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Revision Notes - Year 1 > Haemostasis - 143 > Flashcards

Haemostasis - 143 Flashcards

0
Q

APPT time is which pathway?

A

Intrinsic

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1
Q

PT time is which pathway?

A

Extrinsic

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2
Q

Baby with life threatening nose bleed. All tests normal except slightly prolonged bleeding time. What is wrong?

A

Interference with platelet functioning. THrombo-asthenia

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3
Q

30 year old male, spontaneous swollen knee. APTT long

A

Haemophilia A

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4
Q

36 year old pregnant women, recent SOB and chest pain. Prolonged thrombin time, prolonged APPT. What is wrong?

A

Heparin treatment

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5
Q

7 yr boy, petechiae.

A

ITP

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7
Q

2 week premature baby with IC bleeding. Prolonged APTT, OSPT prolonged

A

Vitamin K deficiency

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8
Q

What is primary hemostasis? Describe the stages

A

The formation of a platelet plug. Starts with vasoconstriction of the vessel, followed by platelets sticking to the exposed collagen forming the ‘plug’

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9
Q

How are platelets activated?

A

Unactivated platelets bind vWF in the subendothelial matrix (via GPlb receptors), which activates them, resulting in the release of their granules and the expression of phospholipids and GPIIb/IIa

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10
Q

What happens in secondary hemostasis?

A

The fibrin clot is formed and the coagulation cascade is initiated.

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11
Q

What initiates the coagulation cascade?

A

FV and FVIII binding tissue factor (TF)

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12
Q

What test is done if you want to assess the intrinsic pathway?

A

APTT

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13
Q

What test is done if you want to assess the extrinsic pathway?

A

PT

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14
Q

What is the end of the coagulation cascade?

A

Fibrinogen being cleaved to fibrin (FIa) by thrombin (FIIa)

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15
Q

How might a patient with a disorder of primary hemostasis present?

A
  • Site of bleeding = mucous membrane & skin
  • Bleeding after minor cuts
  • Petichae
  • Small/absent echymoses
  • Bleeding after surgery is mild & instant
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16
Q

How might a patient with a disorder of secondary hemostasis present?

A
  • Site of bleeding = soft tissues, joints
  • Bleeding after minor cuts not normal
  • NO petichae
  • Echymoses are large
  • Muscle haematomas common
  • Bleeding after surgery delayed and severe
17
Q

Name some disorders of 1 hemostasis

A
  • Hereditary haemorrhagic telengiectasia (autosomal dom)

- Henoch-Schonlein purpura - vasculitis (acquired - if no haematuria you don’t treat)

18
Q

Name some coagulation disorders of 2 hemostasis

A
  • Haemophilia A (x-linked) - FVIII.
  • Haemophilia b (christmas disease) - FIX
  • Acquired diseases, e.g. liver disease, vitamin K deficiency
19
Q

What is the pathogenesis of vWD?

A

Patients are lacking vWF, which means the platelets cannot attach to the epithelium. It would show an abnormal APTT. Autosomal dominant

20
Q

Where are clotting factors produced?

A

Produced in their inactive form in the liver and secreted into the blood

21
Q

What is the role of vWF?

A

Carries FVIII in the blood

22
Q

What is the role of fibrin?

A

It stabilises the clot. Fibrinogen is the most abundant clotting factor

23
Q

What is the first phase of the extrinsic coagulation cascade?

A

TF + VII

24
Q

What could be the cause behind a long TT?

A

Patient has no/low fibrinogen

Something is inhibiting the thrombin, e.g. heparin

25
Q

What could be the cause behind a long APTT?

A

If FXII is low or missing -> this does NOT cause bleeding disorders though
FVIII, FIX, FXI, FXII need to be assessed.

26
Q

Which clotting factor do you need to look at if a patient has a long TT and APTT?

A

FX

27
Q

What does anti-thrombin inhibit?

A

Thrombin and FXa

28
Q

Describe the protein C system

A

Protein C molecules activate Protein S. This then inhibits FVa and FVIIIa.
Note: protein C needs vitamin K for synthesis

29
Q

When would you do a D-dimer?

A

Patient is at low risk for DVT

30
Q

How is a DVT treated?

A

LMWH

31
Q

What investigations would you do to diagnose a PE?

A

ABG, ECG, CXR, USS, D-dimer

32
Q

Which coagulation factors rely on vitamin K?

A

FII, FVII, IX, X

33
Q

Name an anti-fibronolytic drug and what it might be used for

A

Tranexamic acid, stabilises clot. Used when there is bleeding, e.g. epistaxis, menorrhagia

34
Q

Name a vitamin K antagonist

A

Warfarin

Revision Notes - Year 1 (41 decks)

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