Venous Thromboembolism in the Surgical Patient: Prophylaxis and Treatment Pamela Hebbard August 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 surgery Of 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 30 mg 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 repair Patient 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 factors Recommendation • Heparin 5000 bid • LMWH <= 3400 IU/day (Lovenox 30 mg 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 40 mg 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-op DVT’s begin intra-operatively Timing 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 minimum Abdominal 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 30 mg 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 sc Both shown to be equally effective and safe Same treatment for DVT and PE LMWH easier to administer, cheaper-assuming no contraindications
Initial Treatment Start warfarin at same time as heparin Continue heparin for at least 5 days and INR 2 -3 Out-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 months DVT due to transient risk factor (Surgery): 3 months of tx may be considered PREVENT 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 effects LMWH is better than warfarin for longterm 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 venotomy Interventional radiology High 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 PE In general, for use in patients with contraindication to anticoagulation May consider filter + anticoag is patient with severe cardiopulmonary dz where recurrent PE may be fatal. Information based on poor, older studies Retrievable filters (new)
Further Info ACCP Guidelines Chest, Sept 2004, Vol 126, supp 3. AJS 2005, 189: 14 -25.
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