The beneficial influence on the effectiveness of automated peritoneal dialysis of varying the dwell time (short/long) and fill volume (small/large): a randomized controlled trial.

BACKGROUND: It is well known that the efficiency of peritoneal dialysis (PD) varies with the duration of the dwell and with the prescribed fill volume. Automated PD (APD) is classically given as a series of recurrent exchanges, each having the same dwell time and fill volume-that is, conventional APD (APD-C). We propose a new way of giving PD, using a modified version of APD-C. This method first uses a short dwell time with a small fill volume to promote ultrafiltration (UF) and subsequently uses a longer dwell time and a larger fill volume to promote removal of uremic toxins from the blood. We use the term "adapted APD" (APD-A) to describe this modified form of PD. METHODS: We designed a multicenter prospective randomized crossover trial to assess the impact of APD-A in comparison with APD-C on the efficacy of dialysis. The parameters investigated were overnight UF; weekly peritoneal Kt/V(urea); weekly peritoneal creatinine clearance corrected to 1.73 m(2) body surface area (K(creat)); and phosphate (PDR) and sodium dialytic removal (SDR) in millimoles per session, corrected for glucose absorption, which provides an estimate of metabolic cost. Blood pressure was also regularly monitored. Initially, 25 patients were identified for inclusion in the study. There were 6 withdrawals in total: 2 at enrolment, 1 at day 75 (transplantation), 2 at day 30 (catheter dysfunction), and 1 for drainage alarms. All patients received the same duration of overnight APD, using the same total volume of dialysate, with the same 1.5% glucose, lactate-buffered dialysate (Balance: Fresenius Medical Care, Bad Homburg, Germany). RESULTS: Tolerance was good. Compared with APD-C, APD-A resulted in a significant enhancement of Kt/V(urea), K(creat), and PDR. The metabolic cost, in terms of glucose absorption, required to achieve dialytic capacity for urea, creatinine, and phosphate blood purification was significantly lower for APD-A than for APD-C, and UF increased during APD-A. With APD-A, each gram of glucose absorbed contributed to 18.25 ± 15.82 mL UF; in APD-C, each gram of glucose absorbed contributed to 15.79 ± 11.24 mL UF. However, that difference was not found to be significant (p=0.1218). The SDR was significantly higher with APD-A than with APD-C: 35.23 ± 52.00 mmol and 18.35 ± 48.68 mmol per session respectively (p<0.01). The mean blood pressure recorded at the end of each PD period (on day 45) was significantly lower when patients received APD-A than when they received APD-C. CONCLUSIONS: Our study provides evidence that, compared with the uniform dwell times and fill volumes used throughout an APD-C dialysis session, the varying dwell times and fill volumes as described for an APD-A dialysis session result in improved dialysis efficiency in terms of UF, Kt/V(urea), K(creat), PDR, and SDR. Those results were achieved without incurring any extra financial costs and with a reduction in the metabolic cost (assessed using glucose absorption).

Improved in vitro biocompatibility of bicarbonate-buffered peritoneal dialysis fluid.

BACKGROUND: Conventional peritoneal dialysis fluids (PDFs) have been shown to damage the mesothelial layer and are associated with the development of peritoneal fibrosis and neoangiogenesis. New-generation PDFs have therefore been developed with physiological pH and reduced levels of glucose degradation products (GDPs), precursors of advanced glycation end products (AGEs). In this work, we evaluated and compared the improved biocompatibility of two new-generation PDFs (Balance and bicaVera) using mesothelial cell biology; we also compared them to a standard PDF (stay.safe) (all PDFs by Fresenius Medical Care, Fresnes, France). METHODS: stay.safe, Balance, and bicaVera were tested for their effect on human peritoneal mesothelial cell (HPMC) viability by measuring cell proliferation and apoptosis, and oncosis induction. The formation of AGEs was evaluated by immunoassay. Transforming growth factor beta-1 and vascular endothelial growth factor (VEGF) were immunoassayed in HPMC supernatants exposed to the above PDFs. RESULTS: At 15 g/L glucose concentration, HPMC exposure to bicaVera resulted in higher cell proliferation compared to Balance (p < 0.001) and stay.safe (p < 0.001). Compared to the lactate-buffered PDFs (Balance and stay.safe), oncosis was significantly lower in cells exposed to bicaVera (p < 0.05). bicaVera, containing lower amounts of GDPs, generated less AGE formation (p < 0.05) and VEGF production (p < 0.05) than either Balance or stay.safe. CONCLUSIONS: New-generation PDFs with physiological pH and lower GDP levels, especially if bicarbonate-buffered (bicaVera), have fewer in vitro toxic effects on mesothelial cells and may contribute to peritoneal preservation, thus improving long-term treatment of PD patients.