Haemodialysis patient scheduling an extraction

Correct answer: C. Tuesday or Friday

• A. Treating IMMEDIATELY after a session is the wrong end of the window. Circulating heparin is still active, and the patient is hypovolaemic, hypotensive and fatigued from the fluid shift. Bleeding risk is at its highest.
• B. The interval two days after dialysis is workable but is not the optimum; the day immediately after the session is the established recommendation.
• C. CORRECT. Treat on the DAY AFTER dialysis. With Monday and Thursday sessions, that means TUESDAY or FRIDAY. By then the heparin has cleared — its half-life is short, so anticoagulation has resolved within a few hours — while fluid and electrolyte balance and blood pressure have stabilised, and uraemic toxins have not yet re-accumulated to the levels reached just before the next session.
• D. Treating just BEFORE a session means operating at peak uraemia, with the platelet dysfunction and bleeding tendency that uraemia produces, and with fluid overload and elevated blood pressure.

Note: Three further rules for the dialysis patient. NEVER take blood pressure or place a cannula in the arm carrying the FISTULA — use the contralateral arm. Adjust renally cleared drugs and AVOID NSAIDs entirely, since they are nephrotoxic and impair platelet function. Antibiotic prophylaxis is NOT routinely indicated for the fistula itself under current guidance, but a synthetic vascular GRAFT placed within the preceding six months, and any transplant patient on immunosuppression, warrant discussion with the nephrologist.

Correct answer: D. Heparin

• A. Aspirin irreversibly inhibits cyclo-oxygenase and is an antiplatelet taken orally. It is not the circuit anticoagulant.
• B. Clopidogrel blocks the platelet P2Y12 receptor and, like aspirin, is an oral antiplatelet rather than an intradialytic agent.
• C. Warfarin acts on the vitamin-K-dependent factors, is taken orally over days, and is not the intradialytic anticoagulant. Some dialysis patients take it for other indications, but that is separate.
• D. CORRECT. HEPARIN is given during dialysis to stop the blood clotting within the extracorporeal circuit. It acts by potentiating ANTITHROMBIN III, which inactivates thrombin and factor Xa, and it is monitored by the aPTT. Its clinical usefulness here lies in its short half-life — roughly one to two hours — which is precisely why waiting until the following day removes the added bleeding risk. Protamine sulfate is the reversal agent if one is ever needed.

Note: Uraemia impairs platelet FUNCTION independently of heparin, so bleeding time can be prolonged even with a normal platelet count. Have local haemostatic measures ready regardless of timing: oxidised cellulose or collagen in the socket, sutures, and tranexamic acid mouthwash.