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Flashcards in 7 Deck (62):
1

2 stages of hemostasis

1. primary hemostasis--platelet plug2. secondary hemostasis--proteolytic clotting cascade; fibrin clot/mature thrombus

2

platelet characteristics

anucleatemegakaryocyte precursorlife span 6-8 days

3

prostaglandin responsible for platelet aggregation/activation

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

4

platelet MOA after endothelial injury

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

5

cascade model of coagulation INTRINSIC

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

6

cascade model of coagulation

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

7

clotting number of thrombin

II

8

theory behind cell based model of coagulation

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

9

normal inhibitors of platelet reactivity

Prostacyclin (PGI2)NOectoadenosine diphosphatase

10

Three natural anticoagulant pathways

antithrombin IIIactivated protein CTF inhibitor

11

MOA of antithrombin III

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

12

MOA of activated protein C

activated protein C inhibits VII, Vdecreases thrombin formationenhances fibrinolysis

13

MOA TF inhibitor

inhibits TF of extrinsic pathway

14

fibrinolysis

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

15

how is fibrinolysis controlled

plasminogen activator inhibitorsalpha antiplasminthrombin activator fibrinolysis inhibitor

16

cause of pseudothrombocytopenia

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

17

estimate of average platelet count on blood smear

# platelets/HPF x 15,000

18

BMBT

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

19

BMBT is prolonged with what diseases

thrombocytopeniathrombocytopathia (vWF disease)vasculopathy

20

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

25-30% decreased prior to prolongation

21

vitamin K dependent coagulation factors

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

22

what coagulation test to examine for bit K deficient animals

PT7 because of very short half life 4-6 hr

23

PT tests...

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

24

aPTT tests...

intrinsic + common12, 11, 9

25

activated clotting times ACT

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

26

FDP/FSP

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

27

D dimers

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

28

fibrinogen deficiency in relation to thrombin clot time

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

29

list coagulation testing

platelet number and blood smear reviewPT/PTTBMBTACTFDPs/FSPsDDimersFibrinogenTEG

30

Thromboelastography

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

31

TEG parameters

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

which TEG variable measures secondary hemostasis

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

33

Which TEG variable measures clot kinetics

K clotting time (time to clot formation)

34

predictive value of TEG to ID bleeding

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

35

disorders of primary hemostasis

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

36

acute coagulopathy of trauma

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

37

what is the first factor to be decreased with hemodilution

fibrinogen

38

which fluid demonstrates the most pronounced hemodilution effect

hetastarchdecreases fibrinogen, vWF, VIII

39

clinical signs of patients with primary hemostatic disorder

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

40

clinical signs of patients with secondary hemostatic disorder

hematomasbleeding into body cavity

41

indications for use of cryoppt

vWF disease VIII deficiencyhypofibrinogenemia/dysfibrinogenemia

42

list platelet containing blood products

fresh whole blood**platelet rich plasmaplatelet concentrate

43

T/FDesmopressin is effective for all types of vWF

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

44

treatment of hemophiliac patients

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

most common primary hemostatic disorder

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

46

condition of non pathologic thrombocytopenia

Cavalier King Charles Spaniel

47

most common congenital bleeding disorder

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

most common inherited coagulopathy in cats

deficiency in factor 12does not result in bleeding usuallyprolongation aPTT

49

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

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

50

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

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

what is Virchow's triad in thromboembolic discussion

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

52

a study of dogs with THR show what % of thromboembolism

82%

53

what is oligemia in terms of diagnosing pulmonary thromboembolic disease

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

54

Diagnostics for PTE patient

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

55

most common abnormalities in ABG of PTE patient

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

56

management of thromboembolic disease

1. anti platelet drugs (aspirin, clopidogrel)2. anticoagulants (heparin--unfrac, LMW and warfarin)

57

drug protocol for hyperadrenocorticoid dogs undergoing adrenalectomy

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

58

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

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

59

diagnosis of DIC

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

60

most dogs with DIC are hyper or hypo coagulable?

HYPER only 22% hypocoagulable

61

MOA of clopidogrel

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

62

what is the target aPTT when treating for thromboembolic disease

aPTT 1.5-2.0 times normal