Thromboprophylaxis Guideline for Critically Ill Adult Patients ( excludes patients on planned critical care pathways )

Publication: 01/08/2010  
Next review: 10/08/2024  
Clinical Guideline
ID: 2035 
Approved By: Trust Clinical Guidelines Group 
Copyright© Leeds Teaching Hospitals NHS Trust 2021  


This Clinical Guideline is intended for use by healthcare professionals within Leeds unless otherwise stated.
For healthcare professionals in other trusts, please ensure that you consult relevant local and national guidance.

Thromboprophylaxis Guideline for Critically Ill Adult Patients
(excludes patients on planned critical care pathways)

Word version


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


Back to top

Risk Assessment

All patients aged 16 years and over admitted to critical care unit require a VTE risk assessment and a review of bleeding risk within 24hours of admission. This assessment should be completed via PPM+. If thromboprophylaxis is indicated it should then be prescribed and administered within 14 hours of admission.

The VTE and bleeding risk for people in critical care units should be reassessed daily or more often if the person’s condition is changing rapidly (1).

Falls risk: If the patient is at risk of falls consider their risk and VTE risk. Document any decisions regarding prophylaxis and fall risk. Ensure this is regularly reviewed by the multidisciplinary team.


Back to top

Treatment / Management

This guideline excludes patients on a planned pathway through critical care e.g. elective cardiac surgery, liver transplant, elective gastrointestinal surgery etc. for which there are separate guidelines to follow. See Leeds Health Pathways.


  • Low Molecular Weight Heparin (LMWH) should be prescribed to all people admitted to the critical care unit except when pharmacological VTE prophylaxis is contraindicated (1). Always consider the relative risk of thrombosis compared to that for bleeding.
  • The dosage of LMWH should be individualised according to actual body weight, renal function, and use of renal replacement therapy e.g. CVVHD. See details below.
  • All critically ill patients will be started on mechanical VTE prophylaxis such as intermittent pneumatic compression (IPC) devices e.g. Flowtrons. These should be started at admission unless a contraindication exists to their use. Each patient should be reassessed daily until they no longer have reduced mobility relative to their normal or anticipated mobility (1).
  • If there are no contraindications all patients will receive both mechanical and pharmacological thromboprophylaxis.

Contraindications to mechanical VTE prophylaxis devices

  • Severe arteriosclerosis or other ischemic vascular diseases.
  • Severe congestive cardiac failure or any condition where an increase of fluid to the heart may be detrimental.
  • Known or suspected acute DVT, thrombophlebitis or Pulmonary Embolism (PE).
  • Any local condition that the device or garment could disturb, including: gangrene, a recent skin graft, dermatitis or untreated, infected leg wounds.

Contraindications to pharmacological thromboprophylaxis


  • Coagulopathy INR > 2.0.        (or an INR >2.5 for patients with chronic liver disease)
  • Platelet count <75 x 109/L.     (or platelets <50 x 109/L for patients with chronic liver disease, or liver transplant)
  • Active bleeding.
  • Ischaemic or haemorrhagic stroke - discuss with neurology/stroke team.
  • Traumatic Brain Injury <72hrs - discuss with neurosurgical team.
  • Use with caution in patients with a recent (within 3 months) history of GI bleeding.
    • Patients already receiving systemic anticoagulation. This may include some modalities of renal replacement therapy but not continuous haemodialysis using citrate anticoagulation.


Pharmacological thromboprophylaxis

Low Molecular Weight Heparin

The standard treatment for high risk patients weighing 50kg - 100kg is enoxaparin 40mg daily by subcutaneous injection. Other patients should receive a dose adjusted to their actual body weight, see dosing charts below.

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


Dose of Enoxaparin


20mg daily

50 - 100kg

40mg daily

101 - 150kg

40mg twice daily


60mg twice daily

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


Dose of Enoxaparin


20mg daily with caution - consider Factor Xa levels

50 - 100kg

20mg OD daily

101 - 150kg

40mg OD daily


60mg OD daily

Allergy to heparins

If heparins cannot be used alternatives such as Fondaparinux or Danaparoid are available - See below for fondaparinux dosage information. The dosage of danaparoid should be discussed with a haematologist.

Heparin Induced Thrombocytopenia (HIT)

All patients started on any type of heparin should have a baseline platelet count performed, and if the received heparin of any form in the previous 100 days a further platelet count at 24 hours is advised.

If thrombocytopenia occurs and HIT is suspected please refer to the LTH Guideline on The Management of Heparin Induced Thrombocytopenia and Thrombosis

All heparins are porcine (pork) derived.

If a patient does 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). This is contra-indicated if CrCl < 20ml/min.

Patients on anti-platelets: Review bleeding risk and VTE risk. Patients with an increased VTE risk but low bleeding risk should be offered thromboprophylaxis in addition to anti-platelets. Patients with an increased VTE risk but high bleeding risk should be reviewed by a senior doctor regularly.

Patients on warfarin. If the INR is below the target range documented for the warfarin therapy, consider prophylactic or treatment dose LMWH depending on reason for anticoagulation. Recent DVT/PE/stroke history, presence of metal mechanical valve etc. should warrant the prescribing of treatment dose LMWH. Ensure the INR and activity is monitored regularly and stop LMWH once target INR in range.

Patients on Direct Oral Anticoagulants (DOACs).  E.g. apixaban, dabigatran, edoxaban, rivaroxaban, should only receive pharmacological prophylaxis with LMWH when they are unable to receive their usual DOAC therapy.

Back to top


Record: 2035
Clinical condition:

Critical care

Target patient group: Adults
Target professional group(s): Secondary Care Doctors
Adapted from:

Evidence base

  1. National Institute of Health and Care Excellence. Venous thromboembolism in over 16s: reducing the risk of hospital-acquired deep vein thrombosis or pulmonary embolism. Updated August 2019.

Approved By

Trust Clinical Guidelines Group

Document history

LHP version 3.0

Related information

Not supplied

Equity and Diversity

The Leeds Teaching Hospitals NHS Trust is committed to ensuring that the way that we provide services and the way we recruit and treat staff reflects individual needs, promotes equality and does not discriminate unfairly against any particular individual or group.