28. Venous Thromboembolism Prevention Flashcards
What is DVT and venous thromboembolism?
What can VTE cause?
What are the main risk factors for VTE (triad)?
What are some other risk factors?
DVT: thombus formuation in deep vain in leg. VTE: thrombus with in a vein.
DVT, PE, post thrombotic syndrome (pic), leg ulcers.
Virchow’s Triad: Stasis, vessel wall disorder, hypercoagulability. NB 25% hereditary, 50% acquired e.g. factor V leiden more prone to DVT
Major: fracture/replacement of hip/pelvis, major general surgery/trauma, SC injury, hospitalisation with acute medical illness.
Moderate: previous VTE, malignancy/chemo, pregnancy/post-partum, COCP/HRT, central venous line, thrombophilia, medical conditions e.g. IBD, nephrotic syndrome
Weaker: age, travel, varicose veins, diet, smoking, air pollution.
What is post-thrombotic syndrome?
Why do cancer pts have increased DVT risk?
What are 3 VTE risk factors for pregnant pts?
List some things that aim to prevent VTE in hospitals.
Commplicates 40% of DVT cases. Mostly develops within 2 yrs of DVT diagnosis. Pain, swelling, skin induration/discoloration, ulceration. Variable severity, reduced QoL.
Cancer is prothrombotic, immobility, chemo, central venous lines.
Obesity, maternal age >35y, emg C-section.
NICE clinical guidance on VTE prevention. NICE quality standard for VTE prevention. RIsk assessment tool for VTE.
There are 2 different methods of thromboprophylaxis - mechanical and pharmacological. Explain both.
How does heparin work?
Where do DOACs and VKA (vit K antagonists) work?
1) Mechanical: anti-embolism stockings, intermittent pneumatic compression
2) Pharmacological: unfractioned heparin, LMWH (most used), fondaparinux, new DOACs - dabigatran, rivaroxaban, apixaban, edoxaban. (All DOACs partly renally excreted).
Binds to antithrombin, which inactivates factor Xa and thrombin. LMWH preferentially inhibits Xa. Fondaparinux only inhibits Xa.
VKA: Factor VII, IX, X, thrombin
DOACs: Xa (apixaban, edoxaban, rivaroxaban), thrombin (dabigatran)
What are some contraindications to graduated compression stockings?
What are the VTE tx options?
What is warfarin and how does it work?
Peripheral vascular disease, leg/buttock pain on exercise, previous/planned revasc surgery, can’t fit (oedema), dermatitis/recent skin graft.
Anticoagulant therapy std option:
Immediate therapy with treatment dose LMWH
Overlap with warfarin until INR in therapeutic range (5d min)
Stop LMWH, continue warfarin for 3m (monitor in anticoag clinic) and review.
OR
LMWH followed by dabigatran or edoxaban after 5d
OR
Rivaroxaban or apixaban alone
R (less active) and S (more active) enantiomers, T1/2 36h, mainly metabolised in liver, VKA, prevents formation and secretion of vit K dependent clotting factors by liver cells, needs monitoring, major bleeding risk 1-2%/yr. Avoid in pregnancy (teratogenic + bleeding), safe for breast feeding.
