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Lack of interference of icodextrin on creatinine measurements.

Glucose has been reported to interfere in the analysis of creatinine by the Jaffe method. The potential interference of icodextrin and its primary metabolites (maltose, maltotriose, maltotetraose) on creatinine measurements has not previously been addressed. We evaluated the potential interference of icodextrin and its metabolites at various concentrations using both the Jaffe and Creatinine Plus methods. Interference was determined in samples containing 0.6-20 mg/dL creatinine in saline solution or in plasma (n = 6), and in dialysate samples (n = 6) spiked with icodextrin, maltose, maltotriose, and maltotetraose at concentrations up to twofold the level found in plasma and dialysate from patients treated using icodextrin. Results confirm that no interference occurs when using either the colorimetric Jaffe method or the enzymatic Creatinine Plus method at levels up to 65 g/L icodextrin, 2 g/L maltose, 2 g/L maltotriose, and 1 g/L maltotetraose, levels representing worst-case clinical concentrations. In addition, our results confirm that comparable values can be obtained using either the Jaffe or the Creatinine Plus method for the analysis of creatinine in uremic plasma and in dialysate samples.

Creatinine↗

Peritoneal accumulation of advanced glycosylation end-products in diabetic rats on dialysis with icodextrin.

OBJECTIVE: To evaluate and compare the effects of glucose-based solutions to those of icodextrin with respect to peritoneal transport characteristics and formation of advanced glycosylation end-products (AGEs) in the peritoneal membrane in the diabetic rat model of peritoneal dialysis (PD). STUDY DESIGN: Thirty-three male Sprague-Dawley rats weighing between 275 - 300 g were divided into 5 groups: group C (n = 6), control rats with catheter but not dialyzed; group D (n = 5), diabetic rats with catheter but not dialyzed; group G (n = 7), diabetic rats dialyzed with standard 2.5% glucose solution for daytime exchanges and 4.25% glucose solution for the overnight exchange; group H (n = 8), diabetic rats dialyzed with standard 2.5% glucose solution for daytime exchanges and 7.5% icodextrin solution for overnight exchanges; group I (n = 7), diabetic rats dialyzed with 7.5% icodextrin solution for all exchanges. Dialysis exchanges were performed three times daily with an instillation volume of 25 mL per exchange for a period of 12 weeks. Tissue sections were stained using a monoclonal anti-AGE antibody. One-hour peritoneal equilibration tests (PET) were performed every 4 weeks for comparison of transport characteristics. RESULTS: The level of immunostaining was lowest in group C and highest in group G. Significant differences were seen between group C and groups G, H, and I (p < 0.001, p = 0.001, and p< 0.05 respectively). Significant differences were also found between group G and groups D and I (p < 0.05 and p < 0.05 respectively). Over time, glucose concentration at the end of an exchange versus concentration at instillation (D/D0 glucose) decreased and dialysate-to-plasma ratio (D/P) of urea increased. Significant differences were found between groups C and H for D/D0 glucose (0.40+/-0.01 vs 0.35+/-0.01, p < 0.05); and between groups C and H for D/P urea (0.87+/-0.03 vs 0.97+/-0.02, p < 0.05). CONCLUSIONS: These results suggest that AGE formation is lower with the use of peritoneal dialysis solution containing icodextrin than with glucose-based solutions. We conclude that the use of icodextrin may be helpful in slowing the deterioration of the peritoneal membrane, prolonging its use for dialysis.

Animals↗

Effects of peritoneal dialysis with an overnight icodextrin dwell on parameters of glucose and lipid metabolism.

OBJECTIVE: To examine whether a reduced daily glucose load by overnight application of the less-absorbed glucose polymer icodextrin would have favorable effects on lipid profiles of continuous ambulatory peritoneal dialysis (CAPD) patients. STUDY DESIGN: Randomized crossover study with two subsequent periods of 6 weeks. SETTING: Home PD unit of a secondary-care hospital. PATIENTS: Twenty-one nondiabetic CAPD patients (15 male, 6 female; mean age 50.3+/-11.8 years). INTERVENTION: Participants were randomly assigned to receive an overnight dwell with either standard glucose solution or with a 7.5% icodextrin-containing solution. MAIN OUTCOME MEASURES: Relation between reduction in the total amount of intraperitoneal infused glucose and parameters of glucose (plasma glucose, insulin, and HbA1C) and lipid metabolism [free fatty acids, plasma lipids, lipoproteins, and low density lipoprotein (LDL) subfraction profile]. RESULTS: After the icodextrin dwells, a reduction of plasma total cholesterol (from 5.43+/-0.85 to 4.86+/-0.70 mmol/L, p < 0.001) and LDL cholesterol (from 3.38+/-0.87 to 2.93+/-0.73 mmol/L, p = 0.001) was observed. Also, high density lipoprotein (HDL) cholesterol (from 0.95+/-0.27 to 0.90+/-0.24 mmol/L, p = 0.029) was reduced, but the plasma total cholesterol-to-HDL ratio remained similar. Plasma free fatty acids and triglyceride levels tended to decrease (from 0.16+/-0.10 to 0.13+/-0.08 mmol/L, p= 0.06, and from 2.14+/-1.96 to 1.92+/-1.03 mmol/L, respectively). Evaluation of LDL subfraction profiles after ultracentrifugation showed a more buoyant LDL subfraction profile with fewer dense LDL particles in 6 patients and no changes in 14 patients after icodextrin. The effects on lipids were not accompanied by a decrease in fasting plasma glucose (from 5.76+/-1.29 to 5.86+/-0.80 mmol/L) or insulin levels (from 19.5+/-14.4 to 20.3+/-13.0 mU/L). CONCLUSION: These results suggest a beneficial effect on lipid profiles of CAPD patients with the use of an overnight dwell with icodextrin.

Cross-Over Studies↗

Icodextrin: overview of clinical experience.

OBJECTIVE: To review all clinical studies and experience gained with icodextrin to date; primarily its use in peritoneal dialysis in patients with end-stage renal failure, but also its use as an intraperitoneal vehicle. DATA SOURCES: Peer-reviewed original research articles in the literature; abstracts from international scientific meetings; data generated from the compassionate use programme. STUDY SELECTION: All published studies to date are included, some 10-20 studies being included in this review. DATA EXTRACTION: Data have not been specifically extracted from studies; results have been described in the context of overall experience. RESULTS: Over ten years of clinical experience with icodextrin have now been accumulated, in both continuous ambulatory peritoneal dialysis (CAPD) and automated peritoneal dialysis (APD). A small number of patients have received icodextrin for over five years, with no loss of effect. Icodextrin produces sustained ultrafiltration over long dwells while being iso-osmolar, by the process of colloid osmosis. CONCLUSIONS: Icodextrin represents the first viable alternative osmotic agent to glucose, for use in solutions for peritoneal dialysis. It also has a potential use as a vehicle solution for intraperitoneal drug delivery.

Dialysis Solutions↗

Icodextrin provides long dwell peritoneal dialysis and maintenance of intraperitoneal volume.

Icodextrin 7.5% is an isosmolar solution for once-daily use in peritoneal dialysis for patients with end-stage renal failure (ESRF). It produces substantial ultrafiltration (UF), performing best over longer dwells of 8-12 h in continuous ambulatory peritoneal dialysis (CAPD) patients, and up to 16 h in automated peritoneal dialysis (APD) patients. Subsequent use in other clinical areas (ultrafiltration failure) and normal postmarketing clinical experience has established its tolerability and safety profiles; a small number of patients, including those with diabetes, have now received icodextrin for up to 6 years. Icodextrin's ability to maintain intraperitoneal volume over many hours has led to its undergoing development as an intraperitoneal drug delivery system for targeted regional delivery of anticancer drugs and lymphatic delivery of anti-HIV treatment. Isosmolar icodextrin 7.5% solution represents the first major advance in the treatment of ESRF by peritoneal dialysis since the development of CAPD using glucose-based solutions 20 years ago.

Dialysis Solutions↗

Icodextrin with nitroprusside increases ultrafiltration and peritoneal transport during long CAPD dwells.

Addition of the nitric oxide (NO) donor nitroprusside to 1.36% glucose dialysate enlarges the effective peritoneal surface area during four-hour dwells. The theoretical positive effect on ultrafiltration is, however, counteracted by an increase in glucose absorption. The absorption of the glucose polymer icodextrin is much lower in comparison with glucose-based dialysis solutions, due to its high molecular weight. In the present study 7.5% icodextrin dialysis solution with and without the addition of 4.5 mg/liter nitroprusside was studied during eight-hour CAPD dwells. Two Standard Peritoneal permeability Analyses, adapted for eight-hour dwells, were performed in 10 stable CAPD patients. Nitrate and cGMP were measured as parameters of NO synthesis. The transcapillary ultrafiltration increased in a linear way with icodextrin (ICO) and was even higher after the addition of nitroprusside (NP): 666 (ICO) versus 834 (NP) ml/8 hr, P = 0.03. The effective lymphatic absorption rate was not different. The resulting net ultrafiltration increased with nitroprusside: 344 (ICO) versus 540 (NP) ml/8 hr, P < 0.01. The mass transfer area coefficient of urea increased 15% and that of creatinine 26% with nitroprusside, consistent with the expected enlargement of the vascular peritoneal surface area. The increase in protein clearances was more pronounced the larger the protein: beta 2-microglobulin 19%, albumin 47%, IgG 63% and alpha 2-macroglobulin 95%. Dialysate/plasma (D/P) ratios of nitrate were not higher than the expected values on the basis of its molecular weight (P < 0.001). They increased 19% with nitroprusside. Also, the D/P ratio cyclic guanosine monophosphate (cGMP) after four hours increased with nitroprusside (0.39, range 0.13 to 0.55 ICO, and 0.82, range 0.36 to 1.39 NP, P = 0.01). With nitroprusside the D/P ratio cGMP was higher than expected after four and eight hours (P < 0.001). This points to local generation of NO after addition of nitroprusside. The nitroprusside induced increase in the mass transfer area coefficients (MTAC) of creatinine and in the ultrafiltration caused an increase in the creatinine clearance from 4.2 ml/min to 5.0 ml/min during the eight-hour dwell. This means that nitroprusside adds 3 liters/week to the peritoneal clearance of creatinine. The adequacy of peritoneal dialysis can therefore be improved by the addition of nitroprusside to 7.5% icodextrin, used for the long exchange.

Adult↗

Fluid dynamics in man of an intraperitoneal drug delivery solution: 4% icodextrin.

Interest in targeting drugs into the peritoneal cavity for intra-abdominal cancers or infections is undergoing a revival as recent clinical trials have demonstrated, not only a regional advantage in concentration of the active agent, but also improved long-term outcomes. Solutions currently used for intraperitoneal (IP) drug delivery have short residence times, however, which can limit the exposure of all areas of the peritoneum to the active agent. Icodextrin 4% solution was compared with saline and a glucose-based peritoneal dialysis solution in a clinical study of IP residence time. The study was carried out during the fortnightly rest phase in 9 patients undergoing 5-fluorouracil (5-Fu) IP treatment for colorectal cancer. The volume remaining in the peritoneal cavity was measured at 0, 12, 24, 48, 72, and 96 hr after an instillation of 2 liters of each fluid. Saline (n = 3 dwells) and glucose (n = 3 dwells) peritoneal dialysis solutions were almost fully absorbed by 24 hr, and the patients experienced discomfort when using these solutions. In contrast, icodextrin 4% solution (n = 188 dwells) maintained its instilled volume for up to 48 hr, and half the instilled volume remained after 72 and 96 hr. This result would allow extensive and prolonged coverage of the peritoneal surface. Icodextrin 4% solution may be an effective vehicle to deliver therapeutic agents into the peritoneal cavity.

Aged↗

Effect of icodextrin peritoneal dialysis solution on cell proliferation in vitro.

Peritoneal dialysis solutions containing icodextrin are ideal for providing sustained ultrafiltration during long dwells, and they have replaced high glucose for long dwells in some patients. The biocompatibility of these solutions, especially in regard to glucose degradation products, has not been studied in depth. The object of this study was to compare the effects of commercially available dextrose-containing dialysis solutions to those of icodextrin-containing solutions on fibroblast proliferation in vitro. We measured the effect of solutions on cell growth by exposing murine fibroblasts to pH-adjusted test solutions mixed with culture medium, and by comparing cell growth to growth in culture medium only. No statistical difference was observed in the growth of cells exposed to heat-sterilized Extraneal [7.5% icodextrin (Baxter Healthcare, Deerfield, Illinois, U.S.A.)], heat-sterilized Dianeal [1.5% dextrose (Baxter Healthcare)], or filter-sterilized Dianeal [4.25% dextrose (Baxter Healthcare]. Also, no difference was observed in the growth of fibroblasts exposed to heat-sterilized Extraneal or to filter-sterilized Extraneal, but heat-sterilized Dianeal [4.25% dextrose (Baxter Healthcare)] caused a significant reduction in cell growth. Glucose degradation products (GDPs) are known to contribute to reduced cell growth in vitro. Extraneal had lower levels of the GDP acetaldehyde compared to Dianeal (2.5% or 4.25% dextrose). The results demonstrate enhanced in vitro biocompatibility characteristics for Extraneal, possibly related to low GDP levels in Extraneal.

Animals↗

[Icodextrin in peritoneal dialysis therapy].

In the presented review paper we have shown a role of glucose polymers, including icodextrin, in the treatment of uraemia with continuous ambulatory peritoneal dialysis or cyclic continuous peritoneal dialysis. Glucose polymers as a component of peritoneal dialysis solution exert significant ultrafiltration during dialysis solution exchanges lasting 10-16 hpurs. This is especially advantageous in patients with high peritoneal permeability and results in prolongation of peritoneal dialysis treatment by several months. Dialysis solution containing glucose polymers sustains ultrafiltration during peritonitis. In this paper there are also described icodextrin kinetics after intraperitoneal administration, its influence on peritoneal transport and adverse effects observed in some patients using icodextrin solution.

Dialysis Solutions↗

Peritoneal defense using icodextrin or glucose for daytime dwell in CCPD patients.

OBJECTIVE: To investigate peritoneal defense during icodextrin use in continuous cyclic peritoneal dialysis (CCPD). DESIGN: In an open, prospective, 2-year follow-up study, CCPD patients were randomized to either glucose (Glu) or icodextrin (Ico) for their long daytime dwell. SETTING: University hospital and teaching hospital. PATIENTS: Both established and patients new to CCPD were included. A life expectancy of more than 2 years, a stable clinical condition, and written informed consent were necessary before entry. Patients aged under 18 years, those who had peritonitis in the previous month, and women of childbearing potential, unless taking adequate contraceptive precautions, were excluded. Thirty-eight patients (19 Glu, 19 Ico) started the study. The median follow-up was 16 and 17 months for Glu and Ico respectively (range 0.5-25 months and 5-25 months, respectively). OUTCOME MEASURES: Peritoneal defense characteristics and peritoneal dialysis-related infections were recorded every 3 months. RESULTS: Total peritoneal white cell count tended to decrease over time in both groups. After 1 year, absolute numbers and percentages of effluent peritoneal macrophages (PMphis) were significantly higher in Ico than in Glu patients; this difference in the percentage persisted after 2 years. Percentage of mesothelial cells increased overtime in Ico patients. The phagocytic capacity of PMphis decreased over time, resulting in a borderline significant difference for coagulase-negative staphylococci (p = 0.05) and a significant difference for Escherichia coli (p < 0.05) phagocytosis in favor of Ico patients. PMphi oxidative metabolism remained stable over time without a difference between the groups. PMphi cytokine production and effluent opsonic capacity also remained stable over time. Finally, 16 peritonitis episodes in Glu and 14 in Ico patients occurred. Glucose patients had 37 and Ico patients 32 exit-site infections during the study. CONCLUSION: CCPD patients using Ico did equally as well as Glu-treated patients with respect to clinical infections and most peritoneal defense characteristics. However, in a few peritoneal defense tests, Ico-treated patients did better.

Adult↗

Peritoneal kinetics and mesothelial markers in CCPD using icodextrin for daytime dwell for two years.

OBJECTIVE: To evaluate the safety, efficacy, and biocompatibility of icodextrin (Ico), continuous cycling peritoneal dialysis (CCPD) patients were treated for 2 years with either Ico- or glucose (Glu)-containing dialysis fluid for their daytime dwell (14 - 15 hours). Prior to entry into the study, all patients used standard Glu solutions (Dianeal, Baxter BV, Utrecht,The Netherlands). DESIGN: Open, randomized, prospective two-center study. SETTING: University hospital and teaching hospital. PATIENTS: Both established patients and patients new to CCPD were included. A life expectancy of more than 2 years, a stable clinical condition, and written informed consent were necessary before entry. Patients aged under 18 years or with peritonitis in the previous month, and women of childbearing potential unless taking adequate contraceptive precautions, were excluded. Thirty-eight patients entered the study (19 Glu, 19 Ico). MAIN OUTCOME MEASURES: Daytime dwell peritoneal effluents were collected every 3 months in combination with other study variables (clinical data, laboratory measurements, dialysis-related data, and urine collection). Peritoneal transport studies were carried out every 6 months. RESULTS: In Glu- and Ico-treated patients, peritoneal transport of low molecular weight solutes and protein clearances neither changed during follow-up nor differed between the two groups. Peritoneal membrane markers (CA125, interleukin-8, carboxyterminal propeptide of type I procollagen, and aminoterminal propeptide of type III procollagen) measured in effluents did not differ between the groups and did not change over time. All these markers showed a dialysate/plasma ratio of more than 1, suggesting local production. Residual renal function remained stable during follow-up and adverse clinical effects were not observed. CONCLUSIONS: Peritoneal membrane transport kinetics and markers remained stable in both groups over a 2-year follow-up period. Membrane markers were higher in effluents than in serum, suggesting local production. No clinical side effects were demonstrated. Icodextrin was a well-tolerated effective treatment.

Adult↗

Assessment of the effectiveness, safety, and biocompatibility of icodextrin in automated peritoneal dialysis. The Dextrin in APD in Amsterdam (DIANA) Group.

OBJECTIVE: Our study assessed the efficacy, safety, and biocompatibility of icodextrin (I) solution compared to glucose (G) solution as the daytime dwell in continuous cycling peritoneal dialysis (CCPD). DESIGN: In a randomized, open, prospective, parallel group study of two year's duration, either I or G was used for the long daytime dwell in CCPD patients. METHOD: The study was carried out in a university hospital and teaching hospital. Established CCPD patients and patients new to the modality were both included. Clinic visits were made at three-month intervals. In all patients, clinical data were gathered; ultrafiltration (UF) was recorded; and serum, urine, and dialysate samples and effluents were collected. Peritoneal defense characteristics and mesothelial markers were determined. Every six months, peritoneal kinetics studies were performed, and serum samples for icodextrin metabolites were taken. RESULTS: Thirty-eight patients (19 G, 19 I) started the study. The median follow-up was 16 months and 17 months respectively (range: 0.5 - 26 months and 3 - 26 months, respectively). Daytime UF volumes increased significantly (p < 0.001), and 24-hour UF tended to increase from baseline in the I group. Dialysate creatinine clearance increased non significantly in both groups over time. In I patients, serum disaccharides (maltose) concentration increased from 0.05+/-0.01 mg/mL [mean+/- standard error of mean (SEM)] at baseline, to an average concentration in the follow-up visits of 1.15+/- 0.04 mg/mL (p <0.001). At the same time, serum sodium levels decreased from 138.1 +/- 0.7 mmol/L to an average concentration in the follow-up visits of 135.9 +/- 0.8 mmol/L (p < 0.050). At 12 months, the serum sodium concentration increased to a non significant difference from baseline. Serum osmolality increased, but did not differ significantly from G users at any visit. During peritonitis (P), daytime dwell UF decreased significantly compared to non peritonitis (NP) episodes in G patients (p < 0.0 01), but remained stable in I patients. Total 24-hour UF also decreased in G patients (p < 0.001), but not in I patients. In these I patients, serum disaccharides increased from 0.05 +/- 0.01 mg/mL to 1.26 +/- 0.2 mg/mL during follow-up. During peritonitis, serum disaccharides concentration did not increase further (1.47 +/- 0.2 mg/mL, p= 0.56). Thirty P episodes occurred during follow-up: 16 in G patients and 14 in I patients (1 per 17.6 months and 1 per 21.9 months, respectively.) After one year, absolute number and percentage of effluent peritoneal macrophages (PM phi s) were significantly higher in I patients than in G patients. The difference in percentage persisted after two years. The phagocytic capacity of PM phi s decreased over time, resulting in a borderline significant difference for coagulase-negative staphylococci phagocytosis (p=0.005) and a significant difference for E. coli phagocytosis (p <0.05) in favor of I patients. PM phi oxidative metabolism, PM phi cytokine production, and effluent opsonic capacity remained stable over time with no difference between the groups. Mass transfer area coefficients (MTACs) and clearances were stable and appeared unaffected by G or I treatment. Effluent cancer antigen 125 (CA125) was stable in G users and tended to decrease in I users. Effluent interleukin-8 (IL-8), carboxy-terminal propeptide of type I procollagen (PICP ), and amino-terminal propeptide of type III procollagen (PIIINP) did not change over time and did not differ between the groups. CONCLUSION: The use of I for the long daytime dwell in CCPD led to an increase in total UF of at least 261 mL per day, which was maintained over at least 24 months. During I treatment, serum I metabolites increased significantly and serum sodium concentrations decreased initially. As a result, serum osmolality increased slightly. Clinical adverse effects did not accompany these findings. The UF gain in the I patients was even higher during P, without a

Adult↗

Icodextrin effluent leads to a greater proliferation than glucose effluent of human mesothelial cells studied ex vivo.

OBJECTIVE: To compare the effect of glucose (Glu) and icodextrin (Ico) dialysate on in vitro culture of mesothelial cells (MC) from peritoneal dialysis (PD) patients. DESIGN: Prospective, controlled comparative study on the effects of two PD solutions. SETTING: A tertiary-care public university hospital. PATIENTS: Sixteen PD patients regularly using Glu dialysate were asked to collect an 8-hour dwell peritoneal effluent on 2 different days, with an interval shorter than 7 days. In the first collection, 2.27% Glu solution and in the last, 7.5% Ico solution was infused. Human MC were isolated from the nocturnal peritoneal effluent bags and grown ex vivo. MAIN OUTCOME MEASURES: Mesothelial cell proliferative capacity ex vivo. RESULTS: Mesothelial cells were present in all patient dialysates except that of a single patient's Glu dialysate. The number of MC drained was similar with both solutions. After the initial culture reached confluence, MC were identified in 14 and 12 patients receiving Ico and Glu, respectively. However, in 1 patient using Ico and in 2 using Glu, the MC count at this stage was so low that further subculture could not be performed. Cells from Ico-derived solutions exhibited a higher degree of proliferation than cells from Glu-derived solutions. The morphology of MC was also different. Cells from drained effluent were typical in 11 patients using Glu solution in contrast with 14 patients using Ico. At confluence, the percentages of typical appearance were 50% and 92.9% (p < 0.05) in Glu and Ico respectively. CONCLUSIONS: Mesothelial cells taken from icodextrin effluent show a greater proliferation ex vivo than those taken from glucose effluent.

Cell Division↗

Glycation and advanced glycation end-product formation with icodextrin and dextrose.

OBJECTIVE: To review protein glycation and advanced glycation end-product formation with particular reference to its occurrence in the peritoneum following exposure to peritoneal dialysis fluid. DATA SOURCES: Articles identified through searches on MEDLINE and BIDS and references cited therein. STUDY SELECTION: Studies on the interaction of amino groups with glucose, maltose and glucose polymers. Studies containing evidence of peritoneal advanced glycation end-product formation. DATA EXTRACTION: Studies evaluated as to whether they are in vivo, ex vivo or in vitro under non-physiological or physiological conditions. RESULTS: Protein glycation is slower with maltose and glucose polymers than with equimolar glucose. Advanced glycation end-product formation occurs with all three sugars, but to a greater extent after standard heat sterilization of dialysis fluid and to a lesser extent in heat sterilized fluids containing icodextrin rather than glucose. Glucose degradation products significantly contribute to protein-linked advanced glycation end-product-like fluorescence. Histology and immunohistochemistry demonstrate diabetiform changes and advanced glycation end-products in the peritoneal membrane following exposure to glucose-containing peritoneal dialysis fluids. Their presence is likely to be detrimental to peritoneal function and may contribute to loss of ultrafiltration. CONCLUSIONS: Advanced glycation end-product formation is lower but still significant with heat sterilized peritoneal dialysis fluid containing icodextrin than with glucose. More research is needed to investigate the interaction of glucose degradation products and glucose polymers with proteins and the possible consequences of advanced glycation end-product formation on peritoneal function.

Dialysis Solutions↗

Computer simulations of ultrafiltration profiles for an icodextrin-based peritoneal fluid in CAPD.

BACKGROUND: The three-pore model of peritoneal transport has the ability to predict ultrafiltration (UF) profiles rather accurately, even when high molecular weight (MW) solutes are employed as osmotic agents in continuous ambulatory peritoneal dialysis (CAPD). In the present simulations, we wanted to assess, for various theoretical perturbations, the UF properties of a peritoneal dialysis (PD) solution with an osmotic agent having an average MW of 20 kD and a "number average MW" of 6.2 kD, which is similar to that of icodextrin (ICO). METHODS: For a PD solution containing a completely monodispersed 20 kD MW osmotic agent, the degree of UF modeled is much higher than that reported for ICO. Hence, to model the behavior of ICO, we subdivided the ICO molecules into eight or more different MW size fractions. For simulations using six or eight subfractions, we obtained an excellent fit of simulated to reported UF data. More dispersed solutions produced UF profiles similar to that with eight fractions. RESULTS: A 2.05 L 7.5% ICO PD solution, despite being slightly hypotonic, yielded a UF volume of nearly 600 mL in 12 hours, modeled for patients not previously exposed for ICO. After nine hours, the UF volume exceeded that produced by 3.86% glucose. The UF rate and volumes increased in proportion to (1) the ICO concentration, (2) the peritoneal surface area, and (3) the peritoneal UF coefficient, but was almost insensitive to increases in the instilled fluid volume. Simulated for patients previously exposed to ICO, having steady-state plasma concentrations of ICO degradation products, the predicted UF volume at 12 hours was reduced to approximately 400 mL. CONCLUSION: Employing the three-pore model of peritoneal transport and taking into account the polydispersed nature of ICO, it was possible to accurately computer simulate the UF profiles of ICO in accordance with reported data. The simulations suggest an advantage of using ICO in patients with type I UF failure, where UF with a high-MW osmotic agent will exceed that seen in patients not showing UF failure who are on glucose-based PD solutions.

Absorption↗

Ultrafiltration with icodextrins in continuous ambulatory peritoneal dialysis and automated peritoneal dialysis.

Icodextrins (Icos) produce constant linear ultrafiltration (UF). This effect allows Icos to replace glucose during long dwells in continuous ambulatory peritoneal dialysis [CAPD (nighttime)] and automated peritoneal dialysis [APD (daytime)]. However, the effectiveness of Icos in producing UF (IcoUF) is limited by lymphatic reabsorption, whose extent depends partly on posture and physical activity. This paper aims to assess whether the difference in posture and physical activity between daytime dwells in APD and nighttime dwells in CAPD affects IcoUF. Patients undergoing first treatment were retrospectively examined. Ten patients were on CAPD [4 males, 6 females; average age, 73.0 +/- 13.4 years; body surface area (BSA), 1.63 +/- 0.21 m2; total volume per day, 5.6 +/- 1.9 L], and ten were on APD (7 males, 3 females; average age, 67.7 +/- 9.8; BSA, 1.75 +/- 0.22 m2; total volume per night, 10.5 +/- 0.9 L). Ultrafiltration was assessed for seven consecutive days preceding a peritoneal equilibration test (PET) and collection of diuresis. In both groups, 3 patients had no diuresis, and the difference between CAPD and APD was not significant (625 +/- 762 mL vs 780 +/- 878 mL). Moreover, no significant difference was seen in 4-hour dialysate-to-plasma creatinine (D/P) between CAPD (0.65 +/- 0.12) and APD (0.64 +/- 0.05). Dwell times with Icos were shorter in CAPD than in APD (11.5 +/- 1.8 hours vs 14.8 +/- 0.5 hours, p < 0.0005), but the fill volume was not significantly different (1760 +/- 286 mL vs 1790 +/- 249 mL). Water excretion owing to diuresis and dialysis [total water excretion (TWE): 1619 +/- 497 mL CAPD vs 1762 +/- 736 mL APD] and dialytic UF (363 +/- 443 mL CAPD vs 748 +/- 479 mL APD), which is not linked to Icos, were not significantly different between the two groups. The IcoUF and the percentage of IcoUF to TWE were significantly higher in CAPD compared to APD [631 +/- 253 mL (44% +/- 27%) vs 234 +/- 215 mL (19% +/- 19%), p < 0.001 (p < 0.05)]. In conclusion, an upright posture and physical activity seem to produce less IcoUF in APD despite the longer dwell. These factors could, indeed, produce greater intraperitoneal pressure, resulting in increased lymphatic reabsorption during a daytime dwell.

Aged↗