scholarly journals Threefold Peritoneal Test of Osmotic Conductance, Ultrafiltration Efficiency, and Fluid Absorption

2013 ◽  
Vol 33 (4) ◽  
pp. 419-425 ◽  
Author(s):  
Jacek Waniewski ◽  
Ramón Paniagua ◽  
Joanna Stachowska–Pietka ◽  
María-de-Jesús Ventura ◽  
Marcela Ávila–Díaz ◽  
...  

BackgroundFluid removal during peritoneal dialysis depends on modifiable factors such as tonicity of dialysis fluids and intrinsic characteristics of the peritoneal transport barrier and the osmotic agent—for example, osmotic conductance, ultrafiltration efficiency, and peritoneal fluid absorption. The latter parameters cannot be derived from tests of the small-solute transport rate. We here propose a simple test that may provide information about those parameters.MethodsVolumes and glucose concentrations of drained dialysate obtained with 3 different combinations of glucose-based dialysis fluid (3 exchanges of 1.36% glucose during the day and 1 overnight exchange of either 1.36%, 2.27%, or 3.86% glucose) were measured in 83 continuous ambulatory peritoneal dialysis (CAPD) patients. Linear regression analyses of daily net ultrafiltration in relation to the average dialysate-to-plasma concentration gradient of glucose allowed for an estimation of the osmotic conductance of glucose and the peritoneal fluid absorption rate, and net ultrafiltration in relation to glucose absorption allowed for an estimation of the ultrafiltration effectiveness of glucose.ResultsThe osmotic conductance of glucose was 0.067 ± 0.042 (milliliters per minute divided by millimoles per milliliter), the ultrafiltration effectiveness of glucose was 16.77 ± 7.97 mL/g of absorbed glucose, and the peritoneal fluid absorption rate was 0.94 ± 0.97 mL/min (if estimated concomitantly with osmotic conductance) or 0.93 ± 0.75 mL/min (if estimated concomitantly with ultrafiltration effectiveness). These fluid transport parameters were independent of small-solute transport characteristics, but proportional to total body water estimated by bioimpedance.ConclusionsBy varying the glucose concentration in 1 of 4 daily exchanges, osmotic conductance, ultrafiltration efficiency, and peritoneal fluid absorption could be estimated in CAPD patients, yielding transport parameter values that were similar to those obtained by other, more sophisticated, methods.

2004 ◽  
Vol 24 (3) ◽  
pp. 240-251 ◽  
Author(s):  
Danuta Sobiecka ◽  
Jacek Waniewski ◽  
Andrzej Weryński ◽  
Bengt Lindholm

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.


1997 ◽  
Vol 8 (12) ◽  
pp. 1915-1920
Author(s):  
T Wang ◽  
C Chen ◽  
O Heimbürger ◽  
J Waniewski ◽  
J Bergström ◽  
...  

Hyaluronan, exhibiting a high resistance against water flow, acts in the tissue as a barrier against rapid changes in water content. To test whether hyaluronan has any effect on the peritoneal fluid and solute transport, and, in particular, on the peritoneal fluid absorption, a 4-h dwell study with an intraperitoneal volume marker (radiolabeled human serum albumin [RISA]) was conducted in 21 male Sprague Dawley rats (three groups, seven rats in each group). Each rat was injected intraperitoneally with 25 ml of 1.36% glucose solution alone (control group), with 0.005% hyaluronan (HA1 group), or with 0.01% hyaluronan (HA2 group). Dialysate and blood samples were taken frequently for analyses of fluid and solute (urea, glucose, and protein) transport. The intraperitoneal volume was calculated from the dilution of RISA with a correction for RISA disappearance from the peritoneal cavity. This study shows that adding hyaluronan to peritoneal dialysis solution significantly (P < 0.01) increased the net peritoneal fluid removal, mainly due to a significant decrease in the peritoneal fluid absorption rate (P < 0.01). The diffusive mass transfer coefficients for glucose, urea, and protein did not differ between the three groups. The peritoneal clearance of urea increased significantly in the two hyaluronan groups compared with the control group, due to the increased net fluid removal in the hyaluronan groups. These results suggest that intraperitoneal administration of hyaluronan during a single peritoneal dialysis exchange may significantly increase the peritoneal fluid and solute removal by decreasing peritoneal fluid absorption.


2005 ◽  
Vol 28 (10) ◽  
pp. 976-984 ◽  
Author(s):  
J. Waniewski ◽  
D. Sobiecka ◽  
M. DĘbowska ◽  
O. Heimbürger ◽  
A. Werynski ◽  
...  

Background Two major types of permanent loss of ultrafiltration capacity (UFC) were previously distinguished among patients treated with CAPD: 1) type HDR with high diffusive peritoneal transport rate of small solutes and low osmotic conductance, but with normal fluid absorption rate, and 2) type HAR with high fluid absorption rate, but with normal diffusive peritoneal transport rate of small solutes and normal osmotic conductance. However, the detailed pattern of changes in peritoneal transport parameters in patients developing loss of ultrafiltration capacity is not known. Objective Analysis of solute and fluid transport parameters in the same patient before and after UFC loss. Patients Seven CAPD patients who had undergone repeated dwell studies, which were carried out before and/or after the onset of UFC loss. Methods Dialysis fluids (2 L) with glucose or a mixture of amino acids as osmotic agent at three basic tonicities were applied during 6 hour dwell studies. Fluid and solute transport parameters were previously shown not to be affected by these dialysis solutions (except by hypertonic amino acid-based solution). Intraperitoneal dialysate volume and fluid absorption rate were assessed using radiolabeled human serum albumin (RISA). Osmotic conductance (aOS) was estimated by a mathematical model as ultrafiltration rate induced by unit osmolality gradient. Diffusive mass transport coefficients, KBD, for glucose, urea, and creatinine were estimated using the modified Babb-Randerson-Farrell model. Results Five patients had increased KBD for small solutes after the onset of UFC loss, and three of them had decreased aOS, whereas two patients had normal aOS. In one of them, aOS decreased with time after the onset of UFC loss with concomitant normalization of glucose absorption. In all studies of these five patients the fluid absorption rate was within the normal range. Two other patients had increased fluid absorption rate (about 5 ml/min), and one of them also had increased KBD for small solutes, in two consecutive dwell studies in each patient with the second study being carried out at 1 and 7 months respectively after the first one. In all four studies in these two patients, the aOS was within the normal range. The sodium dip during dialysis with 3.86% glucose-based solution was lost, not only among most patients with UFC loss related to reduced osmotic conductance, but also in patients with increased KBD. Conclusions The occurrence of two major types of UFC loss was confirmed. However, a case of a mixed type of UFC loss with high fluid absorption rate and high KBD for small solutes, but normal osmotic conductance, and with normalization of initially high KBD for small solutes, linked with decreasing initially normal osmotic conductance, was also found. As a reduced sodium dip with hypertonic glucose solution is not only seen in patients with reduced osmotic conductance, it cannot reliably be used as a single measure of decreased aquaporin function. Permanent ultrafiltration capacity loss may be a dynamic phenomenon with a variety of alterations in peritoneal transport characteristics.


1998 ◽  
Vol 18 (2) ◽  
pp. 193-203 ◽  
Author(s):  
Tao Wang ◽  
Olof Heimbürger ◽  
Hui-Hong Cheng ◽  
Jonas Bergström ◽  
Bengt Lindholm

Objective To study peritoneal fluid and solute transport characteristics using different polyglucose solutions with and without the addition of glucose. Design Thirty-one rats were divided into three groups. A 4-hour dwell study with frequent dialysate and blood samples was performed in each rat using 25 mL of 7.5% polyglucose solution (PG, n = 11),7.5% polyglucose + 0.35% glucose solution (PG1, n = 12), or 3.75% polyglucose + 1.93% glucose solution (PG2, n = 8). Radiolabeled human albumin (RISA) was added to the solutions as an intraperitoneal volume (IPV) marker. In addition, polyglucose degradation was evaluated ex vivo over 24 hours. Experimental Animals Thirty-one male Sprague Dawley rats (300 g) were used. Main Outcome Measures Fluid and solute (glucose, urea, sodium, potassium, and total protein) transport characteristics as well as changes in dialysate osmolality were evaluated. Results The IPV was higher in the PG1 and PG2 groups than in the PG group during the first 2 hours of the dwell. The IPV, in fact, decreased during the first hour of the dwell in the PG group. However, the net ultrafiltration at 4 hours tended to be lower in the PG2 (3.2 ± 1.5 mL) group compared to the PG (5.1 ± 2.3 mL) and the PG1 groups (5.2 ± 2.1 mL) (p = 0.07), and no significant difference was found between the PG and PG1 groups. Adding glucose to the PG solution increased the RISA elimination rate (KE, representing the fluid absorption rate from the peritoneal cavity): 25.5 ± 8.2, 37.5 ± 12.2, and 42.5 ± 8.9 μL/ min for the PG, PG1, and the PG2 group, respectively, p < 0.01. Dialysate osmolality (Dos) increased with the dwell time in the PG and PG1 groups but decreased in the PG2 group. The increase in Dos was partially due to the degradation of glucose polymer, which was supported by the marked increase in osmolality over 24 hours of incubation of PG solution with peritoneal fluid, ex vivo. The diffusive mass transport coefficient for the investigated solutes did not differ among the three groups (except for glucose, which was significantly lower in the PG group). The sieving coefficient for sodium was significantly higher in the PG group compared to the PG1 group (p < 0.05). Conclusion Our results suggest that, although there was an initial decrease in the intraperitoneal dialysate volume, significant amounts of fluid can be removed by polyglucose solution during a single 4-hour dwell in rats, despite the low osmolality of the solution. The positive fluid removal induced by the PG solution is partially due to the lower fluid absorption rate associated with this solution and may, to some extent, also be due to the degradation of glucose polymer within the peritoneal cavity, resulting in increased dialysate osmolality. The addition of glucose to the polyglucose solution does not seem to improve ultrafiltration in a 4-hour dwell in the rat model. However, the peritoneal fluid absorption rate may be increased, and peritoneal transport of glucose and sodium may be altered, by adding glucose to the polyglucose solution.


1999 ◽  
Vol 19 (2_suppl) ◽  
pp. 106-111 ◽  
Author(s):  
Tao Wang ◽  
Hui-Hong Cheng ◽  
Olof Heimbürger ◽  
Chi Chen ◽  
Jacek Waniewski ◽  
...  

Background It has been shown that hyaluronan (HA) can decrease peritoneal fluid absorption. It is not known, however, how various molecular weights and various concentrations of hyaluronan affect peritoneal fluid absorption rate. Methods A study of 4-hour dwells, with frequent dialysate and blood sampling, was performed in male SpragueCawley rats (6 7 rats in each group) with 1311 albumin as an intraperitoneal volume marker. Each rat was infused intraperitoneally with 25 mL of 1.5% glucose solution alone or 1.5% glucose solution containing hyaluronan at various molecular weights (MW -85 kC, 280 kC, 500 kC, and 4 MC) or containing hyaluronan of MW 500 kC at various concentrations (0.01%,0.05%,0.1%,0.5%). Two additional groups were infused with 40 mL of 1.36% glucose dialysate alone or 1.36% glucose dialysate with 0.01 % hyaluronan (MW 500 kC) to test the effect of hyaluronan when high dialysate fill volume was used. Results Addition of 0.01% hyaluronan significantly decreased peritoneal fluid absorption rate (KE) (by 22%, p < 0.01). The decrease was more marked with hyaluronan at high MW or high concentration, or with high dialysate fill volume. The net ultrafiltration tended to be higher in all hyaluronan groups compared to their control groups except in the 4 MC group; this difference was mainly due to a lower KE in all the hyaluronan groups. The direct lymphatic flow was significantly decreased in the 0.5% HA group. The transcapillary ultrafiltration rate (au) was significantly lower in the 4 MC group as compared to the control group. No difference in au was found between the other groups as compared to their control groups. Conclusions (1) Intraperitoneal addition of hyaluronan may increase net peritoneal fluid removal, mainly because hyaluronan decreases peritoneal fluid absorption rate. The decrease was more marked when high dialysate fill volume was used, indicating that intraperitoneal addition of hyaluronan can prevent the decreased net ultrafiltration caused by an increase in dialysate fill volume. (2) The decrease in peritoneal fluid absorption rate may be both MW-dependent and concentration-dependent: that is, a higher MW as well as a higher concentration of hyaluronan result in a more marked decrease in peritoneal fluid absorption rate. (3) Low concentrations of high MW hyaluronan may also decrease au. However, au did not decrease when high concentrations of hyaluronan were used despite a significant decrease in peritoneal fluid absorption rate.


2008 ◽  
Vol 28 (1) ◽  
pp. 53-60 ◽  
Author(s):  
Jacek Waniewski ◽  
Malgorzata Debowska ◽  
Bengt Lindholm

Objective The three-pore model of peritoneal transport is used extensively for modeling peritoneal fluid and solute transport, but the currently used versions include certain modifications of the transport parameters that have not been validated quantitatively versus detailed data on fluid and solute kinetics. The aim of this study was to evaluate different versions of the three-pore model. Method Detailed clinical peritoneal fluid and solute transport data were obtained from 40 peritoneal dwell studies in clinically stable continuous ambulatory peritoneal dialysis patients in whom the dialysate volume was measured using a macromolecular volume marker (RISA). Results Using a new version of the three-pore model with several adjusted transport parameters, good agreement between the measured and the simulated values of dialysate volume and concentrations of small solutes and RISA (but not of endogenous protein) versus dwell time was obtained; however, the predicted peritoneal absorption for longer than the investigated dwell time would be too high. Conclusion The three-pore model, with some adjustments proposed in this study, may be used for detailed description of peritoneal transport kinetics, but it should be pointed out that, even after these adjustments, it still does not provide the correct description of peritoneal fluid absorption and transport of macromolecules.


2002 ◽  
Vol 13 (4) ◽  
pp. 1055-1060
Author(s):  
Andreas Fußhöller ◽  
Sandra zur Nieden ◽  
Bernd Grabensee ◽  
Jörg Plum

ABSTRACT. The integrity of the peritoneal membrane in peritoneal dialysis (PD) is of major importance for adequate dialysis and fluid balance. However, alterations in peritoneal fluid transport, such as ultrafiltration failure, often develop during long-term PD. To investigate peritoneal solute and fluid transport and to analyze the influence of treatment time, peritonitis incidence, and PD modality (continuous ambulatory PD [CAPD] or automated PD [APD]), a cross-sectional study with an extended peritoneal transport test that used dextran 70 in 2 L of glucose was performed in 23 nonselected chronic PD patients. Compared were long-term (>40 mo) with short-term PD patients (<40 mo), CAPD with APD patients, and those with a peritonitis incidence of >0.25/yr to those with an incidence of <0.25/yr. Dialysate/plasma (D/P) ratio and mass transfer area coefficient of creatinine, lymphatic absorption rate (LAR), transcapillary ultrafiltration, and effective ultrafiltration were measured. Long-term PD patients had higher D/P ratio of creatinine (73.5 ± 2.3% versus 65.9 ± 2.2%; P < 0.01) and higher LAR (243 ± 69 ml/4 h versus 96 ± 31 ml/4 h; P < 0.03), both resulting in lower effective ultrafiltration (242 ± 35 ml/4 h versus 324 ± 30 ml/4 h; P < 0.05). D/P ratio (r = 0.66) and LAR (r = 0.67) were positively correlated to PD duration. Patients on APD compared with those on CAPD and patients with a history of peritonitis compared with those without did not differ in terms of D/P ratio, mass transfer area coefficient, LAR, transcapillary ultrafiltration, and effective ultrafiltration. Lower ultrafiltration after long-term PD is both the result of increased small solute transport and increased lymphatic absorption. APD or CAPD modality and peritonitis incidence do not have a significant influence on small solute transport or fluid kinetics.


2007 ◽  
Vol 27 (5) ◽  
pp. 575-579 ◽  
Author(s):  
Xing-wei Zhe ◽  
Xin-kui Tian ◽  
Lei Cheng ◽  
Tao Wang

Background Peritoneal resting has been used to restore peritoneal ultrafiltration capacity in peritoneal dialysis patients. Therefore, in the present study, we made a detailed investigation on the effects of peritoneal resting on peritoneal fluid transport characteristics in patients on continuous ambulatory peritoneal dialysis (CAPD). Methods A temporary transfer to daytime ambulatory peritoneal dialysis with a nocturnal “empty belly” was applied to let the peritoneal membrane rest overnight in patients with poor ultrafiltration capacity. All included patients were asked to record appropriately their dialysis exchanges for the assessment of peritoneal fluid transport characteristics, which were evaluated before and after peritoneal resting. Results Seven CAPD patients were included in the present study. There was a significant improvement in peritoneal ultrafiltration capacity as assessed by ultrafiltration volume per gram of glucose load. Patients’ daily glucose exposure and dialysate-to-plasma ratio of creatinine were significantly decreased after peritoneal resting. The peritoneal fluid absorption rate was also significantly decreased after peritoneal resting: 1.011 ± 0.4484 versus 0.625 ± 0.3833 mL/minute. Conclusion The present study suggests that peritoneal resting can improve CAPD patients’ ultrafiltration capacity and decrease the use of hypertonic dialysis solution. The improved ultrafiltration capacity by peritoneal resting was due to decreased membrane solute transport rate and decreased peritoneal fluid absorption rate.


1991 ◽  
Vol 11 (4) ◽  
pp. 351-354 ◽  
Author(s):  
Andrzej Breborowicz ◽  
Maciej Radkowski ◽  
Jan Knapowski ◽  
Dimitrios G. Oreopoulos

The effect of chondroitin sulphate (CS) on peritoneal fluid and solute transport was studied in rats undergoing peritoneal dialysis. In the presence of CS, net ultrafiltration increased, while absorption of glucose and horseradish peroxidase from the peritoneal cavity decreased. Albumin, used instead of CS, did not modify either fluid or solute transport. In in vitro experiments on isolated rabbit mesentery, CS decreased transmembrane water flow induced by hydrostatic pressure, and its effect was not fully reversed 60 minutes after “wash-out” of this glycosaminoglycan. We postulate that the polyanionic CS molecules are trapped in the peritoneal interstitium, thus decreasing its hydraulic conductivity and permeability, which in turn increases net fluid removal during peritoneal dialy sis because of its slower absorption from the peritoneal cavity.


2003 ◽  
Vol 23 (2_suppl) ◽  
pp. 65-68 ◽  
Author(s):  
Philip K.T. Li ◽  
Cheuk-chun Szeto

Sufficient data are available to support the contention that renal and peritoneal clearances are not equivalent, and that loss of residual renal function (RRF) cannot be completely compensated by an increase in the exchange volume or frequency of peritoneal dialysis. When RRF is minimal (for example, renal Kt/V is 0.1 – 0.3), increasing the peritoneal Kt/V beyond the “conventional” value recommended by the Dialysis Outcomes Quality Initiative yields little additional clinical benefit. The cut-off peritoneal ( not total) Kt/V is possibly 1.6 – 1.7. However, delivery of peritoneal small-solute clearance below that cut-off level has a major detrimental effect on clinical outcome in CAPD patients with little RRF. Measures to preserve RRF therefore become an important goal in the treatment of CAPD patients. In short, with regard to RRF (renal Kt/V), higher is always better, and we should always try to preserve it. For peritoneal Kt/V, higher is better only up to a certain limit. The importance of aspects of adequate dialysis other than small-solute removal—especially fluid removal, blood pressure control, nutrition, acid–base balance, mineral metabolism, and anemia and lipid control—cannot be sufficiently emphasized.


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