Guidelines for Venous Thromboembolism (VTE) Prophylaxis

Risk Classification

VTE is a major cause of morbidity and mortality among hospitalised patients.  Important clinical risk factors are summarised below and should be assessed in all patients prior to surgery or prolonged medical admissions.  All patients should receive non-pharmacologic ± pharmacologic prophylaxis, the intensity and type being dependent on the relative risks and benefits.  The relative risks of VTE and bleeding should be considered on an individual basis by the surgeon and anaesthetist.

Risk Factors for Venous Thromboembolism

Patient risk factors	Disease risk factors	Procedure risk factors
Age (> 40 yrs) Obesity Varicose Veins Immobility > 3 days Pregnancy Oestrogen Therapy Thrombophilia: ATIII, protein C, protein S or APC resistance Lupus anticoagulant / antiphospholipid syndrome Previous PE or DVT	Malignancy Pelvic / Leg Trauma Uncontrolled Heart Failure Paralysis of Legs Infection Nephrotic Syndrome Polycythaemia / Thrombocytosis Inflammatory Bowel Disease	General Anaesthetic Surgery > 30 minutes Pelvic / Leg Surgery

Risk Stratification of Surgical Patients and Risk of DVT

See guidelines for use of LMWH with spinal/epidural anaesthesia

Risk Group	Criteria	Risk of DVT no prophylaxis	Risk of PE no prophylaxis	PROPOSED ACTION
Low	Surgery < 30min duration with no other risk factors (see above) OR Surgery > 30min, age < 40yrs with no other risk factors	10%	0.01%	· Early mobilisation
Moderate	Surgery > 30min, age > 40yrs OR Surgery any age with risk factors (see above) or General Medical patients with clinical risk factors for VTE, particularly those with CHF or chest infections	10 – 40%	0.1 – 1%	Early  mobilisation  Graduated elastic compression stockings. Enoxaparin  20mg sc two hours pre operatively then daily for 7 days or until patient mobilises
High	· Major orthopaedic surgery of the lower limb · Major pelvic or abdominal surgery for cancer · Major surgery in patients with: · Previous DVT · Previous PE · Thrombophilia	40 – 80%	1 – 10%	· Early mobilisation and graduated elastic compression stockings · Enoxaparin  40mg sc two hours* pre operatively then daily for 7 days or until patient mobilises · CrCl < 30mL/min: Reduce enoxaparin dose to 20 mg sc two hours* pre operatively then daily for 7 days or until patient mobilises

* N.B. 12 hours pre-operatively in orthopaedic surgery. Best avoided pre-operatively if epidural is planned.

The relative risks of VTE and bleeding should be considered on an individual basis by the surgeon and anaesthetist:

Caution:      When VTE prophylaxis is considered appropriate, this must be discussed with the anaesthetist.

Elective patients who are candidates for VTE prophylaxis, should be seen by the pre admission anaesthetist.

Orthopaedic Surgery – Hip & Leg Surgery

The assessment of thrombotic risk and appropriate prophylaxis is controversial. Hip and leg surgery has been reported as being associated with a very high risk of venous thromboembolism. It has been recently strongly argued that (a) much of this is old data and does not reflect the results with current surgical and anaesthetic (spinal practice). (b) many of the thrombi are not clinically significant and (c) even minor bleeding can be a significant problem when prosthetic surgery is being undertaken. Pharmacological and mechanical prophylactic methods offer a similar risk reduction (about 50% as for general surgery).

Recommendations for All Major Limb Arthroplasty Procedures:

1. Antiembolic stockings, i.e. graduated elastic compression stockings

2. Regional anaesthesia

3. Early mobilisation

4. + Venous impulse foot pump

Recommendation for those with risk factors (see above)

High risk:

Enoxaparin 40 mg SC once daily CrCL < 0.5 mL / sec – Enoxaparin 20mg sc daily Commencing 12 hours pre-operatively (special considerations for epidurals, see guideline) Continue for 7-10 days or until patient mobilised

Medical Patients

Medical patients with one or more risk factors are considered a moderate risk.

Suggested VTE prophylaxis is enoxaparin 40mg sc every 24 hours. The MEDENOX study found the risk of proximal DVT was 4.5% with a 20mg dose and decreased to 1.7% with a 40 mg dose every 24 hours. The duration of prophylaxis is usually for 7 days or until the patient is mobilised.

Precautions with UFH and LMWH:

· Uncorrected bleeding disorder, active peptic ulcer or GI ulceration

· Advanced hepatic or renal failure, severe hypertension, endocarditis

· Surgery to brain, eye or spinal cord

· Hypersensitivity to heparins or heparin-induced thrombocytopenia