• Balazs Szamosfalvi, Stanley Frinak, and Jerry Yee.
• Division of Nephrology and Hypertension, Henry Ford Health System, Detroit, Mich., USA. bszamos1@hfhs.org
• Blood Purif. 2010 Jan 1;29(2):204-9.

BackgroundLarge-scale adoption of regional citrate anticoagulation (RCA) is prevented by risks of the technique as practiced traditionally. Safe RCA protocols with automated delivery on customized dialysis systems are needed.MethodsWe applied kinetic analysis of solute fluxes during RCA to design a protocol for sustained low-efficiency dialysis (SLED) for critically ill patients. We used a high-flux hemodialyzer, a zero-calcium (Ca) dialysate, a dialysis machine with online clearance and access recirculation monitoring, and a separate optical hematocrit (Hct) sensor. Flow rates were Q(B) = 200 ml/min for blood; Q(D) = 400 ml/min for dialysate, with Na = 140 mmol/l and HCO(3) = 32 mmol/l; Q(citrate) = 400 ml/h of acid citrate dextrose A; ultrafiltration as indicated. The Q(Ca) was infused into the return blood line, adjusted hourly based on online Hct and a <24-hour-old albumin level.ResultsUsing the SLED-RCA protocol in an anhepatic, ex vivo dialysis system, ionized Ca (iCa) was >1 mmol/l in the blood reservoir and <0.3 mmol/l in the blood circuit after citrate but before Ca infusion (Q(Ca)) with normal electrolyte composition of the blood returning to the reservoir. Clinically, SLED-RCA completely abrogated clotting, without adverse electrolyte effects. The Q(Ca) prediction algorithm maintained normal systemic iCa (0.95-1.4 mmol/l) in all patients. The high citrate extraction on the dialyzer prevented systemic citrate accumulation even in shock liver patients. Safety analysis shows that building a dialysis system for automated SLED-RCA is feasible.ConclusionUsing predictive Q(Ca) dosing and integrating control of the infusion pumps with the dialysis machine, SLED-RCA can be near-automated today to provide a user-friendly and safe system.Copyright (c) 2010 S. Karger AG, Basel.

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