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

Publication: 01/08/2010  --
Last review: 28/11/2019  
Next review: 07/11/2022  
Clinical Guideline
ID: 2035 
Approved By: Trust Clinical Guidelines Group 
Copyright© Leeds Teaching Hospitals NHS Trust 2019  


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


Hospital - associated VTE leads to about 40,000 deaths in England per year, 25,000 of which may be preventable through proper risk management and care.
NICE clinical guideline NG89 Venous thromboembolism in over 16s: reducing the risk of hospital-acquired deep vein thrombosis or pulmonary embolism was issued in March 2018 and updated in August 2019. (1)


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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 on the online PPM + system (1). If electronic completion is not possible due to IT issues a paper risk assessment form should be completed. If thromboprophylaxis is indicated it should then be prescribed appropriately.

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.


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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 or >100kg is tinzaparin 4,500 units daily by subcutaneous injection. Other patients should receive a dose adjusted to their actual body weight.

Moderate (creatinine clearance (CrCl) 30-50mL/min) & mild renal impairment (CrCl 50-80mL/min):  Although no dosage adjustments are recommended for tinzaparin in patients with moderate renal or mild renal impairment. Careful clinical monitoring is advised.

Severe renal impairment (CrCl <30mL/min):

Tinzaparin is contra-indicated in patients with severe renal impairment. Enoxaparin is the recommended medicine in this patient population.


Dosage guide for low molecular weight heparins (LMWH).


Patients weight


Patient’s weight


Patients weight


> 100kg




Severe renal impairment CrCl <30ml/min


Normal to Moderate renal impairment (CrCl>30ml/min)                        and patients receiving CVVHD

Tinzaparin 2500units OD

Tinzaparin 4,500 units OD

 >100kg Tinzaparin

~ 50units/kg OD (dose banded -see eMEDs) 


<100kg        20 mg OD     100-150kg   40mg  OD >150kg        60mg OD



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 and at regularly periods afterwards.

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.

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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 2.0

Related information

Not supplied

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