A Three-Pore Model of Peritoneal Transport

1993 ◽  
Vol 13 (2_suppl) ◽  
pp. 35-38 ◽  
Author(s):  
Bengt Rippe
Keyword(s):  
Peritoneal Cavity ◽  
Protein Transport ◽  
Water Soluble ◽  
Fluid Loss ◽  
Peritoneal Membrane ◽  
Reasonable Accuracy ◽  
Lymphatic Absorption ◽  
Pore Model ◽  
Peritoneal Transport ◽  
Order Of Magnitude

The three-pore model of peritoneal transport treats the capillary membrane as a primary barrier determining the amount of solute that transports to the interstitium and the peritoneal cavity. According to the three-pore model, the principal peritoneal exchange route for water and water-soluble substances is a protein-restrictive pore pathway of radius 40–55 A, accounting for approximately 99% of the total exchange (pore) area and approximately 90% of the total peritoneal ultrafiltration (UF) coefficient (LpS). For their passage through the peritoneal membrane proteins are confined to so-called “large pores” of radius approximately 250 Å, which are extremely few in number (0.01% of the total pore population) and more or less nonrestrictive with respect to protein transport. The third pathway of the three-pore model accounts for only about 2% of the total LpS and is permeable to water but impermeable to solutes, a so-called “water-only” (transcellular?) pathway. In contrast to the classical Pyle-Popovich (P&P) model, the three-pore model can predict with reasonable accuracy not only the transport of water and “small solutes” (molecular radius 2.3–15 Å) and “intermediatesize” solutes (radius 15–36 Å), but also the transport of albumin (radius 36 Å) and larger molecules across the peritoneal membrane. The model operates with reflection coefficientsa (a's) for small solutes <0.1. These are approximately one order of magnitude lower than the & sigma's In the P&P model. Furthermore, the peritoneal LPS is one order of magnitude higher than In the P&P model. As a consequence, the major portion of the “fluid loss” from the peritoneal cavity In continuous ambulatory peritoneal dialysis (CAPD) can be explained by the operation of the so-called Starling forces (the transcapillary hydrostatic pressure gradient opposed by the plasma colloid osmotic pressure as multiplled by the LpS), and to a much lesser extent by lymphatic absorption (L). Furthermore, In contrast to the P&P model, the three-pore model can with reasonable accuracy predict the UF profiles produced when glucose Is substituted by high molecular weight solutes as osmotic agents In CAPO.

Transport of tracer albumin from peritoneum to plasma: role of diaphragmatic, visceral, and parietal lymphatics

1996 ◽  
Vol 270 (5) ◽  
pp. H1549-H1556 ◽  
Author(s):  
E. R. Zakaria ◽  
O. Simonsen ◽  
A. Rippe ◽  
B. Rippe
Keyword(s):  
Peritoneal Dialysis ◽  
Steady State ◽  
Peritoneal Cavity ◽  
Anterior Abdominal Wall ◽  
Membrane Surface ◽  
Peritoneal Membrane ◽  
Lymphatic Absorption ◽  
Capillary Walls ◽  
Lymphatic Pathways

Using a technique to acutely seal off various parts of the peritoneal membrane surface, with or without evisceration, we investigated the role of diaphragmatic, visceral, and parietal peritoneal lymphatic pathways in the drainage of 125I-labeled albumin (RISA) from the peritoneal cavity to the plasma during acute peritoneal dialysis in artificially ventilated rats. The total RISA clearance out of the peritoneal cavity (Cl) as well as the portion of this Cl reaching the plasma per unit time (Cl⇢ P) were assessed. Under non-steady-state conditions, the Cl was fivefold higher than the Cl⇢ P. Evisceration caused a 25-30% reduction in both Cl⇢ P and Cl. Sealing of the diaphragm, however, reduced the Cl⇢ P by 55% without affecting the Cl. A further reduction in the Cl⇢ P was obtained by combining sealing of the diaphragm with evisceration, which again markedly reduced the Cl. However, the greatest reduction in the Cl was obtained when the peritoneal surfaces of the anterior abdominal wall were sealed off in eviscerated rats. The discrepancy between the Cl and the Cl⇢ P can be explained by the local entrance of fluid and macromolecules into periabdominal tissues, where fluid is rapidly absorbed through the capillary walls via the Starling forces, while macromolecules are accumulating due to their very slow uptake by tissue lymphatics under non-steady-state conditions. Of the portion of the total Cl that rapidly entered the plasma, conceivably by lymphatic absorption, 55% could be ascribed to diaphragmatic lymphatics 30% to visceral lymphatics, and only some 10-15% to parietal lymphatics.

Role of Diaphragmatic, Visceral, and Parietal Pathways in Peritoneal Fluid Absorption in Rat Peritoneal Dialysis

1996 ◽  
Vol 16 (1_suppl) ◽  
pp. 80-84 ◽  
Author(s):  
Kazuo Kumano ◽  
Kimitoshi Go ◽  
Me He ◽  
Tadasu Sakai
Keyword(s):  
Peritoneal Dialysis ◽  
Peritoneal Cavity ◽  
Absorption Rate ◽  
Ringer Solution ◽  
Fluid Loss ◽  
Fluid Absorption ◽  
Lymphatic Absorption ◽  
Major Route ◽  
Lymphatic Pathway

Assessment was made of the contribution of lymphatic and non lymphatic fluid absorption to net fluid loss from the peritoneal cavity. Diaphragmatic, visceral, and parietal pathways in lymphatics and nonlymphatics were examined using a rat model with adhesion of the diaphragm to the liver, evisceration, these two procedures in combination, and without treatment. In each of these cases, six rats were used, each dialyzed for 180 min with Krebs–Ringer solution. The peritoneal net fluid absorption rate (PNFAR) was determined based on the disappearance of 1251-bovine serum albumin (BSA) from the peritoneal cavity and the lymphatic absorption rate (LAR), was based on the appearance of this albumin in the blood. Seventy-eight percent of net fluid loss occurred via the non lymphatic pathway, primarily through parietal and visceral absorption, and the remaining 22% through the lymphatics, the main pathway being the subdiaphragmatic lymphatics. Nonlymphatic fluid absorption would thus appear to be a major route of fluid loss from the peritoneal cavity in rat peritoneal dialysis.

Mathematical Models for Peritoneal Transport Characteristics

1999 ◽  
Vol 19 (2_suppl) ◽  
pp. 193-201 ◽  
Author(s):  
Jacek Waniewski
Keyword(s):  
Mathematical Models ◽  
Peritoneal Cavity ◽  
Fluid Transport ◽  
Driving Forces ◽  
Experimental Studies ◽  
Theoretical Description ◽  
Distributed Model ◽  
Transport Parameters ◽  
Pore Model ◽  
Peritoneal Transport

Four mathematical models and for the description of peritoneal transport of fluid solutes are reviewed. The membrane model is usually applied for (1) separation of transport components, (2) formulation of the relationship between flow components and their driving forces, and (3) estimation of transport parameters. The three-pore model provides correct relationships between various transport parameters and demonstrates that the peritoneal membrane should be considered heteroporous. The extended threepore model discriminates between heteroporous capillary wall and tissue layer, which are assumed to be arranged in series; the model improves and modifies the results of the three-pore model. The distributed model includes all parameters involved in peritoneal transport and takes into account the real structure of the tissue with capillaries distributed at various distances from the surface of the tissue. How the distributed model may be applied for the evaluation of the possible impact of perfusion rate on peritoneal transport, as recently discussed for clinical and experimental studies, is demonstrated. The distributed model should provide theoretical bases for the application of other models as approximate and simplified descriptions of peritoneal transport. However, an unsolved problem is the theoretical description of bi-directional fluid transport, which includes ultrafiltration to the peritoneal cavity owing to the osmotic pressure of dialysis fluid and absorption out of the peritoneal cavity owing to hydrostatic pressure.

Impact of the Liver on Peritoneal Transport

1996 ◽  
Vol 16 (1_suppl) ◽  
pp. 205-207 ◽  
Author(s):  
Michael F. Flessner
Keyword(s):  
Peritoneal Cavity ◽  
Transport Coefficients ◽  
Diffusion Chamber ◽  
Solute Diffusion ◽  
Distributed Model ◽  
Peritoneal Membrane ◽  
Peritoneal Transport ◽  
Dialysis Solution ◽  
Mass Transport Coefficient ◽  
Small Solute

Previously, we developed a distributed model of plasma-peritoneal small solute diffusion for specific tissues surrounding the peritoneal cavity and related the transport coefficients to the mass transport coefficient (MTC) of the “peritoneal membrane” model. Based on this theoretical analysis, we calculated tissue-specific MTCs for sucrose from microvascular data in the literature and found that the MTC for the liver was five times the magnitude of other tissues. We hypothesized that the liver was potentially the most significant single transport organ during peritoneal dialysis. To test this hypothesis, we measured the mass transfer from the plasma to fluid contained in diffusion chambers, which were glued to one of four tissues surrounding the peritoneal cavity. We determined that the rate of small solute transport from the plasma to each diffusion chamber was similar for all four tissues. We calculated the MTC of the liver to be no greater than other visceral or parietal surfaces. We therefore disproved our hypothesis concerning the liver. We conclude that the importance of a particular tissue to plasma-peritoneal transport is primarily dependent on the surface area exposed to the dialysis solution.

scholarly journals Peritoneal Fluid Transport rather than Peritoneal Solute Transport Associates with Dialysis Vintage and Age of Peritoneal Dialysis Patients

2016 ◽  
Vol 2016 ◽  
pp. 1-10 ◽  
Author(s):  
Jacek Waniewski ◽  
Stefan Antosiewicz ◽  
Daniel Baczynski ◽  
Jan Poleszczuk ◽  
Mauro Pietribiasi ◽  
...  
Keyword(s):  
Peritoneal Dialysis ◽  
Solute Transport ◽  
Fluid Transport ◽  
Peritoneal Membrane ◽  
Transport Parameters ◽  
Patient Age ◽  
Pore Model ◽  
Peritoneal Transport ◽  
Patient Âgé ◽  
Dialysis Vintage

During peritoneal dialysis (PD), the peritoneal membrane undergoes ageing processes that affect its function. Here we analyzed associations of patient age and dialysis vintage with parameters of peritoneal transport of fluid and solutes, directly measured and estimated based on the pore model, for individual patients. Thirty-three patients (15 females; age 60 (21–87) years; median time on PD 19 (3–100) months) underwent sequential peritoneal equilibration test. Dialysis vintage and patient age did not correlate. Estimation of parameters of the two-pore model of peritoneal transport was performed. The estimated fluid transport parameters, including hydraulic permeability (LpS), fraction of ultrasmall pores (αu), osmotic conductance for glucose (OCG), and peritoneal absorption, were generally independent of solute transport parameters (diffusive mass transport parameters). Fluid transport parameters correlated whereas transport parameters for small solutes and proteins did not correlate with dialysis vintage and patient age. Although LpS and OCG were lower for older patients and those with long dialysis vintage,αuwas higher. Thus, fluid transport parameters—rather than solute transport parameters—are linked to dialysis vintage and patient age and should therefore be included when monitoring processes linked to ageing of the peritoneal membrane.

scholarly journals The First Peritonitis Episode Alters the Natural Course of Peritoneal Membrane Characteristics in Peritoneal Dialysis Patients

2015 ◽  
Vol 35 (3) ◽  
pp. 324-332 ◽  
Author(s):  
Anouk T.N. van Diepen ◽  
Sadie van Esch ◽  
Dirk G. Struijk ◽  
Raymond T. Krediet
Keyword(s):  
Peritoneal Dialysis ◽  
Free Water ◽  
Glucose Absorption ◽  
Natural Course ◽  
Control Group ◽  
Peritoneal Membrane ◽  
Transport Parameters ◽  
Lymphatic Absorption ◽  
Peritoneal Transport ◽  
The Impact

ObjectiveLittle or no evidence is available on the impact of the first peritonitis episode on peritoneal transport characteristics. The objective of this study was to investigate the importance of the very first peritonitis episode and distinguish its effect from the natural course by comparison of peritoneal transport before and after infection.ParticipantsWe analyzed prospectively collected data from 541 incident peritoneal dialysis (PD) patients, aged > 18 years, between 1990 and 2010. Standard Peritoneal Permeability Analyses (SPA) within the year before and within the year after (but not within 30 days) the first peritonitis were compared. In a control group without peritonitis, SPAs within the first and second year of PD were compared.Main outcome measurementsSPA data included the mass transfer area coefficient of creatinine, glucose absorption and peritoneal clearances of β–2-microglobulin (b2m), albumin, IgG and α–2-macroglobulin (a2m). From these clearances, the restriction coefficient to macromolecules (RC) was calculated. Also, parameters of fluid transport were determined: transcapillary ultrafiltration rate (TCUFR), lymphatic absorption (ELAR), and free water transport. Crude and adjusted linear mixed models were used to compare the slopes of peritoneal transport parameters in the peritonitis group to the control group. Adjustments were made for age, sex and diabetes.ResultsOf 541 patients, 367 experienced a first peritonitis episode within a median time of 12 months after the start of PD. Of these, 92 peritonitis episodes were preceded and followed by a SPA within one year. Forty-five patients without peritonitis were included in the control group. Logistic reasons (peritonitis group: 48% vs control group: 83%) and switch to hemodialysis (peritonitis group: 22% vs control group: 3%) were the main causes of missing SPA data post-peritonitis and post-control. When comparing the slopes of peritoneal transport parameters in the peritonitis group and the control group, a first peritonitis episode was associated with faster small solute transport (glucose absorption, p = 0.03) and a concomitant lower TCUFR ( p = 0.03). In addition, a discreet decrease in macromolecular transport was seen in the peritonitis group: mean difference in post- and pre-peritonitis values: IgG: -8 μL/min ( p = 0.01), a2m: -4 μL/min ( p = 0.02), albumin: -10 μL/min (p = 0.04). Accordingly, the RC to macromolecules increased after peritonitis: 0.09, p = 0.04.ConclusionsThe very first peritonitis episode alters the natural course of peritoneal membrane characteristics. The most likely explanation might be that cured peritoneal infection later causes long-lasting alterations in peritoneal transport state.

Peritoneal Kinetics and Mesothelial Markers in CCPD Using Icodextrin for Daytime Dwell for Two Years

2000 ◽  
Vol 20 (2) ◽  
pp. 174-180 ◽  
Author(s):  
Nynke Posthuma ◽  
Henri A. Verbrugh ◽  
Ab J.M. Donker ◽  
Wim Van Dorp ◽  
Hubertina A.Th. Dekker ◽  
...  
Keyword(s):  
Residual Renal Function ◽  
University Hospital ◽  
Type I ◽  
Clinical Effects ◽  
Local Production ◽  
Peritoneal Membrane ◽  
Membrane Markers ◽  
Related Data ◽  
Peritoneal Transport

Objective To evaluate the safety, efficacy, and biocompatibility of icodextrin (Ico), continuous cycling peritoneal dialysis (CCPD) patients were treated for 2 years with either Ico- or glucose (Glu)-containing dialysis fluid for their daytime dwell (14 – 15 hours). Prior to entry into the study, all patients used standard Glu solutions (Dianeal, Baxter BV, Utrecht, The Netherlands). Design Open, randomized, prospective two-center study. Setting University hospital and teaching hospital. Patients Both established patients and patients new to CCPD were included. A life expectancy of more than 2 years, a stable clinical condition, and written informed consent were necessary before entry. Patients aged under 18 years or with peritonitis in the previous month, and women of childbearing potential unless taking adequate contraceptive precautions, were excluded. Thirty-eight patients entered the study (19 Glu, 19 Ico). Main Outcome Measures Daytime dwell peritoneal effluents were collected every 3 months in combination with other study variables (clinical data, laboratory measurements, dialysis-related data, and urine collection). Peritoneal transport studies were carried out every 6 months. Results In Glu- and Ico-treated patients, peritoneal transport of low molecular weight solutes and protein clearances neither changed during follow-up nor differed between the two groups. Peritoneal membrane markers (CA125, interleukin-8, carboxyterminal propeptide of type I procollagen, and aminoterminal propeptide of type III procollagen) measured in effluents did not differ between the groups and did not change over time. All these markers showed a dialysate/plasma ratio of more than 1, suggesting local production. Residual renal function remained stable during follow-up and adverse clinical effects were not observed. Conclusions Peritoneal membrane transport kinetics and markers remained stable in both groups over a 2-year follow-up period. Membrane markers were higher in effluents than in serum, suggesting local production. No clinical side effects were demonstrated. Icodextrin was a well-tolerated effective treatment.

scholarly journals A disposable, ultra-fine endoscope for non-invasive, close examination of the intraluminal surface of the peritoneal dialysis catheter and peritoneal cavity

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Masaaki Nakayama ◽  
Chieko Hamada ◽  
Keitaro Yokoyama ◽  
Yudo Tanno ◽  
Nanae Matsuo ◽  
...  
Keyword(s):  
Peritoneal Dialysis ◽  
Clinical Study ◽  
Peritoneal Cavity ◽  
Abdominal Cavity ◽  
Peritoneal Dialysis Catheter ◽  
Peritoneal Membrane ◽  
Non Invasive ◽  
Luminal Side ◽  
Stage Renal Disease ◽  
End Stage

Abstract The ability to visualize intraluminal surface of peritoneal dialysis (PD) catheter and peritoneal cavity could allow elucidation of the cases of outflow problems, and provide information on changes to the peritoneal membrane leading to encapsulating peritoneal sclerosis. A non-invasive examination that allows those monitoring in need is desirable. We have developed a disposable ultra-fine endoscope that can be inserted into the lumen of the existing PD catheter, allowing observation of the luminal side of the catheter and peritoneal cavity from the tip of the PD catheter, with minimum invasion in practice. In a pre-clinical study in pigs and a clinical study in 10 PD patients, the device provided detailed images, enabling safe, easy observation of the intraluminal side of the entire catheter, and of the morphology and status of the peritoneal surface in the abdominal cavity under dwelling PD solution. Since this device can be used repeatedly during PD therapy, clinical application of this device could contribute to improved management of clinical issues in current PD therapy, positioning PD as a safer, more reliable treatment modality for end-stage renal disease.

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