Unfractionated heparin

Background

• Binds to and activates antithrombin which in turns inactivates factor Xa and thrombin
• Anticoagulation effect lasts up to 3hr after stopping infusion
• Must give IV (not subq) for acute thromboembolic disease
• Safe in pregnancy
• Unpredictable anticoagulation effect
  • Must monitor w/ PTT; therapeutic range is 1.5-2.5x normal value
• 33% of pts develop some form of bleeding complication; 2-6% develop major bleeding

Risk Factors for Major Bleeding Complication

1. Recent surgery or trauma
2. Renal failure
3. Alcoholism
4. Malignancy
5. Liver failure
6. Concurrent use of warfarin, fibrinolytics, steroids, or antiplatelet drugs

Treatment

1. See:
   1. DVT
   2. PE
   3. NSTEMI
   4. STEMI

Complications

1. Bleeding
   1. Treatment
      1. Managed according to clinical severity, NOT PTT value
         1. Heparin-associated bleeding is not always reflected by a supratherapeutic PTT
      2. Stop transfusion
      3. Observation alone may be appropriate in less severe cases
      4. Protamine
         1. Only indicated for major bleeding (0.2% of pts develop severe anaphylaxis)
         2. Give 1mg IV for every 100 units of UFH infused in the prior 3hr
         3. Give slowly over 1-3min; do not exceed 50mg in any 10 minute period
         4. Because half-life is short (7 min) may require second treatment
2. HIT
   1. See HIT (Heparin-Induced Thrombocytopenia)

See Also

• Low Molecular Weight Heparin

Source

Tintinalli