4. VTE

Question 1

Risk factor for DVT/PE (virchow’s triad) → increase risk of clotting

Answer 1

• Hypercoagulability (major surgery, malignancy, pregnancy, thrombophilia, infection, IBD, protein C or S deficiency, factor V Leiden)
• Vascular damage (cellulitis, physical trauma, indwelling catheter/ heart valve)
• Circulatory stasis (immobility, venous obstruction - obesity, pregnancy, AF)

Question 2

Location of DVT

Answer 2

• Legs (above knee): likely to embolise → right heart → PE → occlude blood flow to lungs
• Calf: unlikely to embolise

Question 3

Clinical presentation of DVT (S/S)

Answer 3

• Symptoms: leg swelling, pain, warmth, usually unilateral
• Signs: superficial veins that are palpable (bulging veins), Homan’s sign (pain in back of knee when feet is moved upwards)

Question 4

Diagnosis of DVT - Wells-DVT Score (for DVT)

Answer 4

• 0-2 points: unlikely/ moderate likelihood of DVT → D-dimer test
• > 2 points: likely DVT → carry out proximal compression ultrasound (CUS)

Question 5

Treatment of VTE (DVT)

Answer 5

anticoagulants (no antiplatelets)
thrombolytics not needed

Question 6

UFH (VTET & VTEP doses)

Answer 6

VTET: IV 80 u/kg followed by 18 u/kg/hr
VTEP: ?

Question 7

LMWH (eg enoxaparin) (VTET & VTEP doses)
renally impaired dose?

Answer 7

VTET: SC 1mg/kg BD
Renal: CrCl <30ml/min: 1mg/kg OD

VTEP: SC 40mg OD/ SC 30mg BD

Question 8

Dabigatran (VTET & VTEP doses)
renally impaired dose?

Answer 8

VTET: parenteral anticoagulant x5d → 150mg BD
Renal: CrCl <50ml/min + PGP inhibitor: avoid

VTEP: ??

Question 9

Rivaroxaban (VTET & VTEP dose)
renally impaired dose?

Answer 9

VTET: 15mg BD x21d → 20mg OD (up to 6mths) → 10mg OD
CrCl <30ml/min: avoid

VTEP: 10mg OD

Question 10

Apixaban (VTET & VTEP dose)
renally impaired dose?

Answer 10

VTET: 10mg BD x7d → 5mg BD (up to 6mths) → 2.5mg BD
CrCl 15 to <30ml/min: use with caution

VTEP: 2.5mg BD

Question 11

Edoxaban (VTET & VTEP doses)
renally impaired dose?

Answer 11

VTET: parenteral anticoagulant x5d → 60mg OD
CrCl 30 - 50ml/min OR BW ≤60kg: 30mg OD

VTEP: 30mg OD

Question 12

warfarin for VTET/P

Answer 12

parenteral anticoagulant overlap for ≥5d AND INR ≥2.0
PO Warfarin (INR target 2.5/ 2.0 - 3.0)

Question 13

Duration of tx for VTE

Answer 13

• Transient/reversible RF: sepsis, road traffic accident → stop at 3mths
• Chronic/continuous RF: obesity, prolonged immobility → continue tx (reassess at 6mth)
• @6mth continue anticoagulant if still have chronic RF (antiphospholipid syndrome. prolong immobility)

Question 14

when to use/not use fibrinolytics (rTPA, tenecteplase)

Answer 14

any RF of bleeding is an exclusion criteria for use of thrombolytics (increase risk of bleeding)

Question 15

PE diagnosis

Answer 15

≤4 points: unlikely PE
>4 points: likely PE → imaging

Question 16

S/S of PE (differential dx: MI)

Answer 16

• Symptoms: cough, chest pain, chest tightness, SOB, palpitation, hemoptysis (cough up blood), dizziness, light headedness
• Signs: tachypnea, tachycardia, diaphoretic (sweating profusely), cyanotic (blue), hypotensive, hypoxic (low O2)

Question 17

Criteria for high risk PE

Answer 17

1. Cardiac arrest
2. Obstructive shock - SBP <90mmHg, end organ hypoperfusion (cold, clammy skin, oliguria/anuria, incr serum lactate)
3. Persistent hypotension - SBP <90mmHg or drop ≥40mmHg
4. RV dysfunction on imaging (TTE, CTPA)
5. Elevated cardiac troponin levels (heart muscle die)

Question 18

Tx for high risk PE (+ rationale)

Answer 18

IV bolus UFH + thrombolytics (rTPA)
- UFH is easily reversible in case pt bleeds with thrombolytics use
- Thrombolytics: high risk of mortality > risk of bleeding

Question 19

Tx for intermediate-low risk PE

Answer 19

(parenteral) SC LMWH/ fondaparinux (instead of UFH) - to ensure sufficient AC at clotting site
(oral) DOAC (preferred over VKA)
- parenteral anticoagulant overlap for ≥5d AND INR ≥2.0 [PO Warfarin INR target 2.5/ 2.0 - 3.0]

Question 20

Duration of tx for PE

Answer 20

same as DVT

Question 21

Severe renal impairment (CrCL <30mL/min) VTET

Answer 21

• DOAC not recommended
• Recommended: Warfarin + UFH
• Alternative: warfarin + dose-reduced enoxaparin

Question 22

Pregnancy VTET

Answer 22

Recommended: LMWH (SC enoxaparin 1.0mg/kg BD) → VTEP SC 40mg OD or 30mg BD
- Warfarin teratogenic in 1st trimester
- DOAC can be used but not well studied