Anticoagulation in Hemodialysis Flashcards

What is the typical timing for 'heparin reversal' at the end of a hemodialysis session?

Answer: Heparin infusion is stopped 30–60 minutes before the end of treatment to allow clotting to normalize and reduce post-needle-removal bleeding

Stopping heparin 30–60 minutes before treatment ends (tight heparin protocol) allows the anticoagulant effect to diminish. This reduces post-cannulation site bleeding while maintaining adequate anticoagulation for most of the session.

Regional citrate anticoagulation is sometimes used in CRRT. What is the mechanism by which citrate prevents clotting?

Answer: Citrate chelates ionized calcium in the extracorporeal circuit, and calcium is essential for the coagulation cascade

Citrate binds (chelates) ionized calcium, which is required at multiple steps in the coagulation cascade. By reducing ionized calcium in the circuit to <0.35 mmol/L, clotting is prevented. Calcium is then replaced systemically via a separate infusion.

Which lab value should be monitored in a patient receiving continuous heparin anticoagulation during hemodialysis to detect over-anticoagulation?

Answer: Activated Partial Thromboplastin Time (aPTT) or Activated Clotting Time (ACT)

aPTT and ACT are the primary coagulation tests used to monitor heparin effect. Supratherapeutic values indicate over-anticoagulation and risk of bleeding. aPTT is used for systemic monitoring; ACT for point-of-care assessment during treatment.

What is the antidote for heparin overdose during hemodialysis?

Answer: Protamine sulfate, which binds heparin and neutralizes its anticoagulant effect

Protamine sulfate forms an ionic complex with heparin, neutralizing its anticoagulant activity. The dose is calculated based on the amount of heparin given. It can itself cause adverse reactions (bradycardia, hypotension) and must be given slowly.

Low-molecular-weight heparin (LMWH, e.g., enoxaparin) differs from unfractionated heparin in hemodialysis primarily because:

Answer: LMWH has a more predictable pharmacokinetic profile and longer half-life, allowing single-bolus dosing, but it is not reversible with protamine

LMWH can be given as a single pre-treatment bolus due to its predictable half-life. However, it is only partially reversible with protamine (approximately 60%) and accumulates in renal failure, making dose adjustment critical in dialysis patients.

When inspecting the dialyzer at the end of a hemodialysis session, what finding suggests inadequate anticoagulation?

Answer: Dark streaks or clots visible in the fiber bundle of the dialyzer

Visible clots (dark streaks or solid areas) in the dialyzer fiber bundle indicate thrombosis within the dialyzer. This reduces effective surface area and dialysis adequacy, suggesting anticoagulation was insufficient or the blood flow rate was too low.