CCP Anticoagulation & Heparin Management 2 — Questions and Answers
Question 1: A patient on CPB has an ACT of 380 seconds after the initial heparin dose. What is the most appropriate action?
- Administer protamine immediately
- Administer an additional heparin bolus
- Proceed with CPB as the ACT is adequate (Correct answer)
- Add aprotinin to the circuit
Correct answer: Proceed with CPB as the ACT is adequate
An ACT of 380 seconds is above the minimum threshold of 300–400 seconds required for safe CPB, so the perfusionist may proceed.
Question 2: Which of the following conditions is most likely to cause heparin resistance during cardiac surgery?
- Thrombocytopenia
- Antithrombin III deficiency (Correct answer)
- Factor V Leiden mutation
- Protein C deficiency
Correct answer: Antithrombin III deficiency
Antithrombin III (AT III) deficiency reduces the effectiveness of heparin because heparin exerts its anticoagulant effect by binding to and activating AT III.
Question 3: Fresh frozen plasma (FFP) is administered intraoperatively to a patient with heparin resistance. What is the primary mechanism by which FFP restores heparin responsiveness?
- Provides clotting factors II and V
- Replenishes antithrombin III levels (Correct answer)
- Neutralizes circulating heparin
- Inhibits platelet aggregation
Correct answer: Replenishes antithrombin III levels
FFP contains antithrombin III, restoring the necessary cofactor so that heparin can exert its anticoagulant effect.
Question 4: During CPB, the ACT suddenly drops from 500 to 320 seconds without any change in the patient's condition. What is the most likely cause?
- Protamine contamination of the circuit (Correct answer)
- Heparin metabolism and elimination
- Hypothermia-induced ACT prolongation reversal
- Hemodilution from cardioplegia delivery
Correct answer: Protamine contamination of the circuit
Protamine contamination of the CPB circuit or priming solution can neutralize circulating heparin, causing an unexpected drop in ACT.
Question 5: What is the recommended initial heparin dose for systemic anticoagulation before cannulation for CPB?
- 100 units/kg
- 150 units/kg
- 300 units/kg (Correct answer)
- 500 units/kg
Correct answer: 300 units/kg
The standard initial heparin dose for CPB anticoagulation is 300 units/kg to achieve an ACT greater than 400–480 seconds.
Question 6: A patient's ACT rises excessively to 800 seconds on CPB without additional heparin administration. Which explanation is most likely?
- Heparin rebound from depot sites
- Hypothermia prolonging the ACT (Correct answer)
- Antithrombin III excess
- Factor Xa inhibitor contamination
Correct answer: Hypothermia prolonging the ACT
Hypothermia significantly prolongs the ACT independent of heparin concentration by slowing enzymatic coagulation reactions.
Question 7: Which heparin monitoring method measures anti-Xa activity rather than clot formation time?
- Activated clotting time (ACT)
- Activated partial thromboplastin time (aPTT)
- Heparin protamine titration (HPT) (Correct answer)
- Thromboelastography (TEG)
Correct answer: Heparin protamine titration (HPT)
Heparin-protamine titration (HPT) quantifies actual heparin concentration by measuring anti-Xa activity, independent of temperature and AT III levels.
CCP Anticoagulation & Heparin Management 2
A patient on CPB has an ACT of 380 seconds after the initial heparin dose.
What is the most appropriate action?