Peritoneal dialysis fluids

There have been significant advances in the understanding of peritoneal dialysis (PD) in the last 40 years, and uptake of PD as a modality of kidney replacement therapy is increasing worldwide. PD fluids, therefore, remains the lifeline for patients on this treatment. Developing these fluids to be efficacious in solute clearance and ultrafiltration, with minimal adverse consequences to peritoneal membrane health and systemic effects is a key requirement. Since the first PD fluid produced in 1959, modifications to PD fluids have been made. Nonetheless, the search for that ideal PD fluid remains elusive. Understanding the components of PD fluids is a key aspect of optimizing the successful delivery of PD, allowing for individualized PD prescription. Glucose remains an integral component of PD fluids; however, its deleterious effects continue to be the impetus for the search of an alternative osmotic agent, and icodextrin remains the main alternative. More biocompatible PD fluids have been developed and have shown benefits in preserving residual kidney function. However, high cost and reduced accessibility remain deterrents to its widespread clinical use in many countries. Large-scale clinical trials are necessary and very much awaited to improve the narrow spectrum of PD fluids available for clinical use.

Association of Hypertriglyceridemia and Insulin Resistance in UREMIC Patients Undergoing CAPD

Objective

Hyperlipidemia is frequently encountered in uremic patients and may be worsened by continuous ambulatory peritoneal dialysis (CAPD) treatment. The lipid abnormalities in these patients may be multifactorial. Insulin resistance (or its compensatory hyperinsulinemia) is commonly observed in uremic patients, but its association with hyperlipidemia in these patients has not been studied.

Patients and Methods

Lipid profiles of 35 nondiabetic nonobese patients undergoing CAPD for more than 1 year (mean 52.3 months) were studied. Current laboratory data and parameters related to peritoneal dialysis (PD) within the previous 3 months were recorded. After overnight fasting and interruption of PD, an oral 75-g glucose tolerance test (OGTT) was examined.

Results

After CAPD treatment for more than 12 months, these patients had higher serum triglyceride (TG) ( p = 0.001) and total cholesterol ( p = 0.0058) levels than their values before commencing CAPD. Twelve of 14 patients with serum TG higher than 200 mg/dL (high-TG) were diagnosed de novo, in contrast with only 1 patient diagnosed of de novo hypercholesterolemia (total cholesterol > 240 mg/dL). There was no difference in age, gender, body mass index (BMI), duration of PD treatment, serum albumin, hematocrit, intact serum parathyroid hormone (iPTH), peritoneal glucose load, solute transport, or weekly Kt/V urea between normal-TG and high-TG patients. After adjusting for age, gender, BMI, weekly Kt/V urea, and iPTH, the high-TG patients had higher levels of area under the curve for glucose (AUCGlu), area under the curve for insulin (AUCIns), and AUCIns/AUCGluratios (F = 10.63, 10.14, and 8.65; p = 0.0029, 0.0035, and 0.0065, respectively), indicating that the high-TG patients were more insulin resistant. There were 24 patients with normal glucose tolerance (NGT), and 11 patients with impaired glucose tolerance (IGT). The IGT group had higher serum TG (F = 10.43, p = 0.003) and total cholesterol (F = 8.05, p = 0.009) than the NGT group, after adjusting for BMI, duration of CAPD treatment, peritoneal glucose load, solute transport, serum albumin, and lipid levels before PD treatment. The TG levels after CAPD treatment were positively correlated with AUCGlu, AUCIns, and AUCIns/AUCGluratio ( r = 0.48, 0.53, and 0.49; p = 0.0037, 0.001, and 0.0028, respectively).

Conclusions

These results indicate that insulin resistance is an important factor in the development of hypertriglyceridemia in CAPD patients.

Effect of Dietary Fish Oil on Lipid Abnormalities in Patients on Continuous Ambulatory Peritoneal Dialysis

Fifteen patients receiving continuous ambulatory peritoneal dialysis (CAPD) were given 10 mL of a dietary fish oil rich in omega-3 fatty acids (MaxEPA) b.i.d. for eight weeks without other dietary manipulation. Fasting lipids, vitamins A and E, and glucose were measured at 0, 4, and 8 weeks, and again at 4 and 8 weeks after the cessation of treatment.

Basal serum triglyceride concentrations were raised, and fell by 29% (p < 0.005) with treatment, returning to baseline values over the washout period. The fall in triglyceride during treatment correlated with the initial value (As = 0.57; p < 0.05). Total, HDL and LDL cholesterol, apolipoprotein A, vitamin A, glucose, lean body mass, and dietary fat/CHO intake were unchanged throughout. Apolipoprotein B concentrations tended to rise during the first half of treatment but fell thereafter. Vitamin E concentrations rose significantly during supplementation and fell after withdrawal (p < 0.001 for both).

Supplementation with dietary fish oil significantly reduced hypertriglyceridemia. Its long-term use might be accompanied by beneficial effects on the excess cardiovascular morbidity seen in patients on CAPD.

Effect of Hypertriglyceridemia Correction by Omega-3 Fatty Acids on Peritoneal Transport in Continuous Ambulatory Peritoneal Dialysis Patients

Lipid abnormalities, both hypercholesterolemia and particularly hypertriglyceridemia (hyperTg), are common in long-term continuous ambulatory peritoneal dialysis (CAPO) patients. Hyperviscosity and rheological alterations have been proposed as major hemodynamic problems in hyperTg patients.

The aim of this study was to evaluate whether a hyperTg correction by employing omega-3 fatty acids (ω-3) affects peritoneal transport.

Six hyperTg (>700 mg/dL) CAPO patients were treated with 2–3 g/day of ω-3 until normal Tg values were achieved. The assessment of peritoneal dialysis efficacy was performed by evaluating the peritoneal equilibration test (PET) before ω-3 supplementation, when normal Tg levels were reached, and 3 weeks after stopping therapy when hyperTg returned.

When normal Tg levels were reached, a small but significant Improvement of urea and creatinine O/P was noted: 0.85±0.05 versus 0.93±0.03 (p<0.05) and 0.78±0.03 versus 0.86±0.05 (p<0.05), respectively, with negative correlation between O/P of urea and Tg.

These preliminary data demonstrate that a hyperTg correction with ω-3 may Induce an Increase In peritoneal transport of small molecules in CAPO.

Amino-Acid-Based Continuous Ambulatory Peritoneal Dialysis (CAPD) Fluid over Twelve Weeks: Effects on Carbohydrate and Lipid Metabolism

Aspects of lipid and carbohydrate metabolism were studied in 8 patients established on continuous ambulatory peritoneal dialysis (CAPD) with plasma albumin < 35 g/L, before, during, and after substitution of 1 of the daily glucose exchanges by a commercial 1 % amino acid dialysis fluid for 12 weeks. The amount of glucose absorbed from the dialysis fluid was consequently reduced by about 25%, hence total energy intake decreased by about 100 Kcallday, but peritoneal glucose transfer kinetics were unaffected. Glucose was lost into amino acid dialysate as expected (2 g/day).

Excluding 1 patient with a large rise in calorie intake, total and LDL cholesterol fell at 8 and 12 weeks (LDL cholesterol week 0, 5.26 ± 1.13; week 8, 4.32 ± 0.74; week 12,4.30 ± 1.22; mean ± SD, p < 0.01 for both), but returned to baseline 2 weeks after the restoration of glucose fluid (LDL 4.91 ± 1.22, p < 0.05 vs. week 12). Apolipoprotein B concentration also fell at 12 weeks (p < 0.01). No changes were seen in body weight, body fat, arm muscle circumference, fasting plasma glucose, insulin, growth hormone, triglyceride, non esterified fatty acids, or HDL cholesterol. The response of these biochemical indices to single 8-h glucose and amino acid morning exchanges at 0 and 12 weeks were studied. After 12 week's use of amino acid dialysis fluid, plasma cholesterol and apolipoprotein B were significantly lower throughout the exchange.

The decrease in cholesterol and apolipoprotein B during the substitution of 1% amino acid dialysis fluid may be associated not only with the reduction in glucose intake, but also with a gradual change in lipid metabolism. The routine use of such solutions may lower cardiovascular morbidity and mortality in CAPD but further evaluation is indicated.

The effect of glucose absorption from peritoneal dialysates on changes in lipid profiles in prevalent peritoneal dialysis patients

The majority of peritoneal dialysates contain glucose, which can potentially be absorbed from the peritoneal cavity. Previous studies have reported an observation between dialysate glucose exposure and increases in total cholesterol (TC), low-density lipoproteins (LDLs) and triglycerides (TGs). As most of these studies reported glucose exposure in peritoneal dialysis (PD) patients treated by continuous ambulatory peritoneal dialysis (CAPD), we wished to determine whether measured peritoneal glucose absorption resulted in an increase in lipid profile with CAPD and automated PD (APD) cycler treatments. Glucose absorption was measured in 143 patients; 89 (62.2%) males, 53 (37.1%) diabetics, mean age 61.3 ± 14.9 years, with 90 (62.1%) using a daytime icodextrin exchange; 37 (25.9%) CAPD, attending for their first assessment of peritoneal membrane function, when PD prescriptions were then individualised for peritoneal transporter status and repeated after 12 months. Median glucose absorption was 172.5 (75.5-265.5) mmol/day. Although glycated haemoglobin increased (42 ± 16 to 45.4 ± 17.7 mmol/mol, p = 0.006), there was no change in TC (4.8 ± 1.3 to 4.7 ± 1.3 mmol/L), high-density lipoproteins (1.39 ± 0.45 to 1.33 ± 0.51 mmol/L), LDL (2.48 ± 1.12 to 2.21 ± 0.87 mmol/L) or TGs (2.0 (1.3-2.6) to 2.0 (1.3-2.8) mmol/L, adjusted p > 0.05). We found no association between glucose absorption and either lipid profiles or changes in serum lipids. In the current era of APD cyclers and icodextrin, PD prescriptions can be individualised to accommodate patients with a different peritoneal transport status, so that despite daily glucose absorption from dialysates, and a minor increase in glycated haemoglobin, we were unable to demonstrate any significant increase in standard lipid profiles.

Dietary intake in hemodialysis patients does not reflect a heart healthy diet

OBJECTIVE

Cardiovascular disease is highly prevalent and has a major effect on morbidity and mortality in patients undergoing maintenance hemodialysis (MHD). Dietary factors that may contribute to cardiovascular disease have not been well studied in this population. We hypothesize that dietary intake in this population does not meet the guidelines for cardiovascular risk reduction.

DESIGN

A cross-sectional study was completed using the validated "Block Dialysis 1 Food Frequency Questionnaire" to assess dietary intake of MHD patients.

SETTING AND PATIENTS

A total of 70 patients undergoing MHD at our outpatient dialysis center completed the questionnaire under the supervision of a trained dietitian. The population consisted of 38 men and 32 women.

MAIN OUTCOME MEASURE

Dietary intake was the main outcome measure, with a focus on calories, soluble fiber, saturated fatty acid (SFA), unsaturated fatty acid intake (UFA), and protein.

RESULTS

The mean fiber intake was 10.77 (±5.87) g/day, and only 2 of 71 (2.9%) were in compliance with the recommended daily intake of >25 g/day. As percentage of total calories, of the 70 patients, 5 (7.1%) had a fat intake of <30%, 22 (31.4%) had SFA intake of <10%, 64 (91.4%) had a UFA of ≤30%, 22 (31.4%) had a protein-based diet of ≥15%, and 66 (94.3%) had a carbohydrate diet of <60%.

CONCLUSIONS

Most patients did not meet the dietary guidelines for reducing the risk of cardiovascular disease. Substituting UFA or soluble fiber for SFA improves low density lipoprotein (LDL) cholesterol levels without negative effects on other lipid parameters.

Serum lipids and lipoproteins during continuous ambulatory peritoneal dialysis

The effects of continuous ambulatory peritoneal dialysis (CAPD) on serum lipids and lipoproteins over the initial year of therapy were studied in 23 uremic patients. Lipoprotein abnormalities typical for the uremic dyslipoproteinemia were present at the start of CAPD. During the first months of CAPD these abnormalities were accentuated. The concentrations of very low density lipoprotein (VLDL)-cholesterol (CHOL), low density lipoprotein (LDL)-CHOL, serum CHOL and serum triglycerides (TG) increased significantly. However, after one year of CAPD only the VLDL-CHOL and serum CHOL levels remained significantly higher than the baseline values. VLDL-TG, VLDL-CHOL and serum TG, and the changes of these variables over the study period, correlated with the amount of glucose in the dialysates. We conclude that the continuous peritoneal absorption of glucose (100-200 g/24 h) during CAPD contributes to potentially atherogenic changes in serum lipids and lipoproteins. However, some of the changes are transitory, indicating an adaptation to the peritoneal glucose load.

The relationship between plasma and dialysate lipoproteins and apoproteins in patients treated by continuous ambulatory peritoneal dialysis

End-stage renal disease is frequently associated with lipoprotein abnormalities, manifested primarily by elevated very low-density lipoprotein levels combined with a decrease in high-density lipoprotein levels. These lipoprotein disturbances are further exacerbated in continuous ambulatory peritoneal dialysis. We examined the lipoprotein and apolipoprotein profiles in the blood and dialysate effluents of eight normolipidemic and five hypertriglyceridemic patients with end-stage renal failure treated with continuous ambulatory peritoneal dialysis. The normolipidemic patients were found to have significantly greater losses, as expressed by the fractional catabolic rates through the dialysate, for protein, total cholesterol, and very low-density lipoprotein cholesterol. These results suggest that the hypertriglyceridemia associated with continuous ambulatory peritoneal dialysis may be mitigated in some patients by the excessive loss of very low-density lipoprotein, or some other plasma constituent, into the dialysate effluent.

Current concepts. Continuous ambulatory peritoneal dialysis

As a long-term dialysis therapy, CAPD has attractive features for use in children (in whom access to the circulation and immobility are often problems), adults in whom blood access is difficult, patients with diabetes, patients prone to hypotension, and patients seeking independence from a machine or medical facility. CAPD and related procedures are still evolving and improving. Efforts to reduce the rates of peritonitis are ongoing and should decrease the rates of treatment dropout and increase the use of this alternative method of dialysis. Continued research toward improvements in catheter configuration and connection devices and the tailoring of technique to meet the particular needs of patients have made peritoneal dialysis an acceptable replacement therapy in patients with end-stage renal disease. Neither peritoneal dialysis nor hemodialysis is the superior long-term dialysis therapy for all patients; the choice depends on numerous medical, social, geographic, and life-style considerations.

Effects of dietary fish oil on serum lipids and blood coagulation in peritoneal dialysis patients

The effects of a daily fish oil supplement rich in eicosapentaenoic acid were studied in 11 stable continuous ambulatory peritoneal dialysis (CAPD) patients. Serum lipids, platelet aggregation studies, and template bleeding times were determined before and after 4 weeks of fish oil treatment. The lipid studies were repeated approximately 20 weeks after stopping fish oil supplement. At the end of the treatment period, serum triglycerides (mean +/- SEM) decreased from 297 +/- 42 to 211 +/- 29 mg/dL (P less than .01), high density lipoprotein (HDL) cholesterol fell from 45 +/- 3 to 41 +/- 3 mg/dL (P less than .05), and low density lipoprotein (LDL) cholesterol increased from 172 +/- 16 to 208 +/- 19 mg/dL (P less than .05). After discontinuing the fish oil supplement, the triglycerides increased to 278 +/- 39 mg/dL, which was no different than the value before fish oil treatment. No significant changes occurred in template bleeding time (TBT), platelet count, hematocrit, or platelet aggregation response. Clinically important uremic bleeding was not apparent. We conclude that in CAPD patients a fish oil supplement favorably effects hypertriglyceridemia and can be ingested without promoting uremic bleeding. The likely beneficial impact on atherogenesis resulting from the lowering of the triglycerides may, however, be counteracted by concomitant changes in HDL- and LDL-cholesterol.

Hyperapobetalipoproteinemia: the major dyslipoproteinemia in patients with chronic renal failure treated with chronic ambulatory peritoneal dialysis

In the present study, plasma cholesterol, triglyceride, low density lipoprotein (LDL)-cholesterol, high density lipoprotein (HDL)-cholesterol, and the major protein in LDL, apoB, were measured in 28 patients with chronic renal failure treated with hemodialysis and in 28 patients with chronic renal failure treated with chronic ambulatory peritoneal dialysis (CAPD). Elevated plasma triglycerides and reduced HDL cholesterol were frequent in both the hemodialysis and CAPD patients. However LDL levels were significantly higher in the CAPD patients as evident both by LDL cholesterol and LDL apoB. Even so, only one of the CAPD patients was hypercholesterolemic whereas 14 (or 50%) had hyperapobetalipoproteinemia (HyperapoB). Insulin-dependent diabetes was more frequent in the CAPD group but only 2 of the 9 insulin-dependent diabetics in this group had HyperapoB, and therefore, diabetes mellitus cannot account for the difference between the 2 groups. Thus HyperapoB appears to be a prevalent dyslipoproteinemia in CAPD patients and as such might be another factor which places CAPD patients at particularly increased risk of atherosclerosis.

Analysis of selected plasma constituents in continuous ambulatory peritoneal dialysis effluent

Patients maintained on continuous ambulatory peritoneal dialysis (CAPD) lose plasma constituents into the dialysis effluent. We have analyzed 24-hour CAPD effluents for selected components--total protein, a typical glycoprotein (alpha 1-acid glycoprotein), a typical lipoprotein (high density lipoprotein), and glycosaminoglycans. Our findings suggest that the plasma constituents found in CAPD effluent are similar to those found in urine from nephrotic patients. The loss of one or more of these plasma constituents into the dialysis solution may be linked to the hypertriglyceridemia observed in these patients.