Recent developments in osmotic agents for peritoneal dialysis

Although glucose is still the most widely used osmotic agent for peritoneal dialysis, it has several disadvantages that challenge its long-term use. During the past years several nonglucose molecules have been tested as osmotic agents for peritoneal dialysis. Most of these molecules have some advantages over glucose, but they also have drawbacks. Every new agent should be carefully tested for performance and long-term safety. In the following review, alternative osmotic agents are discussed, including their potential indications and drawbacks. Major issues include the improvement of biocompatibility and preservation of peritoneal membrane integrity by using dialysate with more physiologic pH, the effect on nutritional status by using dialysate with amino acids, and maintenance of peritoneal ultrafiltration in the long-term by using dialysate with polyglucose. It is believed that in the near future, mixtures of osmotic agents will become most appropriate to obtain the best performance.

In vitro effects of glucose polymer-containing peritoneal dialysis fluids on phagocytic activity

Commercially available peritoneal dialysis fluids (PDFs) are known to impair peritoneal cellular defense mechanisms. We have investigated the influence of glucose polymer-containing PDFs on phagocytic function in vitro. Polymorphonuclear neutrophils (PMNLs) and monocytes (MNs) from 10 continuous ambulatory peritoneal dialysis patients and 10 healthy donors were incubated in PDFs containing either 7.5% icodextrin (glucose polymer) or 1.5% glucose at original pH and pH 7.4. Chemiluminescence response and H202 production were measured following stimulation with preopsonized Staphylococcus epidermidis or phorbol myristate acetate. Phagocytosis of radiolabeled bacteria and killing capacity of the cells were determined. A comparison of the impact of glucose polymer versus glucose-containing solutions at their original pH on the oxidative metabolism of the cells showed a highly significant difference (P < 0.0001) in favor of glucose polymers for H202 production of PMNLs (7.78 +/- 4.5 nmol cytochrome C reduction/10(6) cells/min v 1.11 +/- 0.67 nmol cytochrome C reduction/10(6) cells/min) and MNs (7.66 +/- 3.6 nmol cytochrome C reduction/10(6) cells/min v 1.29 +/- 0.86 nmol cytochrome C reduction/10(6)cells/min). Correspondingly, PMNLs and MNs incubated in glucose polymers showed a significantly higher chemiluminescence response irrespective of the stimulant used (P < 0.0001). Applying the killing assay on PMNLs also revealed a significantly higher percentage of inactivated bacteria (45.5% +/- 11.0% v 29.2% +/- 15.5%; P < 0.05). After adjustment of pH to 7.4, a significant difference could only be found for H202 production of PMNLs in favor of glucose polymers (16.73 +/- 6.98 nmol cytochrome C reduction/10(6) cells/min v 11.65 +/- 5.37 nmol cytochrome C reduction/10(6) cells/min; P < 0.05). In addition, we compared the glucose-polymer solution to an otherwise equally composed equiosmolar solution that contained 0.274% glucose instead of glucose polymers. No significant differences were detected with any of the tests applied. Our data suggest that glucose polymer solutions are comparatively less suppressive to phagocytic function than currently used glucose-containing PDFs. This effect may be attributed to the low osmolarity of these solutions.