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3154 Haematology > IC4 VTE > Flashcards

IC4 VTE Flashcards

1
Q

Virchow’s Triad

A
  • Hypercoagulability
  • Vascular damage / vessel injury
  • Circulatory / venous stasis
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2
Q

Examples of risk factors based on Virchow’s Triad

A

Hypercoagulability

  • Inflammation (release of hypercoagulable chemicals)
  • Estrogen, Tamoxifen
  • Dehydration
  • Infection and sepsis
  • Protein C and S deficiency
  • Factor VIII, XI excess
  • APS antibodies
  • Pregnancy + up to 6w post partum

Vascular damage

  • Thrombophlebitis
  • Cellulitis
  • Atherosclerosis
  • Trauma
  • Venous catheters

Circulatory Stasis

  • Immobility
  • Surgery
  • Polycythemia
  • Venous obstruction (obesity, tumor, pregnancy)
  • AFib
  • Congenital abnormalities affecting venous anatomy
  • Bradycardia
  • Low BP
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3
Q

Distal VS Proximal DVT

  • List the veins involved
A

Distal:

  • Peroneal, anterior tibial, posterior tibial veins

Proximal:

  • popliteal, femoral, iliac veins
  • more likely to embolise (IVC => right heart => PE)
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4
Q

Explain how PE might lead to circulatory collapse

A

PE can result in occlusion of blood flow to lung => impaired gaseous exchange => necrosis => impaired O2 delivery to other organs => fatal circulatory collapse

Infarction of lung tissue => back damming into heart => right ventricle failure => left ventricle failure

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5
Q

S&S of DVT

Differential diagnosis

A

Symptoms:
- Leg swelling, pain, warmth (non-specific, hence require testing)
- Unilateral
- May present with fever

Signs:
- Palpable cord in leg (dilated superficial vein)
- Homan’s sign - pain in the back of the knee when foot is flexed

*Differential diagnosis:
- cellulitis (CUS to identify clots)
- HF: fluid overload (bilateral)

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6
Q

S&S of PE

Differential diagnosis

A

(Usually underlying DVT)

Symptoms:
- Cough, chest pain, chest tightness, SOB, palpitation, hemoptysis, pleural effusion
- Dizziness, light-headedness (due to poor perfusion, circulatory collapse)

Signs:
- Tachypnea, tachycardia, diaphoretic (sweating)
- Neck vein distended
- Cyanotic, hypotensive
- Oxymetry: hypoxic
- Cardiogenic shock

*Differential diagnosis:
- MI (both MI and PE can present with ECG changes)

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7
Q

Explain the patho of hemoptysis and pleuritic chest pain in PE

A

Small distal emboli can create areas of alveolar hemorrhage, thus leading to hemoptysis, pleuritis, pleuritic chest pain, pleural effusion

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8
Q

DVT diagnosis

A
  1. Wells-DVT Score
  2. If >2 points, imaging with whole leg or proximal CUS
  3. If 0-2 points, perform D-dimer (if D-dimer positive –> imaging)
  4. Distal DVT –> anticoagulation or surveillance
  5. Proximal DVT –> initiate anticogulation
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9
Q

[DVT diagnosis]

Other investigations to exclude differential diagnosis

A
  • FBC rule out infection (although blood shift can occur in DVT/PE, total whites can incr in MI)
  • Procalcitonin - rule out infection
  • Renal panel
  • NT-proBNP - rule out HF
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10
Q

D-dimer is a by-product of?

A

Degradation of fibrin mesh (when plasmin cleaves fibrin)

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11
Q

[DVT diagnosis]
Explain the utility of D-dimer

What are some other conditions that can raise D-dimer?

A

Good negative predictive value (pre-test probability, rule-in rule-out)

  • If negative –> can rule out DVT
  • If positive –> cannot confirm DVT

Other conditions that can raise D-dimer:

  • pregnancy
  • malignancy
  • pneumonia
  • heart failure
  • post-surgery
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12
Q

[DVT diagnosis]
Well’s score:

A

1 point each:

  • Active cancer (ongoing tx or within previous 6m)
  • Paralysis/paresis/immobilization of lower extremities
  • Recently bedridden for >3 days or major surgery within 4 weeks
  • Localized tenderness
  • Entire leg swollen
  • Calf swelling by more than 3cm (measured 10cm below tibial tuberosity)
  • Pitting edema
  • Collateral superficial veins (non varicose)

High probability: 3 and above
Mod probability: 1-2
Low probability: 0

=> DVT likely: 2 or greater
=> DVT unlikely: 1 or less

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13
Q

[VTE treatment]
Acute treatment of VTE
- Key principles

A
  • Thrombolytic therapy is only considered in pt with severe cardiopulmonary compromise or DVT with high risk of limb loss, thrombolytic therapy must be followed by anticoagulation with UFH or LMWH
  • If pt has active bleeding, unable to use anticoagulation, AND VTE is in lower extremity, consider IVC filter
  • If pt is suitable for outpatient VTE tx (no active bleeding, no PE, not CI w anticoagulants), consider: DOAC/LMWH/Warfarin
  • If pt is unsuitable for outpatient VTE tx (e.g., due to poor prognosis), consider: DOAC/LMWH/UFH/Warfarin
  • If pt is unsuitable for outpatient VTE tx and CrCl <30ml/min, consider: UFH x5d with Warfarin overlap
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14
Q

[VTE treatment]
- Apixaban

A

Apixaban 10mg BD x7d, followed by 5mg BD for 3-6months
Extended: 2.5mg BD

Preferred as it is subsidized (SDL2), however, less convenient than Riva due to twice daily dosing

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15
Q

[VTE treatment]
- Rivaroxaban

A

Rivaroxaban 15mg BD x21d, followed by 20mg OD for 3-6m
Extended: 10mg OD

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16
Q

[VTE treatment]
- Dabigatran/Edoxaban

A

UFN/LMWH/fondaparinux (subQ) for first 5d,
followed by Dabigatran 150mg BD or Edoxaban 60mg OD

*LMWH first line, unless CrCl <30 then use UFH

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17
Q

[VTE treatment]
- Warfarin

A

UFN/LMWH/fondaparinux (subQ) for at least 5 days,
OVERLAP w Warfarin daily, INR range 2-3

*LMWH first line, unless CrCl <30 then use UFH

18
Q

[VTE treatment]

Explain difference between transient and chronic risk factors

How does this affect duration of VTE treatment?

A

Transient/Provoked: e.g., traffic accident, recent surgery
Chronic/unprovoked: antiphospholipid syndrome (APS), hereditary thrombophilia

Transient - 3months

Chronic - typically extend beyond 3m

  • First unprovoked isolated distal DVT - at least 3 months
  • First unprovoked proximal DVT/PE - at least 3 months, consider 6 months (if bleeding risk acceptable, follow up once a year)

*In pt stopping anticoagulation, consider low dose aspirin

19
Q

[VTE treatment]

Recommendation for severe renal impairment CrCl <30ml/min

A

Do not use DOACs

Use UFH/LMWH + Warfarin overlap

UFH + Warfarin is preferred
If use LMWH - must be dose reduced enoxaparin

LMWH => renally excreted, accumulates in renal failure, ma incr risk of major bleeding
UFH => minimal renal excretion, short half-life

20
Q

[VTE treatment]

UFH vs LMWH (Enoxaparin)

Dosing of Enoxaparin

A

IV UFH

subQ enoxaparin preferred

  • dosed by body weight: 1mg/kg q12h OR 1.5mg/kg q24h
  • In CrCl <30ml/min, use 1mg/kg q24h
  • Enoxaparin (Clexane) comes in 20mg/0.2ml, 40mg/0.4ml, 60mg/0.6ml (graduated), 80mg/0.8ml (graduated)
21
Q

[VTE treatment]

Compare protein binding of anticoagulants used in VTE tx

A

DRAW

Dabigatran (most renally cleared)
Rivaroxaban
Apixaban
Warfarin (highest protein binding, most hepatically cleared)

Edoxaban is minimally hepatically and renally cleared

22
Q

[VTE Prophylaxis]

Algorithm

A
  1. Risk factors for VTE
  2. If high risk for VTE, consider pharmacologic prophylaxis or pneumatic compression device (depending on bleeding risk)
  3. If low risk for VTE, VTE prophylaxis not indicated
23
Q

[VTE Prophylaxis]

3 main high risk groups that require VTE prophylaxis

A
  1. Medically ill (e.g., severe sepsis, heart failure, prolonged immobility, thrombophilia)
  2. Surgical patients (e.g., hip replacement surgery, knee replacement)
  3. Cancer patient
24
Q

[VTE Prophylaxis]

  • Dosing of enoxaparin

*SC Enoxaparin preferred to SC UFH

A

No longer by body weight (like in VTE tx or PCI), flat dose of 40mg once daily

THR/HFS: 40mg OD or 30mg BD

Duration for surgical indications: 10-14d, up 35d

Because LMWH is renally excreted, dose adjustment needed in renal impairment:

  • CrCl 30-50ml/min - 30mg q12h
  • CrCl <30ml/min - 20-30mg once daily

NOTE THAT:

  • Bariatric surgery (for obese pt) - VTEP dose is different (BMI >=40: 40mg BD, BMI >50: 60mg BD)
25
Q

[VTE Prophylaxis]

  • DOAC doses
A

Apixaban 2.5mg BD

  • Start within 12-24h post-surgery, provided hemostasis achieved
  • 10-14d TKR; 32-35d THR

Rivaroxaban 10mg OD

  • Start within 6-10h post-surgery, provided hemostasis achieved
  • 14d for TKR, 35d for THR
  • Medically ill up 31-39days

Edoxaban 30mg/day

Dabigatran 220mg/day

  • start within 1-4h post-surgery, provided hemostasis achieved
  • 10d (TKR), 28-53d (THR)
  • CrCl 30-50ml/min: use 150mg OM
26
Q

[VTE tx/prophylaxis]

DOAC renal adjustments

A

Apixaban

  • CrCl 15-29ml/min: use with caution
  • HD: avoid

Rivaroxaban

  • CrCl <30ml/min: avoid use

Edoxaban

  • CrCl 30-50ml/min OR BW =<60kg: 30mg/day (instead of 60mg/day)
  • CrCl >95ml/min: avoid use

Dabigatran (recall most renally cleared)

  • CrCl <50ml/min + concomitant PgP inhibitors: avoid

IN GENERAL,
avoid use when CrCl <30ml/min
for Dabi <50ml/min,
for edoxaban half dose when 30-50ml/min

27
Q

Risk factors for DVT recurrence after first episode of unprovoked VTE

=> therefore consider need for anticoagulation

A
  • Proximal DVT location
  • Obesity
  • Old age
  • Early prothrombotic phlebitic syndrome (PTS) development
  • High D-dimer values
  • Role of inherited thrombophilia (?)
  • Persistence of residual vein thrombosis at ultrasound
  • Male sex
  • Non-zero blood group
28
Q

PE diagnosis algorithm

A
  1. Wells score
  2. If >4: imaging (CTPA - pulmonary angiogram, VQ scan - ventilation-perfusion scan)
  3. If 4 or less: D-dimer (if positive –> imaging)
  4. Positive imaging: initiate anticoagulant
29
Q

[PE diagnosis]
Well’s score

A
  • Clinical symptoms of DVT (leg swelling, pain with palpation) [3]
  • Other diagnosis less likely than pulmonary embolism [3]
  • HR >100 [1.5]
  • Immobilization (>=3 days) or surgery in previous 4 weeks [1.5]
  • Previous DVT/PE [1.5]
  • Hemoptysis [1]
  • Malignancy [1]

High probability: >6
Mod probability: 2-6
Low probability: <2

=> PE likely >4
=> PE unlikely =<4

30
Q

[PE diagnosis]
Indicators of risk (high/intermediate/low)

A
  • Hemodynamic instability (look at BP - hypotensive, shock)
  • Clinical parameters of PE severity and/or comorbidity
  • RV dysfunction (congestion) on TTE or CTPA
  • Elevated cardiac troponin levels

=> Basically, require:
- TTE
- CTPA
- BP
- Cardiac troponin level

31
Q

[PE diagnosis]

Acute high risk PE
- Clinical manifestations

A

Haemodynamic instability:

  • Cardiac arrest (need for cardiopulmonary resuscitation)
  • Obstructive shock (systolic BP <90mmHg or vasopressors required AND end-organ hypoperfusion)
  • Persistent hypotension (systolic BP <90mmHg, or systolic BP drop >=40mmHg, lasting longer than 15min)

*rTPA and UFH indicated for high risk PE

32
Q

[PE treatment]

Acute high risk PE
- treatment

A
  • Recommended to use UFH (weight-adjusted bolus injection) as anticoagulant (because UFH has minimal renal excretion + short half-life, therefore easily reversible)
  • Recommended to start systemic thrombolytic (Alteplase) as high risk of mortality outweighs risks of bleeding
  • Recommend surgical pulmonary embolectomy or Percutaneous catheter-directed treatment can be considered for pt with high risk PE whom thrombolytic is contraindicated/failed
  • Supportive management such as fluid replacement, inotropes should be considered for hemodynamic instability
33
Q

[PE treatment]

Alteplase dosing and administration

A

Used for thrombolysis in PE/DVT/AIS

  • Dose by body weight
  • Via infusion
  • require follow up and monitoring for bleeding processes, BP control, critical to avoid hemorrhagic conversion

Compared to Tenecteplase - used in AMI, dosed by body weight via single IV bolus (easier dosing and administration)

34
Q

[PE treatment]

Intermediate-low risk PE
- treatment

A
  • Recommended to initiate parenteral LMWH/fondaparinux over UFH, OR, oral NOAC over VKA
  • If VKA used, need to overlap with LMWH till INR 2-3
  • NOAC not recommended if CrCl <30ml/min, pregnancy, lactation, antiphospholipid syndrome
  • VKA recommended in APS
  • Use of thrombolytic not recommended
35
Q

[PE treatment]

In the event pt needs to be switched from LMWH/DOAC to thrombolytic (due to deterioration while on the anticoagulant), what are the time intervals to take note?

A

LMWH to thrombolytics (should not be within 24h of LMWH administration)

DOAC to thrombolytic (hold DOAC 48h before thrombolytic administration)

36
Q

[PE treatment]

Contraindications to use of thrombolytics
- Absolute
- Relative

A

Absolute:

  • Hx of hemorrhagic stroke
  • Ischemic stroke in last 6m
  • CNS neoplasm
  • Major trauma/surgery/head injury in past 3w
  • Bleeding diathesis
  • Active bleeding

Relative:

  • TIA in past 6m
  • Oral anticoagulation
  • Pregnancy, first post-partum week
  • Non-compressible puncture sites
  • Traumatic resuscitation
  • Refractory HTN (SBP >180mmHg) - incr risk of hemorrhagic conversion
  • Advanced liver disease
  • Infective endocarditis
  • Active peptic ulcer
37
Q

[PE treatment]

Dose and Duration

Follow up monitoring

A

Similar to DVT treatment

Transient (first VTE with a major transient/reversible risk factor): 3 months

Chronic (recurrent VTE without major transient or reversible risk factor): extension beyond 3 months

Follow up:

  • Drug tolerance, adherence
  • Monitor hepatic and renal function
  • S&S of bleeding and recurrent VTE
38
Q

[DVT/PE in pregnancy]

  • Diagnosis
A
  1. Suspected PE during pregnancy
    High pretest probability OR intermediate-low probability and positive D-dimer result => commence anticoagulation with LMWH
  2. CXR to assess PE, and CUS to assess proximal DVT
  3. If proximal DVT not present, perform CTPA to evaluate PE
  4. If DVT or PE present => continue LMWH at therapeutic dose
39
Q

[DVT/PE in pregnancy]

  • Treatment agent
A

LMWH at therapeutic dose
- dosed by weight (subQ 1mg/kg q12h)

  • DO NOT use DOAC/Warfarin in pregnancy and lactation
40
Q

[DVT/PE in pregnancy]

  • Young females with hist of thrombosis and spontaneous abortions should be worked up for _____
  • Tx OAC choice for these patients?
A

Antiphospholipid syndrome (APS)

  • Determines anticoagulation choice post-partum
  • Cannot use warfarin/DOAC during pregnancy, use LMWH
  • Post-partum: switch back to VKA

3154 Haematology (14 decks)

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