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Clinical Haematology > Assessing haemostasis > Flashcards

Assessing haemostasis Flashcards

1
Q

What are the five steps of haemostasis?

A 
Vessel spasm
platelet plug formation
coagulation
Clot retraction
Clot dissolution
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2
Q

Steps of platelet plug formation:

A

Adhesion
Activation
Aggregation

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3
Q

Adhesion is where:

A

platelets stick to site of damage, occurs between GPIb complex and vW factor bridging site of injury
unstable reaction platelet roll along surface
rolling enables more interactions causing ACTIVATION

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4
Q

Activation is where:

A

interaction between GPVI receptor on platelets and collagen triggering activation 3 things occur:

  1. increase intracellular calcium stores
  2. cause shape change of platelets
  3. Secretion platelets release granules fro inside (alpha granules and dense granules)

Conversion of alpha two b beta 3 receptor, open intergrin = high affinity = bind fibrinogen and stick platelets togethwe

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5
Q

Aggregation is the formation of the

A

platelet plug

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6
Q

In coagulation _______ are wrapped with _______ this traps red cells

A

Platelets

fibrin

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7
Q

fibrin is made up of monomers of

A

fibrinogen

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8
Q

what converts fibrinogen to fibrin?

A

thrombin = protease

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9
Q

thrombin circulates as what?

A

prothrombin

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10
Q

Intrinsic pathway is triggered by?

A

Collagen

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11
Q

Extrinsic pathways is triggered by?

A

tissue damage - calcium factor 4

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12
Q

plasminogen breaks down?

A

fibrin

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13
Q

what is protein C?

A

Serine protease

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14
Q

What is protein S?

A

Cofactor

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15
Q

what does fibrinolysis do?

A

the enzymatic breakdown of fibrin in clots

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16
Q

Fibrin split products are cleared by what organ?

A

the liver

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17
Q

What doe the breakdown of fibrin do?

A

produces D-dimers, made up of fragments X, Y, D, E

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18
Q

What enzyme carries out fibrinolysis?

A

plasmin

19
Q

Where does plasmin come from?

A

plasminogen, activated by enzymes such s tissue plasminogen activator (tPA), these come from healthy endothelial cells

20
Q

High levels of D dimers in the blood indicate?

A

high level of fibrinolysis and a high burden of thrombus in the body

21
Q

assessing haemostasis involves asking?

A

is it a bleeding/thrombotic disorder?

is it under/over action of the system?

22
Q

Bleeding disorders can be broken down into:

A

Primary haemostats disorders - bleeding due to PP

Coagulation disorders - problem with coagulation

23
Q

Thrombotic disorders can be either:

A

platelet plug occurring at wrong time or over active causing ARTERIAL THROMBOSIS = MI/Stroke
Inappropriate activation of coagulation = VENOUS THROMBOSIS = DVT

24
Q

What can inappropriate activation of coagulation cause?

A

Venous thrombosis = DVT

25
Q

What can over active platelet plug formation or platelet plug formation occurring at the wrong time cause?

A

Arterial thrombosis = MI or strok

26
Q

what are the signs and symptoms of a bleeding disorder?

A

Bruising
mucosal bleeding
Haemarthrosis
Complication with surgery, trauma or venipuncture

27
Q

What is a bruise?

A

micro/macroscopic tearing of a blood vessels

28
Q

Haematomas..

A

refers to purple/red colour caused by bleeding under the skin, the colour is non blanching upon pressure

29
Q

How big are petechiae?

A
30
Q

How big are purpura?

A

3mm-1cm

31
Q

How big are ecchymoses?

A

> 1cm

32
Q

What are the 4 causes of bleeding defects?

A

Decreased platelet number
decreased platelet function
decreased coagulation
Vascular defects

33
Q

What are the signs and symptoms of a thrombotic disorder?

A

These vary depending on location of thrombus:

  • Coronary arteries = chest pain
  • Carotid arteries = FAST aschemic stroke
  • Deep veins of the leg = unilateral leg pain
34
Q

What are the haemostatic investigations that are carried out?

A 
FBC
Blood film/smear
Bleeding time
PFA-100
Platelet aggregation studies
Flow cytometry
Serum thromboxane
Aspirin works
Coagulation assays
Factor assay
PCR
D-dimer assay
35
Q

what is the normal bleeding time?

A

3-8min

36
Q

What does a prothrombin time assay assess?

A

Intrinsic pathway of coagulation

37
Q

What coagulation assay tests the intrinsic pathway?

A

activated partial thromboplastin time (aPTT)

38
Q

what does thrombin time assay asses?

A

common pathway of coagulation

39
Q

Which coagulation assay assess patients on warfarin?

A

PT

40
Q

What are the normal values of a PT time?

A

11-16 seconds

41
Q

what re the normal values of the aPPT test?

A

30-40 seconds

42
Q

What are the normal values of TT?

A

15-19 seconds

43
Q

What does a factor assay determine?

A

Helps to determine what clotting factors are missing or reduced by diluting pt plasma with normal plasma

Clinical Haematology (10 decks)

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