Fig. 2

Circuit set up at University of California San Diego, Medical Center. The mean infusion rate of tri-sodium citrate was 180 ml/h and blood flow rate (Qb) was set at 100 ml/min. Tri-sodium citrate was added at the arterial catheter port with ionized calcium levels been measured post-filter. Post-filter ionized calcium levels were used to adjust tri-sodium citrate flow rates. Pre-filter BUN value was measured after the infusion of tri-sodium citrate and after pre-dilution replacement fluid (Qr), thus accounting for the pre-dilutional effect. A fixed ultrafiltration rate (Quf) was used (set at 1000 ml/h) for achieving fluid balance. A target effluent volume was adjusted by hourly modifying substitution fluid rate (Qs) to achieve a negative, zero, or positive fluid balance. Qb, blood flow rate; Qd, dialysate flow rate; Qr, replacement fluid rate; Quf, total ultrafiltration rate; Qnet, net fluid removal rate