scholarly journals Distributed model of peritoneal transport: implications of the endothelial glycocalyx

2008 ◽  
Vol 23 (7) ◽  
pp. 2142-2146 ◽  
Author(s):  
M. F. Flessner
Author(s):  
R. L. Dedrick ◽  
M. F. Flessner ◽  
J. M. Collins ◽  
J. S. Schultz

1999 ◽  
Vol 19 (2_suppl) ◽  
pp. 193-201 ◽  
Author(s):  
Jacek Waniewski

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.


1996 ◽  
Vol 16 (1_suppl) ◽  
pp. 205-207 ◽  
Author(s):  
Michael F. Flessner

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.


2014 ◽  
Vol 128 (1-2) ◽  
pp. 159-165 ◽  
Author(s):  
Carmen A. Vlahu ◽  
Deirisa Lopes Barreto ◽  
Dirk G. Struijk ◽  
Hans Vink ◽  
Raymond T. Krediet

2020 ◽  
Author(s):  
N Rogenhofer ◽  
N Hulde ◽  
F Brettner ◽  
I Götzfried ◽  
JI Buchheim ◽  
...  

This article describes the proposed approaches to creating distributed models that can, with given accuracy under given restrictions, replace classical physical models for construction objects. The ability to implement the proposed approaches is a consequence of the cyber-physical integration of building systems. The principles of forming the data structure of designed objects and distributed models, which make it possible to uniquely identify the elements and increase the level of detail of such a model, are presented. The data structure diagram of distributed modeling includes, among other things, the level of formation and transmission of signals about physical processes inside cyber-physical building systems. An enlarged algorithm for creating the structure of the distributed model which describes the process of developing a data structure, formalizing requirements for the parameters of a design object and its operating modes (including normal operating conditions and extreme conditions, including natural disasters) and selecting objects for a complete group that provides distributed modeling is presented. The article formulates the main approaches to the implementation of an important practical application of the cyber-physical integration of building systems - the possibility of forming distributed physical models of designed construction objects and the directions of further research are outlined.


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