11. Haematology

Question 1

Complication of venous thromboembolism?

Answer 1

• Embolus, causing pulmonary embolism (90% PE cases due to thrombus in leg)  sudden death
• Haemodynamic abnormalities
  o Abnormal venous circulation, venous hypertension, post thrombotic syndrome
  o Venous eczema
  o Dependent oedema, pain, chronic ulcers

Question 2

Risk factors for a VTE

Answer 2

3 broad risk factors predispose people to VTE (aka Virchow’s triad):

• Stagnation of blood flow (venous stasis)
• Enhanced coagulation (hypercoagubility)
• Vascular damage (endothelial injury)

Question 3

Treatment of VTE

Answer 3

Possible approach to treatment is warfarin + LMWH ‘bridging’

- LMWH used in conjunction with warfarin as it counteracts the hypercoagulation when warfarin first started

Question 4

Monitoring warfarin

Answer 4

• heparin is continued until anticoagulant effect of warfarin is confirmed by checking INR, target range 2-3
• LMWH ceased when INR is in range for 2 consecutive days (usually 5-10 days of LMWH)
• Dietary precautions: beetroot, green leafy veg

Question 5

What are NOACS

Answer 5

Novel oral anticoagulant = NOAC
Eg. Apixaban, dabigatran, rivaroxaban

• Currently only approved for TKR or THR pts
• Same recommendations as LMWH with these pts

Question 6

What is enoxaparin

Answer 6

Enoxaparin is a low molecular weight heparin (LMWH) and the most commonly used pharmacological approach to VTE prophylaxis

• Replace unfractionated heparin (UFH) for VTE prophylaxis as they are more convenient and effective in high risk cases
• Used in VTE treatment as it has immediate anticoagulant effect and counteracts the hypercoagulation when warfarin is first started

Question 7

What is heparin?

Answer 7

impairment

- Also cheaper than LMWH

Question 8

Limitations of Warfarin

Answer 8

• slow onset and offset of action
• narrow therapeutic index
• food and dug interaction
• reduce synthesis of all vitamin K dependent prroteins

Question 9

What are the clinical implications of warfarin/

Answer 9

• need for bridging with rapidly acting anticoagulant
• varabilitity in dosing requirements
• need for routine coagulation monitoring
• risk of skin necrosis

Question 10

Advantages of NAOCs

Answer 10

• rapid onset of action
• predicable anticoagulant effect
• spectific coagulation enzyme target
• low potential for food interactions and drug interactions

Question 11

Clinical implications of NAOCs

Answer 11

• no need for bridging
• no need for routine coagulation monitoring
• low risk of off target adverse effects
• no dietary precautions
• few drug restrictions