Remember that Bleeding Associated with Direct Thrombin Inhibitors is not Correctable with Protamine, Fresh-Frozen Plasma, or Platelets
Michael B. Streiff MD
Thrombocytopenia is a common occurrence among hospitalized patients, particularly among patients in the intensive care unit (ICU). When a patient is diagnosed with, or suspected of having, heparin-induced thrombocytopenia (HIT) type 2, ICU caregivers should be familiar with a clear treatment plan. In addition to discontinuation of all heparin products, therapy for HIT may include alternative intravenous anticoagulants, specifically argatroban or lepirudin. It is important to understand alternatives for therapy and how to manage these and their potential complications.
Therapy for patients with HIT consists of the following:
Eliminate all exposure to heparin
Place a sign above the patient’s bed and on the chart indicating heparin allergy
Start a direct thrombin inhibitor (DTI)
Argatroban dosing (half-life 45 min, with normal hepatic function)
For ICU patients or patients with mild hepatic insufficiency (see Table 267.1), begin argatroban at 0.5 μcg/kg/min, and check the first activated partial throm-boplastin time (aPTT) in 4 h (target aPTT ratio 1.5 to 2.5)
Monitor aPTT every 4 h until two consecutive aPTT values are in the therapeutic range, then check aPTT 12 h later and, if still therapeutic, then at least daily
Dose adjustments (argatroban)
If argatroban is subtherapeutic, increase the infusion rate by 20% and recheck the aPTT in 4 h
If supratherapeutic, decrease the infusion rate by 50% and recheck the aPTT in 4 h
If aPTT ratio is >3.0, hold the infusion 30 min
If aPTT ratio is >4.0, hold 1 h before restarting at the lower rate
After any dose adjustment, more frequent aPTT testing is warranted (e.g., every 4 h until aPTT is therapeutic
for two consecutive tests, then 12 h later, then at least daily)
Special note: Argatroban also increases the ratio of prothrombin time to international normalized ratio (PT/INR); however, the aPTT should be used for dose adjustments (prolongation of the PT is an issue with warfarin cotherapy; see later comment)Related posts:
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Strongly Consider Low-Molecular-Weight Heparin in the Treatment of Unstable Angina and Non-ST-Elevation Myocardial Infarction
Consider use of Enoxaparin over Unfractionated Heparin in Trauma Patients
Remember that Activated Protein C is not as Useful for Sepsis as Once Hoped
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