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Background: For continuous renal replacement therapy in small infants, due to the large extracorporeal volume involved, blood priming can be necessary to prevent hypotension and hemodilution. Because packed red blood cells (RBCs) have high levels of potassium and citrate, closed-circuit dialysis is often performed. We assessed the metrics of closed-circuit dialysis and serial citrate concentration changes., Methods: We performed dialysis of closed circuits primed with expired human packed RBC solution and 5% albumin. Blood and dialysate flow rates were 70 and 33.3 mL/min, respectively. The extracorporeal volume was 70 mL. We measured pH, electrolytes, and citrate in the closed circuit every 3 min for 15 min. We also assessed the adequacy of closed-circuit dialysis using the formula: [dialysate flow rate (mL/min) × time of dialysis (min)]/extracorporeal volume (mL) and we assessed the correlation between citrate and ionized calcium concentrations., Results: To reach normal concentrations of sodium, potassium, and chloride, 2.4 times as much dialysate fluid as extracorporeal volume was needed. In contrast, for ionized calcium, bicarbonate, and citrate, 3.8 times as much dialysate fluid as extracorporeal volume was required. By simple linear regression analysis, the concentration of citrate was significantly correlated with that of ionized calcium., Conclusions: For closed-circuit dialysis using an RBC solution, the formula [dialysate flow rate (mL/min) × time of dialysis (min)]/extracorporeal volume (mL) would be a better parameter to estimate efficacy, compared with other metrics. Additionally, the citrate concentration can be readily estimated from the ionized calcium concentration during closed-circuit dialysis.

Background: Calcineurin inhibitors (CIs) with/without intravenous methylprednisolone pulse therapy (MPT) constitute the standard treatment for childhood-onset, steroid-resistant nephrotic syndrome (SRNS). However, some patients fail to achieve remission. We treated SRNS patients resistant to CIs and MPT with additional rituximab combined with MPT and immunosuppressive agents., Methods: Ten patients (aged 2-14 years) with CI- and MPT-resistant SRNS were enrolled. Patients were administered rituximab (1-4 doses; 375 mg/m(2)) followed by MPT (30 mg/kg/day of methylprednisolone for 3 consecutive days) once every 2-4 weeks until complete remission (CR). We analyzed clinical outcome and safety., Results: Six patients received a single dose of rituximab, 2 received two doses, and 2 received four doses. Seven patients achieved CR, 1 achieved partial remission, and 2 showed no response. Although 2 patients with no response progressed to end-stage renal failure, 7 patients with CR preserved normal renal function without proteinuria at the last observation. There were two serious adverse events., Conclusions: Additional rituximab combined with conventional MPT and immunosuppressive agents is a promising option for overcoming refractory SRNS. Aggressive B cell suppression by rituximab may ameliorate resistance to conventional treatments and a cocktail of other immunosuppressive agents, such as CIs, MMF, mizoribine, may be beneficial. However, as intense immunosuppression may cause serious adverse events, further evaluation is necessary.

Rituximab (RTX) has a significant steroid-sparing effect in children with steroid-dependent nephrotic syndrome (SDNS). However, patients are likely to relapse with the recovery of CD20+ cells. We conducted a small prospective cohort study with a historical control to evaluate the effect of RTX infusion followed by mycophenolate mofetil (MMF) as a maintenance therapy. Nine patients with SDNS who stopped their steroid treatment but were treated with MMF after RTX infusion were prospectively observed (group A). Seven patients with SDNS who discontinued steroid and immunosuppressive agents after RTX administration served as a control (group B). During the first year after the administration of RTX, six patients in group A and one patient in group B did not suffer a relapse (p < 0.05). The number of patients who relapsed during the 1 year preceding RTX treatment did not differ between the two groups [4.1 (A) vs. 5.7 (B)], but it was significantly lower in the MMF-treated group 1 year after the RTX treatment [0.4 (A) vs. 2.3 (B), p < 0.005]. The daily amount of prednisolone after the RTX treatment was lower in group A than in group B (0.11 vs. 0.46 mg/kg/day, respectively; p < 0.05). Three patients in group A and five patients in group B relapsed to SDNS and needed additional RTX treatment(s) within 1 year (odds ratio 5.0). Based on these results, we conclude that maintenance therapy with MMF after RTX is a good clinical option.