Heparin dosing and reversal, activated clotting time monitoring, and hemostasis management during cardiopulmonary bypass.
35 cards · basic cards · AI-written, checked twice. Edit anything.
- What anticoagulant is the standard of care for systemic anticoagulation before CPB?
- Unfractionated heparin
- What is the typical initial heparin dose given before cannulation for routine adult CPB?
- About 300 to 400 units per kilogram of body weight
- What test is used to confirm adequate anticoagulation before initiating CPB?
- Activated clotting time (ACT)
- What is a commonly used minimum ACT threshold before initiating full CPB?
- Greater than 400 to 480 seconds, depending on institutional protocol
- What mechanism does heparin use to produce its anticoagulant effect?
- 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?
- Protamine sulfate
- What is protamine's mechanism of reversing heparin?
- 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?
- 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.
- 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?
- 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?
- 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?
- Fresh frozen plasma or recombinant/purified antithrombin concentrate
- What condition is a heparin-induced antibody-mediated drop in platelet count with paradoxical thrombosis risk?
- Heparin-induced thrombocytopenia (HIT)
- What anticoagulant alternatives are used for CPB in a patient with a history of HIT?
- 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?
- 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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