Evaluation of Coagulation and Hemostasis Flashcards Preview

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Flashcards in Evaluation of Coagulation and Hemostasis Deck (94):
1

What is hemostasis

Maintaining blood in its fluid state while stopping bleeding in case of trauma

2

What is hemostasis

Maintaining blood in its fluid state while stopping bleeding in case of trauma

3

What is primary hemostasis

A platelet plug

4

What is secondary hemostasis

Fibrin clot

5

What is Tertiary hemostasis

Breakdown of clot

6

What is the vascular response to injury

There is contraction and narrowing of the lumen of the vessel, which decreases the rate of blood loss and creates a turbulence in which platelets may begin to attach
Loss of endothelium exposes basement membrane (collagen) + releases vWF
Healthy endothelium inhibits platelet activation

7

Describe primary hemostasis

Formation of the temporary platelet plug
Normally Platelets are exposed only to the linings of the blood vessels (endothelium) and heart (endocardium)
blood vessel injury,  platelets are exposed to the subendothelial basement membrane ( collagen)
Damaged endothelium secretes vWF

8

Describe platelet activation

exposure activates the platelets to alter surface membrane properties (become “sticky”) and to adhere to the vessel wall and each other

9

What products are released when platelets activate

ADP (adenosine diphosphate )
Serotonin and histamine vasoconstriction
PF 3coagulation cascade

10

What is purpura

superficial bleeding of skin or mucous membranes

11

What is petechiae

12

What is ecchymoses

larger, small arteriole/venule bleeding

13

What is superficial bleeding

bleeding from mucous membranes (eg epistaxis, hematuria, melena, etc)

14

What is Von Willebrand factor

vWF helps to make the platelets stick to each other and to form the platelet plug,
It is a protein produced by endothelial cells

15

What does the Von Willebrand factor cause

Platelet adhesion to collagen
Platelet–platelet binding or aggregation
vWF helps to activate factor VIII

16

What is Von Willebrand's disease

most common hemostatic defect in dogs,
Von Willebrand’s factor, is not a clotting factor defect but a protein necessary for the platelets to adhere to the endothelium,
Its absence markedly slows or prevents the formation of a clot - vWF is also cofactor for factor VIII ( hemophilia factor)

17

What is Von Willebrand

It is a protein complex made up of 3 separate proteins

18

What is type 1 vWF problem

Type 1- has low amounts of vWF
Doberman Pinscher, the Shetland Sheepdog, the German Shepherd Dog, and the Standard Poodle

19

What is type 2 vWF problem

Type 2- is missing one of the 3 proteins
German Short-Haired and German Wire-Haired Pointers

20

What is type 3 vWF problem

Type 3- completely missing vWF factor
Most severe form

21

How do you treat vWF

Blood product called cryoprecipitate
Can give FRESH Frozen Plasma

hormone called DDAVP (or desmopressin acetate)

22

What does the DDAVP hormone do when given

It causes sudden release of von Willebrand's factor into the bloodstream. After a 30-minute onset period, the use of DDAVP shortens the bleeding time for approximately 2 hours after the injection.

23

Thrombocytopenia

a decrease in platelet number

24

Thrombocytopathia

a decrease in platelet function

25

How do you count platelets

Impedance analysers
Clumped platelets may be read as WBC
Cat platelets are very large and clump easily

ALWAYS DO A SMEAR EVALUATION
Should have 10-20 per 40x Field other wise look for clumped platelets

26

What is the blood mucosal bleeding time

Blood that wells up from the incision is blotted with filter paper applied near (but not touching!!) the incision.
A stopwatch is started when the incision is made and stopped when a crescent of blood no longer develops on the filter paper.

Normal BMBT dogs is

27

What does a BMBT test show

platelets (number and function), vessel wall defects (rare) and vWf.

28

What does a prolonged BMBT show

inherited diseases, including vWD
thrombopathia (uremia and aspirin therapy).
thrombocytopenia (probably

29

In what 2 settings are BMBT used

1- As an in vivo pre surgical screening test for vWD, especially in Dobermans,
Pre Treatment for vWF:
vWF supplementation with fresh or fresh frozen plasma or cryoprecipitate. ( 4 hours)
Injection of Desmopressin –DDAVP ( lasts for 2 hours)


2- As a screening test to identify defects in platelet function (thrombopathia) that cannot be detected with routine hemostatic assays.

30

What is the capillary bleeding time

Done on lateral shaved ,shaved surface of front toe with sphygmomanometer cuff on at a pressure of 60 mm hg
The skin is cut twice with a lancet
Bleeding should stop in 1 – 2.5 minutes

31

What is the intrinsic pathway

intrinsic pathway consists of factors present within the blood stream that can be activated without tissue contact

32

What is the extrinsic pathway

extrinsic pathway is activated by contact with cells and tissue fluid outside the vessel. Tissue thromboplastin

33

What is the common pathway

common pathway – results in formation of the fibrin clot

34

What does the extrinsic pathway provide

EXTRINSIC PATHWAY factor VII + tissue damage

35

What does the extrinsic pathway provide

EXTRINSIC PATHWAY factor VII + tissue damage

36

What is primary hemostasis

A platelet plug

37

What is secondary hemostasis

Fibrin clot

38

What is Tertiary hemostasis

Breakdown of clot

39

What is the vascular response to injury

There is contraction and narrowing of the lumen of the vessel, which decreases the rate of blood loss and creates a turbulence in which platelets may begin to attach
Loss of endothelium exposes basement membrane (collagen) + releases vWF
Healthy endothelium inhibits platelet activation

40

Describe primary hemostasis

Formation of the temporary platelet plug
Normally Platelets are exposed only to the linings of the blood vessels (endothelium) and heart (endocardium)
blood vessel injury,  platelets are exposed to the subendothelial basement membrane ( collagen)
Damaged endothelium secretes vWF

41

Describe platelet activation

exposure activates the platelets to alter surface membrane properties (become “sticky”) and to adhere to the vessel wall and each other

42

What products are released when platelets activate

ADP (adenosine diphosphate )
Serotonin and histamine vasoconstriction
PF 3coagulation cascade

43

What is purpura

superficial bleeding of skin or mucous membranes

44

What is petechiae

45

What is ecchymoses

larger, small arteriole/venule bleeding

46

What is superficial bleeding

bleeding from mucous membranes (eg epistaxis, hematuria, melena, etc)

47

What is Von Willebrand factor

vWF helps to make the platelets stick to each other and to form the platelet plug,
It is a protein produced by endothelial cells

48

What does the Von Willebrand factor cause

Platelet adhesion to collagen
Platelet–platelet binding or aggregation
vWF helps to activate factor VIII

49

What is Von Willebrand's disease

most common hemostatic defect in dogs,
Von Willebrand’s factor, is not a clotting factor defect but a protein necessary for the platelets to adhere to the endothelium,
Its absence markedly slows or prevents the formation of a clot - vWF is also cofactor for factor VIII ( hemophilia factor)

50

What is Von Willebrand

It is a protein complex made up of 3 separate proteins

51

What is type 1 vWF problem

Type 1- has low amounts of vWF
Doberman Pinscher, the Shetland Sheepdog, the German Shepherd Dog, and the Standard Poodle

52

What is type 2 vWF problem

Type 2- is missing one of the 3 proteins
German Short-Haired and German Wire-Haired Pointers

53

What is type 3 vWF problem

Type 3- completely missing vWF factor
Most severe form

54

How do you treat vWF

Blood product called cryoprecipitate
Can give FRESH Frozen Plasma

hormone called DDAVP (or desmopressin acetate)

55

What does the DDAVP hormone do when given

It causes sudden release of von Willebrand's factor into the bloodstream. After a 30-minute onset period, the use of DDAVP shortens the bleeding time for approximately 2 hours after the injection.

56

Thrombocytopenia

a decrease in platelet number

57

Thrombocytopathia

a decrease in platelet function

58

How do you count platelets

Impedance analysers
Clumped platelets may be read as WBC
Cat platelets are very large and clump easily

ALWAYS DO A SMEAR EVALUATION
Should have 10-20 per 40x Field other wise look for clumped platelets

59

What is the blood mucosal bleeding time

Blood that wells up from the incision is blotted with filter paper applied near (but not touching!!) the incision.
A stopwatch is started when the incision is made and stopped when a crescent of blood no longer develops on the filter paper.

Normal BMBT dogs is

60

What does a BMBT test show

platelets (number and function), vessel wall defects (rare) and vWf.

61

What does a prolonged BMBT show

inherited diseases, including vWD
thrombopathia (uremia and aspirin therapy).
thrombocytopenia (probably

62

In what 2 settings are BMBT used

1- As an in vivo pre surgical screening test for vWD, especially in Dobermans,
Pre Treatment for vWF:
vWF supplementation with fresh or fresh frozen plasma or cryoprecipitate. ( 4 hours)
Injection of Desmopressin –DDAVP ( lasts for 2 hours)


2- As a screening test to identify defects in platelet function (thrombopathia) that cannot be detected with routine hemostatic assays.

63

What is the capillary bleeding time

Done on lateral shaved ,shaved surface of front toe with sphygmomanometer cuff on at a pressure of 60 mm hg
The skin is cut twice with a lancet
Bleeding should stop in 1 – 2.5 minutes

64

What is the intrinsic pathway

intrinsic pathway consists of factors present within the blood stream that can be activated without tissue contact

65

What is the extrinsic pathway

extrinsic pathway is activated by contact with cells and tissue fluid outside the vessel. Tissue thromboplastin

66

What is the common pathway

common pathway – results in formation of the fibrin clot

67

What does the intrinsic pathway provide

the intrinsic pathway; factors XII, XI, IX, and VIII are components of the intrinsic system.
- mnemonic -it is not $12, but $11.98” (for factors XII, XI, IX, and VIII).

68

What does the extrinsic pathway provide

EXTRINSIC PATHWAY factor VII + tissue damage

69

What are the Vitamin K dependant clotting factors

FII, FVII, FIX, FX

Clotting proteins produced by the liver

Require Vit K to be activated

70

What is deep bleeding

formation of large hematomas or bleeding into body cavities

Large Hematomas
Hemothorax
hemoperotoneum

71

What happens with a mixed hemostatic defect

Dogs and cats with mixed hemostatic defects (primary plus secondary) develop a combination of petechiae, ecchymoses, mucosal bleeding, hematomas, and intracavitary bleeding. Mixed hemostatic defects are almost exclusively associated with DIC, and are common in dogs and cats

72

What is DIC

disseminated intravascular coagulopathy

Sometimes called a consumptive coagulopathy

73

When does DIC occur

DIC does not occur by itself but as a complicating factor from another underlying condition or critical illness.

74

What are the clinical signs of DIC

Prolonged PT
Prolonged APTT
Increased FDP or D-dimers
Decreased platelets

75

How do you sample for coagulation tests

Clean venipuncture is essential. Poor venipuncture will result in activation of coagulation due to contamination with tissue factor
if the vein is not entered on the first attempt, a fresh needle should be used.
vacutainer collection is preferred
Blue citrate tube
Plastic tube, not glass

76

What is the ACT test used for

evaluation of the intrinsic and common pathways
Clotting Factors must be decreased by 95%
Whole blood without anticoagulant is added to a special tube containing diatomaceous earth
tube should be incubated at 37 C
ACT relies on the patient's platelets for provision of phospholipid to support the reaction – but is not overly prolonged with thrombocytopathias

77

How do you do a ACT test

evaluation of the intrinsic and common pathways
Clotting Factors must be decreased by 95%
Whole blood without anticoagulant is added to a special tube containing diatomaceous earth
tube should be incubated at 37 C
ACT relies on the patient's platelets for provision of phospholipid to support the reaction – but is not overly prolonged with thrombocytopathias

78

What % does a carrier of hemophilia have

A carrier may only have a 40 – 60 % decrease in factor VIII or IX
Bleeding problems occur when you have less than 5% of the factor

79

What is hemophilia A

Factor VIII deficiency

80

What is hemophilia B

Christmas disease; Factor X hemophilia

81

How do you get hemophilia

Sex linked
No breed predisposition
Quite rare

82

What is the normal ACT in dogs

Normal ACT for dogs is 60 - 90 seconds
Due to reliance on endogenous platelets for the reaction, platelet counts of

83

What is the normal ACT in cats

For cats is 45 - 160 seconds.

84

What causes a prolonged ACT

liver disease,
congenital coagulopathies ( hemophilia A and B),
vitamin K-responsive coagulopathies (FII, FVII, FIX, FX)

DIC,

85

What is the aPTT associated with

intrinsic and common pathways like ACT
Collect in blue top tube ( citrate)
Add a contact surface activator of the intrinsic system + Calcium
It will not be affected by low platelets

86

What is PT associated with

Extrinsic( VII) and common pathway factors.
Tissue thromboplastin (a source of tissue factor) and calcium are added to the patient plasma and the time for clot formation is recorded. N= 7-10 sec
sensitive indicator of poisoning with anticoagulant rodenticides ( warfarin)
factor VII is the vitamin K-dependent factor with the shortest half-life (approximately 6 hours in the dog), the PT may be prolonged within 24 hours following rodenticide ingestion

87

What is PIVKA

Proteins induced by Vitamin K Absence

88

Describe PIVKA

vitamin K-dependent coagulation factors (FII, FVII, FIX, FX) are produced in the liver as nonfunctional precursors
precursors are activated, in the presence of vitamin K,
absence of vitamin K, there is an increase in these precursors
Can detect rodenticide poisoning earlier than 6 hours

89

What are the Misc tests for coagulation

Clot retraction
Whole blood clotting time

90

What is fibrinogen

Fibrinogen is an acute phase reactant protein and elevated values are seen in inflammation and renal disease

91

How do you calculate fibrinogen

Heat precipitation:
2 edta microhematocrit tube
second tube is heated at 56 C for 3 minutes to casuse the firinogen to become fibrin
Spin and measure the protein
The difference between the 2 is the fibrinogen

92

What is Fibrolysis

Plasminogen, a proenzyme, is activated by F XIIa to Plasmin
Plasmin biodegrades fibrinogen and fibrin, generating fibrin degradation products (FDPs)
FDPs also exert a profound inhibitory effect on platelet function
contributing to the petechiae and ecchymoses in patients with disseminated intravascular coagulation (DIC)

93

how do you test for tertiary hemostasis

check for Fibrinogen degradation products-FDP

94

Describe DIC

Prolonged PT
Prolonged APTT
Increased FDP or D-dimers
Decreased platelets