CHBT Anticoagulation in Hemodialysis 1 — Questions and Answers
Question 1: Why is anticoagulation necessary during hemodialysis?
- Blood contact with the extracorporeal circuit activates the coagulation cascade, which would clot the dialyzer and tubing (Correct answer)
- Anticoagulation prevents the dialyzer membrane from rejecting blood cells
- It is required to maintain the patient's dry weight during treatment
- It prevents dialysate from entering the bloodstream through the membrane
Correct answer: Blood contact with the extracorporeal circuit activates the coagulation cascade, which would clot the dialyzer and tubing
The extracorporeal circuit (tubing, dialyzer) is a foreign surface that activates platelets and clotting factors. Without anticoagulation, the system would clot within minutes, terminating treatment and potentially causing blood loss.
The extracorporeal circuit (tubing, dialyzer) is a foreign surface that activates platelets and clotting factors. Without anticoagulation, the system would clot within minutes, terminating treatment and potentially causing blood loss.
Question 2: What is the most commonly used anticoagulant in hemodialysis?
- Unfractionated heparin (UFH) (Correct answer)
- Warfarin (Coumadin)
- Aspirin
- Rivaroxaban (Xarelto)
Correct answer: Unfractionated heparin (UFH)
Unfractionated heparin is the standard anticoagulant for hemodialysis. It acts rapidly, has a short half-life (1–2 hours), is reversible with protamine sulfate, and is cost-effective. It is administered as a bolus at initiation and continuous infusion during treatment.
Unfractionated heparin is the standard anticoagulant for hemodialysis. It acts rapidly, has a short half-life (1–2 hours), is reversible with protamine sulfate, and is cost-effective. It is administered as a bolus at initiation and continuous infusion during treatment.
Question 3: For a patient at high bleeding risk (e.g., post-surgery or active GI bleed), which hemodialysis anticoagulation approach is preferred?
- No-heparin (heparin-free) dialysis with frequent saline flushes to maintain circuit patency (Correct answer)
- Double the standard heparin dose to ensure the circuit does not clot
- Use warfarin systemically the night before dialysis instead of heparin
- Switch the patient to peritoneal dialysis permanently
Correct answer: No-heparin (heparin-free) dialysis with frequent saline flushes to maintain circuit patency
For high-bleeding-risk patients, heparin-free dialysis uses saline flushes (50–100 mL every 15–30 minutes) to rinse the circuit and prevent clotting without systemic anticoagulation. High blood flow rates also reduce clotting tendency.
For high-bleeding-risk patients, heparin-free dialysis uses saline flushes (50–100 mL every 15–30 minutes) to rinse the circuit and prevent clotting without systemic anticoagulation. High blood flow rates also reduce clotting tendency.
Question 4: What does ACT (Activated Clotting Time) measure in the context of hemodialysis anticoagulation monitoring?
- The time for whole blood to clot, used to assess the adequacy of heparin anticoagulation (Correct answer)
- The rate at which heparin is cleared from the patient's bloodstream
- The concentration of platelets in the post-filter blood sample
- The osmolarity of the dialysate adjusted for anticoagulant content
Correct answer: The time for whole blood to clot, used to assess the adequacy of heparin anticoagulation
ACT measures the time for whole blood to clot in the presence of an activating agent. Normal ACT is 90–130 seconds; therapeutic range during hemodialysis is typically 150–200 seconds. It guides heparin dose adjustments.
ACT measures the time for whole blood to clot in the presence of an activating agent. Normal ACT is 90–130 seconds; therapeutic range during hemodialysis is typically 150–200 seconds. It guides heparin dose adjustments.
Question 5: A patient on hemodialysis is known to have heparin-induced thrombocytopenia (HIT). Which anticoagulant is safe to use as an alternative?
- Argatroban or lepirudin (direct thrombin inhibitors) (Correct answer)
- Low-molecular-weight heparin (enoxaparin)
- Protamine sulfate
- Citrate only in peritoneal dialysis patients
Correct answer: Argatroban or lepirudin (direct thrombin inhibitors)
HIT is caused by antibodies against heparin-platelet factor 4 complexes. ALL heparin products (including LMWH) are contraindicated. Direct thrombin inhibitors like argatroban do not cross-react with HIT antibodies and are the safe alternative.
HIT is caused by antibodies against heparin-platelet factor 4 complexes. ALL heparin products (including LMWH) are contraindicated. Direct thrombin inhibitors like argatroban do not cross-react with HIT antibodies and are the safe alternative.
Question 6: What is the role of the priming step in anticoagulation preparation before connecting a patient to the hemodialysis circuit?
- Priming with heparinized saline coats the circuit surfaces, reducing thrombogenic activation when blood contacts the lines (Correct answer)
- Priming removes endotoxins from the dialyzer by flushing with heparinized saline
- Priming tests the blood pump speed before the patient is connected
- Priming equilibrates dialysate concentration within the dialyzer fiber bundle
Correct answer: Priming with heparinized saline coats the circuit surfaces, reducing thrombogenic activation when blood contacts the lines
Priming the extracorporeal circuit with heparinized saline pre-coats the tubing and dialyzer with heparin, reducing the thrombogenic surface. It also removes manufacturing residuals and trapped air from the circuit.
Priming the extracorporeal circuit with heparinized saline pre-coats the tubing and dialyzer with heparin, reducing the thrombogenic surface. It also removes manufacturing residuals and trapped air from the circuit.
CHBT Anticoagulation in Hemodialysis 1
Why is anticoagulation necessary during hemodialysis?