Week 5 - VTE Flashcards
When should you suspect DVT?
Any of the following criteria (2+ ==> high chance)
- Unilateral leg swelling
- Tibial swelling >3cm
- Entire leg swollen
- Cancer
- Hx of DVT
- Recent cast/immobilization/surgery
- Superficial veins
- Localized pain over venous area
- No other likely Dx
How do you test for DVT if there is a low/moderate suspicion of DVT?
D-dimer
High sensitivity ==> Neg rules out DVT
==> Pos only suggests need for more testing
What are the imaging tests for DVT and when are they done?
Doppler US
- accurate at assessing proximal veins
- if Neg & low clinical suspicion ==> no DVT
- if Neg & high clinical suspicion ==> retest next week
- If Pos ==> DVT dx confirmed
Used in patients who have:
- low/mod clinical probability & Pos D-dimer
- high clinical probability
What is the presentation of PE?
Either SOB &/or Chest pain may be noticed
SOB
- new onset
- may only notice after exercising
Chest pain
- pleuritic
- pain on inspiration
may also have hemoptysis
When should you suspect PE?
Any of the following criteria and no other dx
- Symptoms of DVT
- HR > 100
- Recent surgery/immobilization
- Hx of DVT/PE
- Hemoptysis
- Malignancy
What are the imaging tests for PE and when are they done?
CT (gives more conclusive results) & V/Q scans
Used in patients who have:
- low/mod clinical probability & Pos D-dimer
- high clinical probability
What are some risk factors for VTE?
Surgery
- ex. hip & knee replacements
- immobility (casts, paralysis)
Hormonal Tx
- pregnancy & 6 wks post-partum
- HRT
- OCP (oral contraceptive pills)
Cancer (active CA or currently in Chemo Tx)
Air travel
- due to immobility
- due to changes in air pressure
What are some hereditary risks of Thrombosis?
Factor V Leiden** (most common)
Prothrombin
More rare but more severe = Deficiency of:
- Protein C
- Protein S
- Antithrombin
ONLY A/W VENOUS THROMBOSIS
List some non-hereditary risks of Thrombosis.
Anti-phospholipid syndrome
- Lupus anti-coagulant
- Anticardiolipin Ab
- B2 Glycoprotein 1 Ab
- *Must all stay persistently positive over 3 mo.
These people are at higher risk of recurrent thrombosis
A/W BOTH VENOUS & ARTERIAL THROMBOSIS
When would testing be ordered?
Not very often because it does not change tx/management and does not change outcome/risk of recurrence.
Only test if we think it would change tx/mgmt for a family.
Why do we treat pts with DVT/PE?
Reduce risk of:
- death
- post-thrombotic syndrome (clotting/swelling in leg)
- pulm HTN due to thromboembolic disease
What is post-thrombotic syndrome?
What is the tx/prevention?
- Chronic venous insufficiency
- Chronic limb aching
- Skin ulceration
Tx/Prevention:
Compression socks
What is the Tx for DVT/PE
- *ANTI-COAGULATION**
- block new clot formation
- -> inhibit production of fibrin
- don’t break down clot
Sometimes use:
- Thrombolytics (Heparin- anti-inflammatory –> help relieve pain)
- Surgical Thrombectomy
- IVC filter
What types of anti-coagulants would be used to treat PE/DVT?
Start both tx immediately:
Immediate-acting:
- Heparin (UFH or LMWH)
Delayed-acting:
- Warfarin/Vit K antagonists
How long does Heparin need to be taken?
> 5 days, INR > 2 for 2 days
How long should Warfarin be taken
> = 3 months
What is Rivaroxaban?
Factor Xa inhibitor Immediate-acting Metabolized similarly between people Don't need to monitor INR ~$3/d
When would IV UFH be used?
Hopitalized/critically ill pts
Post-op, ICU
Risk of bleeding
Renal disease
*UFH has a short half-life and can be reversed with other agents
Explain the pharmacokinetics of LMWH.
SubQ Longer half-life than UFH Does not require monitoring Much harder to reverse Renally excreted ==> can accumulate in pt w renal failure
Adverse effects of Heparin
Increased risk of bleeding &
Heparin-induced-thrombocytopenia (HIT)
What is Heparin-induced-thrombocytopenia (HIT)
Drug-induced, immune mediated syndrome
- Pt makes Ab against Heparin/PF-4 complex
- can lead to thrombocytopenia or thrombosis
- 5-7d after starting Heparin
- Pts should receive CBC 5-7d after starting to monitor for this
How would thrombocytopenia be diagnosed?
4 T Score:
- Degree of Thrombocytopenia
- Timing
- Thrombosis
- Alternative Cause
Can see lots of microthrombi in hand (dark extremities)
Determines low vs high risk
Low–> unlikely HIT
High–> do HIT assay and switch to new anticoagulant
How would you treat HIT?
NOT WITH HEPARIN, EVER!
Alternate anti-coagulants:
- Fondaparinux
- Argatroban
- Danaparoid
- Lepirudin
Tx of VTE?
Start Tx with anti-coagulation
Follow next day with dx US
If Pos, continue anti-coag tx
What is Dabigatran?
Direct thrombin inhibitor
Given 2x/d
Side effects = GI (nausea)
What is the most commonly used tx for venous thrombosis?
Rivaroxaban
What is used to treat atrial fibrillation?
Rivaroxaban, Dabigatran, or Apixaban
When should DVT prophylaxis be given?
For people not on long-term anti-coagulation, but have had previous thrombosis:
- avoid hormonal tx Prophylaxis: - Pregnancy & 6 wks post-partum --> LMWH (Not Warfarin b/c a/w birth defects) - Post-op - Prolonged immobility
