Critical Care Medicine-Neurologic Disorders>>>>>Management Strategies (Coagulation, Vasoactive Medications)
Question 5#

You have decided to place a patient with a history of HIT on a bivalirudin infusion for anticoagulation.

Which laboratory value shown below should you be able to monitor?

A. Activated partial thromboplastin time (PTT)
B. Prothrombin time (PT)
C. Fibrinogen
D. Anti-Xa
E. Platelets

Correct Answer is A

Comment:

Correct Answer: A

Direct thrombin inhibitors act by inhibiting factor IIa (thrombin) independently of antithrombin 3 or cofactors. These anticoagulant drugs are useful in patients with HIT, but the lack of an antidote and a prolonged duration of action are barriers to the drugs being more widely used. Intravenous direct thrombin inhibitors include bivalrudin, desirudin, hirudin, and argatroban. Dabigatran is an oral direct thrombin inhibitor. Activated PTT is the laboratory method of choice for monitoring, which measures both intrinsic and common coagulation pathways. Of note, the presence of antiphospholipid antibodies can prolong aPTT.

References:

1. Di Nisio M, Middeldorp S, Büller HR. Direct thrombin inhibitors. N Engl J Med. 2005;353:1028.
2. Warkentin TE, Greinacher A, Koster A. Bivalirudin. Thromb Haemost. 2008;99:830.
3. Kaplan’s Cardiac Anesthesia. 7th ed. Elsevier; 2016.