DVT PROPHYLAXIS

Predisposing Factors The most common risk factors are recent surgery or hospitalization

Advanced age

Obesity

Infection

Immobilization

Oetrogen-containing forms of hormonal contraception

Tobacco usage

Air travel ("economy class syndrome", a combination of immobility and relative dehydration)

Thrombophilia

VTE Common Complication of Hospital Stay

~70% of all VTE is hospital-acquired

One of the most common complications

Commonest preventable cause of hospital

death

Doubles length of stay and cost

VTE COMPLICATIONS: Important cause of Mortality and Morbidity

Immediate/Early: Pulmonary Embolism

Late: Post- thrombotic Syndrome

Rationale for ThromboprophylaxisHigh prevalence of VTE in most

hospitalized patient groups

Adverse consequences of unprevented VTE

Effectiveness and cost-effectiveness of thromboprophylaxis

PREVENTION STRATEGIES: The Options

 Anticoagulants

Graduated compression stockings (also known as thromboembolic deterrent stockings)

Intermittent pneumatic compression (IPC) devices

Vena Cava Filter

EVIDENCEThromboprophylaxis is the

number 1 ranked patient safety strategy in hospitalized patients

More than 25 published evidence-based guidelines since 1986 show clear evidence of benefit and safety.

IN HOSPITALIZED PATIENTS

American College of Chest Physicians

"In acutely ill medical patients who have been admitted to the hospital with congestive heart failure or severe respiratory disease, or who are confined to bed and have one or more additional risk factors, including active cancer, previous VTE, sepsis, acute neurologic disease, or inflammatory bowel disease, we recommend prophylaxis with low-dose unfractionated heparin-LDUH or LMWH."

LMWH may be more effective than unfractionated heparin (UFH).

If UFH is used, 5000 U 3 times daily may be more effective.

KEY RECOMMENDATIONSModerate-risk general surgery

patients: low-dose unfractionated heparin (LDUH) (5,000 U bid) or low-molecular-weight heparin (LMWH) [≤ 3,400 U once daily]

Higher risk general surgery patients, we recommend thromboprophylaxis with LDUH (5,000 U tid) or LMWH (> 3,400 U daily)

High-risk: combination of pharmacologic methods (LDUH three times daily or LMWH, > 3,400 U daily) with the use of graduated compression stockings and/or intermittent pneumatic compression devices

Major gynecologic surgery or major, open urologic procedures- prophylaxis with LDUH two times or three times daily 

For patients undergoing elective total hip or knee arthroplasty: LMWH, Fondaparinux, or adjusted-dose vitamin K antagonist (VKA) [ (INR) target, 2.5; range, 2.0 to 3.0] (for 10 days)

Hip fracture surgery (HFS): routine use of fondaparinux, LMWH, VKA (target INR, 2.5; range, 2.0 to 3.0) or LDUH. (For 10 days)

All patients should receive VTE prophylaxis within 24 hours of hospital admission or surgery end time (or have documentation why no prophylaxis was given).

Stockings ?In stroke patients: thigh-length stockings

are more effective than knee stockings according to the nonblinded CLOTS 2 randomized controlled trial while thigh-length stockings were not better than no stockings in the CLOTS 1 nonblinded randomized controlled trial.

It is not clear why these two trials conflict.

IN RENAL IMPAIRMENT

Since enoxaparin is entirely excreted by the kidneys, the manufacturers warn against its use in patients with renal insufficiency

Retrospective cohort study, Thorevska et al 2004: overall, the frequency of bleeding increased with worsening renal insufficiency, irrespective of the agent used. However minor bleeding greater with Enoxaparin in patients with severe insufficiency.

Dosing in Renal PatientsDecreased dose is recommended in

renal failure or ESRD patients

For DVT prophylaxis in a patient with GFR < 30, a dose of 30 mg daily is recommended

For DVT prophylaxis in a patient with GFR > 30, full dose (40 mg daily) can be given

IN THE ELDERLY

CERTIFY STUDY: LMWH vs. UFH in Elderly

The analysis confirmed the increased thromboembolic risk in very elderly patients, but demonstrated no increased bleeding risk.

Certoparin and UFH were equally effective and safe with a reduced risk of minor bleeding complications with certoparin in the very elderly.

Journal Geriatric Cardiology 2011

High prevalence of predisposing co-morbidities and acute illnesses in elderly- prophylaxis often delayed for those reasons.

A simple way to overcome this problem is to implement universal VTE prophylaxis for all hospitalized elderly patients instead of selective prophylaxis for some patients only according to individual’s risk of VTE.

Although pharmacological VTE prophylaxis is effective for most patients, a high prevalence of renal impairment

and drug interactions in the hospitalized elderly patients suggests that a multimodality approach may be more appropriate.

MUST (Multimodality Universal STat) strategy: Mechanical VTE prophylaxis, including calf and thigh compression devices

A NOTE ABOUT HEPARIN INDUCED THROMBOCYTOPENIA

HITAcquired, transient, adverse drug

reaction characterized by thrombocytopenia (relative 30-50% drop from baseline) and hypercoagulability.

Caused by heparin-dependent, platelet-activating antibodies that recognize a "self" protein, platelet factor 4 (PF4), bound to heparin. The resulting platelet activation is associated with increased thrombin generation.

HITCan occur early or late

There have been cases which presented with normal platelet counts

Any patient with recent exposure to any type of Heparin (UFH or LMWH) and with either, significant reductions in platelet counts, or thrombosis should be considered for HIT.

RisksFemale

Elderly patients undergoing post-surgical prophylaxis or treatment for deep venous thrombosis, orthopaedic and cardiovascular surgery.

More common with UFH than LMWH- controvercial

Two Clinical Forms

4T scoring system

FACTORS COMPLICATING DIAGNOSIS OF HIT

MANAGEMENT PRINCIPLES Discontinue and avoid all heparin.

Give a non-heparin alternative anticoagulant.

Postpone Warfarin pending substantial platelet count recovery (give vitamin K if Warfarin has already been started)

Test for HIT antibodies.

Investigate for lower-limb deep-vein thrombosis.

Avoid prophylactic platelet transfusions.

ALTERNATE ANTICOAGULATION

Without any form of alternate anticoagulation, >50% of patients can develop thrombosis over the next few days to weeks

Direct thrombin inhibitors such as Argatroban and Lepirudin (renally cleared and antibody formation has been shown to occur).

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