This study shows that the daily UF with the P solution may be lower than with the D solution. The mechanism for this short-term and reversible effect that conceivably reflects differences in biocompatibility is not clear although our results implicate that the peritoneal fluid absorption rate may differ between the two solutions.

Objectives This study was designed to compare the local peritoneal and systemic inflammatory effects of a conventional lactate-based (Lac) peritoneal dialysis (PD) solution and a new biocompatible bicarbonate/lactate-based (Bic/ Lac) solution having low concentration of glucose degradation products. Methods 26 stable, prevalent PD patients were enrolled in this prospective study. They sequentially underwent 3 months of therapy with the Lac solution and 3 months with the Bic/Lac solution in a randomized order. Flow cytometry was used to measure the expression of inflammatory molecules on peritoneal cells in overnight effluent collected at the end of each study period. Results 21 patients successfully completed the study. Mean fluorescence intensity of human leukocyte antigen (HLA)-DR and CD14 expression by macrophages were not different between Lac and Bic/Lac. The peritoneal appearance rate of cancer antigen 125 (kU/minute) was 68 ± 37 with Lac and 133 ± 66 with Bic/Lac ( p < 0.001), and of interleukin (IL)-6 (ng/minute), 0.28 ± 0.2 with Lac and 0.18 ± 0.16 with Bic/Lac ( p = 0.014). HLA-DR macrophage expression and IL-6 peritoneal appearance rates did not correlate. Serum concentrations with Lac and Bic/Lac were, for IL-6, 3.49 ± 2.28 and 3.72 ± 2.46 ng/L ( p = 0.17), and for high-sensitivity C-reactive protein, 2.31 ± 2.98 and 2.71 ± 3.31 mg/L ( p = 0.32) respectively. The concentration of effluent macrophages (x106/L) with Lac was 1.6 ± 1.6 and with Bic/Lac 2.6 ± 3.3 ( p = 0.07). Conclusions We conclude that, although there was a significant reduction in peritoneal IL-6 in patients using Bic/ Lac solution, systemic levels of inflammatory markers did not differ between the two solutions and no changes were present in macrophage surface activation markers, suggesting perhaps a less important role of peritoneal macrophages in the intraperitoneal chronic inflammatory process. The number of effluent macrophages tended to be higher in patients using the Bic/Lac solution, possibly contributing to improved intraperitoneal defense.

The beneficial effects of novel peritoneal dialysis solutions low in glucose degradation products regarding peritoneal cell apoptosis and necrosis are well established in vitro, however in vivo data is lacking. Cell-free DNA quantification is a possible method to determine cell damage through apoptosis and necrosis in vivo. We performed a prospective, cross-over study on 26 stable continuous ambulatory peritoneal dialysis (CAPD) patients, treating each patient for 3 months in a randomized order with a conventional, lactate-buffered, acidic solution (solution D) and a novel, bicarbonate/lactate-buffered neutral solution (solution P). The timed overnight peritoneal effluent was sampled for cell-free DNA quantification using a fluorometric assay. The effluent samples of eighteen patients were finally available for DNA quantification. The concentration range of cell-free DNA in the peritoneal effluents was 1.8-9.5 microg/L. The coefficient of intrapatient variation in overnight effluent cell-free DNA appearance was 15.6 +/- 12.4%. Cell-free DNA peritoneal appearance using solutions D and P was 14.9 +/- 6.8 microg and 11.8 +/- 3.4 microg, respectively (P = 0.02), with the average difference of 3.1 microg (95% CI, 0.7-5.6 microg). Our results show that cell-free DNA is present in the overnight peritoneal effluent of stable CAPD patients. A significant decrease in the cell-free DNA appearance with solution P was found; however, before accepting this as an indicator of a more biocompatible profile causing less peritoneal membrane cell necrosis and apoptosis, confirmatory data on larger patient samples are needed. Our results indicate the potential future role of cell-free DNA in the diagnosis and prognosis of therapy-related peritoneal membrane degeneration.