The Role of Improved Water Quality on Inflammatory Markers in Patients Undergoing Regular Dialysis

Immune Dysfunction in Dialysis Patients—Prevention and Treatment Strategies

Immune dysfunction, resulting in infection or inflammation, or both, is closely associated with poor clinical outcome in end-stage renal disease patients. So far, no single measure can effectively address this condition, because many factors, such as uremia per se and dialysis treatment are involved in the pathogenesis. Our review focuses on currently available treatments and prevention options, and identifies future research needs.

What Medical Directors Need to Know about Dialysis Facility Water Management

The medical directors of dialysis facilities have many operational clinic responsibilities, which on first glance, may seem outside the realm of excellence in patient care. However, a smoothly running clinic is integral to positive patient outcomes. Of the conditions for coverage outlined by the Centers for Medicare and Medicaid Services, one most critical to quality dialysis treatment is the provision of safe purified dialysis water, because there are many published instances where clinic failure in this regard has resulted in patient harm. As the clinical leader of the facility, the medical director is obliged to have knowledge of his/her facility's water treatment system to reliably ensure that the purified water used in dialysis will meet the standards for quality set by the Association for the Advancement of Medical Instrumentation and used by the Centers for Medicare and Medicaid Services for conditions for coverage. The methods used to both achieve and maintain these quality standards should be a part of quality assessment and performance improvement program meetings. The steps for water treatment, which include pretreatment, purification, and distribution, are largely the same, regardless of the system used. Each water treatment system component has a specific role in the process and requires individualized maintenance and monitoring. The medical director should provide leadership by being engaged with the process, knowing the facility's source water, and understanding water treatment system operation as well as the clinical significance of system failure. Successful provision of quality water will be achieved by those medical directors who learn, know, and embrace the requirements of dialysis water purification and system maintenance.

Effect of hemodiafiltration with endogenous reinfusion on overt idiopathic chronic inflammation in maintenance hemodialysis patients: a multicenter longitudinal study

Chronic inflammation is widely diffuse in maintenance hemodialysis (MHD) patients and is associated with poor survival. Hemodiafiltration with endogenous reinfusion (HFR) is a dialysis technique, highly biocompatible, able to adsorb proinflammatory cytokines and to decrease amino acids and antioxidants loss. These features could be helpful in MHD patients affected by idiopathic chronic inflammation, but this issue remains to be elucidated. We performed a multicenter longitudinal study to assess the effect of the switching from bicarbonate HD to HFR in patients with serum C-reactive Protein (CRP) > 5 mg/L coupled with albumin <4.0 g/dL in the last 6 months. We enrolled 24/176 (14%) patients, of which 20 patients were assessed at 4 months and 18 completed the study. We excluded 11 patients with evident causes of inflammation. At baseline, serum levels of CRP (18.7[7.0-39.4] mg/L) and albumin (3.5[3.3-3.7] g/dL) were significantly correlated (r = -0.49; P = 0.028). The effect on CRP and albumin was almost evident in the first 4 months and remained stable until to eighth month. A strict correlation (R = -0.49; 0.040) between percentage change of CRP (-35%) and albumin (+14%) after 8 months of HFR. These effects were associated with the reduction of IL-6, IL-1β, and TNF-α and the increment of pre-albumin and leptin, whereas the serum levels of Branched Chain Amino Acid (BCAA) remained unchanged. In MHD patients affected by idiopathic chronic inflammation the switching from BHD to HFR is associated with improvement of inflammation. Whether these favorable effects may modify the outcomes of these high-risk patients needs to be confirmed by studies ad hoc.

Pre-emptive replacement of water treatment components improves responsiveness to erythropoiesis-stimulating agents in maintenance haemodialysis patients: a quality improvement report

Hypo-responsiveness to erythropoiesis-stimulating agents (ESAs) has been associated with increased mortality. We examined the effect of water treatment component replacement on declining ESA responsiveness in the absence of chemical or microbiological standards failure. Pre-emptive renewal of the water treatment system supplying 802 standard-flux haemodialysis patients resulted in a significant rise in haemoglobin from (mean ± SD) 12.1 ± 1.2 to 12.3 ± 1.0 g/dl (p < 0.0001), accompanied by a significant decrease in prescribed dose of darbepoetin alfa from 47.9 ± 27.3 to 44.7 ± 27.6 μg/week (p < 0.0001). ESA responsiveness improved significantly from 0.060 ± 0.041 to 0.055 ± 0.040 μg/kg/g · dl(-1) (p < 0.0001) and the number of patients no longer requiring ESA therapy increased threefold. These benefits were derived in the absence of haemolysis or significant changes in water quality. Renewal of water system components should be conducted even in the absence of proven microbiological and chemical failure.

Pretransplantation erythropoiesis-stimulating agent hyporesponsiveness is associated with increased kidney allograft failure and mortality

BACKGROUND

Poor response to erythropoiesis-stimulating agents (ESA) is associated with morbidity and mortality among dialysis patients. It is unclear whether the risk associated with poor ESA response during dialysis extends beyond kidney transplantation. We examined pretransplantation ESA response and its effect on allograft failure and mortality.

METHODS

The cohort included all adult Medicare recipients from the U.S. Renal Data System who had received a kidney transplant during years 2000 to 2007 and had at least 6 months of hemodialysis immediately before transplantation. ESA hyporesponsiveness was primarily defined as a monthly ESA dose of 75,000 units or higher and hematocrit 33% or less for at least 3 consecutive months in the pretransplantation period. Crude and adjusted Cox proportional hazards models and Kaplan-Meier methods were used to estimate the effect of ESA hyporesponsiveness on allograft failure and all-cause mortality.

RESULTS

The study group consisted of 36,450 patients; 1004 exhibited hyporesponsiveness. The adjusted hazard ratios (95% confidence interval) for allograft failure and mortality after transplantation were 1.23 (1.10-1.42) and 1.61 (1.43-1.81), respectively, supporting that poor ESA response during hemodialysis is associated with adverse posttransplantation outcomes.

CONCLUSIONS

ESA hyporesponsiveness may be useful in identifying potential allograft recipients who are at high risk for subsequent morbidity and mortality and may benefit from more intensive pretransplantation and posttransplantation monitoring.

The impact of membrane permeability and dialysate purity on cardiovascular outcomes

The effects of high-flux dialysis and ultrapure dialysate on survival of hemodialysis patients are incompletely understood. We conducted a randomized controlled trial to investigate the effects of both membrane permeability and dialysate purity on cardiovascular outcomes. We randomly assigned 704 patients on three times per week hemodialysis to either high- or low-flux dialyzers and either ultrapure or standard dialysate using a two-by-two factorial design. The primary outcome was a composite of fatal and nonfatal cardiovascular events during a minimum 3 years follow-up. We did not detect statistically significant differences in the primary outcome between high- and low-flux (HR=0.73, 95% CI=0.49 to 1.08, P=0.12) and between ultrapure and standard dialysate (HR=0.90, 95% CI=0.61 to 1.32, P=0.60). Posthoc analyses suggested that cardiovascular event-free survival was significantly better in the high-flux group compared with the low-flux group for the subgroup with arteriovenous fistulas, which constituted 82% of the study population (adjusted HR=0.61, 95% CI=0.38 to 0.97, P=0.03). Furthermore, high-flux dialysis associated with a lower risk for cardiovascular events among diabetic subjects (adjusted HR=0.49, 95% CI=0.25 to 0.94, P=0.03), and ultrapure dialysate associated with a lower risk for cardiovascular events among subjects with more than 3 years of dialysis (adjusted HR=0.55, 95% CI=0.31 to 0.97, P=0.04). In conclusion, this trial did not detect a difference in cardiovascular event-free survival between flux and dialysate groups. Posthoc analyses suggest that high-flux hemodialysis may benefit patients with an arteriovenous fistula and patients with diabetes and that ultrapure dialysate may benefit patients with longer dialysis vintage.

Impact of improving quality of dialysis fluid on oxidative stress and lipid profile in hemodialysis patients

The aim of this study was to evaluate the levels of malondialdehyde as an oxidative stress marker in the same hemodialysis patients after changing the quality of dialysate with ultrapure dialysis fluid. Methods. This prospective study concerns hemodialysis patients; all patients were in the first step treated with conventional dialysate, and in the second step (three months later) the same patients were treated with online produced ultrapure dialysis fluid. The malondialdehyde, C-reactive protein, total cholesterol, triglycerides, high-density lipoprotein, low-density lipoprotein, fibrinogen, and albumin were quantified before the two steps. Results. Thirty-seven patients completed the study. Ultrapure dialysis fluid reduced but not significantly the malondialdehyde concentrations. Both dialysis fluids were associated with improvement in the malondialdehyde level before and after the hemodialysis session. In lipid parameters, there was a significant decrease with conventional dialysis fluid versus ultrapure dialysis fluid of triglycerides, total cholesterol, and high-density lipoprotein in patients' blood. Instead, the level of low-density lipoprotein, fibrinogen, albumin, and C-reactive protein does not change significantly. Conclusion. The lipid parameters were improved for triglycerides and total cholesterol. Malondialdehyde increases following the hemodialysis session, and the conventional dialysate increased malondialdehyde levels more than the ultrapure dialysis but the differences were not statistically significant.

Water quality in conventional and home haemodialysis

Dialysis water can be contaminated by chemical and microbiological factors, all of which are potentially hazardous to patients on haemodialysis. The quality of dialysis water has seen incremental improvements over the years, with advances in water preparation, monitoring and disinfection methods, and high standards are now readily achievable in clinical practice. Advances in dialysis membrane technology have refocused attention on water quality and its potential role in the bioincompatibility of haemodialysis circuits and adverse patient outcomes. The role of ultrapure dialysate is increasingly being advocated, given its proposed clinical benefits and relative ease of production as a result of the widespread use of reverse osmosis and ultrafiltration. Many of the issues pertaining to water quality in hospital-based dialysis units are also pertinent to haemodialysis in the home. Furthermore, an increased awareness of the environmental and financial consequences of home haemodialysis has resulted in the development of automated and more efficient dialysis machines. These new machines have an increased emphasis on water conservation and recycling along with a decreased need for a complex infrastructure for water purification and maintenance.

Avoiding harm and achieving optimal dialysis outcomes--the dialysate component

Appropriate dialysate composition is critical for effective and safe hemodialysis. Unfortunately, there are few randomized trials to guide practice, and although solute clearance is well understood, there is a limited understanding of balance in dialysis patients. The current practice of simply trying to normalize serum electrolyte and mineral concentrations measured predialysis may not provide optimal care. More thought should be given to normalizing balance with respect to sodium, bicarbonate, magnesium, and potassium and minimizing wide swings in serum concentrations that may have adverse effects. In practice, this would require longer or more frequent dialysis with less steep chemical gradients. With respect to calcium, the goal should be to optimize bone and vascular health. Clinicians should also be mindful that the dialysis procedure itself exposes patients to potential toxins, and efforts to minimize these risks should be stressed.

Impact of the duration of posttransplant renal replacement therapy on bacterial infections in liver transplant recipients

Whether the duration of renal replacement therapy (RRT) after liver transplantation influences the rate and types of bacterial infections is not known. In this study, 47 of 299 consecutive liver transplant recipients (16%) required posttransplant RRT. The incidence of bacterial infections was higher in the RRT group versus the non-RRT group (8.84 versus 1.38 per 1000 patient days, P < 0.001). In the RRT group, 49% of the patients (23/47) required long-term RRT (≥30 days), and 51% (24/47) required short-term RRT (<30 days). Long-term RRT (hazard ratio = 2.27, 95% confidence interval = 1.16-4.47, P = 0.017) was a significant predictor of infections. Bacteremia and intra-abdominal infections were the most common sources of infections, and Enterobacteriaceae and enterococci were the predominant pathogens in both groups. The mortality rate for patients requiring RRT was higher than the rate for patients not requiring RRT (P < 0.001), but the mortality rates of the short-term RRT group and the long-term RRT group did not significantly differ (P = 0.654). In conclusion, although both short-term RRT and long-term RRT confer a higher risk of bacterial infections, only long-term RRT is a statistically significant predictor of these infections.

Applicability of solid-phase cytometry and epifluorescence microscopy for rapid assessment of the microbiological quality of dialysis water

BACKGROUND

Currently, the gold standard to assess the microbiological quality of dialysis water is the determination of heterotrophic plate counts (HPC). The long waiting time of the HPC method and the fact that most bacteria are not culturable on agar plates provokes the search for rapid alternative methods for monitoring the microbiological quality of dialysis water.

METHODS

We tested the applicability of total viable counts (TVC) and total direct counts (TDC), determined via solid-phase cytometry and epifluorescence microscopy (EFM), in comparison to the standard HPC determination method in 113 samples from 13 dialysis water treatment units (59 drinking water and 54 dialysis water samples). Additionally, for a set of dialysis water samples (n = 22) endotoxin concentrations were also determined.

RESULTS

TVC showed high correlation with HPC and results were of comparable magnitude for most investigated dialysis water samples [median: 3 cells/colony forming units (CFU) 100 mL(-1)]. However, in one dialysis water sample, HPC values (5800 CFU 100 mL(-1)) were >35-fold lower than TVC values (2.05 × 10(5) cells 100 mL(-1)) indicating severe limits of the HPC method to assess the microbiological quality of dialysis water. For drinking water, TVC (median: 4.8 × 10(4) cells 100 mL(-1)) was on average one order of magnitude higher than HPC (median: 2.5 × 10(3) cells 100 mL(-1)). TDCs (median dialysis water: 1.1 × 10(4) cells 100 mL(-1) and median drinking water: 4.9 × 10(6) cells 100 mL(-1)) were always several orders of magnitude higher than HPC or TVC.

CONCLUSIONS

We propose that the TVC/solid-phase cytometry approach is a reliable and rapid alternative to the culture-dependent approach for assessment of the microbiological quality of dialysis water, especially when fast results are needed. TDC determined via EFM lacks sensitivity and reliability for assessing microbial concentrations in low-cell dialysis water samples since the limits of detection and quantification are high.

C-reactive protein and prediction of 1-year mortality in prevalent hemodialysis patients

BACKGROUND AND OBJECTIVES

Measurement of C-reactive protein (CRP) levels remains uncommon in North America, although it is now routine in many countries. Using Dialysis Outcomes and Practice Patterns Study data, our primary aim was to evaluate the value of CRP for predicting mortality when measured along with other common inflammatory biomarkers.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We studied 5061 prevalent hemodialysis patients from 2005 to 2008 in 140 facilities routinely measuring CRP in 10 countries. The association of CRP with mortality was evaluated using Cox regression. Prediction of 1-year mortality was assessed in logistic regression models with differing adjustment variables.

RESULTS

Median baseline CRP was lower in Japan (1.0 mg/L) than other countries (6.0 mg/L). CRP was positively, monotonically associated with mortality. No threshold below which mortality rate leveled off was identified. In prediction models, CRP performance was comparable with albumin and exceeded ferritin and white blood cell (WBC) count based on measures of model discrimination (c-statistics, net reclassification improvement [NRI]) and global model fit (generalized R(2)). The primary analysis included age, gender, diabetes, catheter use, and the four inflammatory markers (omitting one at a time). Specifying NRI ≥5% as appropriate reclassification of predicted mortality risk, NRI for CRP was 12.8% compared with 10.3% for albumin, 0.8% for ferritin, and <0.1% for WBC.

CONCLUSIONS

These findings demonstrate the value of measuring CRP in addition to standard inflammatory biomarkers to improve mortality prediction in hemodialysis patients. Future studies are indicated to identify interventions that lower CRP and to identify whether they improve clinical outcomes.

High-flux dialyzers, backfiltration, and dialysis fluid quality

Currently, high-flux hemodialysis is the most common mode of dialysis therapy worldwide. Its steadily increasing use is largely based on the desire to reduce the excessively high morbidity and mortality of end-stage renal disease patients maintained on conventional dialysis (low-flux, mostly cellulosic membranes) by offering better biocompatibility and enhanced removal of uremic toxins. Two large randomized trials suggest a survival benefit for selected subgroups of high-flux dialysis patients such as diabetics, patients with hypoalbuminemia, or patients who have been on dialysis for a long period (>3.7 years). The major disadvantage of high-flux hemodialysis relates to the use of dialysis fluid, which is commonly not pure and may endanger patients treated with high-flux hemodialysis. Endotoxin fragments and other bacterial substances derived from bacteriologically contaminated dialysis fluid may, even at bacterial counts or endotoxin concentrations within the limits of accepted standards of dialysis fluid purity, enter from the dialysate into the patient's blood either by convective transfer (backfiltration) or by movement down the concentration gradient (backdiffusion). Repeated exposure of high-flux hemodialysis patients to backtransport of dialysate contaminants aggravates the uremia-associated inflammatory response syndrome and contributes to long-term morbidity. At present, the only solution to circumvent the risks of backtransport is the use of dry powder cartridges for bicarbonate concentrate and the use of bacteria- and endotoxin-retentive filters for the online production of ultrapure dialysis fluid. Use of ultrapure dialysis fluid (bacteria <0.1 CFU/ml and endotoxin <0.03 IU/ml) has been found to reduce inflammation and comorbidities in clinical investigations compared to commercial dialysis fluid. The European Renal Association and a number of national societies in Europe or in Japan strongly recommend the use of ultrapure dialysis for high-flux hemodialysis.

Conventional, but not high-purity, dialysate-induced monocyte apoptosis is mediated by activation of PKC-delta and inflammatory factors release

BACKGROUND

Use of conventional dialysate (CD) (powdered sodium bicarbonate dissolved manually with reverse osmosis water before dialysis) is common in Chinese haemodialysis (HD) centres. However, this preparation carries the risk of degradation and contamination, potentially negatively impacting host defense. Commercially available high-purity dialysate (HPD) may decrease inflammation and improve nutritional status in HD patients. However, whether HPD affects immune cells is unclear. The purpose of this study was to investigate the in vitro effect of these dialysates on apoptosis in U937 monocytes and its possible mechanism.

METHODS

Following incubation with two different types of dialysate, U937 cell apoptosis was measured by flow cytometry. Cell morphological changes were observed by Hoechst 33258 fluorescence staining. The expression of protein kinase C-δ (PKC-δ) was assayed by RT-polymerase chain reaction and western blot. Cytokine levels in U937 cells after exposure to CD or HPD for an indicated time were assayed by commercial enzyme-linked immunosorbent assay.

RESULTS

CD contained more bacteria (66 ± 6 CFU/mL) than HPD (7 ± 3 CFU/mL) while there was no difference in endotoxin levels. Compared with cells exposed to HPD and phosphate-buffered saline (PBS), U937 monocytes experienced more apoptosis when exposed to CD for 24 and 48 h, while there was no significant difference between HPD and PBS. Expressions of PKC-δ mRNA and protein in U937 cells were enhanced following exposure to CD for 24 and 48 h, with increased proteolytic cleavage of PKC-δ which could be inhibited by rottlerin, a specific inhibitor of PKC-δ. Moreover, the cultured supernatant in CD-exposed cells contained significantly higher levels of interleukin-6 (4.09 ± 0.36 vs 2.73 ± 0.38 pg/mL, P < 0.01, 24 h; 4.28 ± 0.32 vs 2.83 ± 0.32 pg/mL, P < 0.01, 48 h) and tumour necrosis factor α (3.45 ± 0.79 vs 2.44 ± 0.39 pg/mL, P < 0.05, 24 h; 4.60 ± 0.57 vs 2.50 ± 0.37 pg/mL, P < 0.01, 48 h) than those of HPD.

CONCLUSION

CD, but not HPD, contained more bacterial contamination, increased monocyte apoptosis in a PKC-δ-dependent manner and induced more cell inflammation. These findings suggest that impurity of dialysis fluid may be an important determinant of the elevated inflammation seen in CD-treated patients.

Biochemistry and biomarkers of inflamed patients: why look, what to assess

Specific laboratory tests and physical findings are available to the practicing clinician that should raise the suspicion of inflammation. Inflammation is related to specific clinical outcomes. Once identified, changes in clinical practice may affect the level of inflammation in individual and or groups of dialysis patients with the hope that these changes may in turn affect outcome in a positive manner. Standard clinical tests and observations associated with inflammation are hypoalbuminemia, erythropoietin resistance, decreased iron saturation accompanied by high ferritin, frailty, low serum creatinine, reduced total and LDL-cholesterol, and increased C reactive protein (CRP). Inflammation is strongly associated with loss of physical function, dyslipidemia (low LDL- and HDL-cholesterol, increased triglycerides), and anemia that is unresponsive to erythropoietin. Inflammation is associated with cardiovascular events, increased hospitalization, and death. Correctible causes of inflammation are tunneled dialysis catheters, arteriovenous grafts, catheter infection, periodontal disease, poor water quality, and dialyzer incompatibility. Obesity also is a source of cytokines but may be less amenable to treatment. Inflammation is multifactorial in dialysis patients. Some sources are recognizable and correctable, such as vascular access type, clinical infection, and water quality, and some are not. Inflammation is strongly associated with outcome.

The microbial world and fluids in dialysis

The fluids used in dialysis are all water based. Water, which is necessary for life, is also a good environment for micro-organisms. The result of this is quite simply that microbial growth, i.e., increased numbers of micro-organisms, results in the presence of endotoxins and the formation of metabolites. The situation is not favorable for dialysis and needs to be understood and corrected. In order to act in the right way we must analyze and synthesize the available information, which will lead us to decide what actions and precautions are necessary. The possible negative effects of a too-high microbiological content in dialysis fluid and the importance of hygiene have been well-documented. This chain of events depends on ensuring that the information and thus the understanding we get from that information is accurate. If it is not accurate, any actions taken may be inadequate and result in a situation we can no longer control. The patient will be in contact with the dialysis fluid in every session of dialysis due to the phenomenon of backfiltration, which means that anywhere from 100 ml to multiple liters of dialysis fluid is filtered over the dialyzer membrane and into the blood. The problems that may occur when contaminated dialysis fluid is used range from the acute pyrogenic reaction to chronic reactions over time where no acute symptoms are identified. The immune defense system is, however, constantly tested by the presence of body foreign components in the dialysis fluid. This paper will discuss the microflora (the micro-organisms present in the microbial community) that occur in systems of fluids in dialysis, limits, and methods of cultivation and disinfection. Results presented are original data examples out of some 350 investigations of fluid systems in dialysis units around the world, using analytic methods.

Ultrapure dialysate for home hemodialysis?

Use of ultrapure dialysate (bacteria < 0.1 CFU/mL and endotoxin < 0.03 EU/mL) is associated with a reduction in inflammation and morbidity in patients treated with conventional thrice-weekly dialysis. The improved outcomes obtained with more frequent dialysis schedules have reawakened interest in home hemodialysis. More frequent dialysis also appears to reduce inflammation, and whether combining more frequent dialysis with use of ultrapure dialysate will have an additive effect on inflammation and its consequences remains unclear. Routinely producing ultrapure dialysate in a home environment with a conventional hemodialysis machine poses technical challenges related to the design of the equipment and the intermittent nature of hemodialysis. Solutions to these problems include use of a system in which the water-treatment equipment is fully integrated with the dialysis machine, use of dry-powder cartridges or sterile prepackaged liquids for bicarbonate concentrate, and use of a bacteria-retentive and endotoxin-retentive filter for final purification of the dialysate immediately before it enters the dialyzer. Alternatively, ultrapure dialysate may be achieved with newer machines designed specifically for home hemodialysis that use a new batch of dialysate for each treatment. The volume of dialysate available with these machines, however, currently limits their use to short-daily dialysis.

Composition and clinical use of hemodialysates

A thorough knowledge and understanding of the principles underlying the preparation and the clinical application of hemodialysates can help us provide exemplary patient care to individuals having end-stage renal disease. It is prudent to be conversant with the following: (a) how each ingredient in a dialysate works, (b) the clinical circumstances under which the concentration of an ingredient can be altered, and (c) the special situations in which unconventional ingredients can be introduced into a dialysate. The potential to enrich dialysates with appropriate ingredients (such as iron compounds) is limited only by the boundaries of our imagination.

The Importance of Water Quality and Haemodialysis Fluid Composition

Treatment of renal failure by haemodialysis uses dialysis fluid to facilitate the normalization of electrolyte and acid base abnormalities and the removal of low molecular weight uraemic compounds present in the plasma such as urea. The dialysis fluid is a continuously produced blend of treated tap water and a concentrated solution containing electrolytes, buffer, and glucose. The water used originates as drinking water but undergoes additional treatment. Recent surveys have indicated that the chemical and microbiological content of such water frequently fails to meet the requirements of established standards, and its bacterial content arising from the presence of a biofilm in the water distribution network or the hydraulic circuit of the dialysis machine is a contributory factor to the chronic inflammatory state in patients undergoing regular dialysis. The composition of the dialysis fluid plays an important role in the modulation of complications associated with end-stage renal disease, as well as those associated with the treatment itself. The avoidance of complications arising from water contaminants requires a constant and vigorous attention to water quality, whilst with the composition of electrolytes and buffer there is a trend towards greater individualization to provide a high degree of treatment tolerance.

Ultrapure dialysate reduces plasma levels of beta2-microglobulin and pentosidine in hemodialysis patients

BACKGROUND

beta2-Microglobulin (beta2MG) and carbonyl stress are reported to contribute to the development of dialysis-related amyloidosis. The aim of this study was to determine whether the purity of dialysate affects plasma levels of beta2MG and pentosidine (a surrogate marker of carbonyl stress) in hemodialysis patients.

METHODS

Sixteen patients on hemodialysis with a polysulfone membrane participated in this study. We switched the dialysate from conventional dialysate (endotoxin level 0.055-0.066 endotoxin units (EU)/ml) to ultrapure dialysate (endotoxin level <0.001 EU/ml), followed patients for 6 months, and then switched back to conventional dialysate once again. Plasma levels of beta2MG, pentosidine, CRP and interleukin-6 (IL-6) were determined before the switch to ultrapure dialysate, 1 and 6 months after the switch to ultrapure dialysate, and 1 month after the switch back to conventional dialysate.

RESULTS

The switch from conventional to ultrapure dialysate significantly decreased plasma levels of beta2MG, from 30.1 +/- 1.4 to 27.1 +/- 1.4 mg/dl (p < 0.05) and pentosidine, from 1,535.8 +/- 107.5 to 1,267.6 +/- 102.9 nmol/l (p < 0.01) after 1 month of use. The change of dialysate also significantly decreased plasma levels of CRP, from 0.28 +/- 0.09 to 0.14 +/- 0.05 mg/dl (p < 0.05) and IL-6, from 9.4 +/- 2.7 to 3.5 +/- 0.8 pg/ml (p < 0.01) over the 1-month period. These changes in plasma levels of beta2MG, pentosidine, CRP and IL-6 were maintained over 6 months after switching to ultrapure dialysate and returned to basal levels by switching back to a conventional dialysate.

CONCLUSIONS

Ultrapure dialysate decreases plasma levels of beta2MG, pentosidine and inflammatory markers in hemodialysis patients. The use of ultrapure dialysate might be useful in preventing and/or treating complications of dialysis, such as dialysis-related amyloidosis, atherosclerosis and malnutrition.