Anticoagulation & Heparin Management Flashcards
7 cards from real CCP practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Anticoagulation & Heparin Management flashcards as text
A 70 kg patient requires CPB. The surgeon requests a target ACT of 480 seconds. After 21,000 units of heparin, the ACT is only 290 seconds. What is the most appropriate intervention?
Answer: Administer a concentrate of antithrombin III
When heparin resistance is suspected due to AT III deficiency, antithrombin III concentrate or FFP should be given to restore heparin sensitivity before initiating CPB.
Which of the following correctly describes the mechanism of unfractionated heparin's anticoagulant effect?
Answer: Catalytic acceleration of antithrombin III-mediated inhibition of factors IIa and Xa
Heparin binds antithrombin III and induces a conformational change that dramatically accelerates AT III inhibition of thrombin (IIa), factor Xa, and other serine proteases.
Low molecular weight heparins (LMWH) differ from unfractionated heparin (UFH) in that LMWHs preferentially inhibit:
Answer: Factor Xa more than IIa
LMWHs have an anti-Xa:anti-IIa ratio of approximately 2:1 to 4:1, compared to UFH's 1:1 ratio, due to their shorter chain length.
During a re-do sternotomy, the perfusionist notices the ACT machine is malfunctioning. Which alternative method can be used to assess anticoagulation status?
Answer: Anti-Xa heparin level assay
Anti-Xa heparin level assay can quantify heparin concentration independent of ACT machines and coagulation pathway variables.
What is the significance of the 'celite' versus 'kaolin' ACT activator in point-of-care testing during CPB?
Answer: Celite ACTs run longer than kaolin ACTs at the same heparin concentration
Celite-activated ACTs typically yield longer values than kaolin-activated ACTs at equivalent heparin concentrations, and celite ACTs are falsely prolonged by aprotinin.
A patient undergoing repeat cardiac surgery is found to have HIT antibodies from a prior exposure but currently has a platelet count of 280,000 and no active thrombosis. What is the appropriate anticoagulation strategy?
Answer: Use bivalirudin or argatroban as a heparin alternative
Active HIT antibodies (even with current thrombocytopenia absent) contraindicate heparin use; a direct thrombin inhibitor such as bivalirudin should be used instead.
Which clinical scenario would most likely require a higher-than-standard heparin dose to achieve adequate ACT for CPB?
Answer: A patient receiving preoperative unfractionated heparin infusion
Preoperative heparin infusion increases total heparin requirements due to partial AT III consumption and down-regulation, requiring higher doses to achieve target ACT.