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EM - EBMedicine Summaries > DVT > Flashcards

DVT Flashcards

1
Q

What are the intrinsic risk factors for DVT? (7)

A

Hypercoagulability

(1) Antithrombin deficiency
(2) Protein C/S deficiency
(3) Factor V Leiden
(4) Prothrombin mutations
(5) Antiphospholipid Syndrome
(6) Homocysteinuria
(7) Nephrotic Syndrome

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2
Q

What are the extrinsic risk factors for DVT? (8)

A

(1) Immobilization > 48 hours / Flights > 8 hours
(2) Recent Hospitalization or Surgery
(3) Trauma
(4) Malignancy
(5) Pregnancy
(6) Exogenous Hormone Use
(7) Deterioration in general condition
(8) Prior DVT/PE ** one of strongest risk factors **

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3
Q

What is the mortality rate of DVTs?

A

Major complication of DVTs is PE and causes:

  • ~10% 1 month mortality rate in first time DVT
  • when treated decreases to < 6% mortality
  • ~20% 2 year mortality
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4
Q

What is the prevalence of DVT in patients suspected of having DVT?

A

Overall: 19%
Low risk for DVT: 5%
High risk for DVT: 51%

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5
Q

What is the differential DDx of DVT?

A

(1) Muscle Strain / Tear / Hematoma - 16%
(2) DVT - 13%
(3) Chronic Venous Insufficiency - 12%
(4) Cellulitis - 11%
(5) Superficial Thrombophlebitis 9%
(6) Lymphedema 5%
(7) Baker (popliteal) Cyst - 4%
(8) Other

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6
Q

Phlegmasia Cerulean Dolens

(1) What is it
(2) Treatment

A

(1) Complication of DVT with massive clot burden
- Sudden Onset
- Swelling
- Bluish discoloration
- possible loss of artial pulses
- possible gangrene/loss of limb
(2) Emergent consultation for thrombolysis/thrombectomy

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7
Q

Post-thrombotic Syndrome

(1) Prevalence
(2) What is it

A

Affects up to 50% of DVT patients

  • especially with recurrent ipsilateral DVT
    (2) Chronic symptoms
  • Venous insufficiency
  • Persistent pain/swelling
  • Skin discoloration
  • Varicose veins
  • possible non-healing ulcers
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8
Q

What is the Well’s Clinical Model for Pretest DVT Probability

A
  1. Active Cancer
    - Receiving treatment for cancer within 6 months or currently receiving palliative treatment
  2. Paralysis, Paresis, or Plaster immobilization of the lower extremity
  3. Recently bedridden for 3+ days or Major surgery within 12 week requiring general or regional anesthesia
  4. Localized tenderness along the distribution of the deep venous system
  5. Entire Leg Swollen
  6. Calf swelling >3cm larger than the asymptomatic side
    - measured 10cm below the tibial tuberosity
  7. Pitting edema isolated to the symptomatic side
  8. Collateral superficial veins (nonvaricose)
  9. Previously documented DVT
  10. Alternative Dx at least as likely as DVT
    - Subtract two points

…All Items get + 1point, except for item 10
…Low risk < 0 points - 5% prevalence
…Mod risk 1-2 points - 17% prevalence
…High risk > 3 points - 53% prevalence

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9
Q

What nonthrombotic conditions can increase d-dimer values? (7)

A

(1) Advanced Age
(2) Trauma
(3) Recent Surgery
(4) Infection
(5) Malignancy
(6) Pregnancy
(7) Stroke

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10
Q

What is the difference between high sensitivity and moderate sensitivity D-dimer tests?

A

High-sensitivity (e.g ELISA, latex agglutination)
- 93-94% sensitive

Moderate-Sensitivity (e.g. whole blood SimpliRED)

  • 83% sensitive
  • 71% specific (more specific than High-sensitivity)
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11
Q

How can the different sensitivity tests be used for ruling out DVT for different pretest probability patients?

A

Low-pretest probability for DVT
- Negative mod-sensitivity D-dimer sufficient to rule out DVT

Moderate pretest probability:
- Requires negative high-sensitivity D-dimer to rule out DVT

High pretest probability
- Neither moderate or high sensitivity D-dimer sufficient to rule out DVT

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12
Q

What are the limitations of whole leg ultrasound?

A

(1) Difficult to identify calf veins
(2) Increases time to perform study
(3) Increases number of technically limited studies
(4) Increases number of isolated calf DVTs that are needlessly treated with anticoagulation

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13
Q

What is the sensitivity and specificity of a Venous duplex ultrasonography of the proximal deep veins?

A
  1. 5% sensitive

94. 0% specific

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14
Q

What are the limitations of venous duplex ultrasonography of the proximal deep veins?

A

1) Limited views proximal to common femoral vein (e.g. iliacs)
(2) Inability to visualize femoral vein within adductor canal
(3) Nonimaging of the calf veins

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15
Q

What is the risk of propagation of distal vein DVTs?

A

Initially though to be as high as 25% at 1 week but later literature showed to be 1.3%

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16
Q

What is the sensitivity and specificity of venous duplex ultrasonography of the distal veins?

A

63.5% sensitive

94% specific

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17
Q

What is the sensitivity and specificity of POCUS of proximal veins done by EPs?

A

96.1% sensitivity

95% specific

18
Q

When do to MRI or CT for DVTs?

A

Do NOT perform routine CT venograms or MRIs for first time DVTs

CONSIDER if there are subtle findings on ultrasound or significant symptoms to suggest iliac DVT

19
Q

What are the three time periods of DVT treatment?

A

(1) Initial: 0-7 days
(2) Long term: 7 days to 3 months
(3) Extended: 3+ months

20
Q

What is considered the first line treatment options for DVT tx within the initial time period? Why?

A

LMWH or Fondaparinux (vs UFW)

(2)
Greater convenience
Adaptability to outpt setting
Lower rates of HIT

LMWH vs UFW

  • Less VTE recurrence
  • Less bleeding
  • Less death
21
Q

What should be the dosing of LMWH in the initial time period of DVT treatment?

A

2mg/kg QD (Grade 2C evidence vs 1mg/kg BID)

- No increase in bleeding, extension, or recurrence

22
Q

What is the CrCl that would limit LMWH or Fondaparinux use?

A

CrCl < 30 mL/min will cause accumulation of these medications

23
Q

What are the indications to empiric initiation of anticoagulation in the initial time period of DVT treatment?

A

Americal College of Chest Physician Recommendations:

(1) High-probability patients awaiting confirmatory studies
- Grade 2C

(2) Intermediate-probability patients when delays to diagnosis > 4 hours are expected
- Grade 2C

24
Q

What is the limitation for using dabigatran for long term DVT treatment?

A

Still requires parenteral anticoagulation to bridge

25
Q

What are the recommendations for the treatment of VTE in cancer patients? Why?

A

LMWH QD for 6 months.

2) Use of VKAs in cancer pt is linked with
- Recurrent VTE (12.9% v 6.7% in LMWH)
- Bleeding
- Variable responses to traditional VKA therapy

26
Q

What is the effect of using an IVC filter with anticoagulation vs anticoagulation alone?

A

Decreased rate of PE (15% vs 9%)
Increased rate of recurrent DVT (RR 1.5)

No effect on:
Development of post thrombotic syndrome
Death

27
Q

How does thromboylsis compare with anticoagulation alone?

A

More complete clot lysis at 1mo and 6 mo (RR 4.9, 2.7)
Dec. rates of post thrombotic rates (RR 0.64)

Has more bleeding (RR 2.23)

No change in PE
No change in recurrent DVT
No change in mortality within 1 month
No change in mortality within 6 years

28
Q

What are the current guideline recommendations for use of thrombolysis?

A
  1. Current iliofemoral DVT
  2. Symptom duration < 14 days
  3. Good functional status
  4. Life expectancy > 1 year
  5. Low risk of bleeding
  6. No other contraindications to thrombolysis
29
Q

What are the current guideline recommendations for use of thrombectomy?

A
  1. Current iliofemoral DVT
  2. Symptom duration < 7 days
  3. Good functional status
  4. Life expectancy > 1 year
  5. Readily available resources and expertise
30
Q

ACCP Guidelines for evaluation of reccurent DVT

A

Recommend one of 3 diagnositc workups:
(1) High sensitivity D-dimer, if positive then get proximal compression U/S

(2) Serial proximal compression u/s on day 1 and day 7
(3) Concurrent proximal compression ultrasound and D-dimer (either moderate or high); and if d-dimer is negative then no need for followup

31
Q

What about risk stratification for recurrent DVT?

A

Can use Modified Well’s DVT Criteria (+1 point for prior DVT)

If still low risk, then a negative d-dimer can safely rule out DVT than in an unstratified approach

Limitation: not yet validated

32
Q

Isolated Deep Distal Vein Thrombosis (IDDVT)

(1) What is it?
(2) Risk of IDDVT
(3) Resolution Rate
(4) Who gets them? What is the recurrence rate?
(5) ACCP recommendations for IDDVT?

A

(1) DVT isolated to deep calf veins (AT, PT, Peroneal) or to calf muscle veins

(2)
- Historically have propagation rates up to 25% in one week. Recent studies suggest ~8-16%
- 1.6% to 3.4% risk of PE
- Isolated muscle vein DVT only propagate 3% of time

(3) 90% resolve spontaneously without treatment
(4) Younger with transient provoking factors (surgery, hospitalization, recent surgery, trauma, or travel)
- 2.6% (vs 8.4% in proximal DVT patients)

(5) ONLY use serial imaging of the lower extremities for 2 two weeks, unless patient has severe symptoms or risk factors for extension

33
Q

What are the risk factors for extension of an IDDVT?

A
  1. Positive D-dimer
  2. Irreversible provoked status
    - including inpatient status and active cancer
  3. Severe Symptoms
  4. High Clot Burden
    >5cm in length
    >7mm in diameter
    Affecting multiple veins
34
Q

DVT in pregnancy

(1) Anatomic Differences
(2) Epidemiology of DVT
(3) ACOG recommendations for DVT in pregnancy

A

(1)

  • 80% of DVTs affect the LLE
  • 17% of DVTs may be isolated to the iliac vein
    (2)
  • Prevalence of confirmed DVT is lower than nonpregnant patients (9% vs 13%) [JS: a pregnant patient presenting for r/o DVT will be less likely to have it]
  • Pregnant patients are 4 times higher risk for having VTE
    (3)
  • NO D-dimer
  • Start with ultrasound
  • If negative then consider additional imaging vs serial ultrasounds
35
Q

When should you consider isolated iliac DVT?

A

Swelling of the entire leg, buttocks, or back

36
Q

What three clinical variables are highly predictive of DVT in pregnancy?

A

(1) Symptoms in the left leg
(2) Calf circumference difference > 2 cm
(3) First-trimester pregnancy

In this study, all confirmed DVTs had at least 1
Prevalence with 0: 0.8%
Prevalence with 3: 16.4%

37
Q

What is the treatment of choice for DVT in pregnancy? Duration of treatment? What about other drugs?

A

LMWH (dosed for pregnancy) until 6 weeks after delivery or minimum of 3 months

No VKAs (teratogenic)
No Novel oral anticoagulants (unstudied)
Fondaparinux only if severe reaction to heparin

38
Q

How do upper DVTs compare to lower DVTs:

(1) Prevalence
(2) Risk of PE
(3) Rate of Recurrence
(4) Risk of Post-thrombotic syndrome
(5) Causes

A

(1) Upper DVTs are only 15% of VTE cases
(2) Dec. risk of PE: 5% vs 15-32%
(3) Dec. risk of recurrence: 2-5% vs 19%
(4) Dec. risk of post-thrombotic syndrome: 5 vs 29%
(5)
- 20% are due to venous thoracic outlet obstruction (e.g anatomic causes) or effort-induced repetitive microstress of vessels
- 80% due to secondary etiology (eg. indwelling catheters, pacemaker wires, surgery, trauma)
- Typical LE DVT risk factors (e.g. age, malignancy) are less common etiology

39
Q

What is Paget-Schroetter Syndrome?

A

UE DVT as a result of effort-induced repetitive microstress of vessels

40
Q

What is the sensitivity and specificity of ultrasound for upper extremity DVT?

A

97% sensitive, 96% specific

Limited by inability to compress proximal central deep veins

41
Q

What to do about indwelling catheters associated with upper extremity DVT?

A

Leave the catheter in as long as they are needed and remain functional
- anticoagulation as long as catheter is in place

EM - EBMedicine Summaries (5 decks)

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