Week 21b - Bleeding and Clotting

Question 1

what are the components of the haemostasis system

Answer 1

vasoconstriction
platelet plug formation
blood clotting - lead to formation of fibrin

Question 2

what systems prevent blood clotting

Answer 2

healthy endothelium
anti-thombins - prevent thrombin formation
proteins c and s inactivate clotting factors
fibrinolysis - plasmin breaks down fibrin - breakdown product of this is d-dimer - used in diagnosis

Question 3

platelet plug formation

Answer 3

platelets adhere to site of vascular injury
platelet aggregation and activation
activation of coagulation cascade
formation of fibrin
haemostatic plug formed

Question 4

what is tissue factor

Answer 4

a mix of lipoproteins and phospholipids released from damaged tissue

Question 5

what happens in stage 2 of blood clotting

Answer 5

formation of prothrombin activator

Question 6

what happens in stage 3 of blood clotting

Answer 6

formation of fibrin from fibrinogen

Question 7

in what stage of blood clotting does tissue factor act

Answer 7

stage 1

Question 8

dvt investigation - wells score 0/1

Answer 8

d-dimer
- if negative: consider alternatives, give safety netting advice
- if positive: doppler ultrasound leg

Question 9

dvt investigation - wells score 2 or more

Answer 9

doppler ultrasound leg
- if negative: review in 5-7 days, may still be a dvt
- if positive: treat for dvt

Question 10

dvt treatment

Answer 10

most patients treated with f10a inhibitors e.g. apixaban
low molecular weight heparin e.g. dalteparin followed by f10a inhibitors of warfarin
f10a inhibitors often called direct oral anticoagulants (DOACs)

Question 11

virchow’s triad

Answer 11

thrombosis in the middle
3 corners - stasis, vessel wall injury, hypercoagulability

Question 12

pulmonary embolus presentation - physical

Answer 12

breathlessness - most common
pleuritic chest pain
cough
calf/leg swelling
haemoptysis - less common
syncope - less common

Question 13

pulmonary embolus presentation - clinical

Answer 13

tachycardia including atrial fibrillation
tachypnoea
crackles or reduced breath sounds - ~20%
elevated jugular venous pressure

Question 14

pulmonary embolus treatment

Answer 14

oral f10a inhibitor - e.g. apixaban, rivaroxaban

low molecular weight heparin - e.g. dalteparin followed by either thrombin inhibitor e.g. dabigatran or vit K antagonist e.g. warfarin

treatment normally for 3 months after provoked PE or DVT

Question 15

why is venothromboembolism risk increased in hospital patients

Answer 15

immobility
age
underlying conditions like heart failure
cancer
surgery - activated clotting system
inflammation - release of tissue factor

Question 16

what measures can reduce risk of venothromboembolism

Answer 16

mobilisation
adequate hydration
compression stockings or pneumatic compression devices - sufficient in low risk patients
prophylactic dose low molecular weight heparin - e.g. dalteparin - treatment based on risk assessment