9. Haemostasis

Question 1

Normal haemostasis

Answer 1

1. Vascular injury
2. Platelets
3. Coagulation factors

Question 2

Warfarin

Answer 2

Vitamin K needed for activation of factors II, VII, IX and X

VKOR needed to recycle vit K

Warfarin inhibits VKOR

Question 3

Warfarin Cons

Answer 3

birth defects if given in pregnancy

narrow therapeutic window

food / drug interactions

needs regular blood level monitoring

bleeding risk if level too high

ineffective if level too low

Question 4

Heparins

Answer 4

increases antithrombin

Antithrombin inhibits thrombin and Xa

Available as UFH or LMWH

Question 5

Benefits of LMWH over UFH

Answer 5

Better bioavailability

longer-half life

No need for APTT monitoring

Less bleeding

Less osteoporosis

Less heparin induced thrombocytopenia (HIT)

Question 6

Von Willebrand disease

Answer 6

Quantitative (type 1) defect of VWF

qualitative (type 2) defect of VWF

Complete absence of VWF (type 3)

Question 7

Von Willebrand disease Symptoms

Answer 7

Bleeding

Question 8

Von Willebrand disease Treatment

Answer 8

Anti-fibrinolytic drugs (e.g. tranexamic acid) useful for mucosal bleeding

Many respond to desmopressin (DDAVP) which causes the body to release FVIII and VWF stores

If not respond to DDAVP then FVIII/VWF concentrate

Question 9

Haemophilia

Answer 9

Type A = deficiency of FVIII

Type B = deficiency of FIX

Question 10

Haemophilia Symptoms

Answer 10

Severe haemophiliacs can have major / life-threatening bleeding problems

Classically muscle or joint haematomas

Mild haemophiliac men and female carriers may be asymptomatic or only have problems when provoked e.g. surgery

Question 11

Haemophilia Treatment

Answer 11

Mild haemophilia A may respond to desmopressin (DDVAP)

Usually need specific FVIII or FIX concentrate

Question 12

Haemophilia complications

Answer 12

Intracranial haemorrhage

Long-term joint damage

Question 13

Immune thrombocytopenia (ITP)

Answer 13

Immune destruction of platelets

increased megakaryocytes in Bone marrow

Platelet transfusion ineffective

Need immune suppression or splenectomy

Question 14

Disseminated Intravascular Coagulation (DIC)

Answer 14

Pathological activation of coagulation

depletion of coagulation factors

generalised bleeding

thrombosis

Question 15

Disseminated Intravascular Coagulation (DIC) lab findings

Answer 15

low platelets

prolonged PT

prolonged APTT

reduced fibrinogen

very raised d-dimers

Question 16

DIC treatment

Answer 16

platelet transfusion

FFP

Cryoprecipitate (replaces fibrinogen)

Question 17

Venous thromboembolism (VTE)

Answer 17

DVT in the leg

leg pain / swelling

Long term risk of pulmonary embolism (PE) = Can cause sudden death

Question 18

VTE treatment

Answer 18

LMWH followed by warfarin

compression stockings

Question 19

Heparin benefits

Answer 19

Immediate effect

Few food / drug interactions

Safe in pregnancy

Question 20

Von Willebrand Factor (VWF)

Answer 20

needed for platelet adhesion to vessel wall

carrier protein for FVIII