Effects of lactate-based and bicarbonate-based peritoneal dialysis solutions on neutrophilic oxygen consumption

The Effects of Peritoneal Dialysis Solutions on Peritoneal Host Defense

Conventional peritoneal dialysis fluid (PDF) is a bioincompatible solution owing to the acidic pH, the high glucose concentrations and the associated hyperosmolarity, the high lactate concentrations, and the presence of glucose degradation products (GDPs). This unphysiologic composition adversely affects peritoneal host defense and may thus contribute to the development of PD-related peritonitis. The viability of polymorphonuclear leukocytes, monocytes, peritoneal macrophages, and mesothelial cells is severely depressed in the presence of conventional PDF. In addition, the production of inflammatory cytokines and chemoattractants by these cells is markedly affected by conventional PDF. Further, conventional PDF hampers the recruitment of circulating leukocytes in response to an infectious stimulus. Finally, phagocytosis, respiratory burst, and bacterial killing are markedly lower when polymorphonuclear leukocytes, monocytes, and peritoneal macrophages are exposed to conventional PDF. Although there are a few discrepant results, all major PDF components have been implicated as causative factors. Generally, novel PDF with alternative osmotic agents or with alternative buffers, neutral pH, and low GDP content have much milder inhibitory effects on peritoneal host defense. Clinical studies, however, still need to demonstrate their superiority with respect to the incidence of PD-related peritonitis.

In vivo exposure to bicarbonate/lactate- and bicarbonate-buffered peritoneal dialysis fluids improves ex vivo peritoneal macrophage function

The impact on peritoneal macrophage (PMO) function of acidic lactate-buffered (Lac-PDF [PD4]; 40 mmol/L of lactate; pH 5.2) and neutral-pH, bicarbonate-buffered (TB; 38 mmol/L of bicarbonate; pH 7. 3) and bicarbonate/lactate-buffered (TBL; 25 mmol/L of bicarbonate/15 mmol/L of lactate; pH 7.3) peritoneal dialysis fluids (PDFs) was compared during a study of continuous therapy with PD4, TB, or TBL. During a run-in phase of 6 weeks when all patients (n = 15) were treated with their regular dialysis regimen with Lac-PDF, median PMO tumor necrosis factor alpha (TNFalpha) release values were 203.6, 89.9, and 115.5 pg TNFalpha/10(6) PMO in the patients subsequently randomized to the PD4, TB, and TBL treatment groups, respectively. Median stimulated TNFalpha values (serum-treated zymosan [STZ], 10 microgram/mL) were 1,894.6, 567.3, and 554.5 pg TNFalpha/10(6) PMO in the same groups, respectively. During the trial phase of 12 weeks, when the three groups of patients (n = 5 per group) were randomized to continuous treatment with PD4, TB, or TBL, median constitutive TNFalpha release values were 204.7, 131.4, and 155.4 pg TNFalpha/10(6) PMO, respectively. Stimulated TNFalpha values (STZ, 10 microgram/mL) were 1,911, 1,832, and 1,378 pg TNFalpha/10(6) PMO in the same groups, respectively. Repeated-measures analysis of variance comparing the run-in phase with the trial phase showed that PMO TNFalpha release was significantly elevated in patients treated with both TB (P = 0.040) and TBL (P = 0.014) but not in patients treated with Lac-PDF (P = 0. 795). These data suggest that patients continuously exposed to bicarbonate- and bicarbonate/lactate-buffered PDFs might have better preserved PMO function and thus improved host defense status.

Effect of an pyruvate-based peritoneal dialysis solution on the pH of a residual peritoneal dialysis fluid

An acidic (pH 5.2) pyruvate-based peritoneal dialysis solution or an equally acidic lactate-based counterpart was added to a residual fluid (i.e., peritoneal effluent) obtained from each of 6 continuous ambulatory peritoneal dialysis patients. It was found that the residual fluids were able to raise the pH of the resultant residual fluid/peritoneal dialysis solution mixture to a higher level in the case of the pyruvate-based solution than in the case of the lactate-based one.