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Clinical |
Institute of Biocybernetics and Biomedical Engineering,1 Polish Academy of Sciences, Warsaw, Poland; Department of Nephrology,2 Louis Pasteur District Hospital, Cherbourg, France; Divisions of Baxter Novum and Renal Medicine,3 Department of Clinical Science, Intervention and Technology, Karolinska University Hospital Huddinge, Karolinska Institutet, Stockholm, Sweden
Correspondence to: M. Galach, Institute of Biocybernetics and Biomedical Engineering, Polish Academy of Sciences, 4 Trojdena Str, 02-109 Warsaw, Poland. magda{at}ibib.waw.pl
Background: Controlling extracellular volume and plasma
sodium concentration are two crucial objectives of dialysis therapy, as
inadequate sodium and fluid removal by dialysis may result in extracellular
volume overload, hypertension, and increased cardiovascular morbidity and
mortality in end-stage renal disease patients. A new concept to enhance sodium
and fluid removal during peritoneal dialysis (PD) is the use of dialysis
solutions with two different osmotic agents. Aim: To investigate and compare, with the help of
mathematical modeling and computer simulations, fluid and solute transport
during PD with conventional dialysis fluids (3.86% glucose and 7.5%
icodextrin; both with standard sodium concentration) and a new combination
fluid with both icodextrin and glucose (CIG; 2.6% glucose/6.8% icodextrin; low
sodium concentration). In particular, this paper is devoted to improving
mathematical modeling based on critical appraisal of the ability of the
original three-pore model to reproduce clinical data and check its validity
across different types of osmotic agents. Methods: Theoretical investigations of possible causes
of the improved fluid and sodium removal during PD with the combination
solution (CIG) were carried out using the three-pore model. The results of
computer simulations were compared with clinical data from dwell studies in 7
PD patients. To fit the model to the low net ultrafiltration (366 ± 234
mL) obtained after a 4-hour dwell with 3.86% glucose, some of the original
parameters proposed in the three-pore model (Rippe & Levin. Kidney
Int 2000; 57:2546–56) had to be modified. In particular, the
aquaporin-mediated fractional contribution to hydraulic permeability was
decreased by 25% and small pore radius increased by 18%. Results: The simulations described well clinical data
that showed a dramatic increase in ultrafiltration and sodium removal with the
CIG fluid in comparison with the two other dialysis fluids. However, to adapt
the three-pore model to the selected group of PD patients (fast transporters
with small ultrafiltration capacity on average), the peritoneal pore structure
had to be modified. As the mathematical model was capable of reproducing the
clinical data, this shows that the enhanced ultrafiltration with the
combination fluid is caused by the additive effect of the two different
osmotic agents and not by a specific impact of the new dialysis fluid
on the transport characteristics of the peritoneum.
KEY WORDS: Ultrafiltration; fluid status; sodium; mathematical modeling; combination dialysis solution.
Received 22 August 2007; accepted 23 April 2008.
This article has been cited by other articles:
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  J. Waniewski, M. Debowska, and B. Lindholm WATER AND SOLUTE TRANSPORT THROUGH DIFFERENT TYPES OF PORES IN PERITONEAL MEMBRANE IN CAPD PATIENTS WITH ULTRAFILTRATION FAILURE Perit. Dial. Int., November 1, 2009; 29(6): 664 - 669. [Abstract] [Full Text] [PDF]
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