Pressure Control of the Ultrafiltration Rate During Hemodialysis with High-Flux Dialyzers and the Time Dependence of Membrane Transport Parameters

1981 ◽  
pp. 61-74 ◽  
Author(s):  
ALLEN ZELMAN ◽  
DAVID GISSER ◽  
GARY STRAIT ◽  
VICTOR BASTIDAS ◽  
ROBERT STEPHEN ◽  
...  
Keyword(s):  
Time Dependence ◽  
Membrane Transport ◽  
Pressure Control ◽  
High Flux ◽  
Transport Parameters ◽  
Ultrafiltration Rate

Pressure Control of Ultrafiltration Rate with High-Flux Dialysis Membranes

1981 ◽  
Vol 5 (2) ◽  
pp. 162-167 ◽  
Author(s):  
Carl Kablitz ◽  
Robert L. Stephen ◽  
Allen Zelman ◽  
Jeffrey J. Harrow ◽  
Barry R. Deeter ◽  
...  
Keyword(s):  
Pressure Control ◽  
High Flux ◽  
Ultrafiltration Rate ◽  
Dialysis Membranes

Interactions of cell volume, membrane potential, and membrane transport parameters

1980 ◽  
Vol 238 (5) ◽  
pp. C196-C206 ◽  
Author(s):  
E. Jakobsson
Keyword(s):  
Membrane Potential ◽  
Cell Volume ◽  
Membrane Transport ◽  
Numerical Solutions ◽  
Transport Equations ◽  
Time Varying ◽  
Transport Parameters ◽  
Animal Cells ◽  
Analytic Expressions ◽  
Solute Species

Equations have been written and solved that describe for animal cells the relationships among membrane transport, cell volume, membrane potential, and distribution of permeant solute. The essential system consists of n + 2 equations, where n is the number of permeant solute species. The n of the equations are the n transport equations for the permeant species, one for each species. The other two equations are statements of 1) the condition for bulk electroneutrality inside the cell and 2) the condition for isotonicity between the interior and exterior of the cell. Numerical solutions have been obtained in both the steady-state and time-varying cases for transport equations that are physically and phenomenologically reasonable. In addition to numerical solutions analytic expressions are presented that show the ranges of membrane parameters essential for volume regulation; for values of membrane parameters beyond explicitly defined bounds, the equations do not have real, positive solutions for cell volume.

Peritoneal Fluid Transport in CAPD Patients with Different Transport Rates of Small Solutes

2004 ◽  
Vol 24 (3) ◽  
pp. 240-251 ◽  
Author(s):  
Danuta Sobiecka ◽  
Jacek Waniewski ◽  
Andrzej Weryński ◽  
Bengt Lindholm
Keyword(s):  
Peritoneal Dialysis ◽  
Solute Transport ◽  
Osmotic Pressure ◽  
Absorption Rate ◽  
Fluid Transport ◽  
Transport Coefficients ◽  
Dialysis Fluid ◽  
Transport Parameters ◽  
Ultrafiltration Rate ◽  
Small Solute

Background Continuous ambulatory peritoneal dialysis (CAPD) patients with high peritoneal solute transport rate often have inadequate peritoneal fluid transport. It is not known whether this inadequate fluid transport is due solely to a too rapid fall of osmotic pressure, or if the decreased effectiveness of fluid transport is also a contributing factor. Objective To analyze fluid transport parameters and the effectiveness of dialysis fluid osmotic pressure in the induction of fluid flow in CAPD patients with different small solute transport rates. Patients 44 CAPD patients were placed in low ( n = 6), low-average ( n = 13), high-average ( n = 19), and high ( n = 6) transport groups according to a modified peritoneal equilibration test (PET). Methods The study involved a 6-hour peritoneal dialysis dwell with 2 L 3.86% glucose dialysis fluid for each patient. Radioisotopically labeled serum albumin was added as a volume marker. The fluid transport parameters (osmotic conductance and fluid absorption rate) were estimated using three mathematical models of fluid transport: ( 1 ) Pyle model (model P), which describes ultrafiltration rate as an exponential function of time; ( 2 ) model OS, which is based on the linear relationship of ultrafiltration rate and overall osmolality gradient between dialysis fluid and blood; and ( 3 ) model G, which is based on the linear relationship between ultrafiltration rate and glucose concentration gradient between dialysis fluid and blood. Diffusive mass transport coefficients (KBD) for glucose, urea, creatinine, potassium, and sodium were estimated using the modified Babb–Randerson–Farrell model. Results The high transport group had significantly lower dialysate volume and glucose and osmolality gradients between dialysate and blood, but significantly higher KBD for small solutes compared with the other transport groups. Osmotic conductance, fluid absorption rate, and initial ultrafiltration rate did not differ among the transport groups for model OS and model P. Model G yielded unrealistic values of fluid transport parameters that differed from those estimated by models OS and P. The KBD values for small solutes were significantly different among the groups, and did not correlate with fluid transport parameters for model OS. Conclusion The difference in fluid transport between the different transport groups was due only to the differences in the rate of disappearance of the overall osmotic pressure of the dialysate, which was a combined result of the transport rate of glucose and other small solutes. Although the glucose gradient is the major factor influencing ultrafiltration rate, other solutes, such as urea, are also of importance. The counteractive effect of plasma small solutes on transcapillary ultrafiltration was found to be especially notable in low transport patients. Thus, glucose gradient alone should not be considered the only force that shapes the ultrafiltration profile during peritoneal dialysis. We did not find any correlations between diffusive mass transport coefficients for small solutes and fluid transport parameters such as osmotic conductance or fluid and volume marker absorption. We may thus conclude that the pathway(s) for fluid transport appears to be partly independent from the pathway(s) for small solute transport, which supports the hypothesis of different pore types for fluid and solute transport.

Separation and estimation of nanofiltration membrane transport parameters for cerium and neodymium

Rare Metals ◽  
2012 ◽  
Vol 31 (5) ◽  
pp. 500-506 ◽  
Author(s):  
Zagabathuni Venkata Panchakshari Murthy ◽  
Anshul Choudhary
Keyword(s):  
Membrane Transport ◽  
Nanofiltration Membrane ◽  
Transport Parameters

scholarly journals Standard Peritoneal Permeability Analysis in Children

2000 ◽  
Vol 11 (5) ◽  
pp. 943-950
Author(s):  
ANTONIA H. M. BOUTS ◽  
JEAN-CLAUDE DAVIN ◽  
JAAP W. GROOTHOFF ◽  
SJOERD PLOOS VAN AMSTEL ◽  
MACHTELD M. ZWEERS ◽  
...  
Keyword(s):  
Glucose Absorption ◽  
Test Methods ◽  
Common Belief ◽  
Transport Parameters ◽  
Lymphatic Absorption ◽  
Ultrafiltration Rate ◽  
Cross Sectional ◽  
Peritoneal Permeability ◽  
The Common ◽  
Sectional Analysis

Abstract. Peritoneal transport characteristics in children on peritoneal dialysis (PD) has been reported to be different compared to adults. However, various test methods can influence this difference. Thirty-one standard peritoneal permeability analyses (SPA) were performed in 18 PD children with a median (range) age of 9.8 yr (2 to 19) and a median duration of PD of 2.6 yr (0.19 to 6.8). The median mass transfer area coefficient (MTAC) for creatinine was 9.6 ml/min per 1.73 m2 (4.4 to 18.0), and for urea 17.3 ml/min per 1.73 m2 (12.2 to 22.8). The median dialysate to plasma creatinine ratio (D/PCr) was 0.69 (0.44 to 0.92), the glucose absorption 59% (23 to 75), and the D/D0 for glucose 0.38 (0.23 to 0.62). The median clearance of β2-microglobulin was 923 μl/min per 1.73 m2 (366 to 1828), of albumin 103 μl/min per 1.73 m2 (55 to 211), of IgG 48 μl/min per 1.73 m2 (20 to 105), and of α2-macroglobulin 12 μl/min per 1.73 m2 (5 to 49). No correlation was found between these results and age or PD time. The restriction coefficient for macromolecules indeed increased with duration of PD treatment (r = 0.38, P = 0.03). The median transcapillary ultrafiltration rate was 1.2 ml/min per 1.73 m2 (-0.01 to 2.8), the net ultrafiltration rate 0.2 ml/min per 1.73 m2 (-1.97 to 1.82), and the effective lymphatic absorption rate 1.04 ml/min per 1.73 m2 (-0.06 to 2.91). When corrected for body surface area, no differences were found in peritoneal fluid and solute transport characteristics between children and adults. No effect of time on PD on the transport parameters was found in a cross-sectional analysis, except for an increase of the restriction coefficient to macromolecules. This finding is similar to observations in adults. Therefore, the present study showed no evidence for the common belief that the peritoneal membrane in children is different from that in adult patients.

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