Venous Thromboembolism in the Surgical Patient: Prophylaxis and Treatment

Venous Thromboembolism in the Surgical Patient:

Prophylaxis and Treatment

Pamela HebbardAugust 11, 2005

Prophylaxis

Scenario 1

You are going through consent with a 60 y.o. F going for laparotomy for non-resolving SBO. What is the risk of VTE in the average general surgery patient without prophylaxis?– A. 10% DVT, 0.001% fatal PE– B. 5% DVT, 0.01% fatal PE– C. 25% DVT, 0.05% fatal PE– D. 50% DVT, 1% fatal PE

Incidence

In general surgery patients without prophylaxis:– 15 - 30% DVT– 0.2% - 0.9% fatal PE

Risk is higher with pelvic surgery, cancer surgeryOf all surgery orthopedic surgery carries the highest risk, at 50-60% DVT

Scenario 2

52 y.o. F going for R hemicolectomy for cecal cancer. What will you choose for VTE prophylaxis?– A. aspirin to start post-op– B. a low-dose heparin– C. mechanical compression device/stockings– D. warfarin to start post-op– E. some combination of the above

Methods of Prophylaxis

1. Aspirin• 20% risk reduction compared to placebo (5

trials)

2. Graded compression stockings• 44% risk reduction• Knee-length equally effective and easier to use

than thigh-length• Need to be fitted for them

Methods of Prophylaxis

3. Heparins• Low-molecular weight and unfractionated• ~70% risk reduction• Equally effective• Risk of bleeding related to dose (LMWH)

Methods of Prophylaxis

4. Intermittent pneumatic compression• 88% risk reduction• equally effective as heparin• Probably better than stockings• From small, older studies• Also need to be fitted and requires equipment

Methods of Prophylaxis

5. Warfarin• does have a risk reduction• Older studies, mostly orthopedics• Impractical

6. Heparin + mechanical method• Stockings + LDUH have been shown to

enhance protection from VTE by a further 75% (from 15% to 4%).

Scenario 3

You have chosen to use a heparin as VTE prophylaxis for your post-op patient with cecal ca. Exactly what order will you write?

• A. heparin 5000 u sc bid• B. heparin 5000 u sc tid• C. heparin 15000 u sc bid• D. heparin ACS/DVT protocol• E. enoxaparin 30mg sc bid• F. enoxaparin 40 mg sc od• G. enoxaparin 80 mg sc bid (1 mg/kg)• H. enoxaparin 120 mg sc od (1.5 mg/kg)

Heparin Dosing-Prophylaxis

Unfractionated heparin:– 5000 u bid/tid

Lovenox:– 30 mg sc bid– 40 mg sc od**

Scenario 4

Patient 1: 20 y.o. M - inguinal hernia repairPatient 2: 60 y.o. M - APR

What post-op orders will you write?• A. no heparin for either• B. heparin for both• C.1 - none, 2 - heparin• D.1 - heparin bid, 2 - heparin tid

Risk Stratification

Low - Risk• “Minor” surgery • <40 y.o• No additional risk factors

Recommendation• Early ambulation only

Risk Stratification

Moderate Risk– Minor surgery in patients with additional risk factors– Any surgery in pts aged 40-60 w/o additional risk

factors– Major surgery in patients <40 y.o w/o additional

risk factorsRecommendation

• Heparin 5000 bid• LMWH <= 3400 IU/day (Lovenox 30mg od)• May consider stockings if contraindication to heparin

Risk Stratification

High Risk• Multiple risk factors• age > 60 y.o.• Age 40-60 y.o. with an additional risk

Recommendation• Heparin 5000 tid• LMWH >3400 IU/day (Lovenox 40mg od or

more)

Risk Stratification

Very High Risk• Major surgery in >40 y.o. with: cancer, previous

VTE, or known hypercoagulable state• Major ortho surgery, elective neurosurgery,

multiple trauma, acute SCI

Recommendation• High risk heparin dosing + stockings/ IPC

Scenario 5

You are going to give your pt heparin prophylaxis for major abdominal surgery. When do you give the first does?

• A. 2 hrs pre-op• B. in recovery room• C. once up to the floor• D. after the epidural comes out

Timing

Optimal timing is 2 hrs pre-opDVT’s begin intra-operativelyTiming may need to be adjusted if neuraxial anesthesia is being used (no strict guidelines?)

Scenario 6

Consider again your patient with colon cancer. How long should you continue her VTE prophylaxis?

• A. until ambulating• B. 7 days• C. until discharge• D. 4 weeks• E. 6 months

Timing

For most patients, heparin until ambulating well is satisfactory.For high risk patients, heparin should continue for 7-10 days minimumAbdominal or pelvic surgery for cancer: 4 weeks of LMWH reduces the incidence of DVT compared to 1 week.

Treating DVT/PE

Scenario 7

Your post-op patient is noted to have a swollen firm left calf. U/S documents proximal DVT. What is your initial treatment?

• A. heparin 5000 u sc tid• B. heparin ACS/DVT protocol• C. enoxaparin 30mg sc bid• D. enoxaparin 80 mg sc bid (1 mg/kg)• E. enoxaparin 120 mg sc od (1.5 mg/kg)

Initial Treatment

Choice of heparin infusion or LMWH scBoth shown to be equally effective and safeSame treatment for DVT and PELMWH easier to administer, cheaper--assuming no contraindications

Initial Treatment

Start warfarin at same time as heparinContinue heparin for at least 5 days and INR 2-3Out-patient therapy is equally as safe as in-hospital treatment

Scenario 8

70 y.o. M post-op from Hartmann’s for diverticulitis. DVT post-op. PHx DM, HTN, CAD, and stroke. How long does he continue on warfarin?– A. 3 mo at INR 2-3– B. 6 mo at INR 2-3– C. 12 mo at INR 2-3– D. 6 mo at INR 2-3, then indefinitely at INR 1.5-2– E. Indefinitely at INR 2-3

Warfarin Therapy

First episode of DVT -- usually 6 monthsDVT due to transient risk factor (Surgery): 3 months of tx may be consideredPREVENT and ELATE have shown that indefinite treatment does decrease the risk of recurrence. They disagree on the necessary target INR.Long-term therapy needs to be balanced against the risk of bleeding.

Scenario 9

62 yo w/ recently diagnosed mucinous adenocarcinoma in the liver with no known primary. Presents with syncope, now normotensive, and found to have PE on CT. Treatment?

• A. Start LMWH and warfarin, continue warfarin indefinitely or until cure

• B. Start heparin drip and warfarin, continue warfarin indefinitely.

• C. LMWH indefinitely• D. LMWH for 6 months

VTE in Cancer Patients

LMWH is better than unfractionated heparin for cancer patients.Antithrombotic and antineoplastic effectsLMWH is better than warfarin for long-term tx in cancer patients (less fatal bleeding)

Scenario 10

You are called to see a post-op pt with a swollen leg. It is indeed swollen, tense and a deep red-purple colour. You note some skin necrosis. An U/S documents DVT. Treatment?– A. IV heparin– B. full-dose Lovenox– C. debride skin– D. thrombectomy

Surgery for DVT

Phlegmasia ceruluea dolens/ venous gangrene is an absolute indication for surgery.Femoral venotomyInterventional radiologyHigh incidence of post-phlebitic syndrome

Other Treatments

Thrombolytics• Controversial• Best evidence in unstable patient with PE• Indicated in massive ileofemoral thrombolysis

and low-risk to bleed

New medications• Fondaparinux• ximelagatran

IVC Filters

Protect against fatal PEIn general, for use in patients with contraindication to anticoagulationMay consider filter + anticoag is patient with severe cardiopulmonary dz where recurrent PE may be fatal.Information based on poor, older studiesRetrievable filters (new)

Further Info

ACCP Guidelines Chest, Sept 2004, Vol126, supp 3.

AJS 2005, 189:14-25.