Week 21b - Bleeding and Clotting Flashcards

1
Q

what are the components of the haemostasis system

A

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

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2
Q

what systems prevent blood clotting

A

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

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3
Q

platelet plug formation

A

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

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4
Q

what is tissue factor

A

a mix of lipoproteins and phospholipids released from damaged tissue

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5
Q

what happens in stage 2 of blood clotting

A

formation of prothrombin activator

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6
Q

what happens in stage 3 of blood clotting

A

formation of fibrin from fibrinogen

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7
Q

in what stage of blood clotting does tissue factor act

A

stage 1

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8
Q

dvt investigation - wells score 0/1

A

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

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9
Q

dvt investigation - wells score 2 or more

A

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

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10
Q

dvt treatment

A

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)

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11
Q

virchow’s triad

A

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

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12
Q

pulmonary embolus presentation - physical

A

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

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13
Q

pulmonary embolus presentation - clinical

A

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

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14
Q

pulmonary embolus treatment

A

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

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15
Q

why is venothromboembolism risk increased in hospital patients

A

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

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16
Q

what measures can reduce risk of venothromboembolism

A

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