7 Flashcards

1
Q

2 stages of hemostasis

A
  1. primary hemostasis–platelet plug2. secondary hemostasis–proteolytic clotting cascade; fibrin clot/mature thrombus
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2
Q

platelet characteristics

A

anucleatemegakaryocyte precursorlife span 6-8 days

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3
Q

prostaglandin responsible for platelet aggregation/activation

A

thromboxane (TxA2)made from AA–>cox 1 pathway

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4
Q

platelet MOA after endothelial injury

A
  1. adhere to exposed endothelial collagen via vWF2. activation which leads to granular release (TXA2, ADP) and conformational change exposing binding domains for fibrinogen3. recruitment4. aggregation
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5
Q

cascade model of coagulation INTRINSIC

A

XII converts XI activeXI with VIII, PL, Ca activate IXCOMMONIX activates X X with V, PL, Ca activate THROMBINthrombin converts fibrinogen to fibrinaPTT

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6
Q

cascade model of coagulation

A

TF +PL, Ca activate VIICOMMONVII activates XX with V, PL, Ca activate THROMBINthrombin converts fibrinogen to fibrinPT

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7
Q

clotting number of thrombin

A

II

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8
Q

theory behind cell based model of coagulation

A
  1. TF is primary physiologic activator/initiator2. coagulation is localized to and controlled by cell surfacesinitiation, amplification, propagation
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9
Q

normal inhibitors of platelet reactivity

A

Prostacyclin (PGI2)NOectoadenosine diphosphatase

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10
Q

Three natural anticoagulant pathways

A

antithrombin IIIactivated protein CTF inhibitor

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11
Q

MOA of antithrombin III

A

AT III binds and inactivates factor 10 of the common pathwayalso neutralizes other clotting factors, antiinflammatoryactivity of AT III is increased with the presence of heparin

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12
Q

MOA of activated protein C

A

activated protein C inhibits VII, Vdecreases thrombin formationenhances fibrinolysis

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13
Q

MOA TF inhibitor

A

inhibits TF of extrinsic pathway

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14
Q

fibrinolysis

A

dissolution of fibrin clotmain proteolytic enzyme = plasminogen –>plasmindegrades fibrin to FDP, FSPother enzyme: tissue type and urokinase type plasminogen activators

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15
Q

how is fibrinolysis controlled

A

plasminogen activator inhibitorsalpha antiplasminthrombin activator fibrinolysis inhibitor

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16
Q

cause of pseudothrombocytopenia

A

falsely low due to platelet aggregation and mis countingreported in 71% of feline blood samples

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17
Q

estimate of average platelet count on blood smear

A

platelets/HPF x 15,000

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18
Q

BMBT

A

buccal mucosal bleeding time–tests platelet fx/primary hemostasisN dog 1.7-4.2 minN cat 1.4-2.4 mininter/intraoperative variability up to 2 min

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19
Q

BMBT is prolonged with what diseases

A

thrombocytopeniathrombocytopathia (vWF disease)vasculopathy

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20
Q

what % of coagulation factors must be decr to have prolonged PT/aPTT

A

25-30% decreased prior to prolongation

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21
Q

vitamin K dependent coagulation factors

A

2, 7, 9, 107 has the shortest half life

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22
Q

what coagulation test to examine for bit K deficient animals

A

PT7 because of very short half life 4-6 hr

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23
Q

PT tests…

A

extrinsic + common pathwayTF, 7less sensitive to heparin affects than aPTT

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24
Q

aPTT tests…

A

intrinsic + common12, 11, 9

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25
Q

activated clotting times ACT

A

whole blood + diatomaceous earth (contact factor for XII)tests INTRINSIC and common pathN dog < 110 sN cat < 75 sless sensitive than aPTT

26
Q

FDP/FSP

A

degradation products of fibrin/fibrinogenmarkers of fibrinolysisusually cleared via livercan lead to dysfx in platelets/inhibit coagulationMay be a marker DIC

27
Q

D dimers

A

indicate activation of thrombin and plasminspecific for activation of coagulation and fibrinolysissensitive marker for DIC, thromboembolism with excellent negative predictive valueNOT specific

28
Q

fibrinogen deficiency in relation to thrombin clot time

A

TCT is prolonged and clot formation decreased with 1. hypofibrinogenemia2. dysfibrinogenemia3. presence of factors inhibiting fibrin polymerization (heparin, FDPs)

29
Q

list coagulation testing

A

platelet number and blood smear reviewPT/PTTBMBTACTFDPs/FSPsDDimersFibrinogenTEG

30
Q

Thromboelastography

A

TEG evaluations clot initiation, formation, propagation to fibrinolysisstrength and stability of clotdynamics of its formation and breakdown

31
Q

TEG parameters

A

R reaction time (time of latency until start of clot form)K clotting time (time to clot formation)alpha how fast clot is formedMA max amplitude (overall strength of clot)LY60 (fibrinolysis)

32
Q

which TEG variable measures secondary hemostasis

A

R reaction time (time of latency until start of clot form)

33
Q

Which TEG variable measures clot kinetics

A

K clotting time (time to clot formation)

34
Q

predictive value of TEG to ID bleeding

A

TEG correctly ID bleeding with PPV 89% NPV 9*%

35
Q

disorders of primary hemostasis

A

thrombocytopenia (SPUD)thombopathia (acquired, inherited-vWF)vasculopathy (acquired, inherited-ehler-danlos)pg 101

36
Q

acute coagulopathy of trauma

A

tissue injury, shock, massive fluid resuscitation (>blood volume within 24 hr)hemodilutionhypothermiaacidemiashock

37
Q

what is the first factor to be decreased with hemodilution

A

fibrinogen

38
Q

which fluid demonstrates the most pronounced hemodilution effect

A

hetastarchdecreases fibrinogen, vWF, VIII

39
Q

clinical signs of patients with primary hemostatic disorder

A

ecchymosisspontaneous bleeding from mucosal surfacespetechia (more with thrombocytopenia rather than pathia)

40
Q

clinical signs of patients with secondary hemostatic disorder

A

hematomasbleeding into body cavity

41
Q

indications for use of cryoppt

A

vWF disease VIII deficiencyhypofibrinogenemia/dysfibrinogenemia

42
Q

list platelet containing blood products

A

fresh whole blood**platelet rich plasmaplatelet concentrate

43
Q

T/FDesmopressin is effective for all types of vWF

A

FALSEonly effective for type I vWF were there is not a complete absence of vWF

44
Q

treatment of hemophiliac patients

A

recombinant factor VIIpromotes extrinsic/common pathway especially important for hemophilia A (8) and B (9) deficiencies of the intrinsic pathwayDOSE CANNOT BE REPEATED–Ab develop

45
Q

most common primary hemostatic disorder

A

thrombocytopeniaSPUD (immune mediated destruction is most common cause in dogs)may not have spontaneous bleeding until < 50,000

46
Q

condition of non pathologic thrombocytopenia

A

Cavalier King Charles Spaniel

47
Q

most common congenital bleeding disorder

A

vWF deficiency (ELISA definitive dx 50% cut off)1. all multimers present but reduced concentration–DOBIES2. loss of hi moleculecular weight multimers–GSP GWP3. absence all multimers–sheltie, bay retrievers

48
Q

most common inherited coagulopathy in cats

A

deficiency in factor 12does not result in bleeding usuallyprolongation aPTT

49
Q

% of dogs and cats with hepatobiliary disease that have some sort of hemostatic abnormality

A

dog 93%cat 82%spontaneous bleeding occurs in < 2%

50
Q

T/Fvit K trial therapy is advantageous in patients with cholestatic/liver disease

A

TRUEliver responsible for vit K metabolismdysfunction leads to malabsorption of vit K which leads to decr clotting factors 2, 7, 9, 10may see prolongations of PT (due to factor 7)

51
Q

what is Virchow’s triad in thromboembolic discussion

A

thrombotic tendency depends on 3 major risk factors1. endothelial injury2. blood stasis3. hypercoagulability

52
Q

a study of dogs with THR show what % of thromboembolism

A

82%

53
Q

what is oligemia in terms of diagnosing pulmonary thromboembolic disease

A

oligemia increased radiolucency on VD/DV thoracic filmscorresponds to hypovascular area of lung regions distal to PTE

54
Q

Diagnostics for PTE patient

A

D DimersTEGRadiographs (nonspecific; oligemia)ABGCardiac eval/Echo (right hypokinesis)DEFINITIVE DX: selective pulmonary angiography

55
Q

most common abnormalities in ABG of PTE patient

A

not pathognomonic (in descending order)1. increased Aa gradient2. hypoxemia3. hypocapnia4. decrease oxygen response

56
Q

management of thromboembolic disease

A
  1. anti platelet drugs (aspirin, clopidogrel)2. anticoagulants (heparin–unfrac, LMW and warfarin)
57
Q

drug protocol for hyperadrenocorticoid dogs undergoing adrenalectomy

A

unfrac heparin in plasma at induction followed by 35 U/kg SQ q8hr tapered over 4 days

58
Q

drug used for prophy tx of emboli in renal transplants in dogs

A

low molecular wt heparin enoxaparin before sx0/5 w drug had TE5/10 dogs without drugs had TE

59
Q

diagnosis of DIC

A

3 or more of the following:thrombocytopeniaPT/aPTT prolongationincr FDPs/ D Dimershypofibrinogenemiadecreased antithrombin III activityRBC fragmentation

60
Q

most dogs with DIC are hyper or hypo coagulable?

A

HYPER only 22% hypocoagulable

61
Q

MOA of clopidogrel

A

blocks ADP binding to receptor on platelet (P2Y12)prevents activation/recruitment/aggregation

62
Q

what is the target aPTT when treating for thromboembolic disease

A

aPTT 1.5-2.0 times normal