Critical Care Medicine-Neurologic Disorders>>>>>Management Strategies (Coagulation, Vasoactive Medications)
Question 1#

A 67-year-old male patient had a non-ST elevation myocardial infarction and is currently on a heparin drip and requires coronary artery bypass grafting. His baseline activated coagulation time (ACT) is 189 seconds. He is 78 kg and received a total of 28 000 units of heparin (350 Units/kg). Three minutes later, a second ACT is drawn and repeat ACT is 286 seconds. Another 10 000 units of heparin is administered, and targeted ACT is still not achieved. You suspect heparin resistance.

What is NOT a predictor for heparin resistance?

A. Antithrombin activity level
B. Disseminated intravascular coagulation
C. Prior heparin therapy
D. Sepsis
E. Factor IIa level

Correct Answer is E

Comment:

Correct Answer: E

Heparin resistance is observed when large doses of heparin are required to achieve therapeutic prothrombin time (or ACT) despite an adequate heparin concentration. Some studies have shown that the incidence of heparin resistance before coronary revascularization is anywhere from 21% to 26%. Some of the predictors of heparin resistance include antithrombin activity level, platelet count, age, and prior heparin therapy. Many other clinical conditions are also associated with heparin resistance including sepsis, disseminated intravascular coagulation, liver disease, and elevated fibrinogen levels. On many occasions, a larger dose of heparin is sufficient to achieve adequate anticoagulation. If not, heparin resistance can be overcome by administering antithrombin 3, either by giving fresh frozen plasma or recombinant antithrombin 3.

Reference:

  1. Kaplan’s Cardiac Anesthesia. 7th ed. Elsevier; 2016.