What is the recommended duration of heparin therapy for Deep Vein Thrombosis (DVT) in the Intensive Care Unit (ICU)?

Duration of Heparin Therapy for DVT in the ICU

Heparin therapy for deep vein thrombosis (DVT) in the ICU should be administered for 5-7 days, overlapping with oral anticoagulant therapy until the INR is >2.0 for at least 24 hours. 1

Initial Anticoagulation Options

• Unfractionated heparin (UFH) should be administered as an initial bolus of 80 U/kg followed by a continuous intravenous infusion at 18 U/kg/hour, with dose adjustment to target a partial thromboplastin time corresponding to plasma heparin levels of 0.3-0.7 IU/mL anti-factor Xa activity 1
• Low-molecular-weight heparin (LMWH) can be administered subcutaneously without routine anti-factor Xa monitoring using one of these regimens:
  • Enoxaparin 1 mg/kg twice daily or 1.5 mg/kg once daily 1
  • Dalteparin 200 IU/kg once daily or 100 IU/kg twice daily 1
• Fondaparinux can be administered subcutaneously once daily based on weight:
  • <50 kg: 5 mg
  • 50-100 kg: 7.5 mg

  • 100 kg: 10 mg 1

Duration of Therapy

• Parenteral anticoagulation with heparin should be continued for a minimum of 5 days 1
• Heparin should overlap with oral anticoagulant therapy (typically warfarin) for a minimum of 5 days and until the INR is >2.0 for at least 24 hours 1
• After the initial heparin therapy period, the total duration of anticoagulation depends on risk factors:
  • For DVT secondary to transient risk factors (e.g., surgery): 3 months 1
  • For unprovoked or recurrent DVT: extended duration therapy (>12 months or indefinite) 1
  • For cancer-associated DVT: at least 3-6 months or as long as cancer or its treatment is ongoing 1

Considerations for ICU Patients

• LMWH is preferred over intravenous or subcutaneous UFH for acute lower extremity DVT with or without PE 1
• For patients with renal impairment (CrCl <30 mL/min), caution is advised with LMWH due to accumulation; consider UFH or adjusted LMWH dosing 1
• For patients with suspected or proven heparin-induced thrombocytopenia (HIT), use intravenous direct thrombin inhibitors (e.g., argatroban, lepirudin) 1
• In patients with high risk of HIT (≥1%), monitor platelet count every 2-3 days from day 4 to day 14 while receiving heparin 1

Transitioning to Long-term Anticoagulation

• Most adult patients with DVT should receive oral warfarin as first-line long-term anticoagulant therapy, targeted to an INR of 2.0-3.0 1
• For cancer patients with DVT, first-line therapy should be weight-based LMWH monotherapy for at least 3-6 months 1
• Direct oral anticoagulants (DOACs) are now preferred over vitamin K antagonists for non-cancer patients with DVT 2

Common Pitfalls to Avoid

• Inadequate duration of initial heparin therapy (less than 5 days) may lead to increased risk of recurrent venous thromboembolism 3
• Failure to achieve adequate anticoagulant response (APTT >1.5 times control) is associated with a high risk (25%) of recurrent venous thromboembolism 3
• Premature discontinuation of heparin before therapeutic INR is achieved with warfarin can increase risk of recurrence 1
• Not adjusting LMWH dosing for patients with renal impairment or extreme body weight 1

By following these evidence-based recommendations, clinicians can optimize the management of DVT in ICU patients, ensuring adequate initial anticoagulation while preparing for appropriate long-term therapy based on individual risk factors.