Venous Thromboembolism Guidelines for Cardiac Surgery Patients

• Aims
• Background
• Risk Assessment
• Treatment/Management

Aims

Reducing the risk of venous thromboembolism (deep vein thrombosis and pulmonary embolism) in patients admitted to hospital for cardiac surgery

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Background

NICE clinical guideline 92; Venous thromboembolism: reducing the risk was issued in January 2010, updated June 2015 and replaced by NICE guideline NG89 Venous thromboembolism in over 16s: reducing the risk of hospital-acquired deep vein thrombosis or pulmonary embolism in March 2018

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Risk Assessment

Leeds Teaching Hospitals risk assessment tool is used to stratify the risk of VTE for each patient.

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Treatment / Management

Clinical algorithm

(see Treatment Pathway flow diagram document)

On admission to hospital all patients should be risk assessed and identified for risk of VTE and risk of bleeding using the Leeds Teaching Hospitals risk assessment tool. This should be completed electronically via PPM+.

VTE risk assessment should be repeated 24 - 48 hours after admission and whenever the patients clinical condition changes.

VTE Risk Factors

• Active cancer or cancer treatment
• Age over 60 years
• Pro-thrombotic state (eg dehydration, acute infection)
• Known thrombophilias
• Obesity (BMI >30kg/m²)
• One or more significant medical comorbidities (eg. heart disease; metabolic, endocrine or respiratory pathologies; acute infectious disease, inflammatory conditions)
• Personal history or first degree relative with a history of VTE
• Use of hormone replacement therapy
• Use of oestrogen containing contraceptive therapy
• Varicose veins with phlebitis
• Critical Care admission
• Total anaesthetic + surgical time > 90 minutes
• Significantly reduced mobility for 3 days or more

Consideration should be given to cease hormone replacement therapy or oestrogen containing contraceptives for 4 weeks prior to surgery, where possible, to reduce VTE risk.

Anti-Embolism Stockings (AES)

All patients should be fitted with anti-embolism stockings on admission and should continue to wear them until they are discharged (unless they are contraindicated).

On the Cardiac Intensive Care Unit on the first postoperative day, those patients with saphenous vein harvest should have their dressings removed, the wound inspected, and AES applied (unless contraindicated) before transfer from the unit. This link is to the Trust guideline on anti-embolic stockings including assessment of contra-indications and appropriateness

Low Molecular Weight Heparins (LMWH)

The LMWH of choice at Leeds Teaching Hospitals NHS Trust is enoxaparin.

All cardiac surgery patients should receive prophylactic LMWH (enoxaparin) within 14 hours of admission unless they have a risk factor for bleeding:

• Active bleeding
• Acquired bleeding disorders (such as acute liver failure)
• Concurrent use of anticoagulants eg. warfarin with therapeutic INR
• Thrombocytopenia (platelets < 75 x 10⁹ / L)
• Uncontrolled systolic hypertension (230/120mmHg or higher)
• Untreated inherited bleeding disorders eg. haemophilia
• Acute stroke

Prescribing guidelines

Complete the Leeds Teaching Hospitals VTE risk assessment tool for every patient admitted for cardiac surgery, then prescribe using the dosing chart below and round to the nearest measurable dose.

Enoxaparin Dosing for patients with creatinine clearance (CrCl) over 30mL/min

Enoxaparin Dosing for patients with creatinine clearance (CrCl) less than 30mL/min

Male: Creatinine Clearance = 1.23 x (140-age) x weight(kg) / Serum creatinine(micromoles/litre)

Female: Creatinine Clearance = 1.04 x (140-age) x weight(kg) / Serum creatinine(micromoles/litre)

Extended Prophylaxis

Patients prescribed LMWH should receive this until discharge.  The NICE recommendation to consider extending VTE prophylaxis to 7 days post-op is acknowledged and has been considered; however, the majority of patients discharged prior to 7 days post cardiac surgery are not thought to require extended VTE prophylaxis"

Discontinuing treatment

The VTE risk assessment should be repeated 24 - 48 hours after admission and whenever the clinical situation changes.

Treatment with LMWH should be discontinued:

1. if any of the above bleeding risks arise
2. when the patient has been fully mobile for >24 hours

Long-stay patients

Pre-operative should commence enoxaparin and AES as indicated if immobile; The last dose of enoxaparin should be given 12 hours prior to surgery

Patient Information

All patients should be given verbal and written information about their risk of VTE on admission, this should include what will happen, side effects and how they can help to reduce the risk. On discharge they should be given verbal and written information about the signs and symptoms of VTE and what to do should they occur, they should also be given instructions on how to use their thromboprophylaxis if required on discharge and how long it should continue for. Leaflet LN004075 contains this information and is available to order from the print unit

Information for Discharge

Notify the patient's GP if they have been discharged with pharmacological and/or mechanical VTE prophylaxis to be used at home

All heparins are porcine based

If patients do not want a porcine based product consider fondaparinux 2.5mg s/c once a day reduced to 1.5mg s/c once a day if CrCl 20-50ml/min) Contra-indicated if CrCl < 20ml/min. Do not use if the patient has a latex allergy.

Monitoring for Heparin-Induced Thrombocytopenia (HIT)

The risk of heparin-induced thrombocytopenia is higher in patients undergoing cardiac surgery.  The following monitoring is recommended:

• All patients started on any type of heparin should have a baseline platelet count performed
• For patients who have received heparin of any form in the previous 100 days a platelet count at 24 hours is advised
• For patients who have had cardiac bypass surgery, platelets should be monitored every 2-4 days from day 4-14 while they remain on any form of heparin
• All patients on unfractionated heparin require platelet counts every 2-4 days from day 4-14 of heparin therapy

If cardiac surgery patients are discharged from hospital on LMWH, the need for repeat platelet counts as above should be communicated on the eDAN for the GP to follow-up.

If HIT is suspected, please refer to the Guideline on Diagnosis and Management of HIT; this is based on national guidance from the British Committee for Standards in Haematology November 2012.

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