An exploratory study of a novel peritoneal combination dialysate (1.36% glucose/7.5% icodextrin), demonstrating improved ultrafiltration compared to either component studied alone

OBJECTIVE

Concerns regarding the impact of ultrafiltration failure on peritoneal dialysis and the effect of hypertonic glucose on the peritoneal membrane have lead to a search for alternative dialysates. Computer simulations based on the three-pore theory suggest that a combination of 1.36% glucose and 7.5% icodextrin (glucose polymer) offers an improved ultrafiltration profile. The aim of the present study was to investigate the ultrafiltration profile of this combination fluid.

DESIGN

Prospective open study comparing 1.36% glucose, 3.86% glucose, 7.5% icodextrin, and the combination fluid (1.36% glucose/7.5% icodextrin).

SETTING

Sheffield Kidney Institute, Northern General Hospital, Sheffield, UK.

PATIENTS

11 patients currently using peritoneal dialysis not previously exposed to icodextrin.

MAIN OUTCOME MEASURE

Intraperitoneal volume was measured using a radioisotope dilution method.

RESULTS

The combination fluid showed a biphasic ultrafiltration profile, with a steep initial increase in intraperitoneal volume, then a maintained plateau phase for the duration of the study dwell (7 hours). The final volume was greater than that with the 1.36% glucose dwell and the 7.5% icodextrin dwell. The fluid was well tolerated by the patients.

CONCLUSIONS

These findings are in keeping with computer simulations using the three-pore model. The combination fluid offers an improved ultrafiltration profile, with a final volume similar to 3.86% glucose, while avoiding exposing the peritoneal membrane to high glucose concentrations. It may have a role as a long dwell to optimize ultrafiltration and possibly prolong peritoneal dialysis technique survival.

[Experience with sevelamer in peritoneal dialysis]

BACKGROUND

Sevelamer is a non-absorbable phosphorus chelator that is not a source of aluminium, calcium or base. The clinical experience with sevelamer in peritoneal dialysis and in daily clinical practice is scarce. The aim of this study is to evaluate the results of therapy of hyperphosphoremia with sevelamer on serum phosphorus and phosphorus chelators requirements, in a peritoneal dialysis clinical practice.

METHODS

Sevalamer 400 mg was prescribed to peritoneal dialysis patients with hyperphosphoremia who were treated with aluminium hydroxide or with calcium salts in the absence of hypocalcemia. Fourteen patients completed 12 months of therapy.

RESULTS

The initial sevelamer dose was 2,280 +/- 760 mg/day, and was increased to 2,760 +/- 1,160 mg/day at 12 months. At 12 months no patient was on aluminium salts and calcium salts had been significantly reduced. Phosphoremia (5.9 +/- 0.6 to 5.0 +/- 1.4 mg/dL, p = 0.049), calcium-phosphorus product (59.8 +/- 5.8 to 48.6 +/- 12.5 mg2/dL2, p = 0.01) and serum cholesterol (191 +/- 29 to 167 +/- 33 mg/dL, p = 0.02) decreased at 12 months. No significant changes were observed in serum triglycerides, total CO2 or PTH. Serum alkaline phosphatase increased at 6 months, but values returned to normal at 12 months. No changes were observed in serum gamma-glutamyl-transpeptidase. Five patients were started on 1.25 (OH)2 vitamin D therapy.

CONCLUSION

In peritoneal dialysis patients, sevelamer allows a satisfactory control of serum phosphorus levels and calcium-phosphorus product, while decreasing the amount of aluminium and calcium salts prescribed.

Oral sodium bicarbonate for the treatment of metabolic acidosis in peritoneal dialysis patients: a randomized placebo-control trial

Acidosis causes malnutrition in peritoneal dialysis (PD) patients. The effect of oral bicarbonate in PD patients with Kt/V <2.1 has not been studied. We randomly assigned 60 PD patients with acidosis and Kt/V <2.1 to oral sodium bicarbonate (0.9 g thrice daily) or placebo. Patients were followed for 12 mo. We compared their nutritional status, including subjective global assessment (SGA) score and normalized protein nitrogen appearance (NPNA), hospitalization and all-cause mortality. Treatment with oral bicarbonate resulted in a higher plasma bicarbonate level at 4 wk (27.8 +/- 2.6 versus 24.7 +/- 3.9 mmol/L, P = 0.002), and the difference persisted until 52 wk. Bicarbonate treatment had a significant effect on the change in overall SGA score (repeated measures ANOVA, P = 0.0003). The overall SGA score of the treatment group was higher than the placebo group at 24 wk (5.07 +/- 0.94 versus 4.40 +/- 1.00, P = 0.015), and the difference persisted thereafter. NPNA rose in the treatment group (1.17 +/- 0.32 to 1.28 +/- 0.26 g/kg per d, P = 0.034), but declined in placebo group (1.13 +/- 0.25 to 1.03 +/- 0.28 g/kg per d, P = 0.054). The treatment group had a shorter hospitalization than the placebo group (8.4 +/- 17.7 versus 16.8 +/- 21.7 d/yr; P = 0.02). Mortality was not significantly different. Although our trial has limited statistical power, we find that in PD patients with mild acidosis and Kt/V <2.1, oral sodium bicarbonate probably improve nutritional status and reduce the duration of hospitalization.

Intraperitoneal microdialysis (IPM): a new technique for monitoring intestinal ischemia studied in a porcine model

Acute mesenteric thrombosis, vascular complications of intestinal transplantation, sepsis, and multiple organ failure are all associated with intestinal ischemia. To improve the outcome of these patients, better monitoring devices are needed. A new technique, intraperitoneal microdialysis (IPM), was evaluated for detection of intestinal ischemia in a porcine model, with the intention of evaluating the technique for future use on humans. Fourteen pigs divided into two studies were used. In a total ischemia study a microdialysis catheter was placed intraperitoneally and the superior mesenteric artery was occluded for 1 h 40 min. In a local ischemia study, the arcus vessels supplying a 30-cm long small bowel segment were occluded for 3 h 20 min. One IPM catheter was placed next to the ischemic area and another IPM catheter 10 cm caudally as an intraperitoneal reference. In both studies reference catheters were placed subcutaneously. Glucose, lactate, pyruvate, and glycerol were analyzed every 20 min. In both studies vessel occlusion resulted in decreased glucose and increased lactate, glycerol, and lactate/pyruvate ratio. Significant changes were reached after 60 min of ischemia in most analytes, whereas the values from the reference catheter were stable. Our conclusion is that intestinal ischemia is detectable with IPM based on the analysis of well-documented markers of ischemia (increased lactate/pyruvate ratio) and cell membrane damage (elevated glycerol levels). It allows semi-continuous monitoring of the intestines with a minimally invasive procedure, which we believe will be possible to apply in human routine clinical use.

Continuous flow peritoneal dialysis: assessment of fluid and solute removal in a high-flow model of "fresh dialysate single pass"

BACKGROUND

Growing concern over the limited capacity of the peritoneal dialysis (PD) system has revived interest in continuous flow peritoneal dialysis (CFPD), a modality in which continuous circulation of PD fluid is maintained at a high flow rate using two separate catheters or one dual-lumen catheter. The CFPD regimen contrasts the "inflow/outflow" regimen, which requires specific times devoted to filling and draining the peritoneum via a single-lumen catheter. Historical data established CFPD capabilities in providing higher solute clearance and ultrafiltration rate (UFR) using either an open loop system with a single pass of fresh PD fluid, or various external purifications of the spent dialysate.

OBJECTIVE

To compare, in patients with various peritoneal transport patterns, fluid and solute removal achieved during a standardized program of CFPD versus two control schedules: nightly intermittent peritoneal dialysis (NIPD) and nightly tidal peritoneal dialysis (NTPD). This study focused on small solute clearances and UFR using only isotonic PD solution (Dianeal PD1 1.36%; Baxter Healthcare, Castlebar, Ireland). The model of fresh dialysate, single pass, was used to optimize solute gradients and to characterize the impact of a continuous flow regimen on peritoneal transport characteristics.

METHODS

In a crossover trial, 4-hour CFPD sessions were performed at a fixed dialysate flow rate (100 mL/ minute) in 5 patients being treated with automated PD. A hemofiltration monitor (BM25; Baxter Healthcare, Brussels, Belgium) was adapted to the CFPD technique. The peritoneal cavity was filled through a temporary second catheter and simultaneously drained using the permanent peritoneal access. Fluid and solute removal were compared to data obtained from a control period based on 8-hour sessions of NIPD or NTPD using 13 L of isotonic dialysate.

RESULTS

High-flow CFPD enhanced the diffusive transport coefficient compared with the alternative flow regimen in patients ranging from low to high transporters. Weekly creatinine clearance increased from 36.9 L (22.3 - 49.6 L) and 37.3 L (27.5 - 45.0 L) with NIPD and NTPD respectively, to 74.9 L (42.3 - 107.5 L) with CFPD. Mean UFR was 2.44 mL/min with CFPD versus 0.92 and 0.89 mL/min with NIPD and NTPD respectively. The mass transfer area coefficient (MTAC) of creatinine with CFPD was 2.5-fold that obtained from the peritoneal equilibration test data.

CONCLUSION

Our results confirm that CFPD is highly effective in increasing fluid and solute removal. Furthermore, consistent with historical data, our findings indicate that the enhanced solute transfer is not due only to steeper solute gradients, but also depends on increased MTAC in a wide range of peritoneum transport characteristics.

Intraperitoneal pressure in children: fill-volume related and impacted by body mass index

OBJECTIVE

Prescription of intraperitoneal volume (IPV) in children on peritoneal dialysis (PD) should be individualized in order to optimize both efficiency and tolerance. Intraperitoneal pressure (IPP) can be used as an objective assessment of IPV. Despite IPP being correlated with IPV, there is an important interindividual variability presumed to be secondary to other implicated factors.

DESIGN

Over the past 2 years, we conducted a prospective study in our patients on PD (N = 17). For each child, we recorded, at every third month of follow-up, IPV (in milliliters per square meter body surface area), age, gender, body mass index (BMI), and IPP (measured as centimeters of water), collecting a total of 53 data points.

RESULTS

There was a positive correlation between IPV and IPP (r = 0.36), but this correlation was weak in contrast to the strong correlation noted between BMI and IPP (r = 0.82). Age had a different influence on IPP: in the younger-aged group (< 2 years), IPP decreased with age; in the older-aged group (> 2 years), IPP increased with age. In some infants, we noted a paradoxical result: a low IPV with a high IPP.

CONCLUSIONS

The strong correlation noted between IPP and BMI gives a better understanding of the interindividual variability of the previously described unique relationship between IPP and IPV. The more obese the child (i.e., the higher the BMI), the higher is his IPP for a fixed IPV.

Peritoneal dialysis in acute renal failure

Given the discussion so far, it might be apparent that factors beyond efficacy have dictated the decline in the use of PD for ARF. The importance of these factors should not be underestimated. They might be related to the perceived "labor intensive" aspect of PD, fear of a malfunctioning catheter (which in some instances may be real), insufficient exposure to PD during nephrology training, and, last, the comfort offered by the technology used for HD. Such psychological barriers are difficult to overcome, much more so than technical barriers (which can be and have been overcome). Only a concentrated effort by the PD community in educating the general nephrologist concerning the feasibility of PD in ARF, better clinical trials that harness the full potential of PD, and careful patient selection for the use of PD will bring PD back to the mainstream in the treatment of ARF.

Mesothelial toxicity of peritoneal dialysis fluids is related primarily to glucose degradation products, not to glucose per se

OBJECTIVES

High concentrations of glucose and/or formation of glucose degradation products (GDPs) during heat sterilization of peritoneal dialysis fluids (PDFs) are believed to be key factors in the limited biocompatibility of PDFs. We have previously shown that several identified GDPs can specifically impair human peritoneal mesothelial cell (HPMC) function. In the present study we aimed at differentiating the respective roles of glucose and GDPs in the toxicity of PDF to mesothelial cells.

METHODS

HPMCs were acutely pre-exposed to or incubated chronically in the presence of pH-neutral PDF sterilized by either heat (H-PDF) or filtration (F-PDF). In addition, HPMCs were treated with commercially available H-PDF manufactured either conventionally, that is, in single-chamber containers, or using novel dual-chamber bags that help to substantially decrease GDP formation. Functional assessment of HPMCs included viability, release of interleukin (IL)-6, and proliferation.

RESULTS

Viability and release of IL-6 from HPMCs pretreated with H-PDF (pH 7.3) for 1 to 4 hours were significantly reduced compared to cells exposed to corresponding F-PDF. Incubation in medium mixed (1:1) with H-PDF considerably impaired growth of HPMCs, and over a period of 10 days gradually decreased both the viability of HPMCs and their ability to generate IL-6. These effects were either absent from or significantly less in HPMCs exposed to F-PDF. Similar differences were observed when commercial GDP-containing H-PDFs were compared with newly designed H-PDFs free of GDPs.

CONCLUSIONS

Impaired viability and function of HPMCs exposed to glucose-containing pH-neutral PDF is related predominantly to the presence of GDP and, to a significantly lesser extent, to the presence of glucose per se. Prevention of GDP formation during autoclaving markedly improves the biocompatibility of H-PDF with HPMCs.

Three purse-string sutures allow immediate start of peritoneal dialysis with a low incidence of leakage

Peritoneal dialysis (PD) depends to a great extent on a well-functioning dialysis catheter. The number of patients choosing PD also depends on the possibility of starting dialysis with this technique without needing to use hemodialysis (HD) intermediate or in the beginning of the procedure. This review describes various insertion techniques focusing on a surgical insertion technique using purse-string sutures to fix the peritoneum around the catheter with the inner cuff of a Tenckhoff catheter invaginated between purse-string sutures of the peritoneal membrane and the inner rectus muscle fascia. A third purse-string suture is used to fix the catheter and to tighten the hole in the external rectus fascia. This technique enables immediate start of PD with only a limited risk for early and late leakage. Similar fixation sutures could be considered when inserting catheters, using other insertion modes, to tighten the hole and the position of the cuff and the catheter.

Treatment data during pediatric home peritoneal teledialysis

Peritoneal teledialysis (telePD) is a modem-based communication link between the patients' cyclers and a computer in the dialysis unit that allows the transmission and storage of a series of automated peritoneal dialysis (APD) treatment data. In order to evaluate the usefulness of telePD in quantifying the problems that may occur during pediatric APD, we retrospectively studied four patients with a median age of 14.1+/-1.8 years during their initial months of telePD. The selection criteria were potential non-compliance in two cases (patients 1 and 2) and catheter malposition or fibrin occlusion in two (patients 3 and 4). The patients were treated using a Fresenius PD Night Cycler with teledialysis software. Thirty consecutive treatments per patient in the 1st and 4th months were examined, and a series of treatment parameters was calculated. The percentage of treatments with alarms and the number of alarms per treatment were high in both the 1st and the 4th month, particularly in patients 3 and 4. The main causes of the alarms were tube kinking, catheter malfunction, fibrin occlusion, and failure of electrical power. The number of shortened treatments significantly decreased in the 4th month of telePD. One non-compliant family was identified during the 1st month of PD, but psychosocial support helped to decrease the number of shortened treatments due to non-compliance in the 4th month. During the 4th month of telePD, the dwell time/total treatment time ratio (which represents the time of contact between the peritoneum and dialysis fluid) increased as a result of technical interventions aimed at reducing the infusion plus drain time. In conclusion, telePD proved to be useful in detecting and solving the clinical and technical problems of APD.

Peritoneal dialysis: changes to the structure of the peritoneal membrane and potential for biocompatible solutions

BACKGROUND

Peritoneal dialysis (PD) is now established as a viable and successful alternative to hemodialysis (HD) for patients starting on renal replacement therapy. A number of studies have confirmed that equivalent adequacy and fluid balance are provided at least for the first four to five years of renal replacement therapy (RRT). Loss of peritoneal membrane function remains a major factor leading to treatment failure in a significant number of patients on PD. Numerous studies have suggested a relationship between these changes in function and structural changes in the membrane. A careful analysis of peritoneal biopsies from PD patients would allow the clear identification of those changes unique to PD, in addition to indicating possible correlations with glucose exposure as well as other functional parameters.

METHODS

We systematically examined peritoneal biopsies from 13 normal individuals, 29 uremic predialysis patients, 55 HD patients, and 157 patients on long-term PD. Well-oriented specimens were stained with toluidine blue and examined by a blinded pathologist. Limited clinical data has allowed a preliminary analysis of structure-function relationships.

RESULTS

The median thickness of the submesothelial compact collagenous zone was 40 microm in normal individuals, 150 microm in uremic patients, 150 microm in patients on HD, and 2550 microm in patients on PD (P < 0.001 for all vs. normal individuals). Compact zone thickness increased significantly with duration of PD therapy (0 to 24 months, 180 microm;>97 months, 600 microm). Vascular changes comprised progressive subendothelial hyalinization of postcapillary venules, with luminal narrowing or obliteration. These changes were present in uremic patients and increased significantly with PD duration (P = 0.0001).

CONCLUSIONS

These data indicate that morphologic changes in the postcapillary venules and the submesothelial compact zone of PD patients begin during the uremic phase of their illness. This is then worsened by time spent on PD. The relationships with glucose exposure or glucose degradation products have yet to be established.

Effects of conventional and new peritoneal dialysis fluids on leukocyte recruitment in the rat peritoneal membrane

Peritonitis remains an important cause of morbidity and technique failure in peritoneal dialysis (PD). Conventional peritoneal dialysate fluids (PDF) inhibit peritoneal leukocyte function in vitro and may thus adversely affect the immune response to peritonitis. New PDF have been designed with neutral pH, low glucose degradation product (GDP) contents, and bicarbonate as buffer. The present intravital microscopy study examined the effects of conventional and new PDF on leukocyte behavior in the peritoneal microcirculation of Wistar rats. The visceral peritoneum was superfused by a control solution (EBSS), a conventional (CAPD), or a new bicarbonate-buffered PDF with neutral pH and low GDP content (CAPD BicaVera). In addition, spent conventional and new PDF were tested. The number of rolling, adhering, and extravasated leukocytes and leukocyte rolling velocity were assessed at different time intervals after exposure to lipopolysaccharide (LPS) or cell-free supernatants of coagulase-negative staphylococci (CNS-CFS). Exposure to LPS or CNS-CFS dissolved in EBSS dramatically increased the number of rolling, adhering and extravasated leukocytes and decreased leukocyte rolling velocity. Superfusion by CAPD abolished the LPS- or CNS-CFS-induced leukocyte recruitment, whereas CAPD BicaVera had significantly fewer depressant effect. Spent PDF affected the leukocyte response in a similar way as fresh PDF. High lactate concentrations, GDP, and hypertonicity appeared to be mainly responsible for the inhibition of leukocyte recruitment. In conclusion, conventional PDF abolish in vivo leukocyte recruitment in response to potent inflammatory stimuli. Bicarbonate-buffered pH-neutral PDF with low GDP contents have fewer depressant effects and may therefore contribute to a better preservation of peritoneal host defense.

Glucose degradation products in peritoneal dialysis fluids: do they harm?

BACKGROUND

Severe limitations in biocompatibility of conventional peritoneal dialysis fluids (PDF) can be partially attributed to the presence of glucose degradation products (GDP), which are generated during autoclaving of PDF. Formation of GDP can be significantly reduced by the use of multi-chamber bag systems. Recent clinical studies have revealed increased dialysate levels of pro-collagen I C-terminal peptide (PICP) in patients dialyzed with these solutions. Here, we briefly review the current knowledge on various aspects of GDP toxicity toward peritoneal cells and analyze the impact of GDP on PICP release by human peritoneal mesothelial cells (HPMC) in vitro.

METHODS

HPMC were exposed to a mixture of known GDP added to culture medium at clinically relevant doses. After 12 days, the amount of PICP released was measured using an immunoassay. Furthermore, the protein synthesis was assessed by 3H-proline incorporation in HPMC exposed to peritoneal effluent obtained from patients after three months of CAPD with either conventional PDF or low-GDP solution.

RESULTS

Exposure to GDP resulted in a significant decrease in PICP release by HPMC. In addition, the synthesis of new proteins secreted by HPMC was preserved significantly better in HPMC treated with effluent obtained when patients were dialyzed with low-GDP solutions rather than conventional PDF.

CONCLUSIONS

Exposure to GDP may impair protein synthesis and secretion by HPMC. Therefore, increased dialysate PICP levels in response to GDP-free PDF may be viewed as evidence of improved mesothelial cell function.

Effect of glucose polymer on the intercellular junctions of cultured human peritoneal mesothelial cells

BACKGROUND

Glucose polymer is an active osmotic agent that is increasingly used as an alternative to glucose in peritoneal dialysis fluids. It was recently reported that the duration of peritoneal dialysis can be extended by using glucose polymer in patients with poor ultrafiltration. We previously demonstrated that high glucose levels damage the intercellular junctions of cultured human peritoneal mesothelial cells (HPMC), but little is known about the influence of glucose polymer. Therefore, we investigated the effects of glucose polymer on the intercellular junctions of HPMC.

METHODS

HPMC were isolated, cultured, and identified according to the modified method of Stylianou. M199 medium was supplemented with peritoneal dialysis solutions containing 7.5% glucose polymer or 1.5, 2.5, and 4.25% glucose. After 6 h, cell viability was assessed, intercellular junction proteins were examined by immunofluorescence techniques, and the concentration of transforming growth factor-beta1 in the culture supernatant was determined.

RESULTS

Glucose significantly suppressed cell viability and significantly increased transforming growth factor-beta1 production when compared with control or glucose polymer cultures. Peritoneal dialysis solutions containing 4.25% glucose caused the detachment of HPMC. Immunofluorescence of intercellular junction proteins (tight junctions: ZO-1, occludin, and claudin-1; adherens junctions: beta-catenin) became weak and uneven after culture with glucose. On the other hand, glucose polymer caused little change in the immunofluorescence of these proteins when compared with control cultures.

CONCLUSIONS

Glucose polymer seems to be less toxic to HPMC than glucose itself, suggesting that the glucose polymer may be better for peritoneal dialysis.

Catheter design for continuous flow peritoneal dialysis

A new catheter for continuous flow peritoneal dialysis is presented. One of the main issues in this field is the safety and good clinical tolerance of the catheter. In this case, the size and diameter of the cannula has not been increased in comparison to previous PD catheters. Furthermore, the materials utilized are designed for maximum comfort of the patient and minimal traumatisation of the peritoneal membrane. Nevertheless, the two compartments of the catheter allow for high dialysate flows without creating high resistance and the rate of recirculation is minimal in conditions of simulated continuous flow PD. Furthermore, the characteristic of the new catheter is the presence in the inflow branch of a special diffuser designed like a shower cap that is intended to improve the dialysate inflow distribution in the peritoneal cavity and to increase the contact of the peritoneal membrane with the solution. At the same time, the diffuser prevents a traumatic effect of the inflow dialysate due to high speed infusion or jet flow conditions.

Continuous flow peritoneal dialysis: clinical applications

Continuous flow peritoneal dialysis (CFPD) can be considered a special form of hemodialysis, during which peritoneal effluent, rather than blood, is being dialyzed using standard hemodialysis technology. Preliminary clinical data have identified poor mixing of the dialysis solution, streaming and recirculation as a significant limitation in achieving maximal solute removal and ultrafiltration. Better catheter designs remain a research priority in this field. Although the clinical experience is limited to short-lasting experiments with CFPD, the preliminary data strongly support the superiority of CFPD as the most effective peritoneal dialysis modality in removing small solutes and providing high ultrafiltration rates. The levels of clearance attained are similar to quotidian hemodialysis. In addition, it is expected that the current methodology will provide a new standard of solution biocompatibility.

Effect of icodextrin on volume status, blood pressure and echocardiographic parameters: a randomized study

Overhydration is a risk factor for hypertension and left ventricular hypertrophy in peritoneal dialysis patients. Recently, a high prevalence of subclinical overhydration was observed in peritoneal dialysis patients. Aim of the present open-label randomized study was to assess the effect of a icodextrin 7.5% solution on fluid status [extracellular water (ECW) bromide dilution], blood pressure regulation (24-hour ambulatory measurements) and echocardiographic parameters during a study period of 4 months, and to relate the effect to peritoneal membrane characteristics (dialysate/plasma creatinine ratio). Forty peritoneal dialysis patients (22 treated with icodextrin, 18 controls) were randomized to either treatment with icodextrin during the long dwell or standard glucose solutions. Thirty-two patients (19 treated with icodextrin, 13 controls] completed the study. The use of icodextrin resulted in a significant increase in daily ultrafiltration volume (744 +/- 767 mL vs. 1670 +/- 1038 mL; P = 0.012) and a decrease in ECW (17.5 +/- 5.2 L vs. 15.8 +/- 3.8 L; P = 0.035). Also the change in ECW between controls and patients treated with icodextrin was significant (-1.7 +/- 3.3 L vs. +0.9 +/- 2.2 L; P = 0.013). The effect of icodextrin on ECW was not related to peritoneal membrane characteristics, but significantly related to the fluid state of the patients (ECW:height) (r = -0.72; P < 0.0001). Left ventricular mass (LVM) decreased significantly in the icodextrin-treated group (241 +/- 53 grams vs. 228 +/- 42 grams; P = 0.03), but not in the control group. In this randomized open-label study, the use of icodextrin resulted in a significant reduction in ECW and LVM. The effect of icodextrin on ECW was not related to peritoneal membrane characteristics, but was related to the initial fluid state of the patient.

Glucose degradation products increase apoptosis of human mesothelial cells

BACKGROUND

The heat sterilization of glucose solutions for peritoneal dialysis (PDS) induces the formation of glucose degradation products (GDPs), a phenomenon amplified by lactate and neutral pH. In the new three-compartment bag (3CB) PDS, a glucose solution at pH 3 is kept apart from the buffer until use, and the final solution delivers glucose concentrations that are similar to traditional PDS (TPD), with pH 6 and a lower content of GDPs. As GDPs have oxidant activity that may favour apoptosis, we investigated mesothelial cell apoptosis modulation by 12 h cultures in media supplemented with: (i) two relevant GDPs, methylglyoxal (MGly) and formaldehyde (For) in time and dose-dependence assays, (ii) GDPs at concentrations detected in TPD and 3CB, and (iii) commercial TPD and 3CB PDS, both with 1.36% glucose.

METHODS

Apoptosis was evaluated by terminal 3' uridine labelling. Key proteins involved in the apoptotic pathway were investigated by reverse transcription polymerase chain reaction (RT-PCR) mRNA expression and immunoperoxidase staining (caspase 9, tumour suppressor protein p53, inducible cyclooxygenase COX-2).

RESULTS

The apoptotic effects of MGly and For were dose and time dependent. GPDs at concentrations detected in TPD induced greater transcription and translation of apoptotic pathway proteins (caspase 9, p53 and COX-2) than GPDs in 3CB. This resulted in a higher apoptotic rate, which was not influenced by addition of sterile glucose. A similar enhancement of apoptosis was detected when mesothelial cells were incubated with TPD, whereas incubation in 3CB PDS resulted in less enhanced apoptosis. The 12 h incubation effect of PDS on cultured mesothelial cells was not related to advanced glycosylated end-product formation.

CONCLUSIONS

As the rate of mesothelial cell apoptosis is lower in 3CB than in TPD solutions, the 3CB appears to provide improved biocompatibility.

A case study: telemedicine technology and peritoneal dialysis in children

We investigated the feasibility and effectiveness of a telemedicine system for monitoring pediatric patients undergoing automated peritoneal dialysis (APD) at home. The system uses modem-based communication between the patient's cycler and a computer in the dialysis unit, which allows data transmission and storage, and live patient-physician interaction by ISDN lines, modem, microphone with stereo speakers, and digital cameras for private video-conferencing and image capture. Two children aged 10 and 12 years, who live 1500 and 40 km from the dialysis unit, respectively, have been using the system for 7 months. All of the APD treatment data were stored and examined; 122 televisits were performed. The APD data show that both patients have complied with their dialysis prescription. The telemedicine system broadens patient/physician interchange and increases the quality of care and the life of children on peritoneal dialysis.

Empirical aminoglycosides for peritonitis do not affect residual renal function

BACKGROUND

Aminoglycosides have been proven to be an efficacious treatment for peritonitis in peritoneal dialysis patients for many years. Consequently, they have been recommended in previous guidelines for the empirical treatment of peritonitis. However, with the increasing emphasis on preserving residual renal function (RRF), there has been concern about the nephrotoxic potential of these compounds. The 2000 International Society of Peritoneal Dialysis (ISPD) guidelines recommended that aminoglycosides not be used in patients with RRF, and that ceftazidime be used instead. In 1997, in response to the 1996 ISPD guidelines, we changed our peritonitis regimen from vancomycin and ciprofloxacin to cefazolin and gentamicin. The aim of this study is to compare the change in renal function occurring after treatment of peritonitis with and without gentamicin.

METHODS

Using 6-monthly urine and dialysis clearance measurements, preperitonitis and postperitonitis RRF (mean of 24-hour urea and creatinine clearance) were determined for 70 peritonitis episodes treated with the aminoglycoside-based regimen (group A), 61 episodes treated without aminoglycosides (group B), and 74 control patients without peritonitis (group C).

RESULTS

Group A had mean declines in estimated glomerular filtration rate and urine output of -0.08 +/- 0.50 mL/min/mon and -8.82 +/- 88.09 mL/24 h/mon compared with -0.17 +/- 0.27 mL/min/mon and -34.68 +/- 69.58 mL/24 h/mon in group B and -0.20 +/- 0.39 mL/min/mon and -14.61 +/- 77.33 mL/24 h/mon in group C, respectively. There were no significant differences between groups.

CONCLUSION

In our patients, there was no evidence of an accelerated decline in RRF when using an empirical regimen containing aminoglycosides for peritonitis. Because there are few data to contradict this finding, we recommend the continued use of these drugs in peritonitis regimens, even in patients with significant RRF.

Calcium-channel blockers and end-stage renal disease: pharmacokinetic and pharmacodynamic considerations

PURPOSE OF REVIEW

To characterize the pharmacokinetics and pharmacodynamics of the different calcium-channel blockers.

RECENT FINDINGS

Calcium-channel blockers have been in use for some time in the end-stage renal disease population. Their primary use has been as antihypertensive and antianginal therapies. In this regard, they are effective agents. Recently, it has been noted that dialysis-related hypotension occurs less frequently in calcium-channel blocker treated patients. Also, access patency and overall patient survival are improved with calcium-channel blocker therapy.

SUMMARY

Calcium-channel blockers are useful agents for the control of hypertension in end-stage renal disease patients and appear to favorably influence survival in this population. Calcium-channel blockers are not dialyzable and their pharmacokinetics do not substantially change with renal failure therefore they do not require dose adjustment based on level of renal function. Too few studies exist to determine if individual calcium-channel blockers differ in their effects. Prospective, randomized, controlled clinical trials are needed in the end-stage renal disease population to better understand the role of calcium-channel blockers in the excess cardiovascular disease burden of this population.