Ch4 - 1) Primary Hemostasis and Bleeding Related Disorders Flashcards Preview

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Flashcards in Ch4 - 1) Primary Hemostasis and Bleeding Related Disorders Deck (67):
1

What is hemostatsis?

Damage to the wall is repaired by hemostasis,

2

Hemostasis involves the formation of?

a thrombus (clot) at the site of vessel injury

3

Hemostasis stages?

primary and secondary.

4

Primary hemostasis?

forms a weak platelet plug

5

Primary hemostasis is mediated by?

interaction between platelets and the vessel wall

6

Secondary hemostasis?

stabilizes the platelet plug

7

Secondary hemostasis is mediated by?

the coagulation cascade.

8

What is Step 1 in secondary hemostasis?

Transient vasoconstriction of damaged vessel

9

How is Step 1 in secondary hemostasis mediated?

by reflex neural stimulation and endothelin release from endothelial cells

10

What is Step 2 in secondary hemostasis?

Platelet adhesion to the surface of disrupted vessel

11

In step 2 of secondary hemostasis, how does platelet adhesion occur?

Von Willebrand factor (vWF) binds exposed subendothelial collagen,

12

How do platelets bind to vWF?

via the GPIb receptor

13

vWF is derived from?

the Weibel-Palade bodies of endothelial cells and a-granules of platelets.

14

What is Step 3 in secondary hemostasis?

Platelet degranulation

15

In step 3 of secondary hemostasis what does Adhesion induce?

shape change in platelets and degranulation with release of multiple mediators

16

What are the mediators released in step 3 of secondary hemostasis?

ADP and TXA

17

What is the role of ADP in step 3 of secondary hemostasis?

it is released from platelet dense granules; promotes exposure of GPIIb/IIIa receptor on platelets.

18

What is the role of TXA in step 3 of secondary hemostasis?

it is synthesized by platelet cyclooxygenase (COX) and released; promotes platelet aggregation

19

What is step 4 in secondary hemostasis?

Step 4?Platelet aggregation

20

Where and how do Platelets aggregate in step 4 of secondary hemostasis?

at the site of injury via GPIIb/IIIa using fibrinogen (from plasma) as a linking molecule;

21

What does platelet aggregation result in?

formation of platelet plug

22

Platelet plug?

It is weak; coagulation cascade (secondary hemostasis) stabilizes it.

23

What are disorders of primary hemostasis usually due to?

Usually due to abnormalities in platelets;

24

Disorders of primary hemostasis are divided into?

quantitative or qualitative disorders

25

What are some Clinical features for disorders of primary hemostasis?

mucosal and skin bleeding.

26

What is the most common overall symptom in mucosal bleeding?

epistaxis

27

What are symptoms of mucosal bleeding?

epistaxis, hemoptysis, GI bleeding, hematuria, and menorrhagia. Intracranial bleeding occurs with severe thrombocytopenia.

28

What are the symptoms of skin bleeding?

include petechiae (1-2 mm), ecchymoses (> 3 mm), purpura (> 1 cm), and easy bruising;

29

Petechiae are a sign of what?

thrombocytopenia and are not usually seen with qualitative disorders.

30

What are some useful laboratory studies for disorders of primary hemostasis?

platelet count, bleeding time, blood smear, bone marrow biopsy

31

Platelet count

normal 150-400 K/pL; < 50 K/pL leads to symptoms,

32

Bleeding time

normal 2-7 minutes; prolonged with quantitative and qualitative platelet disorders

33

Blood smear

used to assess number and size of platelets

34

Bone marrow biopsy

used to assess megakaryocytes, which produce platelets

35

What is immune thrombocytopenic purpura?

(ITP) is an autoimmune production of IgG against platelet antigens (GPIIb/IIIa)

36

What is the most common cause of thrombocytopenia in children and adults?

immune thrombocytopenic purpura

37

In ITP what results in thrombocytopenia?

Antibody-bound platelets are consumed by splenic macrophages

38

ITP is divided into?

acute and chronic forms

39

Acute form of ITP?

arises in children weeks after a viral infection or immunization;selflimited, usually resolving within weeks of presentation

40

Chronic form of ITP?

arises in adults, usually women of chilbearing age. May be primary or secondary (e.g SLE).

41

What is the risk involved in chronic ITP?

May cause short-lived thrombocytopenia in offspring since antiplatelet IgG can cross the placenta.

42

laboratory findings for ITP include

decreased platelet count, often < 50 K/pL, Normal PT/FTT, Coagulation factors are not affected. increased megakaryocytes on bone marrow biopsy

43

What is the Initial treatment for ITP?

corticosteroids.

44

How will children and adults respond to the initial treatment for ITP?

Children respond well; adults may show early response, but often relapse.

45

In addition to corticosteroids what else is used in the treatment of ITP?

IVIG is used to raise the platelet count in symptomatic bleeding, but its effect is short-lived,

46

What is a permenant solution for patients with ITP?

Splenectomy eliminates the primary source of antibody and the site of platelet destruction (performed in refractory cases).

47

What is microangiopathic hemolytic anemia?

Pathologic formation of plateletmicrothrombin small vessels

48

How are plateletmicrothrombin formed and what is the result?

Platelets are consumed in the formation of microthrombi sheering the RBCs as they cross microthrombi, resulting in hemolytic anemiawith schistocytes

49

What is microangiopathic hemolytic anemia seen in?

thrombotic thrombocytopenic purpura (TTP) and hemolytic uremic syndrome (HUS)

50

What is TTP due to?

decreased ADAMTS13 which is an enzyme that normally cleaves vWF multimers into smaller monomers for eventual degradation.

51

How does TTP lead to microangiopathic hemolytic anemia?

1. Large, uncleaved multimers lead to abnormal platelet adhesion, resulting in microthrombi.

52

Decreased ADAMTS13 is usually due what?

an acquired autoantibody;

53

TTP is most commonly seen in?

adult females

54

HUS is due to?

Hemolytic uremic syndrome is due to endothelial damage by drugs or infection.

55

HUS is classically seen in?

children with E coli G157;H7 dysentery, which results from exposure to undercooked beef

56

How is E Coli related to microangiopathic hemolytic anemia?

E coli verotoxin damages endothelial cells resulting in platelet microthrombi

57

The clinical findings for HUS and TTP include

Skin and mucosal bleeding, Microangiopathic hemolytic anemia, Fever, Renal insufficiency, CNS abnormalities

58

Renal insufficiency is more common in HUS or TTP?

HUS ? thrombi involve vessels of the kidney

59

CNS abnormalities are more common in HUS or TTP?

TTP ? Thrombi involve vessels of the CNS

60

Laboratory findings for microangiopathic hemolytic anemia include?

Thrombocytopenia with increased bleeding time Normal PT/PTT (coagulation cascade is not activated), anemia with schistocytes, increased megakaryocytes on bone marrow biopsy

61

Treatment for microangiopathic hemolytic anemia?

involves plasmapheresis and corticosteroids, particularly in TTP.

62

What are the qualitative platelet disorders?

bernard-soulier, Glanzmann thrombasthenia, asprin, uremia

63

Bernard-Soulier syndrome

is due to a genetic GPIb deficiency; platelet adhesion is impaired.

64

In Bernard-Soulier what lab test are you interested in?

Blood smear which shows mild thrombocytopenia with enlarged platelets.

65

Glanzmann thrombasthenia is due to?

a genetic GPIIb/IIIa deficiency; platelet aggregation is impaired.

66

Aspirin and microangiopathic hemolytic anemia?

it irreversibly inactivates cyclooxygenase; lack of TXA, impairs aggregation.

67

Uremia and microangiopathic hemolytic anemia

disrupts platelet function; both adhesion and aggregation are impaired.