Validation by Computer Simulation of Two Indirect Methods for Quantification of Free Water Transport in Peritoneal Dialysis

2005 ◽  
Vol 25 (1) ◽  
pp. 77-84 ◽  
Author(s):  
Daniele Venturoli ◽  
Bengt Rippe
Keyword(s):  
Peritoneal Dialysis ◽  
Water Transport ◽  
Free Water ◽  
Hydraulic Permeability ◽  
Nephrol Dial Transplant ◽  
Peritoneal Equilibration Test ◽  
Simple Method ◽  
Sodium Removal ◽  
Relative Contribution ◽  
Small Pore

Background In peritoneal dialysis, approximately 40% of the total osmotic ultrafiltration (UF) induced by glucose can be predicted to be due to “free” water transport across aquaporin-1 (APQ-1). Theoretically, it would be possible to assess the fraction of free water transport in the early phase of a hypertonic dwell, when UF rate is high and the relative contribution of Na+ diffusion is low. La Milia et al. [La Milia V. et al. Fast-fast peritoneal equilibration test (FAST-FAST-PET): a simple method for peritoneal hydraulic permeability study [Abstract]. Nephrol Dial Transplant 2002; 17 (Suppl 1):17–18] suggested a technique to assess sodium-associated water transport based on sodium removal (Na+R) divided by the plasma Na+ concentration during a “fast-fast” (60 minute) peritoneal equilibration test (PET) for 3.86% glucose, yielding an estimate of the UF passing through the small pores (UFSP). Free water transport (UF through ultrasmall pores; UFUSP) was obtained by subtracting UFSP from total UF. Although peritoneal Na+ transport is almost totally convective, this technique will slightly overestimate small-pore UF due to the presence of some small-pore Na+ diffusion from the circulation during the dwell. A way of dealing with this problem was presented recently by Smit (Smit W. et al. Quantification of free water transport in peritoneal dialysis. Kidney Int 2004; 66:849–854). Methods In the present study we used the three-pore model of peritoneal transport to predict the degree of overestimation of UFSP for the technique presented by La Milia et al., and any potential deviations from theory for the technique presented by Smit et al. Simulations were performed under ordinary conditions and during simulated UF failure for 3.86% glucose. The fractional UF coefficient accounted for by APQ-1 was set at 2%. Results Estimating the UFSP from the sodium-associated water transport according to the method by La Milia et al. consistently overestimated UFSP and underestimated UFUSP. These errors were, however, minimal for dwells lasting between 30 and 80 minutes. The technique by Smit et al. to calculate aquaporin-mediated water flow (UFUSP), using an elaborate correction for Na+ diffusion from the circulation during the dwell, seemed accurate in most situations but, in general, tended to moderately overestimate UFUSP at early dwell times (<30 minutes) and underestimate UFUSP at long dwell times (4 hours). Conclusions The technique presented by La Milia et al. to calculate free water transport during a fast-fast PET was found to be surprisingly accurate, although the procedure would further improve by the introduction of a correction algorithm. The technique by Smit is even more accurate for dwells up to 4 hours’ duration. However, since the Smit technique is elaborate, it is less practical for routine determinations of aquaporin-mediated water transport in peritoneal dialysis.

scholarly journals Peritoneal Water Transport Characteristics of Diabetic Patients Undergoing Peritoneal Dialysis: A Longitudinal Study

2017 ◽  
Vol 46 (1) ◽  
pp. 47-54 ◽  
Author(s):  
Ana Fernandes ◽  
Roi Ribera-Sanchez ◽  
Ana Rodríguez-Carmona ◽  
Antía López-Iglesias ◽  
Natacha Leite-Costa ◽  
...  
Keyword(s):  
Peritoneal Dialysis ◽  
Water Transport ◽  
Free Water ◽  
Volume Overload ◽  
Diabetic Patients ◽  
Longitudinal Analyses ◽  
Cross Sectional ◽  
Sodium Removal ◽  
Essential Stability ◽  
Stability Of Water

Background: Volume overload is frequent in diabetics undergoing peritoneal dialysis (PD), and may play a significant role in the excess mortality observed in these patients. The characteristics of peritoneal water transport in this population have not been studied sufficiently. Method: Following a prospective, single-center design we made cross-sectional and longitudinal comparisons of peritoneal water transport in 2 relatively large samples of diabetic and nondiabetic PD patients. We used 3.86/4.25% glucose-based peritoneal equilibration tests (PET) with complete drainage at 60 min, for these purposes. Main Results: We scrutinized 59 diabetic and 120 nondiabetic PD patients. Both samples showed relatively similar characteristics, although diabetics were significantly more overhydrated than nondiabetics. The baseline PET disclosed lower ultrafiltration (mean 439 mL diabetics vs. 532 mL nondiabetics, p = 0.033) and sodium removal (41 vs. 53 mM, p = 0.014) rates in diabetics. One hundred and nine patients (36 diabetics) underwent a second PET after 12 months, and 45 (14 diabetics) underwent a third one after 24 months. Longitudinal analyses disclosed an essential stability of water transport in both groups, although nondiabetic patients showed a trend where an increase in free water transport (p = 0.033) was observed, which was not the case in diabetics. Conclusions: Diabetic patients undergoing PD present lower capacities of ultrafiltration and sodium removal than their nondiabetic counterparts. Longitudinal analyses disclose an essential stability of water transport capacities, both in diabetics and nondiabetics. The clinical significance of these differences deserves further analysis.

scholarly journals Measuring Peritoneal Absorption with the Prolonged Peritoneal Equilibration Test from 4 to 8 Hours Using Various Glucose Concentrations

2014 ◽  
Vol 34 (6) ◽  
pp. 605-611 ◽  
Author(s):  
Josep Teixidó–Planas ◽  
Maria Isabel Troya–Saborido ◽  
Guillermo Pedreira–Robles ◽  
Milagros Del-Rio–Lafuente ◽  
Ramon Romero–Gonzalez ◽  
...  
Keyword(s):  
Water Transport ◽  
Peritoneal Fluid ◽  
Glucose Solution ◽  
Free Water ◽  
Random Order ◽  
Practical Method ◽  
University Hospital ◽  
Transport Parameters ◽  
Peritoneal Equilibration Test ◽  
Small Pore

BackgroundPeritoneal 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.MethodsThe 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.ResultsThe 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.ConclusionsUsing 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.

Ultrafiltration and Absorption in Evaluating Aquaporin Function from Peritoneal Transport of Sodium

2007 ◽  
Vol 27 (6) ◽  
pp. 687-690 ◽  
Author(s):  
Jacek Waniewski ◽  
Malgorzata Debowska ◽  
Bengt Lindholm
Keyword(s):  
Water Transport ◽  
Sodium Transport ◽  
Fluid Transport ◽  
Free Water ◽  
Nephrol Dial Transplant ◽  
Simple Method ◽  
Water Fraction ◽  
Sodium Diffusion ◽  
The Impact ◽  
Dialysate Sodium

Background Evaluation of free water transport is a tool for assessing aquaporin function in peritoneal dialysis patients. The dialysate “sodium dip” and estimation of sieving coefficient for sodium may be used for quantification of the free water fraction in ultrafiltration flow from blood to the peritoneal cavity. Method The mini peritoneal equilibration test (mini-PET) [La Milia et al., Nephrol Dial Transplant 2002; 17(Suppl 3):17–18] is a simple method for evaluating free water transport using sodium as a marker. We compared the evaluation of free water transport using the mini-PET against detailed data on fluid and sodium transport from clinical dwell studies using a macromolecular volume marker to estimate fluid absorption and ultrafiltration rates, and the modified Babb–Randerson–Farrell model to assess the sodium transport components. Results and Conclusion According to our results, the mini-PET may result in underestimation of fluid transport by about 20% because it neglects the impact of peritoneal fluid and solute absorption and sodium diffusion during the peritoneal dwell time. Nevertheless, estimation of the free water fraction in the mini-PET yields values (about 0.4) similar to the more detailed analysis.

scholarly journals The contribution of free water transport and small pore transport to the total fluid removal in peritoneal dialysis

2005 ◽  
Vol 68 (4) ◽  
pp. 1849-1856 ◽  
Author(s):  
Alena Parikova ◽  
Watske Smit ◽  
Dirk G. Struijk ◽  
Machteld M. Zweers ◽  
Raymond T. Krediet
Keyword(s):  
Peritoneal Dialysis ◽  
Water Transport ◽  
Free Water ◽  
Fluid Removal ◽  
Small Pore ◽  
Total Fluid

scholarly journals Analysis of Ultrafiltration Failure Diagnosed at the Initiation of Peritoneal Dialysis with the Help of Peritoneal Equilibration Tests with Complete Drainage at Sixty Minutes. A Longitudinal Study

2016 ◽  
Vol 36 (4) ◽  
pp. 442-447 ◽  
Author(s):  
Daniela Machado Lopes ◽  
Ana Rodríguez-Carmona ◽  
Teresa García Falcón ◽  
Andrés López Muñiz ◽  
Tamara Ferreiro Hermida ◽  
...  
Keyword(s):  
Peritoneal Dialysis ◽  
Water Transport ◽  
Time Course ◽  
Free Water ◽  
Control Group ◽  
First Year ◽  
Study Group ◽  
Ultrafiltration Failure ◽  
Small Pore

BackgroundUltrafiltration failure (UFF) diagnosed at the initiation of peritoneal dialysis (PD) has been insufficiently characterized. In particular, few longitudinal studies have analyzed the time course of water transport in patients with this complication.ObjectiveTo investigate the time course of peritoneal water transport during the first year on PD in patients presenting UFF since the initiation of this therapy (study group).MethodProspective, observational, single-center design. We analyzed, at baseline and after 1 year of follow-up, peritoneal water transport in 19 patients incident on PD with UFF. We used incident patients without UFF as a control group. Water transport was characterized with the help of 3.86/4.25% dextrose-based peritoneal equilibration tests (PETs) with complete drainage at 60 minutes.ResultsThe study group revealed a disorder of water transport affecting both small-pore ultrafiltration (SPUF) ( p = 0.054 vs incident without UFF) and free water transport (FW T) ( p = 0.001). After 1 year of follow-up, FWT displayed a general increasing trend in the study group (mean variation 48.9 mL, 95% confidence interval [CI] 15.5, 82.2, p = 0.012), while the behavior of SPUF was less predictable (-4.8 mL, 95% CI -61.4, 71.1, p = 0.85). These changes were not observed in incident patients without UFF. Neither initial clinical characteristics, baseline PET-derived parameters, or suffering peritoneal infections during the first year predicted the time course of the capacity of UF in the study group. Recovery from incident UFF was apparently linked to improvement of SPUF.ConclusionsPatients with UFF at the start of PD suffer a disorder of peritoneal water transport affecting both FWT and SPUF. Free water transport increases systematically in these patients after 1 year of follow-up. The evolution of SPUF is less predictable, and improvement of this parameter marks reversibility of this complication.

MO687FREE WATER TRANSPORT AND ABSOLUTE DIP OF DIALYSATE SODIUM CONCENTRATION: EARLY CLINICAL PARAMETERS FOR PERITONEAL FIBROSIS IN PD PATIENTS?

2021 ◽  
Vol 36 (Supplement_1) ◽  
Author(s):  
Marisa Roldão ◽  
Rachele Escoli ◽  
Hernâni Gonçalves ◽  
Francisco Ferrer ◽  
Karina Lopes
Keyword(s):  
Peritoneal Dialysis ◽  
Water Transport ◽  
Pearson Correlation ◽  
Statistical Significance ◽  
Sodium Concentration ◽  
Ca 125 ◽  
Sodium Removal ◽  
Small Pore ◽  
Dialysate Sodium ◽  
Sodium Sieving

Abstract Background and Aims Reduction of peritoneal salt and water removal is an important cause of shortened patient and technique survival in peritoneal dialysis (PD). The aim of this study was to longitudinally analyze changes in fluid and solute transport parameters in PD patients during the first year of treatment, using peritoneal equilibration test (PET). Method Retrospective observational study of incident PD patients who underwent 4-hour 3.86% glucose PET with additional measurement of ultrafiltration at 1 hour, 1 month after PD initiation and 12 months later. Parameters of peritoneal transport such as dialysate-to-plasma ratio of creatinine (D/Pcreat), ultrafiltration at 1 and 4 hours, small-pore ultrafiltration (SPUF), free water transport (FWT), sodium removal and absolute dip of dialysate sodium concentration (ΔDNa) at 1 hour (as an expression of sodium sieving), were calculated. Serum cancer antigen 125 (CA-125) was also assessed. Clinical, analytical and demographic data were analyzed. Statistical analysis was performed using SPSS (Version 23 for Mac OSX). Results The average age of 16 incident PD patients was 58.69 ± 8.51 years, 10 (62.5%) were male and 5 (31.8%) were diabetic. Ten patients (62.5%) were on automated peritoneal dialysis (APD). One month after PD initiation, membrane characteristics were: D/P = 0.684 ± 0.589, total UF at 4h = 0.696 ± 0.283L, UF at 1h = 0.487 ± 0.162L, SPUF = 0.303 ± 0.359L, FWT = 0.207 ± 0.738L, %FWT = 51.855 ± 11.828%, sodium removal = 38.048 ± 16.087mmol/L and ΔDNa = 11.125 ± 3.34mmol/L. Average serum CA-125 was 51.206 ± 22.6U/mL. A paired sample t-test was performed to compare these parameters 1 and 12 months after PD initiation and revealed a statistically significant increase of 0.11± 0.196L (p=0.042) on SPUF and 18.607 ± 7.1mmol/L (p=0.019) on sodium removal. ΔDNa showed a decrease of 2.5 ± 0.743mmol/L (p=0.005) and % FWT of 11.782 ± 12.831% (p=0.002). FWT also showed a decrease of 0.168 ± 0.019L, total UF at 4h of 0.206 ± 0.142L and UF at 1h of 0.114 ± 0.243L, however did not reach statistical significance. D/Pcreat remained stable. CA-125 showed a mild decrease of 3.644 ± 22.364U/mL although not statistically significant. Pearson correlation revealed a positive correlation between the variation of total UF at 4h and the variation of FWT (r=0.553, p=0.026) and ΔDNa (r=0.503, p=0.047), but not with SPUF, sodium removal, D/Pcreat or CA-125, during the study follow-up period. Conclusion The reduction of FWT through aquaporins and, particularly, the reduction of ΔDNa as a sodium sieving measure, appear to be the first functional changes in peritoneal membrane, suggesting that fibrosis may begin soon after PD initiation. Our results indicate that FWT and ΔDNa can be used to access fibrotic peritoneal alterations earlier than other conventional parameters such as D/Pcreat.

Quantification of Free Water Transport during the Peritoneal Equilibration Test

2009 ◽  
Vol 29 (5) ◽  
pp. 523-527 ◽  
Author(s):  
Trijntje T. Cnossen ◽  
Watske Smit ◽  
Constantijn J.A.M. Konings ◽  
Jeroen P. Kooman ◽  
Karel M. Leunissen ◽  
...  
Keyword(s):  
Peritoneal Dialysis ◽  
Water Transport ◽  
Peritoneal Cavity ◽  
Glucose Solution ◽  
Free Water ◽  
Peritoneal Equilibration Test ◽  
Additional Information

Objective Free water transport (FWT) can be calculated after a dwell of 1 hour with a 3.86% glucose solution using sodium kinetics (mini-PET, as developed by LaMilia et al.). This requires measurement of the intraperitoneal volume after drainage of the abdomen. Since valuable information of a 4-hour peritoneal equilibration test (PET) may be lost, the aim of the present study was to investigate whether temporary drainage of the peritoneal cavity after 1 hour and re-instillation thereafter would influence the results of the 4-hour PET. Methods and Patients Two PETs were performed in 10 stable peritoneal dialysis (PD) patients (mean age 59 ± 13 years, mean duration on PD 33 ± 15 months) within a mean period of 54 (range 13 – 104) days: one standardized 4-hour PET using 3.86% glucose (PET A) and one with drainage after 1 hour followed by re-instillation (PET B). Results Mean total ultrafiltration (UF) of PETs A and B was 667 ± 210 mL and 621 ± 206 mL (NS). Mean FWT at 60 minutes was 164 ± 74 mL and mean UF through the small pores was 204 ± 181 mL; FWT correlated well with total UF ( r = 0.720, p = 0.019). Classification of transport categories was identical for 9 of the 10 patients. Comparison of 1-hour and 4-hour results in test B showed a good correlation between dialysate-to-plasma ratios (D/P) of creatinine and urea and Dt/D0 ratios of glucose. Conclusion A 4-hour 3.86% glucose PET, including temporary drainage after 1 hour for assessment of free water transport, does not influence the results of D/P creatinine or Dt/D0 glucose and gives essential additional information on aquaporin function.

scholarly journals Customization of Peritoneal Dialysis in Cardiorenal Syndrome by Optimization of Sodium Extraction

2019 ◽  
Vol 9 (2) ◽  
pp. 117-124 ◽  
Author(s):  
Amir Kazory ◽  
Abhilash Koratala ◽  
Claudio Ronco
Keyword(s):  
Peritoneal Dialysis ◽  
Patient Population ◽  
Therapeutic Option ◽  
Free Water ◽  
Volume Overload ◽  
Cardiorenal Syndrome ◽  
Waste Products ◽  
Specific Patient ◽  
Fluid Removal ◽  
Sodium Removal

Background: Peritoneal dialysis (PD) has emerged as a mechanistically relevant therapeutic option for patients with heart failure (HF), volume overload, and varying degrees of renal dysfunction (i.e., chronic cardiorenal syndrome). Congestion has been identified as a potent ominous prognostic factor in this patient population, outperforming a number of established risk factors. As such, excess fluid removal is recognized as a relevant therapeutic target in this setting. Methods: Accumulating evidence points to the importance of sodium removal as part of any decongestive strategy because extraction of sodium-free water has little or no impact on the outcomes of these patients. Hence, optimization of sodium removal by PD should be the primary focus in the setting of HF and cardiorenal syndrome, especially if PD is started when the patient still has adequate residual renal function for clearance of waste products. Results: Herein, we provide an overview of approaches that can tailor PD treatment to the patients’ characteristics and clinical needs (e.g., choice of PD modality) to fully exploit its decongestive properties. Other methods that could prove helpful in the future will also be briefly discussed. Conclusion: While these strategies could help with efficient sodium extraction and volume optimization, future studies are needed to evaluate their impact on the outcomes of this specific patient population.

Sign in / Sign up

Export Citation Format

Share Document