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Cardiorespiratory > Haemostasis - Bleeding: Disorders of Primary Haemostasis > Flashcards

Haemostasis - Bleeding: Disorders of Primary Haemostasis Flashcards

1
Q

What is haemostasis?

A

the cellular and biochemical processes that enables both the specific and regulated cessation of bleeding in response to vascular injury

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2
Q

What is haemostasis for?

A

Prevention of blood loss from intact vessels
Arrest bleeding from injured vessels
enable tissue repair

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3
Q

Briefly outline the process of haemostasis.

A

vessel constriction > primary haemostasis > secondary haemostasis > fibrinolysis

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4
Q

What is involved in primary haemostasis?

A

formation of an unstable platelet plug (platelet adhesion/aggregation)

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5
Q

What is involved in secondary haemostasis?

A

stabilisation of the plug with fibrin (blood coagulation)

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6
Q

What is involved in fibrinolysis?

A

vessel repair + dissolution of clot (cell migration/proliferation)

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7
Q

Why do we need to understand haemostatic mechanisms?

A

diagnose/treat bleeding disorders, control bleeding, identify risk factors for thrombosis, treat thrombotic disorders, monitor drugs used for treatment

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8
Q

Normal haemostasis is a balance between?

A

bleeding vs thrombosis

fibrinolytic factors, anticoagulant proteins vs platelets, coagulant factors

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9
Q

What are two reasons why haemostatic balance is tipped towards bleeding?

A

lack of specific factor (production failure, increased clearance) or defective fx of specific factor (genetic or acquired)

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10
Q

In what two ways does platelet adhesion occur?

A

indirectly via VWF + GIpIb or directly to collagen via GIpIa

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11
Q

The release of what factors causes platelet aggregation?

A

release of ADP and thromboxane

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12
Q

What factors are involved in platelet aggregation?

A

Ca2+

fibrinogen

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13
Q

What is low numbers of platelets called?

A

thrombocytopenia

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14
Q

Causes of low platelets?

A

bone marrow failure e.g. leukaemia, B12 deficiency

accelerated clearance e.g. ITP, disseminated intravascular coagulation

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15
Q

What does ITP stand for?

A

immune thrombocytopenic purpura

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16
Q

Categorise platelet disorders.

A

low numbers (thrombocytopenia) or impaired function

17
Q

How can platelet function be impaired?

A

hereditary absence of glycoproteins or storage granules, acquired from drugs (aspirin, NSAIDs, clopidogrel)

18
Q

How does aspirin act as an anti-platelet therapy?

A

irreversibly blocks COX

19
Q

How does clopidogrel act as an anti-platelet therapy?

A

irreversibly blocks the ADP receptor on platelets

20
Q

How do you get Von Willebrand Disease?

A

hereditary decrease of quantity/fx or acquired due to antibody

21
Q

What two functions does von willebrand factor have in haemostasis?

A

binding to collagen and capturing platelets

stabilising Factor VIII

22
Q

What inheritance pattern does von willebrand disease have?

A

autosomal

23
Q

What is type 1, 2, 3 von willebrand disease?

A

Type1/3 VWF deficiency

VWF with abnormal function

24
Q

List categories of primary haemostasis disorders.

A

platelets
VWF
vessel wall

25
Q

What are vessel wall causes of disorders of primary haemostasis?

A

inherited (Ehlers-Danlos, connective tissue disorders, hereditary haemorrhagic telangiectasia)
acquired (steroids, ageing, vasculitis, scurvy)

26
Q

How does ITP (Idiopathic thrombocytopenic purpura) work?

A

antiplatelet autoantibodies bind to sensitised platelets > engulfed by macrophages

27
Q

Describe typical primary haemostasis bleeding.

A

immediate, prolonged bleeding from cuts, prolonged nose/gum bleeds, menorrhagia, bruising, prolonged bleeding after trauma or surgery

28
Q

Petechiae and purpura are caused by?

A

bleeding under the skin

29
Q

When purpura have pressure applied what happens?

A

do not blanch

30
Q

Clinical feature of thrombocytopenia?

A

petechiae

31
Q

Clinical feature of severe VWD?

A

haemophilia like bleeding

32
Q

Clinical features of disorders of primary haemostasis

A

ecchymosis
petechiae
purpura
increased skin elasticity in connective tissue disorders

33
Q

What are tests for disorders of primary haemostasis?

A

platelet count/morphology, bleeding time, VWF assays, clinical observation

34
Q

What are the principles of treatment of abnormal haemostasis where production/function failure is the root cause?

A 
replace missing factor/platelets (prophylactic/therapeutic)
stop drugs (e.g. aspirin, NSAIDs)
35
Q

What are the principles of treatment of abnormal haemostasis where immune destruction is the root cause?

A

immunosuppression (e.g. prednisolone)

splenectomy for ITP

36
Q

What are the principles of treatment of abnormal haemostasis where increased consumption is the root cause?

A

treat cause

replace as necessary

37
Q

List some additional haemostatic treatments.

A

desmopressin
tranexamic acid
fibrin glue/spray
other (oral contraceptive pill for menorrhagia)

Cardiorespiratory (20 decks)

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