VTE

Question 1

Pulmonary embolism happens when an embolism gets lodged in a (blank blank).
It can decrease the amount of (blank blank) that gets out to the body.

Answer 1

Pulmonary artery

Oxygenated blood

Question 2

How does the superficial and deep venous system connect and what mechanisms are in place to stop blood flowing backwards?

Answer 2

Superficial veins drain to deep veins (great saphenous into femoral vein, and small saphenous into popliteal vein)
These veins rely on muscle pumps to move the blood forward and valves to stop back-flow of blood

Question 3

How does a clot form?

Answer 3

Damage to endothelium
Vasoconstriction (limits blood flow)
Platelets adhere to damaged vessel wall and become activated by collagen and tissue factor
Platelets require additional platelets to form a platelet plug (primary haemostasis)
Coagulation cascade activated
Fibrinogen to fibrin, forming mesh around platelets (secondary haemostasis)
Hard clot at site of injury

Question 4

Physiological response to pulmonary embolus

Answer 4

Ventilation-perfusion mismatch as alveoli are getting fresh air but not blood flow
Body gets less oxygenated blood
Causes hyperventilation –> resp alkalosis

Question 5

What is Virchow’s triad?

Answer 5

Venous stasis, endothelial injury, hypercoagulability

Question 6

How common is VTE?

Answer 6

1:1000 per year

Commonest cause of preventable hospital-related death

Question 7

VTE prophylaxis for pregnant women/post-partum (within 6 weeks)

Answer 7

Consider LMWH for all women who are admitted if pregnant or gave birth, had a miscarriage or had a termination of pregnancy in the past 6 weeks, and whose risk of VTE outweighs their risk of bleeding.

• UNLESS IN ACTIVE LABOUR
• IF AFTER BIRTH/MISCARRIAGE/TOP, start within 4-8 hours, for min 7 days
• Consider combined with mechanical prophylaxis (intermittent pneumatic compression) if immobilised, reduced mobility (inc after c section)

Question 8

Anti-embolism stockings contraindications

Answer 8

Acute stroke
Peripheral arterial disease
Peripheral neuropathy
Severe leg oedema
Gangrene
Dermatitis

Question 9

When should prophylaxis be started?

Answer 9

ASAP or within 14 hours of admission

Question 10

Prophylaxis for elective hip replacement

Answer 10

LMWH for 10 days followed by low-dose aspirin for a further 28 days
OR
LMWH for 28 days with anti-embolism stockings until discharge
OR rivaroxaban

Question 11

Prophylaxis for elective knee replacement

Answer 11

Low-dose aspirin for 14 days
OR
LMWH for 14 days + anti-embolism stockings until discharge
OR
Rivaroxaban

Question 12

Prophylaxis for major trauma, or cranial/abdo/bariatric/thoracic/max-facial/ENT/cardiac/elective spinal surgery

Answer 12

Mechanical prophylaxis (e.g. anti-embolism stockings or intermittent pneumatic compression) until sufficiently mobile or discharged

Question 13

Prophylaxis for general or ortho surgery + how long

Answer 13

Pharmacological prophylaxis e.g. LMWH or unfractionated heparin if renal impairment
For at least 7 days or until sufficiently mobile
30 days for spinal surgery
28 days for major cancer surgery in abdo

Question 14

Prophylaxis for acutely ill medical patients

Answer 14

Pharmacological prophylaxis - either LMWH or fondaparinux for at least 7 days

Question 15

Prophylaxis for acute stroke patients

Answer 15

Mechanical prophylaxis with intermittent pneumatic compression within 3 days and continued for 30 days
or until sufficiently mobile or discharged

Question 16

Dabigatran mechanism

Answer 16

Orally administered direct thrombin inhibitor

Question 17

Unfractionated heparin mechanism

Answer 17

Binds antithrombin III which affects thrombin and factor Xa

Question 18

LMWH mechanism

Answer 18

Binds antithrombin resulting in inhibition of factor Xa