Fluid Tonicity Affects Peritoneal Characteristics Derived by 3-Pore Model.

Background:It is typically assumed that within short time-frames, patient-specific peritoneal membrane characteristics are constant and do not depend on the initial fluid tonicity and dwell duration. The aim of this study was to check whether this assumption holds when membrane properties are estimated using the 3-pore model (3PM).Methods:Thirty-two stable peritoneal dialysis (PD) patients underwent 3 8-hour peritoneal equilibration tests (PETs) with different glucose-based solutions (1.36%, 2.27%, and 3.86%). Temporary drainage was performed at 1 and 4 hours. Glucose, urea, creatinine, sodium, and phosphate concentrations were measured in dialysate and blood samples. Three-pore model parameters were estimated for each patient and each 8-hour PET separately. In addition, model parameters were estimated using data truncated to the initial 4 hours of peritoneal dwell.Results:In all cases, model-estimated parameter values were within previously reported ranges. The peritoneal absorption (PA) and diffusive permeability for all solutes except sodium increased with fluid tonicity, with about 18% increase when switching from glucose 2.27% to 3.86%. Glucose peritoneal reflection coefficient and osmotic conductance (OsmCond), and fraction of hydraulic conductance for ultrasmall pores decreased with fluid tonicity (over 40% when switching from glucose 1.36%). Model fitting to the truncated 4-hour data resulted in little change in the parameters, except for PA, peritoneal hydraulic conductance, and OsmCond, for which higher values for the 4-hour dwell were found.Conclusion:Initial fluid tonicity has a substantial impact on the 3PM-estimated characteristics of the peritoneal membrane, whereas the impact of dwell duration was relatively small and possibly influenced by the change in the patient's activity.

Carer's burden of peritoneal dialysis patients. Questionnaire and scale validation. / Sobrecarga de los cuidadores de pacientes de diálisis peritoneal. Validación de cuestionario y baremos.

INTRODUCTION: Carers of peritoneal dialysis patients may suffer from burden, the characteristics of which differ from burden due to dementia, cancer or other dependent conditions. AIMS: To ascertain the reliability and validity of the Peritoneal Dialysis Carer Burden Questionnaire (PDCBQ), previously created, and to design the burden scale. METHODS: Observational, multicentre study of carers and patients on peritoneal dialysis for more than 3 months. Sociodemographic characteristics of patients and carers, patient dependency, perceived health (SF-36) and carer burden (Zarit scale) were recorded, as well as PDCBQ via 3 scales: dependence, subjective burden and objective burden. RESULTS: One hundred seven patients and their carers from 8 hospitals were evaluable. Carers were mainly women (83.2%), aged 57.50±14.69 years, and 36.4% worked out of the home. The internal consistency of the Zarit scale and the PDCBQ were high (Cronbach's α between 0.808 and 0.901). Significant correlation was found between the Zarit scale and PDCBQ (r=0.683). The concordance analysis between 3 degrees of Zarit Scale and PDCBQ tertiles was good or acceptable (Kendall τ-b: 0.570, P<.001). The exploratory factor analysis of the main factors revealed 3 factors, which were successfully correlated with the design of the PDCBQ. A new carer burden scale was designed. CONCLUSIONS: The study shows good reliability with high internal consistency of the PDCBQ. Factorial analysis shows good construct and good correlation, and acceptable concordance with the Zarit Burden Scale confirmed criterion validity. The questionnaire is suitable to be applied in clinical practice.

Measuring peritoneal absorption with the prolonged peritoneal equilibration test from 4 to 8 hours using various glucose concentrations.

BACKGROUND: Peritoneal fluid flows such as small-pore ultrafiltration and free water transport can now be calculated by means of the modified peritoneal equilibration test (PET). To calculate peritoneal fluid absorption, volume markers have been used, but that method is not easily applicable in clinical practice. Alternatively, absorption can be estimated using the personal dialysis capacity test. However, a method of measuring overall peritoneal absorption together with the PET is lacking. The aim of the present study was to assess whether overall peritoneal absorption was different when measured from the 4th to 8th hour in a prolonged PET using three different glucose solutions. METHODS: The study enrolled 32 stable peritoneal dialysis (PD) patients from a tertiary university hospital, who underwent three 8-hour prolonged PETs with 1.36%, 2.27%, and 3.86% glucose solution. The PETs were performed in random order over a period of less than 1 month. During the prolonged PET, the peritoneal volume was emptied and reinfused at 60 and 240 minutes and drained at 480 minutes. Peritoneal absorption was calculated as the volume difference between the 4th and the 8th hour. RESULTS: The dialysate-to-plasma ratio (D/P) of urea, the D/P creatinine, and the mass transfer area coefficient (MTC) of creatinine at 240 minutes were not significantly different with the three glucose solutions. The end-to-initial (D/D0) glucose, MTC urea, and MTC glucose were significantly different. All water transport parameters were significantly different, except for the 4- to 8-hour absorption volumes and rates. The peritoneal absorption rates were, for 1.36% solution, 1.03 ± 0.58 mL/min [95% confidence interval (CI): 0.83 to 1.24 mL/min]; for 2.27% solution, 0.86 ± 0.71 mL/min (95% CI: 0.61 to 1.11 mL/min); and for 3.86% solution, 1.05 ± 0.78 mL/min (95% CI: 0.77 to 1.33 mL/min). Peritoneal absorption volumes and rates from the 4th to the 8th hour showed good correlations for the various solutions. CONCLUSIONS: Using any glucose solution, the prolonged PET with voiding and reinfusion at the 4th hour could be a practical method for calculating overall peritoneal absorption from the 4th to the 8th hour in PD patients.

Oral protein-energy supplements in peritoneal dialysis: a multicenter study.

BACKGROUND: Protein-energy malnutrition is prevalent in peritoneal dialysis (PD) patients and is associated with increased morbidity and mortality. OBJECTIVE: To evaluate the impact of prophylactic treatment with an oral protein-energy supplement (Protenplus; Fresenius AG, Bad Homburg, Germany) on nutritional parameters in patients starting PD. DESIGN: Prospective, multicenter, randomized study of group A patients (Protenplus, n = 35) and group B (controls, n = 30), with evaluations at baseline and at 6 and 12 months. STATISTICAL METHODS: Efficacy of factors by linear mixed model analysis for repeated measurements, chi-square, t-test, and Mann-Whitney test. OUTCOME PARAMETERS: Patient compliance, serum albumin, and other nutritional parameters. RESULTS: No significant differences were found at baseline evaluation. During follow-up, a significant number of group A patients abandoned intake of the supplement due to non-compliance (n = 7) or side effects (n = 8) (chi2 p < 0.01). Patients with lower residual renal function were less likely to comply. The mixed model in the "intention to treat" analysis showed a significant increase related to supplement intake only in total lymphocyte count in group A. The "as treated" analysis of the 29 patients who fulfilled the study (9 in group A, 20 in group B) disclosed that belonging to group A constituted an independent factor for increased lymphocyte count (p < 0.001), body weight (p < 0.03), tricipital skinfold thickness (p < 0.01), middle-arm muscle circumference (p < 0.025), lean body mass (LBM) (p < 0.002), creatinine LBM related to body surface area (p < 0.001), and creatinine generation rate (p < 0.002). However, these data may have been biased by the high rate of noncompliance in group A. CONCLUSIONS: Protenplus proved to be unsuitable as a long term, oral protein-energy supplement in PD patients due to a high rate of noncompliance and intolerance, primarily among patients with lower residual renal function. The question of whether other products, better-tolerated as nutritional supplements, could compensate for daily protein peritoneal losses in long-term PD remains open.

Peritoneal function and adequacy calculations: current programs versus PD Adequest 2.0.

OBJECTIVE: Our current programs (CPs) were compared to PD Adequest 2.0 (PD-A) for calculations of peritoneal membrane transport and dialysis adequacy. DESIGN: Thirty peritoneal equilibration tests (PETs) and 24-hour balances (24hBs) were conducted and calculated using our CPs and PD-A. PATIENTS AND METHODS: Thirty hospital-controlled peritoneal dialysis (PD) patients were studied. The inclusion of correction factors (for glucose or plasmatic water) and of residual volume, and the use of 3 or 6 peritoneal samples were analyzed to discover the differences between programs. The main outcome measures were peritoneal permeability and adequacy parameters, evaluated by Student t-test (mean and paired comparisons) and linear regression for correlation. RESULTS: No significant differences were found in D/P values for small solutes. At the first step, mass transfer area coefficient (MTAC) urea and MTAC creatinine were significantly higher in DP-A than in CP, but MTAC glucose did not differ. The causes of differences were: (1) inclusion of a correction factor for aqueous plasmatic concentration of small solutes in CP; (2) lack of Inclusion of residual volume in peritoneal volumes in CP; and (3) use of 6 peritoneal samples in CP versus 3 in PD-A. At the second step, when the input data were made equivalent for both programs, the differences disappeared for MTAC urea, creatinine, and glucose (mean comparison), but creatinine and glucose remained different by paired comparison. Similar results were obtained when a correction for plasmatic aqueous concentration was applied to the data in both programs [MTAC urea: 22.60 +/- 4.27 ml/min (CP) vs 22.43 +/- 4.61 mL/min (PD-A), nonsignificant, r= 0.97; MTAC creatinine: 9.76 +/- 3.83 mL/min (CP) vs 10.61 +/- 3.07 mL/min (PD-A), nonsignificant, r = 0.98; MTAC glucose: 13.30 +/- 3.12 mL/min (CP) vs 11.87 +/- 3.41 m/min (PD-A), nonsignificant, r= 0.92]. Creatinine and glucose were different by paired t-test. No significant differences were found in Kt/V and urea generation rate. Weekly creatinine clearance [WCCr: 70.71 +/- 16.71 L (CP) versus 79.33 +/- 18.73 L (PD-A), p < 0.001] and creatinine generation rate [CrGR: 0.56 +/- 0.18 mg/min (CP) versus 0.61 +/- 0.19 mg/min (PD-A), p < 0.001) were significantly higher in PD-A than In CP owing to the lack of creatinine correction according to glucose concentration In the PD-A adequacy program. Finally, normalized protein nitrogen appearance according to Bergström [1.09 +/- 0.20 g/kg/d (CP) versus 1.03 +/- 0.21 g/kg/d (PD-A), p = 0.01] was different owing to the different algorithms and normalization method: standardized body weight in CP and actual body weight in PD-A. CONCLUSIONS: Provided that equivalent data are used, PD-A and CP yield similar results. The PD-A program needs external correction of data input: (1) for plasmatic water concentration in MTAC calculations, and (2) for peritoneal glucose interference with creatinine analysis (Jaffé method) In WCCr and CrGR calculations; otherwise, It may give falsely optimistic results.