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Phase II 2023 flashcards > Bleeding and Hemostasis > Flashcards

Bleeding and Hemostasis Flashcards

1
Q

What are the most common causes of DIC in dogs/cats?

A

Dogs: sepsis/SIRS
Cats: neoplasia then pancreatitis

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2
Q

What is the strongest predictor of nonsurvival with acute traumatic coagulopathy (ATC)?

A

APTT

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3
Q

Warfarin:
MOA?
Adv?
Disadv?
Monitor with?

A

Vit K antagonist -> 2,7,9,10 protein C/S
Adv: once daily oral dose, cheap
Disadv: low therapeutic index, PK influenced by diets, comorbidities, drugs, needs strict owner compliance

Monitor: PT adjust dose to get PT 1.25 to 1.5 times baseline

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4
Q

List tests that can definitively diagnose venus thromboembolism (TE?)

A

Gold standard is selective pulmonary angiography
Pulmonary scintigraphy
CT pulmonary angiography

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5
Q

How does hepatic disease contribute to both thrombopathy and hypercoagulability?

A

Thrombopathy: platelet defects, imparied signalling, decreased THA synthesis, storage pool defects, increased inhibitors (bile acids etc)

Hypercoagulability: decreased synthesis of antithrombin and activated protein C + portal hypertension(change in blood flow)

Congenital PSS -> hypercoag on TEG

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6
Q

Desmopressin:
MOA?
Duration of effect?
Treats?

A

Synthetic vasopressin induces release of vWF from stores -> increased platelet function by increasing vWF, FVIII, plasminogen

Duration of action: 2 hours

Treats: Type 1 vWD, acetylsalicylic acid coagulopathies NOT Type 2/3 vWD

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7
Q

What are the three major inhibitors of the fibrinolytic system?

A

Plasminogen activator-inhibitor (PAI-1), TAF-1 and alpha2-AP (stored in platelet granules)

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8
Q

What breed of cat has Vit K dependent factor deficiency?

What factor is most commonly deficient in cats?

A

Devon rex

XII

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9
Q

Clopidogrel:
MOA?
Side effects?

A

Blocks ADP binding to P2Y12 receptor on platelet surface -> prevents activation of integrin, fibrinogen binding, and sustained aggregation

Also inhibits serotonin release which decreases the ischemic impact of thromboembolism.

Side effect is (D) in cats?

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10
Q

Heparin:
MOA?
Sizes of unfractionated/low molecular weight?
Adv of low molecular weight?
How do you monitor?

A

MOA: inactivates Factor II (thrombin) and Factor Xa

Unfractionated = 5,000 to 30k daltons thrombin > Xa inhibition
LMWHeparin = 4k-6500 da Xa > thrombin effects

Adv: prolonged half life, more predictable responses and renal clearance

Monitor with TEG for LMWH, use APTT for unfractionated

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11
Q

Aspirin:
MOA?
pharmacokinetics?
Side effects?

A

inactivates COX-1 -> suppresses TXA2 -> irreversible platelet dysfunction (must wait for new PLT)

onset rapid, antithrombotic effect blocked by parallel inhibition of prostacyclin which is prothrombotic

side effects are GI lesions, (D), w/steroids

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12
Q

What is Virchow’s Triad?

A

The three risk factors for thrombosis
- endothelial injury
- vascular stasis
- hypercoagulability

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13
Q

Activated clotting time tests what?
How is it performed?

A

Intrinsic and common pathways
- whole blood + celite, kaolin, glass beads to activate FXII

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14
Q

What are the types of vWD?

How do you diagnose it?

A

Type 1 vWD has all multimers but low concentration -> Dobermans
Type 2 has a disproportionate loss of the high MW multimers (German Pointers)
Type 3 is an almost complete absence of vWF -> they are high risk of life threatening hemorrhage (sheepdogs, scottish terriers, chessies etc.)

Diagnosis: ELISA is gold standard with <51% being deficient, a BMBT is an indirect test for it.

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15
Q

What are the 4 technical causes of bleeding?

A
  1. Inadequate repair of vessels or vascular structures opened
  2. Occult or undiagnosed
  3. Damage to structures in the operative filed during surgery
  4. damage during the course of surgery to structures remote from the surgery site
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16
Q

TEG:
At what temp is the sample set?
oscillated through angle of ____?
How long should your test wait (max)?
What are the things measured with TEG?

A

37C
4 degrees 45’
Perform test <30 min from sampling

R = reaction time -> indicates fibrin formation
K = clotting time
Angle alpha: slope of R to K
Max amplitude = ultimate strength of clot
G = clot shear elastic modulus “overall status”

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17
Q

Explain the three phases of the cell model of coagulation:

A

Initiation = extrinsic (generates thrombin!)
- TF on fibroblasts
-fVIIa and fVa produce thrombin (fIIa)
-fIIa-TF complexes activate fIX

Amplification = platelets adhered in proximity to TF bearing cells
-Activated by thrombin from initiation phase
-fV activated by thrombin
-vWF/fVII binds to activated platelets and activates fVIII / releases more vWF

Propagation = fXI binds and activated by thrombin and makes fXIa which complexes with fVIIIa to stimulate fX. Xa-Va activate prothrombin -> thrombin -> fibrin

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18
Q

What is in cryoprecipitate?

What does it primarily treat?

A

vWF, fVIII, fibrinogen, fibronectin

treats hypofibrinogenemia, vWD, hemophilias

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19
Q

After giving one blood volume of platelet -deficient fluid, how much platelets remain in circulation?

A

35-40%

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20
Q

What is the MOA of Yunnan Baiyao?

A

increased expression of surface glycoproteins on platelets -> shortened bleeding times

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21
Q

What is needed in order to have coagulation proceed?

A

Tissue factor (TF)

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22
Q

Which test is best to predict surgical bleeding?

What does that test not detect?

A

TEG

It doesn’t detect thrombopathies of vWD

23
Q

Prolonged PT indicates what?

Prolonged APTT indicates what?

How much do factors need to decrease for prolongation to occur?

Which test is sensitive to vitamin K deficiency?

What are disadvantages of PT/APTT?

A

Extrinsic/common issue

Intrinsic/common issue

down to 25-30%

PT

Do not assess hypercoagulability and cannot accurately predict bleeding

24
Q

How do the following contribute to acute trauma coagulopathy (ACT)?
- tissue injury/hypoperfusion
- inflammation
- acidemia
- hypothermia
- hemodilution

A

tissue injury/hypoperfusion -> exposes collagen to vWF and TF to fVII etc

inflammation -> TNF-a IL-1/6 complement etc

acidemia -> pH<7.2 increases the degredation of fibrinogen and impairs coag activity (giving buffers does not reverse this)

hypothermia -> temp <33C decreases platelet function and activity of fVII/TF complex

hemodilution -> decreases vWF/fVIII, decreases fibrinogen, shift of coag deficient fluid to the plasma

25
Q

The lifespan of platelets is ___days in cat/dog?

How many platelets are released per day?

A

6-8 days

10’

26
Q

What are the most common causes of venous TE in dogs/cats?

A

Dogs: PLN, neoplasia, IMHA, necrotizing pancreatitis
Cats: heart disease, neoplasia

27
Q

An increased MA on TEG test indicates what?

What does a decreased R indicate?

A

Increased MA = platelet hyperaggregability

Decreased R = enzymatic hyperactivity

28
Q

What are some blood gas changes seen with venous TE?

A

Increased A-a gradient, hypoxemia (O2 responsive), hypocapnia

29
Q

The cascade model of coag is all initiated from which factor?

A

XII

30
Q

What are secondary antagonists that recruit more platelets?

A

vWF to start -> TXa2/ADP are secondary agonists

31
Q

What is the suspected mechanism for post-op bleeding in greyhounds?

A

Fibrinolysis

32
Q

What bleeding condition is not treatable with fresh frozen plasma? Why?

A

Heparin-induced bleeding because it is caused by a factor inhibitor, not a deficiency -> new factors just get inhibited. Also antithrombin may actually enhance effects of heparin.

33
Q

What 3 components in endothelium control platelet activity?

A

Prostacyclin (PGI2); ectoadenosine diphosphatase (ectoADPase); nitric oxide (NO)

34
Q

What are 3 natural anticoagulant pathways?

A

Antithrombin, activated protein C, tissue factor pathway inhibitor

35
Q

What are different factors that contribute to fibrinolysis?

A

t-PA (endothelial cells),u-PA, FDPs, thrombin activatable fibrinolysis inhibitor (TAFi), A-2 antiplasmin (A2-AP)

36
Q

At what value x normal do increases in PT/APTT indicate risk for hemorrhage?

A

1.5x normal

37
Q

Patients with platelet counts < ____ suffer operative bleeding?

A

50,000

38
Q

What is in frozen plasma?

A

Factors II, VII, IX, X, albumin and globulins

39
Q

What breed can be known to have low platelet counts?

A

Cavalier King Charles Spaniel

40
Q

How are d-dimers helpful?
When is it not helpful?

A

Sensitive indicator for thrombotic conditions like DIC and PTE
- specificity/sensitivity is low for CATS

41
Q

What test is used to look at fibrinogen?

A

Thrombin clot time or thrombin time

42
Q

How does decreased albumin cause increased platelet hypercoagulability?

A

TXA2 synthesis is increased

43
Q

Hemophiliacs have what factor deficiencies?

A

VIII, IX

44
Q

What does a coag panel look like for vitamin K deficiency?

A

Increased PT first, then increased APTT
FSP, d-dimer, fibrinogen and platelet counts are normal.

45
Q

Decreased factor synthesis requires how much liver dysfunction?

A

> 70% decrease in functional hepatic mass

46
Q

How do you estimate platelet count on a smear?

A

Number of platelets per HPF x 15,000

47
Q

BMBT tests for what?

What elevates BMBT?

A

Primary hemostasis

Thrombocytopenia, thrombopathia, vasculopathy

48
Q

How does endothelial thrombomodulin help control fibrinolysis?

A

Activates protein C comlex (pro-fibrinolysis and anti-coagulation) also stimulates fibrinolysis inhibitor?

49
Q

Antifibrinolytics:
Examples?
MOA?
Indications?

A

Epsilon aminocaproic acid, tranexamic acid

-blocks binding/activation of plasminogen and exerts anti-inflammatory effects through IL-inhibition

Treats: greyhounds as pre-sx prophylaxis
minimal side effects

50
Q

What 3 hypothesis contribute to ATC?

A
  • DIC w/hyperfibrinolytic phenotype
  • Enhanced thrombomodulin-thrombin protein C pathway
  • Catecholamine-induced endothelial damage
51
Q

What 6 factors influence development of ATC?

A

tissue injury, hypoperfusion, systemic inflammation, acidemia, hypothermia, hemodilution

52
Q

What is the lethal triad or trauma triad of death?

A

coagulopathy, acidosis, hypothermia

53
Q

What are the initiators of DIC?

A

TNF-a ; IL-6

54
Q

What is generally seen in hemostatic tests for DIC?

A

deficiency in everything

Phase II 2023 flashcards (26 decks)

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