Effect of heparin modeling on delivered hemodialysis therapy

Heparin anticoagulation is standard practice in hemodialysis. To assess the effect of adequate heparinization on dialysis delivery, 28 chronic dialysis patients (mean age, 55 +/- 17 years; 18 men, 10 women) were selected for heparin modeling (HM). Polysulfone dialyzers were used. The dialysis prescription was kept unchanged, and an automated nonbleach reuse procedure was used. Measurements of time average concentration of urea (TACurea), KT/V delivered, normalized protein catabolic rate (nPCR), hematocrit, and dialyzer total blood compartment volumes [TBCVs] (fiber bundle volume [FBV] + header volume) were evaluated before and after heparin dosages were changed as indicated by HM. Heparin dosage increased from 2,400 +/- 841 IU to 4,398 +/- 3,112 IU (P < 0.002). While there was no significant change in nPCR (pre 0.84 +/- 0.34 v post 0.83 +/- 0.30), the effective clearance as measured by urea clearance improved from 212.8 +/- 37 to 240.1 +/- 49 mL/min (P < 0.05), KT/V remained unchanged, and TACurea decreased from 48.8 +/- 22.3 to 35.8 +/- 21.5 mg/dL (P < 0.05). Dialyzer TBCVs were unchanged (from 116 +/- 17 to 114 +/- 17 mL, NS). We conclude that the use of an appropriate dose of heparin during hemodialysis will improve polysulfone dialyzer clearance, increase the delivered KT/Vurea, and reduce TACurea. Heparin dosing should be given close attention because it does affect the dialysis dose delivered.