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Kidney International. Supplement Nov 2006Malnutrition is a major complication of peritoneal dialysis (PD) and is associated with increased morbidity and mortality. Daily losses of proteins and amino acids (AAs)... (Review)
Review
Malnutrition is a major complication of peritoneal dialysis (PD) and is associated with increased morbidity and mortality. Daily losses of proteins and amino acids (AAs) into dialysate contribute to this problem. Previous metabolic balance study demonstrated that treatment with 1.1% AA-based dialysis solution is safe and may improve protein malnutrition in continuous ambulatory peritoneal dialysis (CAPD) patients ingesting low protein intake. Other prospective studies also showed that AA solution can provide nutritional benefit for malnourished PD patients resulting in a significant improvement in some biochemical and/or anthropometric nutritional parameters. However, there are other studies showing no particular improvement in nutritional parameters after long-term use of AA solution. This may be related to the differences in the study design, sample size, methods used to assess nutritional status, and other factors such as dietary intake and comorbidities of study subjects. Published data will be reviewed to further emphasize the nutritional benefit of long-term use of AA solution in malnourished PD patients along with a brief discussion on the various reasons that may partly explain the different study results. We will also present the results of a longitudinal observational study evaluating changes in nutritional parameters following use of one exchange of 1.1% AA solution in malnourished Korean PD patients. A significant improvement of somatic protein status such as lean body mass (LBM) and hand grip strength was observed. No significant change in serum albumin level was noted. Patients with a positive estimated coefficient for LBM in the fitted regression model to the repeated observations over 1 year were classified as responders and patients with neutral or negative coefficient were considered as non-responders. Thirty-one out of 43 malnourished patients (72%) showed nutritional benefit based on the change of LBM. Hand grip strength and back lift strength were significantly higher in responders at baseline. Other baseline parameters did not differ between the two groups.
Topics: Amino Acids; Dialysis Solutions; Humans; Kidney Failure, Chronic; Peritoneal Dialysis
PubMed: 17080099
DOI: 10.1038/sj.ki.5001925 -
Kidney International Jan 2001Dipeptide-based peritoneal dialysis solutions may have potential advantages compared with the glucose or amino acid-based solutions. Dipeptides may hydrolyze in the...
BACKGROUND
Dipeptide-based peritoneal dialysis solutions may have potential advantages compared with the glucose or amino acid-based solutions. Dipeptides may hydrolyze in the peritoneal cavity, generating constituent amino acids and thereby increasing the osmolality of the dialysate. Dipeptides can also be a valuable source of amino acids, which are poorly soluble in water, such as tyrosine.
METHODS
Dwell studies in rats were performed during four hours with dipeptide solutions containing five dipeptides (Gly-His, Ala-Tyr, Thr-Leu, Ser-Phe, Val-Lys), 8, or 16 mmol/L of each dipeptide (low or high dipeptide group). Dwell studies were also performed with a 1.1% amino acid solution (Nutrineal(R)). The model of dipeptide hydrolysis (hydrolysis rate, KH), diffusive (rate constant, KBDD) and convective transport as well as transport of constituent amino acids consisted of mass balance equations, written for each dipeptide and amino acid.
RESULTS
Peritoneal volume with the amino acid solution decreased much faster than that with the high and low dipeptide solutions. KH for all dipeptides did not differ between the high and low dipeptide groups. In the low dipeptide group, KH was 0.004 +/- 0.004 mL/min (mean +/- SD) for Gly-His (the lowest) and 0.088 +/- 0.048 mL/min for Thr-Leu (the highest). KBDD was higher than KH for all dipeptides, the average being 0.2 +/- 0.05 mL/min.
CONCLUSIONS
Dipeptides are hydrolyzed in the peritoneal cavity, generating constituent amino acids. However, the hydrolysis rate appears to be several times lower than the dipeptide diffusive transport rate from dialysate to blood. Due to the higher molecular weight and intraperitoneal generation of amino acids, the dipeptide-based solutions provide more sustained ultrafiltration than the amino acid solution. The plasma concentration of amino acids at 60 minutes, in relation to the dose of amino acids delivered between 0 and 60 minutes, is considerably higher during the dwells with amino acid-based solution than during dwells with the dipeptide-based solutions.
Topics: Amino Acids; Animals; Biological Transport; Dialysis Solutions; Diffusion; Dipeptides; Hydrolysis; Kinetics; Male; Models, Biological; Osmolar Concentration; Peritoneal Cavity; Peritoneal Dialysis; Rats; Rats, Sprague-Dawley
PubMed: 11135092
DOI: 10.1046/j.1523-1755.2001.00499.x -
Pediatric Nephrology (Berlin, Germany) Sep 2009There is no unique optimal peritoneal dialysis prescription for all children, although the goals of ultrafiltration and blood purification are universal. In turn, a... (Review)
Review
There is no unique optimal peritoneal dialysis prescription for all children, although the goals of ultrafiltration and blood purification are universal. In turn, a better understanding of the physiology of the peritoneal membrane, as a dynamic dialysis membrane with an exchange surface area recruitment capacity and unique permeability characteristics, results in the transition from an empirical prescription process based on clinical experience alone to the potential for a personalized prescription with individually adapted fill volumes and dwell times. In all cases, the prescribed exchange fill volume should be scaled for body surface area (ml/m(2)), and volume enhancement should be conducted based on clinical tolerance and intraperitoneal pressure measurements (IPP; cmH(2)O). The exchange dwell times should be determined individually and adapted to the needs of the patient, with particular attention to phosphate clearance and ultrafiltration capacity. The evolution of residual kidney function and the availability of new, more physiologic, peritoneal dialysis fluids (PDFs) also influence the prescription process. An understanding of all of these principles is integral to the provision of clinically optimal PD.
Topics: Adolescent; Body Surface Area; Child; Child, Preschool; Dialysis Solutions; Humans; Infant; Kidney Failure, Chronic; Peritoneal Dialysis; Peritoneum; Point-of-Care Systems
PubMed: 18807074
DOI: 10.1007/s00467-008-0979-7 -
Kidney International Jul 2010Morphological changes of the peritoneal membrane that occur over time among patients on peritoneal dialysis include fibrosis and neoangiogenesis. While the... (Review)
Review
Morphological changes of the peritoneal membrane that occur over time among patients on peritoneal dialysis include fibrosis and neoangiogenesis. While the pathophysiologic mechanisms underlying these changes are not fully understood, the activation of the renin-angiotensin-aldosterone system (RAAS) may have an important role. Components of the RAAS are constitutively expressed within peritoneal mesothelial cells, and are upregulated in the presence of acute inflammation and chronic exposure to peritoneal dialysate. The high glucose concentration, low pH, and the presence of glucose degradation products in peritoneal dialysis solutions have all been implicated in modulation of peritoneal RAAS. Furthermore, activation of the RAAS, as well as the downstream production of transforming growth factor-beta, contributes to epithelial-to-mesenchymal transformation of mesothelial cells, resulting in progressive fibrosis of the peritoneal membrane. This process also leads to increased vascular endothelial growth factor production, which promotes peritoneal neoangiogenesis. Functionally, these changes translate into reduced ultrafiltration capacity of the peritoneal membrane, which is an important cause of technique failure among patients on long-term peritoneal dialysis. This brief review will describe our current state of knowledge about the role of peritoneal RAAS in peritoneal membrane damage and potential strategies to protect the membrane.
Topics: Dialysis Solutions; Epithelial Cells; Epithelium; Fibrosis; Glucose; Humans; Inflammation; Kidney; Neovascularization, Pathologic; Peritoneal Dialysis; Peritoneum; Renin-Angiotensin System; Transforming Growth Factor beta; Ultrafiltration
PubMed: 20336052
DOI: 10.1038/ki.2010.90 -
Kidney International Jan 1996Free, acetyl-, medium- and long-chain acylcarnitine and total plasma carnitine concentrations were measured in eight continuous ambulatory peritoneal dialysis (CAPD)...
Free, acetyl-, medium- and long-chain acylcarnitine and total plasma carnitine concentrations were measured in eight continuous ambulatory peritoneal dialysis (CAPD) patients and eight age- and sex-matched healthy controls. Daily loss of carnitine was also quantified in both groups, by analysis of urine and dialysis fluid. Plasma total carnitine concentration in CAPD patients was not significantly different from controls (42.8 +/- 1.6 and 43.1 +/- 2.3 mumol/liter, respectively). However, the plasma free carnitine concentration of CAPD patients was significantly lower than that of controls (28.5 +/- 1.4 and 36.2 +/- 2.5 mumol/liter, respectively; P < 0.05). No difference in the daily loss of total carnitine was found between CAPD patients and controls (269.7 +/- 30.0 and 240.5 +/-33.0 mumol/liter, respectively), but the daily loss of free carnitine was significantly greater in CAPD patients (175.8 +/- 17.3 and 105.8 +/- 16.4 mumol/liter, respectively; P < 0.05). The ratio of total acylcarnitine (acetyl-, medium- and long-chain acylcarnitine) to free carnitine was significantly greater in plasma of CAPD patients than in controls (P < 0.01) and was lower in daily fluid losses (P < 0.001). These ratio differences suggests that an alteration in acyl group metabolism is occurring in CAPD patients. This may be attributable to an accumulation of medium- and long-chain acylcarnitine in liver of CAPD patients which would be exchanged for plasma free carnitine and/or to a differential loss of free and acylcarnitine across the peritoneal cavity.
Topics: Adult; Carnitine; Dialysis Solutions; Female; Humans; Kidney Failure, Chronic; Male; Middle Aged; Peritoneal Dialysis, Continuous Ambulatory
PubMed: 8770962
DOI: 10.1038/ki.1996.21 -
Journal of the American Society of... Jul 2018Osmosis drives transcapillary ultrafiltration and water removal in patients treated with peritoneal dialysis. Crystalloid osmosis, typically induced by glucose, relies...
Osmosis drives transcapillary ultrafiltration and water removal in patients treated with peritoneal dialysis. Crystalloid osmosis, typically induced by glucose, relies on dialysate tonicity and occurs through endothelial aquaporin-1 water channels and interendothelial clefts. In contrast, the mechanisms mediating water flow driven by colloidal agents, such as icodextrin, and combinations of osmotic agents have not been evaluated. We used experimental models of peritoneal dialysis in mouse and biophysical studies combined with mathematical modeling to evaluate the mechanisms of colloid versus crystalloid osmosis across the peritoneal membrane and to investigate the pathways mediating water flow generated by the glucose polymer icodextrin. modeling and studies showed that deletion of aquaporin-1 did not influence osmotic water transport induced by icodextrin but did affect that induced by crystalloid agents. Water flow induced by icodextrin was dependent upon the presence of large, colloidal fractions, with a reflection coefficient close to unity, a low diffusion capacity, and a minimal effect on dialysate osmolality. Combining crystalloid and colloid osmotic agents in the same dialysis solution strikingly enhanced water and sodium transport across the peritoneal membrane, improving ultrafiltration efficiency over that obtained with either type of agent alone. These data cast light on the molecular mechanisms involved in colloid versus crystalloid osmosis and characterize novel osmotic agents. Dialysis solutions combining crystalloid and colloid particles may help restore fluid balance in patients treated with peritoneal dialysis.
Topics: Animals; Aquaporin 1; Biological Transport; Colloids; Computer Simulation; Crystalloid Solutions; Dialysis Solutions; Genotype; Glucose; Icodextrin; Mice; Models, Theoretical; Osmosis; Peritoneal Dialysis; Peritoneum; Water
PubMed: 29844208
DOI: 10.1681/ASN.2017080828 -
International Journal of Molecular... Nov 2021Sodium overload is common in end-stage kidney disease (ESKD) and is associated with increased cardiovascular mortality that is traditionally considered a result of... (Review)
Review
Sodium overload is common in end-stage kidney disease (ESKD) and is associated with increased cardiovascular mortality that is traditionally considered a result of extracellular volume expansion. Recently, sodium storage was detected by Na23 magnetic resonance imaging in the interstitial tissue of the skin and other tissues. This amount of sodium is osmotically active, regulated by immune cells and the lymphatic system, escapes renal control, and, more importantly, is associated with salt-sensitive hypertension. In chronic kidney disease, the interstitial sodium storage increases as the glomerular filtration rate declines and is related to cardiovascular damage, regardless of the fluid overload. This sodium accumulation in the interstitial tissues becomes more significant in ESKD, especially in older and African American patients. The possible negative effects of interstitial sodium are still under study, though a higher sodium intake might induce abnormal structural and functional changes in the peritoneal wall. Interestingly, sodium stored in the interstial tissue is not unmodifiable, since it is removable by dialysis. Nevertheless, the sodium removal by peritoneal dialysis (PD) remains challenging, and new PD solutions are desirable. In this narrative review, we carried out an update on the pathophysiological mechanisms of volume-independent sodium toxicity and possible future strategies to improve sodium removal by PD.
Topics: Animals; Dialysis Solutions; Humans; Kidney Failure, Chronic; Peritoneal Dialysis; Peritoneum; Sodium
PubMed: 34884617
DOI: 10.3390/ijms222312804 -
Toxins Feb 2021Peritoneal dialysis (PD) is a feasible and effective renal replacement therapy (RRT) thanks to the dialytic properties of the peritoneal membrane (PM). Preservation of...
Peritoneal dialysis (PD) is a feasible and effective renal replacement therapy (RRT) thanks to the dialytic properties of the peritoneal membrane (PM). Preservation of PM integrity and transport function is the key to the success of PD therapy, particularly in the long term, since the prolonged exposure to unphysiological hypertonic glucose-based PD solutions in current use is detrimental to the PM, with progressive loss of peritoneal ultrafiltration capacity causing technique failure. Moreover, absorbing too much glucose intraperitoneally from the dialysate may give rise to a number of systemic metabolic effects. Here we report the preliminary results of the first clinical experience based on the use in continuous ambulatory PD (CAPD) patients of novel PD solutions obtained through partly replacing the glucose load with other osmotically active metabolites, such as L-carnitine and xylitol. Ten CAPD patients were treated for four weeks with the new solutions. There was good tolerance to the experimental PD solutions, and no adverse safety signals were observed. Parameters of dialysis efficiency including creatinine clearance and urea Kt/V proved to be stable as well as fluid status, diuresis, and total peritoneal ultrafiltration. The promising tolerance and local/systemic advantages of using L-carnitine and xylitol in the PD solution merit further research.
Topics: Adult; Aged; Carnitine; Dialysis Solutions; Female; Glucose; Humans; Italy; Kidney Failure, Chronic; Male; Middle Aged; Peritoneal Dialysis, Continuous Ambulatory; Prospective Studies; Time Factors; Treatment Outcome; Xylitol
PubMed: 33668249
DOI: 10.3390/toxins13030174 -
Jornal Brasileiro de Nefrologia 2014Continuous exposition of the peritoneal membrane to conventional dialysis solutions is an important risk factor for inducing structural and functional alterations.
INTRODUCTION
Continuous exposition of the peritoneal membrane to conventional dialysis solutions is an important risk factor for inducing structural and functional alterations.
OBJECTIVE
To compare in vitro mouse fibroblast NIH-3T3 cell viability after exposition to a neutral pH dialysis solution in comparison to cells exposed to a standard solution.
METHODS
Experimental study to compare the effects of a conventional standard or a neutral-pH, low-glucose degradation products peritoneal dialysis solution on the viability of exposed fibroblasts in cell culture. Both solutions were tested in all the commercially available glucose concentrations. Cell viability was evaluated with tetrazolium salt colorimetric assay.
RESULTS
Fibroblast viability was significantly superior in the neutral pH solution in comparison to control, in all three glucose concentrations (Optical density in nm-means ± SD: 1.5% 0.295 ± 0.047 vs. 0.372 ± 0.042, p < 0.001; 2.3% 0.270 ± 0.036 vs. 0.337 ± 0.051, p < 0.001; 4.25% 0.284 ± 0.037 vs. 0.332 ± 0.032, p < 0.001; control vs. neutral pH respectively, Student t Test). There was no significant difference in cell viability between the three concentrations of glucose when standard solution was used (ANOVA p = 0.218), although cell viability was higher after exposition to neutral pH peritoneal dialysis fluid at 1.5% in comparison to 2.3 and 4.25% glucose concentrations (ANOVA p = 0.008: Bonferroni 1.5% vs. 2.3% p = 0.033, 1.5% vs. 4.25% p = 0.014, 2.3% vs. 4.25% p = 1.00).
CONCLUSION
Cell viability was better in neutral pH dialysis solution, especially in the lower glucose concentration. A more physiological pH and lower glucose degradation products may be responsible for such results.
Topics: Animals; Cell Survival; Dialysis Solutions; Fibroblasts; Hydrogen-Ion Concentration; Mice; Peritoneal Dialysis
PubMed: 25055354
DOI: 10.5935/0101-2800.20140024 -
Peritoneal Dialysis International :... 2008Conventional peritoneal dialysis (PD) solutions elicit vasodilation, which is implicated in the variable rate of solute transport during the dwell. The components...
BACKGROUND
Conventional peritoneal dialysis (PD) solutions elicit vasodilation, which is implicated in the variable rate of solute transport during the dwell. The components causing such vasoactivity are still controversial. This study was conducted to define the vasoactive components of conventional and new PD solutions.
METHODS
Three visceral peritoneal microvascular levels were visualized by intravital video microscopy of the terminal ileum of anesthetized rats. Anesthesia-free decerebrate conscious rats served as control. Microvascular diameter and blood flow by Doppler measurements were conducted after topical peritoneal exposure to 4 clinical PD solutions and 6 prepared solutions designed to isolate potential vasoactive components of the PD solution.
RESULTS
All clinically available PD solutions produced a rapid and generalized vasodilation at all intestinal microvascular levels, regardless of the osmotic solute. The pattern and magnitude of this dilation was not affected by anesthesia but was determined by arteriolar size, the osmotic solute, and the solution's buffer anion system. The greatest dilation occurred in the small precapillary arterioles and was elicited by conventional PD solution and heat re-sterilized solution containing low glucose degradation products (GDPs). Hypertonic mannitol solutions produced a dilation that was approximately 50% less than the dilation obtained with glucose solutions with identical osmolarity and buffer. Increasing a solution's osmolarity did not produce a parallel increase in the magnitude of dilation, suggesting a nonlinear relationship between the two variables. Lactate dissolved in an isotonic solution was completely non-vasoactive unless the solution's H(+) concentration was increased. At low pH, isotonic lactate produced a rapid but transient vasodilation. This vascular reactivity was similar in magnitude and pattern to that obtained with the isotonic 7.5% icodextrin solution (Extraneal; Baxter Healthcare, Deerfield, Illinois, USA).
CONCLUSIONS
(1) Hyperosmolarity is the major vasoactive component of PD solution. (2) Hyperosmolarity and active intracellular glucose uptake account together for approximately 75% of PD solution-induced dilation, whereas GDPs contribute to approximately 25%. (3) Lactate is vasoactive only at low pH (high [H(+)]). (4) The magnitude of PD solution-mediated vasodilation is partially dependent on the nature of the osmotic solute, the GDP contents, and the [H(+)], which determine the vasoactivity of the lactate-buffer anion system. Studies are required to define the molecular mechanisms of PD-induced vasodilation and to determine the vasoactive properties of these solutions after chronic infusion.
Topics: Animals; Biological Transport; Buffers; Dialysis Solutions; Glucans; Glucose; Icodextrin; Lactates; Male; Microcirculation; Osmolar Concentration; Peritoneal Cavity; Peritoneal Dialysis; Peritoneum; Random Allocation; Rats; Rats, Sprague-Dawley; Rats, Wistar; Regional Blood Flow; Vasodilation
PubMed: 18474922
DOI: No ID Found