Peritoneal Dialysis International: Journal of the International Society for Peritoneal Dialysis

To describe the characteristics of abnormal cells present in the peritoneal effluent of 4 continuous ambulatory peritoneal dialysis (CAPD) patients; the cells were accidentally detected in a longitudinal study of cell populations in 83 patients.

Descriptive study.

Four stable CAPD patients (2 male, 2 female).

Peritoneal cells were collected from nocturnal peritoneal effluent (NPE) by centrifugation.

Light microscopy, ultrastructural, cytochemical, and immunohistochemical characteristics were studied.

The abnormal cells were characterized by a flat appearance, large size (diameter 100 μm) -six to ten times larger than a normal macrophage, a broad acidophilic cytoplasm with rare granulations, and a low nucleus/cytoplasm ratio. The nucleus was pyknotic, with dense chromatin and sometimes appeared fragmented. Its number presented a considerable variability between the patients and was much higher in the 2 females. This number remained stable in each patient over time. These cells were negative for betaglucuronidase and positive for PAS stain with variable intensity. A very low number of flat cells were positive for vimentin with weak intensity, whereas cytokeratin and epithelial membrane antigen (EMA) were positive in a higher number of cells with medium to strong intensity. Ultrastructural studies showed numerous short surface microvilli, cytoplasm well-developed with intracytoplasmic lumina and abundant, dispersed intermediate filaments, scattered mitochondria, and stacks of rough endoplasmic reticulum were observed. Dispersed secretory vacuoles and isolated lipid vacuoles were present.

All these features imply that they are mesothelial in origin and are suggestive of a change known as peritoneal squamous metaplasia. To date, the clinical follow-up of our patients has shown a benign outcome; further studies are necessary to elucidate the significance of this peritoneal squamous metaplasia in CAPD patients.

To investigate the possible effect of unphysiologically low pH in dialysis fluid on peritoneal transport.

A 4-hour single-cycle experimental session of peritoneal dialysis was performed in six 5prague-Dawley rats using Dianeal 3.86% solution modified by adding 5 mmol/L of sodium hydroxide, neutral pH solution (NpH5) (pH 7.4). The intraperitoneal volume (V D) and peritoneal bulkfluid reabsorption (aa) were calculated using a marker, 1311–labeled human serum albumin (RI5A). The diffusive mass transport coefficient (KBD) as well as sieving coefficient (5) for glucose, urea, sodium, and potassium were calculated using the Babb-Randerson-Farrell model. The same study was performed in seven rats using Dianeal 3.86% solution, acidic pH solution (ApH5) (pH 5.7) to provide control values.

The dialysate pH was stable with NpH5; 45 min after the infusion of ApH5 it increased rapidly and reached the physiological value 7.4. Dialysate volume and KBD values for sodium and potassium with NpH5 were significantly higher than with ApH5, while the KBD values for glucose and urea did not differ between the two solutions. 5 values for sodium and urea did not differ between the two solutions, while the values for glucose and potassium with NpH5 were significantly higher and lower, respectively, than the values with ApH5 (0.92±1.04 vs 0.04±0.63 and 0.56±060 vs 1.15±0.39, p < 0.05). The absorption of glucose from the dialysis solution expressed as a percentage of the initial amount of dialysate glucose was significantly lower with NpH5 than with ApH5 at 30 min (17.3±1.7% vs 29.7±2.0%, p < 0.05).

We conclude that the peritoneal transport of fluid and small solutes might to some extent be influenced by the acidity of the dialysis solution. The vasodilatory effect of acidic dialysis solution might be the most important mechanism for these differences. However, a larger KBD value and a lower 5 value for potassium and higher 5 values for glucose during dialysis with the neutral dialysis solution may indicate that transport mechanisms other than simple passive transport are involved in peritoneal transport for glucose and electrolytes.

To determine the effect of dialysis fluid containing various glucose concentrations on the phagocytosis and killing of Staphylococcus aureus by rat peritoneal cells under conditions mimicking the in vivo situation.

Phagocytosis and killing were evaluated by quantitation of the killing capacity of macrophages after in vivo phagocytosis of the bacteria as well as by an in vitro flow cytometric assay of the phagocytosis and killing of adhered bacteria by peritoneal cells.

Male Wistar rats.

It was expected that the intraperitoneal administration of dialysis fluid would im pair the capacity of peritoneal cells to eliminate bacteria.

The first test revealed no effects of glucose concentration or dwell time on the killing of phagocytosed bacteria by macrophages, median percentages ranging between 29% and 64%. In the second series of experiments no effect of glucose concentration on the phagocytosis and killing of adhered bacteria was found either; however, longer dwell times significantly enhanced both the phagocytosis (at a dwell time of 1 hour, under 20%; at dwell times of 4 or 18 hours, above 20%, p < 0.02) and the killing (at a dwell time of 1 hour, under 53%; at dwell times of 4 and 18 hours, above 70%, p < 0.01).

Glucose concentration has no effect on the phagocytosis and killing of Staphylococcus aureus, whereas the dwell time significantly enhances both of these functional capacities of peritoneal cells if the bacteria are adhered to surfaces.

The primary literature was reviewed to determine the stability of drug additives in peritoneal dialysis solutions.

A MEDLINE search and retrieval, covering the period 1981 to 1994, was undertaken to identify relevant original literature. Additional references were identified from citations within the original literature. Non-English literature was excluded unless an English abstract was provided.

Forty-nine studies were identified. Of these, 24 were directly related to drug stability, 13 were related to the clinical use of the drug additives but included no stability data, and 12 examined other, nonstability aspects of in vitroactivity of antibiotics, additives, or drug adsorption in peritoneal dialysis bags and tubing.

Data included concentrations of drug additives and dialysate solutions, duration and temperatures of storage conditions, types of assay, and whether they were stability-indicating.

Stability was defined as the duration of time that the drug concentration remained at 90% or more of the original concentration. Stability was examined under a large variety of conditions. Thirty-one drugs were identified from 20 manuscripts as single-drug additives. Most beta-Iactams were stable for 1 –2 weeks in a refrigerator and for several days at room temperature. Aminoglycosides were stable for 1 –2 days at room temperature. Glycopeptides were stable for several weeks refrigerated or at room temperature. Prolonged storage at room temperature resulted in instability of cefotaxime, ceftazidime, ceftriaxone, and miconazole. Eleven drugs were identified from seven manuscripts as drug combination studies and showed similar stability as single agents. Dialysate concentration appeared to have minimal effect on stability.

Drug additives in peritoneal dialysate, singly or combined, should be avoided unless data are available to support their stability. Additives should be made as close as possible to the time of the exchange. Alternatively, additives should be stored refrigerated, then warmed prior to use. The practice of preparing numerous bags at one time should be avoided. Finally, stability data do not indicate sterile integrity of the dialysate.

To evaluate bicarbonate fluxes across the peritoneal membrane and bicarbonate gain in patients treated with continuous ambulatory peritoneal dialysis (CAPD) using dialysis solutions with different bicarbonate concentrations.

Ninety-seven exchanges, using different dwell times and glucose and bicarbonate concentrations were performed in 43 stable CAPD patients. Dialysate effluent bicarbonate concentration and volumes were measured at different dwell times. Net dialytic bicarbonate gain was calculated. Patients’ acid-base status was determined at the middle of the dwell.

In prolonged dwells (6 –12 hours)thedialysate effluent bicarbonate concentration correlated with arterial plasma bicarbonate concentration (F = 129, p < 0.0001), but not with ultrafiltration rate or dialysis solution bicarbonate concentration. In 4-hour dwells, effluent bicarbonate concentration correlated with both plasma bicarbonate concentration and ultrafiltration rate (F = 32.52, p < 0.0001 and F = 4.4, p < 0.05, respectively). The effluent bicarbonate concentration may be predicted from the patient's plasma bicarbonate concentration and net ultrafiltration rate for either a 4-hour or prolonged (6 –12 hours) dwell time. Net bicarbonate gain by the patient correlated with ultrafiltration rate, plasma bicarbonate, and dialysis solution bicarbonate concentration (F = 100.56, p < 0.0001 at 4 hours and F = 108.08, p < 0.0001 at 6 12 hours), with the ultrafiltration rate being the predominant parameter.

The effluent bicarbonate concentration is related to plasma bicarbonate concentration, with ultrafiltration playing a marginal role only during short dwells. However, the ultrafiltration rate has a profound effect on net patient bicarbonate gain. Multiple linear regression analysis allows the prediction of the effect of acid-base status, ultrafiltration, dwell time, and dialysis solution bicarbonate content on net patient bicarbonate gain. It seems that bicarbonate content in the CAPD dialysis solution should be progressively increased with increasing solution osmolality.

Oyslipidemia possibly contributes to the vascular complications commonly afflicting uremic patients. Lipoprotein (a) [Lp(a)] has been identified as an independent risk factor for atherosclerotic vascular dis ease. The aim of our study was to compare lipidparameters, including Lp(a), between hemodialysis (HO) and continuous ambulatory peritoneal dialysis (CAPO) patients.

A cross-sectional study.

University Medical Center.

Forty CAPO and 40 HO patients carefully matched for age, sex, body mass index (BMI), smoking habits, and duration of dialysis were studied. A group of 40 healthy individuals matched for age, sex, BMI, and smoking habits was used as control.

None.

Serum lipid parameters and atherogenic risk ratios were the main outcome measures.

Both groups of dialysis patients had increased serum triglycerides and decreased levels of Apo AI and HOL cholesterol compared to controls. Moreover, the risk ratios total cholesterol/HOL cholesterol and LOL cholesterol/HOL cholesterol were significantly higher, and the ratio ApoA1/ApoB was significantly lower in both groups of patients in comparison to the normal subjects. Both groups of dialysis patients exhibited decreased ratios of LOL cholesterol/ApoB and HOL cholesterol/ApoAI, suggesting the presence of compositional lipoprotein changes. CAPO patients had a more atherogenic lipid profile compared to HO patients, since they exhibited higher levels of total and LOL cholesterol, of ApoB as well as of the ratios total cholesterol/HOL cholesterol and LOL cholesterol/ HOL cholesterol, and lower levels of the ratio ApoA1/ApoB compared to HO patients. Both groups of dialysis patients had increased serum Lp(a) levels. Even though CAPO patients had higher serum Lp(a) levels than HO patients, the differences between these two groups were only marginally statistically significant (p = 0.056 by Mann-Whitney U-test). Uremic dyslipidemia was positively correlated with serum albumin levels in both groups of patients.

CAPO patients exhibit a more atherogenic lipid profile than that of HO patients. The marked disturbances in Lp(a) levels may further increase the vascular risk in both groups of patients.

Chemical analysis of several brands of peritoneal dialysis fluids (PD fluids) has revealed the presence of 2-furaldehyde, 5-HMF (5-hydroxymethylfuraldehyde), acetaldehyde, formaldehyde, glyoxal, and methylglyoxal. The aim of this study was to investigate if the in vitro side effects caused by glucose degradation products, mainly formed during heat sterilization, are due to any of these recently identified aldehydes.

Cell growth media or sterile filtered PD fluids were spiked with different concentrations ofthealdehydes.

In vitro side effects were determined as the inhibition of cell growth of cultured mouse fibro blasts or stimulated superoxide radical release from human peritoneal cells.

Our results demonstrate that the occurrences of 2-furaldehyde, 5-HMF, acetaldehyde, formaldehyde, glyoxal, or methylglyoxal in heat-sterilized PD fluids are probably not the direct cause of in vitro side effects. In order to induce the same magnitude of cell growth inhibition as the heat-sterilized PD fluids, the concentrations of 2-furaldehyde, glyoxal, and 5-HMF had to be 50 to 350 times higher than those quantified in the PD fluids. The concentrations of acetaldehyde, formaldehyde, and methylglyoxal observed in the heat-sterilized PD fluids were closer to the cytotoxic concentrations although still 3 to 7 times lower.

Since none of these aldehydes caused in vitro toxicity at the tested concentrations, the toxicity found in PD fluids is likely to be due to another glucose degradation product, not yet identified. However, it is possible that these aldehydes may still have adverse effects for patients on peritoneal dialysis.

To examine the impact of peritoneal catheter configuration on mechanical complications, catheter survival, probability of episodes of peritonitis, and probability of exit -site infections associated with the use of catheters for continuous ambulatory peritoneal dialysis (CAPD).

Prospective randomized trial.

CAPD unit in one university hospital, serving a population of 1.2 million.

Forty consecutive patients requiring their first dialysis catheter for future CAPD were randomized to receive either a two-cuff permanently bent Swan neck catheter or a two-cuff straight Tenckhoff catheter. The skin exit was downward-directed in the Swan neck group and upward-directed in the Tenckhoff group.

Dialysate leak, catheter migration, or tunnel infection did not occur in any of the patients. Three outer cuff extrusions needing cuff shaving occurred, all in the Tenckhoffgroup(p =0.1). No significant differences could be demonstrated in catheter survival at 2 years, probability of episodes of peritonitis, or probability of exit-site infections.

Catheter configuration did not influence the catheter-related mechanical or infectious complications, and equally good results were obtained with both catheter types studied.

This study describes the results of the insertion of a straight Tenckhoff peritoneal catheter (PC) in an arcuate, caudally concave tunnel using a tunneler designed by the authors. It has a semicircular shape and a bending radius of 4.5 cm.

A hospital renal unit.

From June 1988 to February 1994, 112 straight Tenckhoff PCs, 62 with one deep cuff (single-cuff PC) and 50 with two cuffs (double-cuff PC), were inserted as first catheters in 112 patients (mean age 62±13 years), who underwent continuous ambulatory peritoneal dialysis (CAPD). The follow-up was 1099 months (mean 18±13 months)forsingle-cuff PC sand 1264 months (mean 25±15 months) for double-cuff PCs, respectively.

After intraperitoneal placement of the PCs by median laparotomy, a 180° arc bend tunnel, with both external and peritoneal exits directed downwards, was created by means of the tunneler.

The rate of exit-site infection (ESI) was 0.27 episodes/year (epis/year). The probability of remaining ESI-free was 76%, 60%, and 55% at 1, 2, and 3 years. The rate of tunnel infection (TI) was 0.046 epis/year. The incidence of the double-cuff PC-related ESI and TI tended to be lower than the incidence observed with the singlecuff PC. Episodes of peritonitis were 60 (0.30 epis/year), where 6 were subsequent to ESI and/or TI. Two PCs were lost due to ESI, 3 due to TI, and 11 due to peritonitis. Drainage failure, due to displacement of the PC caused by straightening, involved 3 PCs; 2 were lost. PC survival was 92%, 82%, and 74% at 1, 2 and 3 years, respectively.

By an easily used semicircular tunneler, the standard straight Tenckhoff PC can be stably positioned in an arcuate tunnel with both inner and outer exits directed downwards. This tunnel shape, as already suggested by some authors, appears to be an effective technical solution to reducing the PC-related complication rates.

To review peritoneal dialysis catheter failures and to describe a technique of repairing malpositioned catheters.

Two prospective case reports utilizing this technique are reported.

A tertiary care hospital.

Two patients on chronic peritoneal dialysis with malfunctioning catheters.

Both patients underwent reposition of their malpositioned continuous ambulatory peritoneal dialysis catheters by laparoscopic suture technique.

Outcome was measured by the successful return of adequate peritoneal dialysis.

Both case studies show correction of malpositioned catheters with the return of successful peritoneal dialysis.

The repositioning and suture application of malpositioned Tenckhoff catheters by laparoscopic surgery is a viabletechnique that can salvage the majority of mal positioned catheters and save the patients additional hospital time and recovery.