Optimization of heparin anticoagulation for hemodialysis

Unfractionated heparin remains the most commonly used anticoagulant for extracorporeal therapies worldwide due to cost, years of clinical experience showing effectiveness and safety for outpatient hemodialysis. Most centers administer unfractionated heparin as an initial bolus followed by a constant infusion, which is then stopped prior to the end of the dialysis session. Although the anticoagulant effect of heparin can be monitored at the bedside, most centers take a pragmatic stance for routine outpatient hemodialysis, and adjust bolus doses and infusion rates based on visual inspection of the dialyzer header and venous air detector chamber for clots, and stop the heparin infusion based on the time taken for needle puncture sites to stop bleeding at the end of the hemodialysis session. Heparin is negatively charged and can bind to plasma proteins, leukocytes, and plastic. As such, it is important to achieve adequate mixing of heparin with blood to optimize anticoagulation within the extracorporeal circuit, by administering an intravenous bolus a few minutes prior to connecting the patient to the circuit and ensuring thorough mixing of the heparin infusion.