Pharmacology · patient case question
Which drug is administered during each dialysis session, and is the reason timing matters?
Patient case: Haemodialysis patient scheduling an extraction
Patient: Male, 66 years old
Chief Complaint: “This broken tooth needs to come out.”
Background: End-stage renal disease on haemodialysis every MONDAY and THURSDAY through a left forearm arteriovenous fistula. Type 2 diabetes, hypertension. Renal transplant workup under way.
Vital Signs: BP 148/86 mmHg (right arm) · HR 78 bpm · T 98.4°F
Findings: Non-restorable tooth #19. Generalized moderate periodontitis, xerostomia, enamel hypoplasia. No acute swelling.
Show answer and explanation
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.