Peritoneal Membrane Transport Characteristics Research Articles

Baseline Peritoneal Membrane Transport Characteristics Are Associated with Peritonitis Risk in Incident Peritoneal Dialysis Patients.

The peritoneal equilibration test (PET) is a semi-quantitative measurement that characterizes the rate of transfer of solutes and the water transfer rate across the peritoneum in patients treated with peritoneal dialysis (PD). The results of the PET are used to maximize daily peritoneal ultrafiltration and solute clearances. Previous studies have shown that high transport status is associated with ultrafiltration failure, malnutrition, and reduced survival; however, the way in which peritoneum transport characteristics affect peritonitis risk is unknown. In the current cohort study, we recruited 898 incident-PD patients and used intention-to-treat analysis to test if baseline PET affected the subsequent 3-year peritonitis rate. Among all recruited PD patients, 308 (34.2%) developed peritonitis within three years. Multivariate Cox regression analysis showed that the high-transport group has the greatest peritonitis risk (HR 1.98, 95% CI: 1.08–3.62) even after an adjustment for demographics, comorbid diseases, and biochemical measurements. We concluded that a baseline high peritoneal membrane transport rate is an independent risk factor for peritonitis in incident PD patients.

The Effect of Far-Infrared Therapy on the Peritoneal Membrane Transport Characteristics of Uremic Patients Undergoing Peritoneal Dialysis: An Open-Prospective Proof-of-Concept Study.

Long-term peritoneal dialysis (PD) can lead to detrimental changes in peritoneal membrane function, which may be related to the accumulation of glucose degradation products. A previous study demonstrated that 6 months of far-infrared (FIR) therapy may decrease glucose degradation products in PD dialysate. Due to limited literature on this matter, this study aims to investigate the effect of FIR therapy on the peritoneal membrane transport characteristics of PD patients. Patients were grouped according to baseline peritoneal transport status: lower transporters (low and low-average) and higher transporters (high-average and high). Both groups underwent 40 min of FIR therapy twice daily for 1 year. In lower transporters, FIR therapy increased weekly dialysate creatinine clearance (6.91 L/wk/1.73 m2; p = 0.04) and D/P creatinine (0.05; p = 0.01). In higher transporters, FIR therapy decreased D/P creatinine (−0.05; p = 0.01) and increased D/D0 glucose (0.05; p = 0.006). Fifty percent of high transporter patients shifted to high-average status after FIR therapy. FIR therapy may decrease D/P creatinine for patients in the higher transporter group and cause high transporters to shift to high-average status, which suggests the potential of FIR therapy in improving peritoneal membrane function in PD patients.

MO710GALECTIN-3, IS IT A NEW PLAYER IN PERITONEAL INFLAMMATION AMONG PATIENTS UNDERGOING PERITONEAL DIALYSIS?

Abstract Background and Aims Peritoneal dialysis (PD) is a common used method for renal replacement therapy. Prolonged PD treatment causes structural and functional changes in the peritoneal membrane which are attributed to local inflammatory process in the peritoneal cavity. Galectin-3 (Gal-3) is a galactoside-binding lectin with pro-inflammatory and pro-fibrotic effects. The aim of this study was to assess correlation between Gal-3 serum and dialysate effluent levels with peritoneal membrane transport characteristics. Method Gal-3 levels in serum and dialysate effluent were measured simultaneously in prevalent PD patients in morning visit or during peritoneal equilibration test (PET). Gal-3 levels were correlated with clinical and laboratory parameters. Interlukin (IL) -6 levels were measured in dialysate effluent. Gal-3 mRNA and protein expression were evaluated after exposure of primary endothelial cell culture to several dialysate solutions. Results 37 PD patients were included in the study; mean age was 65.7±13.1 years, mean dialysis vintage was 17.5±13 months. Gal-3 levels in dialysate effluent correlated with peritoneal equilibration test (PET) results (0.663, p=0.005) and effluent IL-6 levels (0.674, p=0.002) but not with serum Gal-3 levels or dialysis vintage. Patients with high PET results had higher effluent Gal-3 levels as compared average low PET results. In multivariate regression analysis effluent IL-6 level was the most dominant predictor of effluent Gal-3 levels. Gal-3 mRNA and protein expression in primary endothelial cell culture were not affected by stimulation with dialysate solutions. Conclusion Our study demonstrated presence of Gal-3 within the dialysate effluent in PD patients. Gal-3 levels correlated with peritoneal membrane transport characteristics and effluent IL-6 levels suggesting a role in the inflammatory process within the peritoneal cavity.

Peritoneal Membrane Transport Characteristics in Uni-PET with Preceding Icodextrin Dwell as Compared to Classic PET with Preceding Glucose Dwell: A Prospective Study

Peritoneal Membrane Transport Characteristics in Uni-PET with Preceding Icodextrin Dwell as Compared to Classic PET with Preceding Glucose Dwell: A Prospective Study

Randomized controlled trial to compare the tolerability and efficacy of treatment with Icodextrin 7.5% versus Dextrose 2.5% in chronic peritoneal dialysis patients with high/high average solute transport characteristics and low residual renal function

Aim: Comparison of tolerability and efficacy of treatment with icodextrin vs. dextrose 2.5% amongst high risk cohort of chronic peritoneal dialysis patients (high/high average solute transport characteristics and low residual renal function) over 3 months. Study Design and Methodology: The study was an open-label, comparative, prospective, randomized controlled trial, conducted at department of Nephrology, Postgraduate Institute of Medical Education and Research, Chandigarh, India. A total of 349 end stage renal disease patients on chronic peritoneal dialysis were screened for eligibility over a period of 6 months and 41 patients with high / high average solute transport characteristics and low residual renal function were randomized to receive either icodextrin 7.5% solution or 2.5% dextrose solution in long dwell. Patients were assessed for adequacy of peritoneal dialysis (creatinine & urea clearance), peritoneal membrane transport characteristics including solute clearance (standard peritoneal equilibration test), body composition, total body water, fat mass and fat free mass (using whole body tetrapolar bioimpedance analyzer) at baseline and at the end of 3 months. Statistical Analysis: Continuous variables were compared with independent samples paired t test if normally distributed, or with Mann–Whitney U test if the distribution was skewed. Categorical variables were analyzed with Chi-square test or Fisher exact test as appropriate. Pearson's correlation coefficient was calculated between different quantitative variables. Paired t test and Wilcoxon signed-rank test were used for within-group comparisons. Repeated measure ANOVA was used to compare bioelectrical impedance between intervention groups. Results: The study has shown that use of icodextrin based continuous ambulatory peritoneal dialysis resulted in better ultrafiltration and improved solute clearance when compared to 2.5% dextrose based peritoneal dialysis in a select cohort of patients having high/high average transporter characteristics with poor residual renal function, however, it didn't significantly alter total body water and failed to translate into improvements in either patient's or physician's assessment of global health of response to therapy atleast at 3 months. Conclusions: Although use of icodextrin based peritoneal dialysis solution for long dwell resulted in significant improvement in solute clearance and ultrafiltration nevertheless failed to translate into better hydration status or subjective improvement scores atleast at 3 months.

MON-072 FAST PERITONEAL MEMBRANE PERMEABILITY WAS NOT ASSOCIATED WITH MORTALITY IN PATIENTS ON PERITONEAL DIALYSIS

Peritoneal dialysis (PD) patients have different peritoneal membrane transport characteristics. In this study, we aimed to investigate the relationship between the peritoneal membrane transport and mortality in incident PD patients. The study included 231 PD patients. A standardized peritoneal equilibration test (PET) test was performed on all patients, 4-6 weeks after initiation of regular PD. The patients were divided two groups according to PET result: fast group (fast and fast-average) and slow group (slow-average and slow). The mean patient age was 50.4±14.1 years. Fast group included more male patients (70% vs 56.4%, p=0.038). Fast group had a lower peritoneal Kt/V (1.67±0.37 vs 1.84±0.45, p=0.02) and ultrafiltration (744±627 vs 1050±703, p=0.012), compared to slow group. However, the survival of the PD patients was comparable between the two groups (log-rank P=0.481). Cox-multivariate analysis revealed only age (RR=1.075, p < 0.001), and diabetes (RR = 2.958, p = 0.001) to be independent predictors of mortality. In our study, initial fast peritoneal membrane permeability was not associated with mortality in PD patients.

The relationship between vascular endothelial growth factor (VEGF) in the serum and drained dialysate with the quality of peritoneal dialysis and peritoneal membrane transport rates

Vascular endothelial growth factor (VEGF), a powerful angiogenetic agent crucial for microvascular hyperpermeability and neoangiogenesis in the peritoneum, is associated with increased solute transport rates in chronic peritoneal dialysis (PD) patients. We investigated the correlation between serum and drained dialysate (dd) concentrations of VEGF and the transport characteristics of peritoneal membrane and dialysis quality in 20 patients with end-stage renal failure at the beginning and after six months of PD. The serum VEGF (sVEGF) concentration rose significantly (149.33?}116.71 pg/ mL vs 239.36?}102.23 pg/mL; p=0.012) and ddVEGF concentration increased slightly (38.44?}50.47 pg/mL vs 43.55?}51.10 pg/mL) during the first 6 months of PD. At the beginning of chronic PD, ddVEGF concentrations correlated inversely with the peritoneal equilibrium test (PET) glucose (R=-0.565; p=0.009) and creatinine (R=-0.506; p=0.023) and residual renal function (RRF) (R=-0.691; p=0.001); sVEGF concentrations inversely correlated with PET creatinine (R=-0.457; p=0.043) and residual diuresis (RD) (R=-0.691; p=0.001). After 6 months of treatment, ddVEGF concentrations correlated directly with PETcreatinine (R=0.450; p=0.047), and inversely with RRF (R=-0.552; p=0.012) and residual renal weekly Kt/V (R=-0.488; p=0.029). The sVEGF concentration inversely correlated with RD (R=-0.589; p=0.006). High ddVEGF at the beginning of PD is predictive of adverse alterations of the peritoneal membrane, i.e. increased transport rate of glucose and creatinine. ddVEGF values may help to identify patients who will preserve adequate transport characteristics of the peritoneal membrane and maintain successful long-term PD.

Associations Between Peritoneal Glucose Exposure, Glucose Degradation Product Exposure, and Peritoneal Membrane Transport Characteristics in Peritoneal Dialysis Patients: Secondary Analysis of the balANZ Trial.

Glucose is the most commonly used osmotic medium in peritoneal dialysis (PD) solutions, and its use has been associated with both local and systemic adverse effects. Previous, single-center, observational cohort studies have reported conflicting findings regarding whether a relationship exists between peritoneal glucose exposure and peritoneal small solute transport rate. In this secondary analysis of the balANZ multicenter, multinational, randomized controlled trial of a neutral pH, ultra-low glucose degradation product (biocompatible) versus conventional PD solutions over a 2-year period, the relationship between time varying peritoneal glucose exposure and change in peritoneal solute transport rate, (measured as dialysate to plasma creatinine ratio at 4 hours [D:PCr4h]), was evaluated using multivariable, multilevel linear regression. Baseline peritoneal glucose exposure was also assessed as either a continuous or categorical variable. The study included 165 patients (age 58.1 ± 14.2 years, 55% male, 33% diabetic). Peritoneal glucose exposure increased over time (coefficient 1.49, 95% confidence interval [CI] 1.07 - 1.92 and was not significantly associated with change in D:PCr4h (coefficient 0.00004, 95% CI -0.0001 - 0.0002, p = 0.68). Similar results were found when peritoneal glucose exposure was examined as a baseline continuous or categorical variable. A significant 2-way interaction was observed with PD solution type, whereby a progressive increase in D:PCr4h was seen in the patients receiving conventional PD solution, but not in those receiving biocompatible solution. Increases in peritoneal solute transport rate in PD patients over time were not associated with peritoneal glucose exposure, although a strong and positive association with PD solution glucose degradation product content was identified. Peritoneal glucose exposure may be a less important consideration than peritoneal glucose degradation product exposure with respect to peritoneal membrane function over time.

Effluent and serum protein N-glycosylation is associated with inflammation and peritoneal membrane transport characteristics in peritoneal dialysis patients

Mass spectrometric glycomics was used as an innovative approach to identify biomarkers in serum and dialysate samples from peritoneal dialysis (PD) patients. PD is a life-saving treatment worldwide applied in more than 100,000 patients suffering from chronic kidney disease. PD treatment uses the peritoneum as a natural membrane to exchange waste products from blood to a glucose-based solution. Daily exposure of the peritoneal membrane to these solutions may cause complications such as peritonitis, fibrosis and inflammation which, in the long term, lead to the failure of the treatment. It has been shown in the last years that protein N-glycosylation is related to inflammatory and fibrotic processes. Here, by using a recently developed MALDI-TOF-MS method with linkage-specific sialic acid derivatisation, we showed that alpha2,6-sialylation, especially in triantennary N-glycans from peritoneal effluents, is associated with critical clinical outcomes in a prospective cohort of 94 PD patients. Moreover, we found an association between the levels of presumably immunoglobulin-G-related glycans as well as galactosylation of diantennary glycans with PD-related complications such as peritonitis and loss of peritoneal mesothelial cell mass. The observed glycomic changes point to changes in protein abundance and protein-specific glycosylation, representing candidate functional biomarkers of PD and associated complications.

Comparison of Change in Peritoneal Function in Patients on Continuous Ambulatory PD vs Automated PD.

Patients on automated peritoneal dialysis (APD) may have greater exposure to glucose in the PD fluid than those on continuous ambulatory PD (CAPD). If this causes long-term damage to the peritoneal membrane, it will have implications for a patient's choice of modality. Membrane function of long-term APD or CAPD patients was followed prospectively. The data were collected from electronic patient records in our unit from 2000 to 2014. The rate of change in membrane transport status (D/Pcr) and ultrafiltration (UF4) for each patient was calculated using the least square regression line equation. We identified 106 APD and 123 CAPD patients who had a mean of 8.4 peritoneal equilibration test (PET) over 5.6 years. No differences were found in the rate of changes in D/Pcr or UF4. Baseline solute clearance (Kt/V) was lower in APD patients (1.66 vs 1.76, p = 0.04). However, APD patients experienced incremental changes to dialysis prescription that resulted in a greater increase in Kt/V compared with CAPD patients. This is the largest study comparing the long-term effect of APD vs CAPD prescriptions. Despite more glucose being prescribed, there were no differences in the evolution of peritoneal membrane transport characteristics. The lower baseline Kt/V of APD patients might be explained by our aggressive use of incremental APD (tidal with dry day). Despite greater glucose prescriptions, initiating patients on APD based on patient preference appears to be safe for the long-term integrity of the peritoneal membrane.

Association between Redox Status of Serum Albumin and Peritoneal Membrane Transport Properties in Patients on Peritoneal Dialysis

Background: Albumin, the most abundant protein in the extracellular fluid, displays an important antioxidant activity. Increased levels of oxidized albumin levels (high human non-mercaptoalbumin (HNA) level) have been reported in the serum of patients with end-stage renal disease. In this study, we attempted to identify the albumin redox status in the serum of patients on peritoneal dialysis (PD) and examined the relationship between these proteins and the transport type of the peritoneal membrane and other clinical and laboratory variables. Methods: We performed a cross-sectional study of a cohort of 80 patients with end-stage renal disease receiving PD. Peritoneal transport characteristics were identified and after peritoneal equilibration test patients were grouped as high (high(H)/high-average (HA) group, n = 31) or low (low (L)/low-average (LA) group, n = 49) transporters. The redox state of human serum albumin was measured using high-performance liquid chromatography. Results: The fraction of human mercaptoalbumin (HMA) showed significantly higher values in patients with high transport status than those with low transport status (f(HMA) 64.0 ± 5.4 and 52.7 ± 10.4%, respectively). Our data showed that the H/HA transport characteristic was associated with lower albumin (3.76 ± 0.48 vs. 4.00 ± 0.35, p < 0.05), and lower levels of advanced oxidized protein product (p = 0.008) when compared with the L/LA type. A correlation analysis showed that there was a positive correlation between dialysate/plasma (D/P) creatinine and f(HMA) levels (r = 0.511, p < 0.0001), as well as hemoglobin levels r = 0.231, p = 0.044 and a negative correlation between D/P creatinine and serum albumin, cholesterol and LDL levels (r = -0.236, p = 0.039; r = -0.237, p = 0.038; r = -0.272, p = 0.018, respectively). Conclusions: This study showed that higher serum levels of reduced albumin f(HMA) appear to be associated with high/high average peritoneal membrane transport characteristics in the incident PD patients.

Automated Peritoneal Dialysis Prescriptions for Enhancing Sodium and Fluid Removal: A Predictive Analysis of Optimized, Patient-Specific Dwell Times for the Day Period

Remaining edema-free is a challenge for many automated peritoneal dialysis (APD) patients, especially those with fast ("high") transport characteristics. Although increased use of peritoneal dialysis (PD) solutions with high glucose concentrations may improve volume control, frequent use of such solutions is undesirable. We used the 3-pore kinetic model to evaluate 4 alternative therapy prescriptions for the APD day exchange in anuric patients with high, high-average, and low-average transport characteristics. Four prescriptions were modeled: Therapy 1: Optimal, individualized dwell times with a dry period. Therapy 2: Use of a midday exchange. Therapy 3: Use of an icodextrin-containing dialysate during a 14-hour dwell. Therapy 4: Use of optimal, individualized dwell times, followed by an icodextrin dwell to complete the daytime period. The alternative therapies were compared with a reference standard therapy using glucose solution during a 14-hour dwell. The nighttime prescription was identical in all cases (10 L over 10 hours), and all glucose solutions contained 2.27% glucose. Net ultrafiltration (UF), sodium removal (NaR), total carbohydrate (CHO) absorption, and weekly urea Kt/V for a 24-hour period were computed and compared. The UF and NaR were substantially higher with therapy 1 than with standard therapy (1034 mL vs 621 mL and 96 mmol vs 51 mmol respectively), without significant changes in CHO absorption or urea Kt/V. However, therapy 1 resulted in reduced β2-microglobulin clearance (0.74 mL/min vs 0.89 mL/min with standard therapy). Compared with therapy 1, therapy 2 improved UF and NaR (1062 mL vs 1034 mL and 99 mmol vs 96 mmol); however, that improvement is likely not clinically significant. Therapy 2 also resulted in a higher Kt/V (2.07 vs 1.72), but at the expense of higher glucose absorption (difference: 42 g). The UF and NaR were highest with a long icodextrin-containing daytime dwell either preceded by a short optimized dwell (1426 mL and 155 mmol) or without such a dwell (1327 mL and 148 mmol). The 3-pore model predictions revealed that patient-specific optimal dwell times and regimens with a longer day dwell might provide improved UF and NaR options in APD patients with a variety of peritoneal membrane transport characteristics. In patients without access to icodextrin, therapy 1 might enhance UF and NaR and provide a short-term option to increase fluid removal. Although that approach may offer clinicians a therapeutic option for the overhydrated patient who requires increased UF in the short term, APD prescriptions including icodextrin provide a means to augment sodium and fluid removal. Data from clinical trials are needed to confirm the predictions from this study.

Influence of Renin‐Angiotensin‐Aldosterone System‐Blocking Drugs on Peritoneal Membrane in Peritoneal Dialysis Patients

Therapy with renin-angiotensin-aldosterone system (RAAS)-blocking drugs prevents the development of fibrosis and angiogenesis in animal models and humans. In our study we have evaluated the systemic effect of RAAS blockade and the effect on peritoneal growth factors, cytokine production and membrane transport characteristics in patients on peritoneal dialysis. Thirty-seven peritoneal dialysis (PD) patients were enrolled in our cross-sectional study. Aldosterone and angiotensin II concentrations were measured in serum to determine the RAAS activity. The inflammatory and profibrotic activity was evaluated by measuring the concentration of C-reactive protein (CRP), serum albumin, and peritoneal concentration of interleukin-6 (IL-6), vascular endothelial growth factor (VEGF), plasminogen activator inhibitor-1 (PAI-1), transforming growth factor-β (TGF-β) and cancer antigen-125 (CA-125). The transport characteristics of the peritoneal membrane were analyzed with a peritoneal equilibration test (PET). Results were compared between the group with RAAS-blocking drugs (RAAS group) and the group without them (non-RAAS group). Mean serum aldosterone concentration was significantly lower in patients treated with ARB-blocking drugs (P = 0.001) and serum angiotensin II concentration was lower in patients treated with ACE inhibitors (P = 0.009). RAAS blockade resulted in lower peritoneal PAI-1 levels (748.1 to 1222.7 ng/L; P = 0.07) without any influence on CRP, peritoneal concentrations of IL-6, VEGF, TGF-β and CA-125, or alteration in peritoneal membrane characteristics tested by PET. RAAS-blocking drugs could be effective in preventing peritoneal fibrosis due to possible reduction of peritoneal PAI-1 concentrations that have already been etiologically linked with fibrin deposition in the pathogenesis of encapsulating peritoneal sclerosis.

Effects of neutral pH and low-glucose degradation product-containing peritoneal dialysis fluid on systemic markers of inflammation and endothelial dysfunction: a randomized controlled 1-year follow-up study

The local peritoneal effects of low-glucose degradation product (GDP)-containing peritoneal dialysis fluid (PDF) have been extensively described. However, the systemic effects of prolonged prescription of these solutions are unknown. This study aimed to evaluate the effects of neutral pH and low-GDP PDF on systemic inflammation and endothelial dysfunction markers in peritoneal dialysis (PD) patients. This is a multicenter, open labeled, randomized controlled trial including one hundred fifty-two patients initiating continuous ambulatory peritoneal dialysis for end-stage renal disease from seven centers in Korea. Participants were randomly allocated to conventional PDF (Stay safe®; Fresenius Medical Care, Bad Homburg, Germany) or low-GDP PDF (Balance®; Fresenius Medical Care) and were followed for 1 year. Primary outcome variable was the inflammation and endothelial dysfunction index (IEDI), a composite score derived from serum levels of soluble intercellular adhesion molecule (sICAM)-1, soluble vascular cellular adhesion molecule (sVCAM)-1 and high-sensitivity C-reactive protein (hs-CRP). sICAM-1, sVCAM-1, residual renal function (RRF), peritoneal membrane transport characteristics, ultrafiltration volume and nutritional parameters were measured as secondary outcome variables. Of 152 patients randomized, 146 (low-GDP: conventional PDF, 79:67) patients entered the trial (46% male, 53% with diabetes mellitus). At 12-month follow-up, the low-GDP group had significantly lower levels of IEDI, sICAM-1 and sVCAM-1 compared to the conventional group; hs-CRP was not different between groups. Peritoneal transport characteristics, RRF, nutritional parameters, incidence of peritonitis and death-censored technique survival were not different between groups. Neutral pH and low-GDP PDF likely produce fewer changes in markers of endothelial dysfunction compared to conventional PDF in incident PD patients.

BMP-7 stops TGF- in peritoneal fibrosis

In this issue, Loureiro, and Cabrera et al. study the regulation of transforming growth factor beta-1 (TGF-β) signalling by bone morphogenetic protein-7 (BMP-7) in the biology of peritoneal dialysis-related peritoneal fibrosis. Peritoneal dialysis (PD) is a highly effective and convenient mode of renal replacement therapy, the success of which depends on the structural and functional integrity of the peritoneal membrane. Progressive alterations in peritoneal membrane transport characteristics commonly cause technique failure in PD, and are associated with fibroproliferative changes in the peritoneal membrane, including vasculopathy, accumulation of submesothelial extracellular matrix, and denudation and altered appearance of mesothelial cells [1]. The fundamental causes of these changes are likely to be long-term exposure to bioincompatible dialysate, together with recurrent episodes of bacterial peritonitis. Fibroproliferative diseases are largely driven by fibroblasts, spindle-shaped, motile, contractile cells that respond to pro-fibrotic stimuli by synthesizing and organizing extracellular matrix. Fibroblasts may originate from proliferation of local tissue fibroblasts, from circulating bone marrow-derived precursors (fibrocytes) and from resident epithelial cells by epithelial-to-mesenchymal transition (EMT) [2]. During EMT, epithelial cells lose intercellular adhesiveness and apical–basal polarity, and acquire a motile and contractile phenotype [3]. High-glucose concentrations typical of peritoneal dialysate induce such phenotypic change in mesothelial cells in vitro [4]. Additionally, the previous work of Cabrera et al. demonstrated progressive loss of epithelial morphology in mesothelial cells

High Peritoneal Transport Status is Not an Independent Risk Factor for High Mortality in Patients Treated with Automated Peritoneal Dialysis

We undertook this study to elucidate whether baseline peritoneal membrane transport characteristics are associated with high mortality in incident automated peritoneal dialysis (APD) patients. This retrospective study includes 117 patients who started APD at Yonsei University Health System from 1996 to 2008 and had a PET within 3 months of APD initiation. High transporters were significantly older and had a higher incidence of cardiovascular disease. Patient survival for years 1, 3, and 5 were 85%, 64%, and 35% for high transporter and 94%, 81%, and 68% for non-high transporter group (P<0.01). Multivariate analysis revealed that age, diabetes, cardiovascular disease, serum albumin level, and residual renal function were independently associated with high mortality in APD patients. In contrast, high transport status was not a significant predictor for mortality in this population when the other covariates were included. Even though high transport was significantly associated with mortality in the univariate analysis, its role seemed to be influenced by other comorbid conditions. These findings suggest that the proper management of these comorbid conditions, as well as appropriate ultrafiltration by use of APD and/or icodextrin, must be considered as protective strategies to improve survival in peritoneal dialysis patients with high transport.

Relationship between dialysate oxidized protein and peritoneal membrane transport properties in patients on peritoneal dialysis

Increased levels of oxidized proteins have been reported in the serum of patients with end-stage renal disease, though little is known regarding the oxidized protein content of the dialysate in patients on peritoneal dialysis (PD) and no information is available as to how this may correlate with important clinical and laboratory variables, including abnormal peritoneal membrane function. In this study we attempted to identify oxidized proteins in the dialysate of patients on PD using western blot analysis, and examined the relationship between these proteins and the function of the peritoneal membrane and other clinical and laboratory variables. Peritoneal dialysate and serum samples were obtained from 18 patients on PD, and western blot analysis using an antibody to oxidized protein was carried out with reprobing for albumin. Oxidized protein/albumin ratios were determined and compared with various clinical and laboratory variables including peritoneal equilibration test results. Oxidized protein/albumin ratios were higher in the dialysate of patients who were high/high average transporters compared to low/low average transporters. Oxidized protein ratios were also found to be higher in the dialysate of patients who had diminished urine output as a reflection of loss of residual renal function. Negative correlations were noted between oxidized protein ratios in the dialysate and serum albumin levels and creatinine clearance. Higher levels of oxidized protein in the dialysate appear to be correlated with high/high average peritoneal membrane transport characteristics and may be related to loss of residual renal function. These preliminary findings suggest that it is plausible that oxidized proteins in the dialysate might play a contributory role in complications including membrane damage and ultrafiltration failure in patients on PD.

Encapsulating peritoneal sclerosis-a life-threatening condition treated successfully with adhesiolysis and Jones tube insertion.

Sir, Encapsulating sclerosing peritonitis, a life-threatening abdominal disease, is characterized by the formation of multiple fibrous adhesions. This leads to a ‘cocoon’ of fibrous tissue, encapsulating either the small or whole bowel— causing intestinal obstruction. It was first recognized as a complication of peritoneal dialysis (PD) in 1980 [1], where it usually presents as small bowel obstruction, ascites or ultrafiltration failure. It is thought to be related to both duration of catheter use and peritoneal membrane transport characteristics, being more common in ‘fast transporters’ [2]. Convincing evidence of cure has come only from adhesiolysis, which releases the fibrous adhesions [1]. Intraluminal stenting after adhesiolysis for small bowel obstruction was first described by White in 1956. Despite the technique being modified by Munro and Jones in 1978 [3], it has never gained widespread popularity in the UK. The major complication of surgery is a high recurrence rate. In one series, 11/47 patients (23.4%) experienced recurrence, 10 undergoing a second operation, and 4 requiring a third operation [4]. The mortality is uncertain, with a wide range reported (2–56%). The rationale for our technique was to further reduce mortality and recurrence rate, and provide an alternative to drug treatments (e.g. immunosuppression) whose side effects carry considerable morbidity. A 69-year-old woman, on PD for 10 years for ERF, was converted to haemodialysis in January 2003 due to recurrent peritonitis. In June 2003, she presented with recurrent ascites. An abdominal CT scan (below) suggested multiple encapsulating loculated collections in the abdomen. TPN was given for 6 weeks before surgical intervention. In September 2003, a laparotomy revealed encysted dense adhesions and a large pseudocyst in the pelvis entrapping the bowel. The adhesions were released and a Jones tube was placed through the entire length of the gastrointestinal tract. A Jones tube is a 3 m (18 gauge) tube with side perforations and a balloon at the distal end. During surgery, the tube was advanced via the nasogastric route through the entire length of the bowel and the distal end came out of the rectum. The balloon was inflated and the small bowel arranged in orderly fashion, so that even if fibrosis did occur, the bowel did not get entrapped. This was left in situ for 1 week, with TPN and haemodialysis continuing. She was discharged 7 months later and is currently well on haemodialysis, with no evidence of recurrence. In ERF patients, encapsulating peritoneal sclerosis is a rare disease and is usually a long-term complication of peritoneal dialysis. This type of surgery has to be slow (4 h in our case) and careful, releasing bowel from fibrous bands all along its length. Adhesiolysis with intraluminal stenting should be considered as an option in the treatment of encapsulating peritoneal sclerosis. Conflict of interest statement. None declared.

Comparison between Bicarbonate/Lactate and Standard Lactate Dialysis Solution in Peritoneal Transport and Ultrafiltration: A Prospective, Crossover Single-Dwell Study

It has been proposed that biocompatible bicarbonate/lactate based (Bic/Lac), physiologic-pH peritoneal dialysis (PD) solutions will be beneficial in long-term PD. However, we do not yet have detailed knowledge concerning the comparative physiology of buffer transport for these new solutions and their impact on underlying peritoneal transport of solutes and ultrafiltration (UF). The purpose of this study was to investigate the profile of buffer handling and peritoneal membrane transport characteristics during a single dwell of the new Bic/Lac-based versus standard lactate-based (Lac) PD solution. In this prospective crossover study, we compared a 25 mmol/L bicarbonate/15 mmol/L lactate buffered, physiologic pH, low glucose degradation product (GDP) solution (Physioneal; Baxter Healthcare, McGaw Park, Illinois, USA) with a standard lactate buffered, acidic pH, conventional solution (Dianeal; Baxter). 18 patients underwent two peritoneal equilibration tests (PETs) with 2.5% Dianeal and 2.5% Physioneal separated by 1 week. Buffer transport, mass transfer area coefficients (MTACs), solute transport, and UF were determined for the two PETs. All bags were weighed by a nurse before instillation and after drainage to assess the net UF in each dwell. 18 patients that met the inclusion criteria were enrolled in this study. Whereas intraperitoneal pH remained constant at 7.52 +/- 0.11 throughout the dwell with the Bic/Lac solution, pH was still in the acidic range with the Lac solution after 1 hour (7.29 +/- 0.13, p < 0.001); this difference disappeared after the second hour of dwell. The MTACs for creatinine (10.68 +/- 3.66 vs 10.73 +/- 2.96 mL/minute/1.73 m(2), p > 0.05) and urea (27.94 +/- 10.50 vs 27.62 +/- 6.95 mL/min/1.73 m(2), p > 0.05), for Bic/Lac versus Lac respectively, did not differ between these two solutions; transport of glucose and other solutes was also similar. However, after a 4-hour dwell with Bic/Lac solution, net UF was significantly lower than that observed with Lac solution (274.2 +/- 223.3 mL vs 366.1 +/- 217.3 mL, p = 0.026). Compared to standard Lac-based solution, Bic/Lac based, pH neutral, low-GDP solution avoids intraperitoneal acidity. Peritoneal mass transport kinetics are similar for small solutes. Net UF is significantly lower with Bic/Lac solution; the mechanism for this is unclear.

Peritoneal Transport in Peritoneal Dialysis Patients Using Glucose-Based and Amino Acid-Based Solutions

To evaluate peritoneal transport of fluid and solutes in continuous ambulatory peritoneal dialysis (CAPD) patients using amino acid (AA)-based versus glucose-based dialysis solutions. Using iodine-labeled human serum albumin ((125)I-HSA) as intraperitoneal volume marker, peritoneal transport was investigated in a group of 20 clinically stable patients (11 females and 9 men, age 53 +/- 15 years) on CAPD for 15 - 101 months. Two paired 4-hour dwells, one with 1.36% glucose and one with 1.1% AA dialysis solution, were performed in each patient. Intraperitoneal dialysate volume, fluid absorption rate, and diffusive mass transport coefficients (K(BD)) and sieving coefficients (S) for glucose, creatinine, urea, potassium, and total protein were estimated for each dwell study. Dwell studies with AA solution were used to estimate K(BD) values for individual AAs. Intraperitoneal dialysate volume was higher for AA solution in comparison with glucose solution due to the higher osmolality of the AA solution. No statistically significant difference was found for K(BD) or S for creatinine, urea, potassium, or total protein in the dwell studies with either solution, whereas K(BD) for glucose was higher with AA than with glucose solution. Mean values of K(BD) of AA were similar but with high standard deviation, reflecting inter-individual variations in peritoneal transport rate. Our results indicate that the AA peritoneal transport rate is strongly dependent on transport characteristics of the individual peritoneal membrane.