New concepts in peritoneal dialysis: new wine in old barrels?

Antibiotic Prophylaxis in an Animal Model of Chronic Peritoneal Exposure

Objectives

Acute infection in an animal model of chronic peritoneal dialysis (PD) induces structural changes in the peritoneum and alters functional characteristics of transport. These changes may compromise observations of the chronic effects of dialysis solutions. To test the hypothesis that antibiotics would prevent acute infection without affecting transport and structural properties, we characterized the frequency of infection in our rat model of PD and examined whether the inclusion of antibiotics in the dialysis solution altered the transport and structural properties of the peritoneum.

Design

Female Sprague–Dawley rats were aseptically injected daily under gas anesthesia with 30 – 40 mL of a sterile solution for 2 months via a peritoneal catheter tunneled to a subcutaneous port. Solutions used were Krebs–Ringer bicarbonate (KRB) alone, KRB with antibiotics (cefazolin 200 mg/L and gentamicin 2 mg/L), KRB with 4% glucose, and KRB with both glucose and antibiotics. After 2 months, osmotic filtration and solute transport were assessed in each animal and peritoneal fluid was collected for bacterial culture. Angiogenesis was evaluated by quantitative image analysis of tissue sections stained with CD31. Tissue content of collagen, hyaluronic acid, and sulfated glycosaminoglycan was determined.

Results

Technique survival (successful PD for 2 months) and infection rate were comparable among all treated groups. There were no differences between the groups in transport properties. Structural changes were comparable between groups, with or without antibiotics.

Conclusions

Addition of antibiotics to the dialysis solution did not affect the transport characteristics of the peritoneum or the pathologic reaction of the tissue to the PD solution.

Prognostic predictors of technique and patient survival in elderly Southeast Asian patients undergoing continuous ambulatory peritoneal dialysis

The population of elderly patients entering chronic dialysis programmes is increasing. Elderly patients are susceptible to malnutrition and have multiple complicating disorders in addition to uraemia. Selecting appropriate dialysis modality is particularly critical in elderly patients. Continuous ambulatory peritoneal dialysis (CAPD) has many advantages to elderly patients; however, the clinical outcome varies for elderly CAPD patients. In comparison with Westerners, Southeast Asians have a small body mass index and may be more suited to CAPD therapy. To identify the prognostic predictors in elderly Southeast Asian patients, this historical cohort study analysed 144 patients aged > or = 65 years at initiation of CAPD. A group of haemodialysis (HD) patients aged > or = 65 years was utilised as the control group. Survival curves for patient and technique were derived from Kaplan-Meier analysis and were further analysed by Cox-Mantel log-rank test. To elucidate the impact of individual factors on patient survival, various significant univariables were further subjected to multivariate analysis. No significant increase existed for relative risk of technique failure in elderly patients compared with younger patients. This analytical data indicates that CAPD was as good as HD for elderly uraemic patients regarding to the patient survival. Diabetes, dependent patients, low albumin levels and previous HD history were significant poor prognostic factors for survival of elderly CAPD patients. In conclusion, CAPD is an effective modality of renal replacement therapy for Southeast Asian elderly patients. The technique survival was not affected by patient age.

Icodextrin: a review of its use in peritoneal dialysis

Icodextrin (Extraneal) is a high molecular weight glucose polymer developed specifically for use as an alternative osmotic agent to dextrose during the once-daily long-dwell exchange in peritoneal dialysis (PD). Isosmotic 7.5% icodextrin solution induces transcapillary ultrafiltration (UF) by a mechanism resembling 'colloid' osmosis (unlike hyper-osmolar dextrose-based solutions, which induce UF by crystalline osmosis). In addition, absorption of icodextrin from the peritoneal cavity is relatively slow compared with that of dextrose; this results not only in UF of longer duration, but also a lower carbohydrate load compared with medium (2.5%) and strong (4.25%) dextrose exchanges. In randomised clinical trials of up to 2 years in duration, administration of icodextrin for the long (8- to 16-hour) overnight exchange in continuous ambulatory peritoneal dialysis (CAPD) or daytime exchange in automated peritoneal dialysis (APD) produced net UF which exceeded that with 1.5% and 2.5% dextrose solutions (thereby improving fluid balance), and was equivalent to that with 4.25% dextrose solution. Icodextrin also increased peritoneal clearances of creatinine and urea nitrogen compared with 2.5% dextrose solution. The increase in UF volume with icodextrin was enhanced in CAPD patients with high peritoneal membrane permeability (i.e. high and high-average transporters), maintained in the small number of patients followed-up for 2 years and sustained during episodes of peritonitis. Icodextrin reduced the percentage of patients with net negative UF in contrast to 1.5% and 2.5% dextrose and, in noncomparative studies, extended PD technique survival in patients who had failed dextrose-based dialysis. The use of icodextrin was also associated with some symptomatic improvements and health-related quality of life advantages, and no adverse effect on patient survival, compared with dextrose, although confirmation of these findings is ideally required in appropriately designed studies. The tolerability of icodextrin was generally similar to that of dextrose-based solutions in controlled clinical trials, although there was an approximate three-fold increase in the risk of new skin rash (5.5% vs 1.7%). However, reports of severe cutaneous hypersensitivity reactions remain rare; this possibility should not preclude the use of the polymer.

CONCLUSION

7.5% icodextrin solution offers the first feasible alternative to conventional dextrose solutions for the once-daily long-dwell exchange in PD. It is effective, generally well tolerated and appears to be most useful in situations of reduced or inadequate UF with dextrose, including in high and high-average transporters, during episodes of peritonitis and patients who have failed dextrose-based dialysis.