparin has synergic anticoagulant effect?

A

The complexes of 10-5 and 9-8 are more resistant to AT inactivation than 10 or 9 are alone.
Activation of the APC pathway leads to the reduced production of 5 and 8 → decreases 10-5 and 9-8 complex formation

212
Q

True or False: The effect of inflammation on endothelial cells appears to initially result in increased concentrations of plasminogen activators (tPA), but a more sustained rise in PAI-1 predominates.

A

True

213
Q

The diagnosis of DIC is based on a clinical condition capable of inciting DIC plus two of the laboratory abnormalities. What are they?

A

Thrombocytopenia
Prolong aPTT/PT
Hypofibrinogenemia
Decreased AT
Elevated FDPs or D-dimer
Erythrocyte fragmentation on a blood smear (schistocytes, keratocytes, acanthocytes)

3/6 parameters abnormal = significantly higher mortality rate and a sensitivity of 72% and specificity of 81% in diagnosing DIC

214
Q

Define type 1 and type 2 TRALI.

A

The major difference: whether there is an ARDS risk factor or the presence of mild ARDS

Type 1
- Patients who have no risk factor of ARDS and meet the following criteria
1) Acute onset
2) Hypoxemia: P/F ≤ 300 or SPO2 < 90% on room air
3) No evidence of left atrial hypertension (LAH) on echo (if LAH is present, it is judged not to be the main cause)
4) Clear evidence of bilateral pulmonary edema on imaging (chest radiographs, chest CT or ultrasound)
5) Onset of pulmonary signs within 6 hours of transfusion
6) No temporal relationship to an alternative risk factor for ARDS

Type 2
- Patients who have risk factors for ARDS or who have existing mild ARDS (P/F 200–300), but whose respiratory status deteriorates and is judged to be due to transfusion based on
1) Findings as described in the type 1 (1) to (5)
2) Stable respiratory status in the 12 hr before transfusion

215
Q

What is the incidence of TRALI in dogs?

A

3.7%

216
Q

Describe the pathophysiology of TRALI.

A

In human medicine, it has been hypothesized that TRALI is the result of two clinical insults,
which is also call the “Two-hit model,” or “Two-event model.”

The first insult is that the pulmonary vascular endothelium is activated (pro-inflammatory) resulting in priming (adherence) and sequestration of neutrophils by one or more endogenous stimuli (i.e. sepsis, surgery)

The second insult is the blood product transfusion. The antibodies in the blood products, such as antibodies to human leucocyte antigen (HLA) class I and II, and various neutrophil antigens (HNA), can cause compliment activation and result in a full activation of those sequestrated neutrophils and released of cytotoxic agents, which eventually lead to endothelial injury and pulmonary edema

217
Q

Define febrile non-hemolytic transfusion reaction (FNHTR).

A
  • Acute non-immunologic or immunologic reaction
  • Temperature > 39C (102.5 F) AND an increase in temperature of > 1C (1.8 F) from the pre-transfusion body temperature during or within 4 hrs of the end of a transfusion
  • External warming, underlying patient infection, AHTR, TRALI, and TTI have been ruled out.
218
Q

What cause FNHTR?

A

Secondary to donor WBCs or platelet antigen-antibody reactions or due to transfer of pro-inflammatory mediators in stored blood products.

219
Q

List 5 causes of respiratory reaction during transfusion.

A

1) TRALI
2) TACO
3) FNHTR
4) TAD (transfusion associated dyspnea)
5) allergy reaction

220
Q

Define transfusion associated dyspnea (TAD).

A
  • acute
  • development of acute respiratory distress during or within 24 hours of the end of a transfusion
  • TACO, TRALI, allergic reaction, and underlying pulmonary disease have been ruled out
221
Q

What is the incidence of TACO in dogs and cats?

A

Dog 4.7%
Cat 3%

222
Q

Define transfusion associated fluid overload (TACO).

A
  • acute, non-immunologic reaction secondary to an increase in blood volume mediated by blood transfusion
  • acute respiratory distress and hydrostatic pulmonary
    edema within 6 hours of transfusion
  • Evidences of LA hypertension or volume overload
  • These patients typically have a positive response to diuretic therapy.
223
Q

Describe Threshold model of TRALI.

A

The neutrophils need to be primed/activated by either substances in the donor blood or by the recipient’s condition (e.g. surgery, sepsis). For TRALI reaction to happen, the primed/activated neutrophils need to overcome a threshold.

224
Q

What type of hypersensitivity is allergic transfusion?

A

Type I hypersensitivity

225
Q

True or False: hemolytic transfusion reaction is always immunogenic.

A

False

Non-immunogenic: mechanical, chemical, osmotic, thermal

226
Q

When is the timeframe of delayed hemolytic transfusion reaction?

A

24 hours to 28 days after transfusion

227
Q

For cats receiving canine RBC, what is the lifespan of these RBC?

A

2-4 days

  • compared to feline RBCs 30 days
228
Q

What is the proposed mechanism of hypotensive transfusion reaction?

A
  • A hypotensive transfusion reaction is an acute, non-immunologic reaction.
  • There is usually a decrease in systolic blood pressure of at least 30 mmHg from baseline.
  • Activation of coagulation factor XII → high-molecular-weight kininogen to bradykinin → vasodilation and increased vascular permeability
  • Bradykinin is metabolized via ACE, and the use of ACE inhibitors before or during a transfusion has been associated with the development of HyTRs.
229
Q

True or False: According to the TRACS guidelines, it is recommended to used fresher RBC transfusion products in dogs with sepsis or hemolytic causes of anemia.

A

True

230
Q

According to the TRACS guidelines, is it recommended to administer antihistamine prior to transfusion routinely?

A

No

231
Q

What is the recommended transfusion method for dogs and cats pRBC transfusion?

A

Dog: standard 170–260 micron in-line blood administration set with gravity flow
* Peristaltic and rotary infusion pumps should be avoided!!!

Cat: syringe pump + 18-micron microaggregate filter works

232
Q

What are the three ways neutrophils execute their innate immunologic effect?

A

1) Phagocytosis
2) Degranulation
3) Neutrophil Extracellular Traps (NETs)

233
Q

What are the three main components of NETs?

A

1) Cell free DNA
2) Histone
3) Neutrophil granule proteins & peptides
- Myeloperoxidase (MPO), Lactoferrin, Cathepsin G, Neutrophil elastase (NE), Defensins

234
Q

Explain NETosis.

A

Neutrophils expose to PAMPs, DAMPs, cytokines, pathogens, autoantibodies, immune complexes → citrullination of histone, disassembly of the nuclear envelope, chromatin decondensation → release of NETs.

235
Q

NETs are prothrombogenic or anti-thrombotic?

A

Prothrombogenic

236
Q

What are the two ways of platelet to activate NETs?

A

Adhesive interaction
Soluble interaction

237
Q

Which biomarker is highly specific for NETs?

A

citrullinated histone

238
Q

What is the equation used to calculate whole blood transfusion?

A

Transfusion volume (ml) = (PCVdesire - PCVcurrent)/PCVdonor x body weight x blood volume

239
Q

List 5 things that can stimulate tPA.

A

Histamine
Acetylcholine
Bradykinin
Platelet activating factor
𝜶 adrenergic agonist

240
Q

What are the two things that activate TAFI?

A

Thrombin-thrombomodulin complex
Plasmin

241
Q

Draw the traditional coagulation cascade.

A
242
Q

What is the function of dimethyl sulfoxide (DMSO) in cyropreserved platelet?

A

It inhibits platelet activation via thromboxane A2-dependent, COX-1-mediated effect

243
Q

Describe DOGiBAT score.

A

It is used to evaluate the severity of bleeding

9 categories
0-2 → the higher the worse

Correlates with needs of transfusion and inversely proportional to plt count

244
Q

How long can the refrigerated plasma last?

A

2-6C for 14 days

245
Q

List 2 difference between FFP and FP

A

FFP
- Frozen with 24 hours after being made
- Last 1 year in -30C
- Contains all the clotting factors, vWf, fibrinogen, Albumin

FP
- FFP stored in -30C for more than 1 year
- Last 5 years in -30C
- Contains everything minus fV and fVIII

246
Q

The extrinsic tenase complex activates factor X and factor…

A

IX which then combines with factor VIII and Ca++ coming from platelet granules and forms intrinsic tenase

247
Q

Role of factor XI

A

Factor XI is activated by thrombin. Once activated, factor XIa serves to activate more factor IX to factor IXa. This continuous activation of factor IX provides a sustained supply of factor IXa for the formation and persistence of the intrinsic tenase complex.

248
Q

What is fondaparinoux?

A

It is an ultra-low molecular weight heparin (no tail, just binds to exosite II) .
There is no tail, so can’t be reversed by protamine!

249
Q

What’s the difference between ULMWH and direct thrombin inhibitors?

A

DTIs bind to the active site not to the exosite so they are more efficient in binding thrombin linked to fibrinogen.

250
Q

What are throphins and why are they important?

A

Trophins are platelet derived factors that are key in stabilising the endothelial juntions –> reasons for petecchiae in thrombocytopenic patients

251
Q

Difference between clopidogrel and ticagrelor or congrelor?

A

They all act on ADP receptors, but clopi works on P2Y12 and it binds irreversibly vs ticagrelor and congrelor act on P2Y12 and binds reversibly.
Ticagrelor also very short acting (IV just before procedure)

252
Q

In a recent study comparing clopidogrel and aspirin…

A

clopi group had less incidence of ATE recurrence, longer time to recurrence and decreased likelihood of cardiac death

253
Q

Dual therapy with clopi and riva in cats has shown…

A

low rate of recurrence of ATE with no significant adverse events

254
Q

Primary hemostasis

A

From initial interaction of platelets with injured endothelium to platelet aggregation

  • initiation: vWf exposure + GPIb platelet receptor –> plt monolayer
  • extension: platelet activation and aggregation (degranulation and inside-out signalling)
  • stabilisation: fibrinogen GbIIb/IIIa outside in activation with myosin retraction and tightening of platelets bond
255
Q

Immunothrombosis

A

Interaction between innate immune system and coagulation:
- inflammatory cytokines increase TF expression and formation of microparticles
- coagulation factors increase cytokine expression by binding onto immune-cells
- NETosis and microparticles formation –> pro-coagulants
- C4 complement binds to protein C and protein S to de-activate them
- platelets can interact with WBC via P-selectin
- thrombin activates WBC via PAR receptors

256
Q

BLASTT study

A

Cats with ATE treated with thrombolysis vs placebo - overall discharge rate of 37.5%.
No difference in limb score improvement between group and numerous complications with thrombolysis:
- AKI
- Hyperkalemia
- bleeding
- coagulopathies

257
Q

REVEAL study and cumulative risk of FATE in cats with and without cardiomyopathies

A

1y 3.5 vs 0%
5y 9.5% vs 0.4%
10y 11.3% vs 0.7%

Cats with renal infarcts have 8x more chances of developing ATE

258
Q

Poor prognostic indicators for FATE

A
  • low rectal temperature (<35.5C)
  • CHF (80% of cats with FATE)
  • high limb lactate (>11.5)
  • both hind limbs affected
259
Q

SUPERCAT study

A

Clopi vs riva

Clopi>riva for time to recurrence rate and time to death

260
Q

Mechanisms of thrombocytopenia in sepsis

A
  • microbe-platelet interaction
    *leukocytes-platelet interaction
    *NETosis
261
Q

Congenital plt disorders

A

Type A
* vWf disease
* Glanzmann thrombasthenia (GPIIb/IIIa receptor abnormalities - Pyrenese)
*Bernard-Souliler syndrome (GpIb receptor abnormalities - Cocker Spaniel)

Type B
*P2Y12 polymorphism and deficiency with clopidogrel resistance

Type C
*Chediak-Higashi syndrome (lysosome disease and albinism)

Type D
* integrin activation defect (Basset hounds)

Type E
*Scott syndrome of GSD defect of scramblase (no experiorisation of PS and no plt activation)

262
Q

Aggregometry

A

*light (PRP)
*Impedance (heparin sample)

263
Q

Closure time

A

Membrane coated with plt activators - time to close the gap in the membrane

264
Q

Global coagulation indeces

A

Values calculated from TEG and ROTEM value to attempt an overall determination of coagulability (hypo vs hypercoagulable)

*Clot elasticity (MCE) = (100xMA)/(100-MA)
*Coagulation index (takes into consideration all parameters) if >4 hypercoagulable vs hypo if <4

265
Q

clopidogrel resistance is due to P2Y12 or P2Y1 mutation?

A

Recent study showed P2Y1 mutation most common with hyperactivity

266
Q

Hypercoagulability in PLN is not only due to loss of AT, but also…

A
  • loss of Plasminogen
  • increased activity og factor V, VII and VIII
  • increased platelet reactivity

98% of dogs with PLN had hypercoagulable TEG but not all had concurrent low AT

267
Q

Hypercoagulability in DM

A
  • toxic effect of glucose on plt with hyperactivation and hyperexpression of receptors
  • dyslipidemia and endothelial damage
  • hypertension and endothelial damage
268
Q

What is the issue with administering UFH in patients with PLN-related hypercoagulability?

A

UFH is not effective once AT<60%
UFH also partially cleared by kidneys with unreliable GFR –> subtherapeutic doses of UFH might be pro-coagulant

269
Q

Is hemophylia an hyperfibrinolytic disorder?

A

Yes, as it leads to reduced thrombin production = reduced TAFI production and increased plasmin activity

270
Q

94% of dogs are KAI1 ___ and KAI2 ___

A

positive
negative

271
Q

Lower vs higher transfusion threshold

A

Evidence widely supports restrictive apporach with TRISS (septic shock), TRICC (critical care), FOCUS (CV patients), TRICOP (cancer patients) trials

272
Q

According to a 2024 prospective study, what is the incidence of transfusion reactions for pRBCs and plasma transfusions?

A

8.9% for pRBCs and 4.5% for plasma
Most common pRBC reactions were FNHTRs and for plasma were allergic ones

273
Q

According to a 2024 prospective study, what is the incidence of AHTRs in dogs?

A

2.3%
increased odds with older pRBCs units which suggests a non-immunologic cause

274
Q

The administration of units stored for over 21 days is associated with a higher odds of TRs

A

True

According to a recent prospective studies older units had higher odds of causing TRs but no significant difference was observed for individual TRs.

275
Q

Is the volume of blood products transfused associated with a higher odd of developing a TR?

A

Yes, for each 1ml/kg of pRBCs = increased 4% odd of any TR and 6% of allergic TRs.

This supports a conservative vs liberal transfusion strategy

276
Q

Dogs receiving blood product transfusion under GA showed a higher incidence of TR

A

False

A recent retrospective study showed a significantly lower incidence of TR when dogs were undergoing GA. Possibly due to hypothermia masking the signs of potential TRs.

ECVECC Board Exam (24 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions