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Exodontia > Haemostasis: Physiology and inherited coagulation disorders > Flashcards

Haemostasis: Physiology and inherited coagulation disorders Flashcards

1
Q

Normal haemostasis

A

Localized vasoconstriction at site of injury
Adhesion of platelets to damaged vessel wall and formation of platelet aggregate or plug
Activation of coagulation cascade leading to fibrin formation, reinforcing platelet plug
Activation of fibrinolytic system which digests haemostatic plug, re-establishing vascular patency

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2
Q

Vessel injury –>

A

–>local vasoconstriction –> platelet adhesion and activation of coagulation cascade
Platelet adhesion –> platelet aggregation –> haemostatic plug –> fibrinolytic activity –> repair of vessel damage
Activation of coagulation cascade –> fibrin formation –> haemostatic plug –> fibrinolytic activity –> repair of vessel damage

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3
Q

Platelets

A 
Small non-nucleated cells
Fragments of megakaryocyte cytoplasm
Essential for primary haemostatic plug
Normal platelet count is 140-350x109/l
Platelets <20 Spontaneous bleeding
		         >80 Haemostatic
Thrombocytopenia = reduced platelet count
Thrombocytosis = increased platelet count
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4
Q

Coagulation problems: primary haemostasis

A

Involves vessel wall, platelets, and von Willebrand factor

Present with purpura, bruising, bleeding from cuts, heavy periods and surgical bleeding

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5
Q

Coagulation problems: secondary haemostasis

A

Involves the coagulation cascade

Presents with joint and muscle haematomas and surgical bleeding. Bruising is not prominent

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6
Q

Management of patient with bleeding disorder

A

History
Examination
Investigations
Treatment

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7
Q

Management of patient with bleeding disorder: history

A 
Easy bruising ?spontaneous
Bleeding after cuts/minor injury
Epistaxis
Menorrhagia
Bleeding after dental extractions
Bleeding after surgery
Family history of a bleeding disorder
Drugs eg aspirin, warfarin, cytotoxics
Alcohol
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8
Q

Menorrhagia

A

Heavy menstrual periods

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9
Q

Epistaxis

A

Nosebleed

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10
Q

Haemoptysis

A

Coughing blood

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11
Q

Haematemesis

A

Vomiting blood

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12
Q

Haematuria

A

Blood in the urine

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13
Q

Malaena

A

Black stool due to bleeding from upper GI tract

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14
Q

Management of patient with bleeding disorder: examination

A 
Ecchymoses (Bruises)
Purpura
Haemarthrosis
Damaged joints
Anaemia (due to bleeding)
Signs of liver disease
Splenomegaly
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15
Q

Management of patient with bleeding disorder: investigations

A 
Full Blood Count - Platelet count
Clotting screen
-Prothrombin time (PT)
-APTT 
-Thrombin time
-Fibrinogen
Bleeding time or PFA (automated Platelet Function Analysis)
Depending on the above results, more specialised investigations can be performed
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16
Q

Management of patient with bleeding disorder: treatment

A

Depends on diagnosis eg

  • haemophilia A - FVIII concentrate
  • haemophilia B – FIX concentrate
  • thrombocytopenia – Platelet transfusion
  • warfarin overdose – Vitamin K
17
Q

Vascular Bleeding Disorders

A 
Inherited 
-hereditary haemorrhagic telangiectasia
-Ehlers-Danlos syndrome
Acquired
-senile Purpura
scurvy (Vitamin C deficiency)
steroid Purpura
18
Q

Coagulation factor disorders

A 
Haemophilia A
-X-linked
Haemophilia B
-X-linked
Von Willebrand disease
-autosomal dominant
Others
-autosomal recessive
-deficiency of fibrinogen, FII, FV, FVII, FX, FXI, FXIII
19
Q

Frequency of Haemophilia A

A

Sheffield: 250
UK: 5000
Prevalence: 1:5000

20
Q

Frequency of Haemophilia B

A

Sheffield: 50
UK: 1000
Prevalence: 1:25000

21
Q

Frequency of VWD

A

Sheffield: 300
UK: 6000
Prevalence: 1:100-1:1000

22
Q

Haemophilia

A 
Haemophilia A – FVIII deficiency
Haemophilia B – FIX deficiency
Identical clinical features
Sex linked inheritance
Sites of bleeding
-joints, muscles, post trauma, post operative
Severity
-<1% severe
-1-5% moderate
->5% mild
(Normal FVIII level 50-150%)
23
Q

Haemophilia treatment

A

If mild haemophilia A: Desmopressin (DDAVP)
-releases FVIII from endothelium
For all severities: FVIII/IX concentrate
-in UK recombinant products, elsewhere could be plasma derived
-main side effect of plasma derived products is risk of infection as each batch is made from up to 30,000 blood/plasma donations
-all products virally inactivated since 1985
BEWARE: Haemophiliacs treated prior to 1985
-HIV 30%, Hepatitis B 5%, Hepatitis C 98%

24
Q

Von Willebrand Disease

A

Commonest inherited bleeding disorder
Affects up to 1% of the population
Autosomal dominant
3 main types with many subtypes
In general, a milder bleeding disorder than haemophilia
Clotting factor PLUS platelet abnormality
Sites of bleeding: Bruising, cuts, gums, epistaxis, menorrhagia, post operative, post trauma
Treatment:
-DDAVP
-intermediate purity (plasma derived) FVIII

25
Q

Platelet disorders

A

Reduced count
-thrombocytopenia
Reduced function

26
Q

Thrombocytopenia

A 
Inherited
-TAR syndrome
-MYH-9 related thrombocytopenia
Acquired
-failure of platelet production
-increased consumption of platelets
-hypersplenism
27
Q

Platelet function abnormalities

A 
Inherited
-Glanzmann’s thrombasthenia
-storage pool disease
Acquired
-aspirin or Clopidogrel usage
-renal disease
-liver disease
-DIC
28
Q

Thrombosis

A

Blood vessels should be fluid

Thrombosis is blood coagulation inside a vessel

29
Q

Arterial thrombosis

A

High pressure
Platelet rich
Examples: myocardial infarction (MI), stroke
Treat with antiplatelet drugs

30
Q

Venous thrombosis

A

Low pressure
Fibrin rich
Examples: deep vein thrombosis (DVT), pulmonary embolism (PE)
Treat with anticoagulants

31
Q

Venous thrombosis: risk factors

A 
Acquired
-age, previous VTE
-surgery/trauma, immobility, obesity
-cancer, serious illness
-pregnancy, contraceptive pill, HRT
Inherited (Thrombophilia)
-5 known causes
32
Q

Inherited thrombophilia

A 
Antithrombin deficiency: 1 in 3,000
Protein C	 deficiency: 1 in 300
Protein S	 deficiency: 1 in 300
Factor V Leiden: 1 in 20
Prothrombin G20210A: 1 in 75
33
Q

Arterial thrombosis risk factors

A 
Smoking
Obesity
Hypertension
Diabetes mellitus
Older age
Not inherited thrombophilia

Exodontia (21 decks)

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