Net Ultrafiltration in Peritoneal Dialysis: Role of Direct Fluid Absorption into Peritoneal Tissue

Flessner, Michael F.

doi:10.1159/000170041

Cited by 47 publications

(19 citation statements)

References 18 publications

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“…Scaling from 2,000 ml in a 70-kg human to a 275-g rat, the volume would be 41.4 ml, which produces similar intraperitoneal (ip) pressures to that observed in humans (5,12,27). The volume is completely absorbed in 18 -24 h. At no time after injection did the animal display any signs of distress with the use of this volume.…”

Section: Design Of the Animal Modelmentioning

confidence: 92%

Correlating structure with solute and water transport in a chronic model of peritoneal inflammation

Flessner¹,

Choi²,

Vanpelt³

et al. 2006

American Journal of Physiology-Renal Physiology

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. Correlating structure with solute and water transport in a chronic model of peritoneal inflammation. Am J Physiol Renal Physiol 290: F232-F240, 2006. First published August 23, 2005 doi:10.1152/ajprenal.00211.2005.-To study the process of chronic peritoneal inflammation from sterile solutions, we established an animal model to link structural changes with solute and water transport. Filtered solutions containing 4% N-acetylglucosamine (NAG) or 4% glucose (G) were injected intraperitoneally daily in 200-to 300-g rats and compared with controls (C). After 2 mo, each animal underwent transport studies using a chamber affixed to the parietal peritoneum to determine small-solute and protein mass transfer, osmotic filtration, and hydraulic flow. After euthanasia, parietal tissues were sampled for histological analysis, which demonstrated significant differences in peritoneal thickness (m; C, 42.6 Ϯ 7.5; G, 80.4 Ϯ 22.3; NAG, 450 Ϯ 104; P Ͻ 0.05). Staining for VEGF correlated with CD-31 vessel counts (no./mm 2 : C, 53.1 Ϯ 16.1; G, 166 Ϯ 32; NAG, 183 Ϯ 32; P Ͻ 0.05 ). Tissue analysis showed treatment effects on tissue hyaluronan (g/g: C, 962 Ϯ 73; G, 1,169 Ϯ 69; NAG, 1,428 Ϯ 69; P Ͻ 0.05) and collagen (g/g: C, 56.9 Ϯ 12.0; G, 107 Ϯ 12; NAG, 97.6 Ϯ 11.4; P Ͻ 0.05) but not sulfated glycosaminoglycan. Transport experiments revealed no significant differences in mannitol transfer or osmotic flow. Changes were seen in hydrostatic pressure-driven flux (l ⅐ min Ϫ1 ⅐ cm Ϫ2 : C, 0.676 Ϯ 0.133; G, 0.317 Ϯ 0.124; NAG, 0.284 Ϯ 0.117; P Ͻ 0.05) and albumin transfer (l ⅐ min Ϫ1 ⅐ cm Ϫ2 : C, 0.331 Ϯ 0.028; G, 0.286 Ϯ 0.026; NAG, 0.229 Ϯ 0.025; P Ͻ 0.04). We conclude that alteration of the interstitial matrix correlates with diminished hydraulic conductivity and macromolecular transport.

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Section: Design Of the Animal Modelmentioning

confidence: 92%

Correlating structure with solute and water transport in a chronic model of peritoneal inflammation

Flessner¹,

Choi²,

Vanpelt³

et al. 2006

American Journal of Physiology-Renal Physiology

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“…Briefly, we assume that the disappearance o f RISA from the peritoneal cavity is proportional to its con centration in dialysate (i.e. that RISA absorption is due to a bulk llow and that back diffusion is negligible [ 19,27]):…”

Section: Study Protocolmentioning

confidence: 99%

“…and (2) fluid absorption into tissues (due to hydrostatic pressure differences be tween the peritoneal cavity and the surround ing tissues). From the tissues, the fluid is absorbed into the capillaries due to the Star ling forces, whereas the macromolecules are absorbed slowly via local lymphatics [19,20].…”

Section: Relative Importance O F Lymphatic Absorption and Absorption mentioning

confidence: 99%

“…However, several studies have shown that the plasma appearance rate of a macromolecular marker is on average only about 10-20% of its disappearance rate from the peritoneal dialysate (in clinically stable CAPD patients [8][9][10] as well as in animals [11][12][13][14][15]). Furthermore, studies in animals have demonstrated that a major part of the lost marker accumulates inside the tissues ad jacent to the peritoneal cavity, mainly in the liver, diaphragm and anterior abdominal wall [13,[15][16][17], The direct lymphatic and non lymphatic (convective absorption into tis sues) absorption of fluid in peritoneal dialysis has recently been reviewed [18][19][20].…”

Section: Introductionmentioning

confidence: 99%

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Lymphatic Absorption in CAPD Patients with Loss of Ultrafiltration Capacity

Heimbürger¹,

Waniewski²,

Weryński³

et al. 1995

Blood Purif

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During continuous ambulatory peritoneal dialysis (CAPD) treatment, loss of ultrafiltration capacity (UFC) is a common complication that can be associated with increased peritoneal fluid absorption rate. The aim of the present study was to investigate the relative importance of lymphatic absorption for total peritoneal fluid absorption in patients with permanent loss of UFC associated with a high peritoneal absorption rate (K_E, ml/min; high-K_E group, n = 4). Clinically stable CAPD patients (n = 23) as well as patients with loss of UFC associated with increased diffusive mass transport coefficients (K_BD, ml/min; high-K_BD group, n = 8) served as control groups. The patients were investigated with a 6-hour dwell study with 3.86% glucose solution. The total fluid absorption rate was estimated by the disappearance rate (K_E) of ¹³¹I-radioiodinated human serum albumin (RISA) from the peritoneal cavity, and the lymphatic absorption rate was estimated by the rate of RISA appearance in plasma (K_PP, ml/min). The values of K_E and K_PP in the high-K_E group (4.65 ± 0.93 and 0.42 ± 0.31 ml/min, respectively) were markedly higher than in the clinically stable CAPD patients (1.77 ± 0.60 and 0.15 ± 0.06 ml/min, respectively; both p < 0.001 vs. the high-K_E group). In the high-K_BD group, K_E was lower (2.19 ± 0.38 ml/min, p < 0.001) compared to the high-K_E group, whereas K_PP was similar (0.26 ± 0.09 ml/min, NS). The fraction of K_E which could be accounted for by K_PP was on average only 9 + 5% in the high-K_E group and did not differ from the fractions in the clinically stable patients or in the high-K_BD group (9 ± 5 and 12 ± 4%, respectively). In 5 patients in whom plasma RISA activity was measured for 24 h from the beginning of the 6-hour dwell study, a continuous increase of the RISA level in plasma was observed during this time period. We conclude that although K_PP was increased in patients with UFC loss associated with high K_E, it accounted for only a minor part of K_E. Furthermore, the relatively slow but prolonged appearance of RISA in plasma indicates that the interstitial compartment may serve as a reservoir of macromolecules which are slowly absorbed by local lymphatics. The present study supports previous findings that direct lymphatic absorption is only of relatively minor importance for the fluid absorption in peritoneal dialysis.

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“…How can fluid be convected si multaneously in opposite directions? Some investigators have explained this paradox by assuming that any tracer found in the intersti tium is transported there by diffusion, while the majority of tracer and fluid leaves the peritoneal cavity together via the lymphatic system [9], However, protein transport stud ies provide strong evidence for significant convection of fluid (and tracer) through the interstitial pathway [10]. An alternative ex planation for this paradox is the nonuniform nature of the peritoneal 'membrane' (e.g., vis ceral vs. parietal, diaphragmatic vs. mesenter ic).…”

Section: Pathways For Fluid Loss From the Peritoneal Cavity During Pdmentioning

confidence: 99%

Pathways for Fluid Loss from the Peritoneal Cavity

Shockley

Ofsthun²

1992

Blood Purif

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During peritoneal dialysis, fluid is transported out of the peritoneal cavity by lymphatic and nonlymphatic pathways, thereby decreasing net ultrafiltration by 40-50% and reducing small solute clearance by 15-20%. The direct lymphatic pathway consists of the diaphragmatic lymphatics, which directly connect the peritoneal cavity to the bloodstream. The interstitial lymphatic and direct blood entry pathways convey fluid that has been driven into the interstitial space of the tissue surrounding the peritoneal cavity by the increased intraperitoneal pressure, and return it to the bloodstream. Since flow through lymphatic pathways is only a portion of the flow through all pathways, total fluid loss is greater than lymph flow. The best technique for estimating lymph flow is direct measurement by cannulation of lymphatic vessels, a technique that is not clinically feasible. The tracer disappearance technique, which measures the rate at which macromolecules leave the peritoneal cavity, is an indirect measure of fluid loss. The tracer appearance technique, which measures the rate at which macromolecules reach the blood from the peritoneal cavity, slightly overestimates lymph flow because some tracer may enter the bloodstream directly from the tissues. Much of the previous controversy over the contribution of the lymphatic pathways to total fluid loss can be resolved by understanding the differences in what these techniques measure.

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Net Ultrafiltration in Peritoneal Dialysis: Role of Direct Fluid Absorption into Peritoneal Tissue

Cited by 47 publications

References 18 publications

Correlating structure with solute and water transport in a chronic model of peritoneal inflammation

Correlating structure with solute and water transport in a chronic model of peritoneal inflammation

Lymphatic Absorption in CAPD Patients with Loss of Ultrafiltration Capacity

Pathways for Fluid Loss from the Peritoneal Cavity

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