Exam 3 - Disorders of Primary Hemostasis Flashcards

1
Q

what does the endothelium of the vessels synthesize?

A

collagen, fibronectin, & VWF

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2
Q

what is the platelet phase of primary hemostasis?

A

platelet adhesion

  1. vessel damage exposes subendothelium & platelets adhere
  2. VWF helps bind the platelets to the subendothelium

platelet aggregation

  1. platelet conformational change - release of substances that stimulate aggregation
  2. primary plug forms serving as the surface for secondary hemostasis
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3
Q

what clinical signs are associated with disorders of primary hemostasis?

A

petechiae/ecchymoses, bleeding from mucosal surfaces, melena/hematochezia/hematemesis, hematuria, & pulmonary bleeds

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4
Q

what is the purpose of using a BMBT in disorders of primary hemostasis?

A

test for primary hemostatic disorder other than thrombocytopenia

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5
Q

T/F: vasculitis is a common cause of primary hemostatic disease

A

false - uncommon

can cause petechiae/ecchymoses

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6
Q

if vasculitis is to be definitively diagnosed for a primary hemostatic disease, what must happen?

A

biopsy is the only way to definitively diagnose

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7
Q

what is von willebrand’s disease?

A

deficiency of vWF

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8
Q

why does von willebrand’s disease resemble a platelet disorder?

A

VWF is a part of normal primary hemostasis

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9
Q

what is the most common inherited bleeding disorder in the dog?

A

von willebrand’s disease

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10
Q

when should you test for von willebrand’s disease?

A

patients that are clinically bleeding, making decisions about breeding, & prior to surgery

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11
Q

how is type I VW disease characterized? what breeds are affected?

A

low concentration & normal structure of vWF - variable severity of disease

dobermans

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12
Q

how is type II VW disease characterized? what breeds are affected?

A

low concentration & abnormal structure of vWF - severe

GSP & GWP

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13
Q

how is type III VW disease characterized? what breeds are affected?

A

vWF markedly reduced or absent

familial - shetlands, scotties
sporadic - blue heelers, labs

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14
Q

if doing a surgery on a VWD patient, what should you do in prep & have on hand?

A

prep - give VWF, cryoprecipitate & plasma

give donor desmopressin to the blood donor prior to collection

have blood products on hand in case a transfusion is required

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15
Q

what are the 2 general diseases that are included in decreased platelet function?

A

VWD & thrombocytopathia

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16
Q

what are some causes of acquired thrombocytopathies?

A

drugs - nsaids, clopidogrel, & high dose colloids

neoplasia

infectious agents - ehrlichia canis & platys

hepatic disease

uremia

DIC

17
Q

what are 4 general mechanisms of decreased platelet numbers?

A
  1. destruction
  2. sequestration
  3. decreased production
  4. utilization or loss
18
Q

what is the common signalment of a patient with immune mediated thrombocytopenia?

A

common in dogs, some breed predispositions, young-middle aged

19
Q

what are some primary causes of ITP?

A

idiopathic

evan’s syndrome - ITP & IMHA

systemic lupus erythematous

20
Q

what are some secondary causes of ITP?

A

infectious - ehrlichia, babesia, leishmania, leptospira, HW, FeLV/FIV

neoplasia - lymphoma, hemangiosarcoma, carcinoma

drugs - sulfas, cephalosporin, phenobarbital

21
Q

how is ITP diagnosed?

A

diagnosis of exclusion

medication/vaccine history, infectious disease testing, thoracic rads, abdominal ultrasound, FNA of enlarged peripheral lymph nodes, & bone marrow evaluation only when there is no response to therapy

22
Q

T/F: thrombocytopenia is a contraindication to bone marrow collection

A

false - not a contraindication

23
Q

how is ITP treated?

A

avoid or d/c nsaids, cage rest, avoid trauma, monitor for rapid blood loss usually through the gi tract, & transfuse with packed red blood cells or whole blood

24
Q

how does vincristine help in treating ITP?

A
  • increases circulating platelet count
  • accelerates fragmentation of megakaryocytes
  • stimulates thrombopoiesis
  • impairs platelet phagocytosis by macrophage
25
what are the risks of using vincristine for treating ITP?
severe tissue damage if extravasated
26
how do glucocorticoids help in treating ITP?
mainstay of therapy - immunosuppression may also give doxycycline while tests are pending
27
what is the dosage used for glucocorticoids when treating ITP? when is a response expected?
pred 2mg/kg/day 2-11 days - mean of 4 days
28
why is a 2nd line immunosuppressive drug added when treating ITP with glucocorticoids?
allows for more rapid tapering of prednisone
29
how does monitoring of ITP affect treatment?
monitor every 2-3 weeks if platelet count is normal - taper pred by 25% continue on pred at 0.5mg/kg every 48 hours for 2-3 weeks & discontinue monitor for relapse!!
30
what is the prognosis for most cases of ITP? what are some negative prognostic factors?
overall good - 89% survived to discharge bleeding into CNS/lungs - typically fatal 60% survival rate in dogs with ITP & melena or elevated BUN
31
what is the percentage of relapse of ITP?
31% at an average of 79%
32
what are some differentials that should be considered for pancytopenia?
drugs - chloramphenicol, sulfas, chemo drugs, anti-fungals, phenobarbital toxins - estrogen or radiation infection - chronic ehrlichia, parvo, histoplasmosis immune-mediated dysmyelopoiesis (hematopoietic neoplasia)/myelophthisis (crowding out) myelofibrosis - idiopathic or secondary myelodysplasia
33
what clinical signs are common in patients with a primary hemostatic disorder?
petechiae are common, hematomas are rare, bleeding at mucosal membranes, & bleeding after venipuncture
34
what clinical signs are common in patients with a secondary hemostatic disorder?
petechiae are rare, hematomas are common, bleeding into muscles, joints, body cavities, & delayed bleeding after venipuncture