Heparin dosing and reversal, activated clotting time monitoring, and hemostasis management during cardiopulmonary bypass.
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- What anticoagulant is the standard of care for systemic anticoagulation before CPB?
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Unfractionated heparin- What is the typical initial heparin dose given before cannulation for routine adult CPB?
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About 300 to 400 units per kilogram of body weight- What test is used to confirm adequate anticoagulation before initiating CPB?
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Activated clotting time (ACT)- What is a commonly used minimum ACT threshold before initiating full CPB?
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Greater than 400 to 480 seconds, depending on institutional protocol- What mechanism does heparin use to produce its anticoagulant effect?
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It binds antithrombin and greatly accelerates antithrombin's inhibition of thrombin and factor Xa- What drug is used to pharmacologically reverse heparin after separation from CPB?
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Protamine sulfate- What is protamine's mechanism of reversing heparin?
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Protamine is positively charged and binds ionically to negatively charged heparin, forming an inactive complex- What is a commonly used protamine to heparin reversal dosing ratio?
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Approximately 1 mg of protamine per 100 units of heparin remaining, though institutional protocols vary- Name a serious adverse reaction that can occur with rapid protamine administration.
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Systemic hypotension from rapid administration, or a severe anaphylactoid reaction with cardiovascular collapse and pulmonary hypertension- Which patient population has an increased risk of protamine allergy?
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Patients with prior protamine exposure (such as prior cardiac surgery or protamine-containing insulin use) and those with fish allergy- What condition causes heparin resistance due to insufficient endogenous antithrombin?
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Antithrombin deficiency, which can be congenital or acquired (such as from prior heparin exposure or sepsis)- What product is used to treat heparin resistance from antithrombin deficiency?
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Fresh frozen plasma or recombinant/purified antithrombin concentrate- What condition is a heparin-induced antibody-mediated drop in platelet count with paradoxical thrombosis risk?
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Heparin-induced thrombocytopenia (HIT)- What anticoagulant alternatives are used for CPB in a patient with a history of HIT?
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Direct thrombin inhibitors such as bivalirudin, since they do not depend on heparin-antithrombin binding- Why is bivalirudin more difficult to manage on CPB than heparin?
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It has no direct pharmacologic reversal agent and is cleared partly by proteolysis, so stagnant blood in the circuit can clot
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