ICU · Resuscitation
Venous thromboembolism prophylaxis in the ICU
Also known as DVT prophylaxis · VTE prevention · Pharmacological thromboprophylaxis · Intermittent pneumatic compression · ENOXACAN trial · ENDORSE study · Padua Prediction Score · PROTECT trial
ICU patients are among the highest-risk groups for venous thromboembolism (VTE) — immobility, inflammation, vascular injury (Virchow triad). ACCP-9 and ASH 2018 recommend pharmacological prophylaxis (LMWH, low-dose UFH or fondaparinux) for acutely/critically ill inpatients at acceptable bleeding risk, with mechanical prophylaxis (IPC or graduated stockings) when bleeding risk is high. Proven regimens: enoxaparin 40 mg SC daily (MEDENOX — VTE 5.5% vs 14.9% with placebo) and dalteparin 5000 IU SC daily vs UFH 5000 IU twice daily (PROTECT — no difference in proximal leg DVT, half the pulmonary emboli, fewer HIT events with dalteparin). Enoxaparin accumulates when creatinine clearance falls below 30 mL/min and requires dose reduction; dalteparin and tinzaparin do not accumulate at prophylactic doses. In confirmed HIT stop all heparin and use a non-heparin agent such as argatroban. Allow at least 12 hours after a low-dose LMWH injection (24 hours after intermediate-dose) before neuraxial puncture.
Checked against its sources on 14 Oct 2026
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- All ICU patients at acceptable bleeding risk should receive pharmacological VTE prophylaxis (ASH 2018 strong recommendation) — ENDORSE found only 39.5% of at-risk medical patients received it
- Renal impairment: enoxaparin accumulates below a creatinine clearance of 30 mL/min and requires dose reduction — dalteparin and tinzaparin show no accumulation at prophylactic doses
- HIT (heparin-induced thrombocytopenia): stop ALL heparin, switch to a non-heparin anticoagulant such as argatroban
- Neuraxial: allow at least 12 hours after a low-dose LMWH injection, and at least 24 hours after an intermediate-dose LMWH injection, before neuraxial puncture or catheter handling
- High bleeding risk is an indication for mechanical prophylaxis (IPC or stockings), not for omitting prophylaxis altogether
- Prophylactic anti-Xa goal range commonly cited as 0.2 to 0.4/0.5 IU/mL — levels over 0.5 IU/mL are associated with major bleeding
Meet the patient
An older man is intubated for severe community-acquired pneumonia. He has a BMI of 34, a previous DVT, an eGFR of 25, and a platelet count that has fallen sharply over four days of heparin exposure. The registrar has stopped the LMWH pending a 4Ts score and is asking what to give for thromboprophylaxis in the meantime.[1]
This is the question every ICU patient silently poses at admission: who gets the drug, who gets the sleeves, and who gets both? The ICU patient is high-risk by default — immobility, inflammation, and vascular injury (the Virchow triad) drive a 14.9 per cent VTE rate without prophylaxis in hospitalised medical patients (MEDENOX placebo arm). The bedside job is to prescribe prophylaxis for every patient, adjust for renal failure and weight, and switch to mechanical the moment bleeding risk intervenes.[12]
References28ShowHide
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