BACKGROUND: Online haemodiafiltration (OL-HDF) is considered to confer clinical benefits over haemodialysis (HD) in terms of solute removal in patients undergoing maintenance HD. The aim of this study was to compare postdilution OL-HDF and high-flux HD in terms of morbidity and mortality. METHODS: In this prospective, randomized, controlled trial, we enrolled 782 patients undergoing thrice-weekly HD and randomly assigned them in a 1:1 ratio to either postdilution OL-HDF or high-flux HD. The mean age of patients was 56.5 ± 13.9 years, time on HD 57.9 ± 44.6 months with a diabetes incidence of 34.7%. The follow-up period was 2 years, with the mean follow-up of 22.7 ± 10.9 months. The primary outcome was a composite of death from any cause and nonfatal cardiovascular events. The major secondary outcomes were cardiovascular and overall mortality, intradialytic complications, hospitalization rate, changes in several laboratory parameters and medications used. RESULTS: The filtration volume in OL-HDF was 17.2 ± 1.3 L. Primary outcome was not different between the groups (event-free survival of 77.6% in OL-HDF versus 74.8% in the high-flux group, P = 0.28), as well as cardiovascular and overall survival, hospitalization rate and number of hypotensive episodes. In a post hoc analysis, the subgroup of OL-HDF patients treated with a median substitution volume >17.4 L per session (high-efficiency OL-HDF, n = 195) had better cardiovascular (P = 0.002) and overall survival (P = 0.03) compared with the high-flux HD group. In adjusted Cox-regression analysis, treatment with high-efficiency OL-HDF was associated with a 46% risk reduction for overall mortality {RR = 0.54 [95% confidence interval (95% CI) 0.31-0.93], P = 0.02} and a 71% risk reduction for cardiovascular mortality [RR = 0.29 (95% CI 0.12-0.65), P = 0.003] compared with high-flux HD. CONCLUSIONS: The composite of all-cause mortality and nonfatal cardiovascular event rate was not different in the OL-HDF and in the high-flux HD groups. In a post hoc analysis, OL-HDF treatment with substitution volumes over 17.4 L was associated with better cardiovascular and overall survival.

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Mortality and cardiovascular events in online haemodiafiltration (OL-HDF) compared with high-flux dialysis: results from the Turkish OL-HDF Study

Background Malnutrition and chronic systemic inflammatory response syndrome not only coexist in uraemia, but may also have a bi-directional cause-and-effect relationship. To evaluate the role of dialysate-related cytokine induction in inflammatory response and nutritional status, we conducted a prospective comparison of two dialysis fluids differing in their microbiological quality. Methods Forty-eight early haemodialysis patients were assigned to either treatment with conventional (potentially microbiologically contaminated) or on-line produced ultrapure dialysis fluid. Study parameters were bacterial growth, markers of systemic inflammation (C-reactive protein (CRP) and interleukin 6), and parameters of nutritional status (estimated dry weight, upper mid-arm muscle circumference, serum albumin concentration, insulin-like growth factor 1, leptin, and protein catabolic rate). Patients were followed for 12 months. Results There were no statistically significant differences in demographic and treatment characteristics, degree of bacterial contamination of the dialysate, markers of systemic inflammation, or parameters of nutritional status among the two treatment groups at recruitment. Changing from conventional to ultrapure dialysis fluid reduced significantly the levels of IL-6 (19+/-3 pg/ml to 13+/-3 pg/ml) and CRP (1.0+/- 0.4 mg/dl to 0.5+/-0.2 mg/dl), and resulted in significant increases in estimated dry body weight, mid-arm muscle circumference, serum albumin concentration, levels of the humoral factors, and in protein catabolic rate after 12 months. Continuous use of conventional dialysis fluid (median 40-60 c.f.u./ml) was not associated with significant alterations in markers of inflammation (IL-6 21+/-4 pg/ml vs 24+/-6 pg/ml, CRP 0.9+/-0.3 mg/dl vs 1.1+/-0.4 mg/dl) or of nutritional status at any time of the study. All differences in systemic inflammation and nutritional parameters observed during the study period (from recruitment to month 12) were significant between the two patient groups. Conclusions Cytokine induction by microbiologically contaminated dialysis fluid has a negative impact on nutritional parameters of early haemodialysis patients. The microbiological quality of the dialysis fluid represents an independent determinant of the nutritional status in addition to known factors, such as dose of dialysis and biocompatibility of the dialyser membrane. Ultrapure dialysis fluid adds to the cost of the dialytic treatment, but may improve the nutritional status in long-term haemodialysis patients.

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Effects of ultrapure dialysis fluid on nutritional status and inflammatory parameters

Background Sustained low-efficiency daily dialysis (SLEDD) is an increasingly popular renal replacement therapy for intensive care unit (ICU) patients. SLEDD has been previously reported to provide good solute control and haemodynamic stability. However, continuous renal replacement therapy (CRRT) is considered superior by many ICU practitioners, due first to the large amounts of convective clearance achieved and second to the ability to deliver treatment independently of nephrology services. We report on a program of sustained low-efficiency daily diafiltration (SLEDD-f) delivered autonomously by ICU nursing personnel, and benchmark solute clearance data with recently published reports that have provided dose-outcome relationships for renal replacement therapy in this population. Methods SLEDD-f treatments were delivered using countercurrent dialysate flow at 200 ml/min and on-line haemofiltration at 100 ml/min for 8 h on a daily or at least alternate day basis. All aspects of SLEDD-f were managed by ICU nursing personnel. Clinical parameters, patient outcomes and solute levels were monitored. Kt/V, corrected equivalent renal urea clearance (EKRc) and theoretical Kt/V(B12) were calculated. Results Fifty-six SLEDD-f treatments in 24 critically ill acute renal failure patients were studied. There were no episodes of intradialytic hypotension or other complications. Observed hospital mortality was 46%, not significantly different from the expected mortality as determined from the APACHE II illness severity scoring system. Electrolyte control was excellent. Kt/V per completed treatment was 1.43+/-0.28 (0.96-2.0). Kt/V(B12) per completed treatment was 1.02+/-0.21 (0.6-1.38). EKRc for patients was 35.7+/-6.4 ml/min (25.0-48.2). Conclusion SLEDD-f provides stable renal replacement therapy and good clinical outcomes. Logistic elements of SLEDD-f delivery by ICU nursing personnel are satisfactory. Small solute clearance is adequate by available standards for CRRT and intermittent haemodialysis, and larger solute clearance considerable. SLEDD-f is a viable alternative to CRRT in this setting.

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Sustained low-efficiency daily diafiltration (SLEDD-f) for critically ill patients requiring renal replacement therapy: towards an adequate therapy

Background and objectives: Theoretical advantages exist of online hemodiafiltration (HDF) over high-flux hemodialysis (HD), but outcome data are scarce. Our objective was to compare outcomes between these modalities. Design, setting, participants, & measurements: We studied 858 incident patients in our incremental high-flux HD and online HDF program during an 18-yr period. We compared outcomes, including survival, in those who were treated predominantly with HDF (>50% sessions) and those with high-flux HD. Survival comparisons used a Cox model taking into account the time-varying proportion of time spent on HDF. All data were prospectively collected. Results: A total of 152,043 sessions were delivered as HDF and 291,222 as high-flux HD. A total of 232 (27%) patients were treated predominantly with HDF and 626 (73%) with high-flux HD. Total Kt/V, serum albumin, erythropoietin resistance index, and BP were similar in both groups up to 5 yr after HD initiation. Intradialytic hypotension was less frequent in the predominant HDF group. Predominant HDF treatment was associated with a reduced risk for death after correction for confounding variables. In a second Cox model, proportion of time spent on HDF predicted survival, such that patients who were treated solely by HDF would have a hazard for death of 0.66 compared with those who solely used high-flux HD. Conclusions: We found no benefits of HDF over high-flux HD with respect to anemia management, nutrition, mineral metabolism, and BP control. The mortality benefit associated with HDF requires confirmation in large randomized, controlled trials. These data may contribute to their design.

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Long-Term Outcomes in Online Hemodiafiltration and High-Flux Hemodialysis : A Comparative Analysis

Background: Controlled randomised studies to prove improved cardiovascular stability and improved anaemia management during on-line haemodiafiltration (oHDF) are scarce. Me

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On-Line Haemodiafiltration versus Haemodialysis: Stable Haematocrit with Less Erythropoietin and Improvement of Other Relevant Blood Parameters

Background. Microbial contamination is Conclusion. On-line HDF treatment can routinely be provided with ultra-pure dialysis fluids and sterile characterized not only by the presence of bacteria, but substitution fluids at pyrogen-free levels. The on- also by high concentrations of biologically active line preparation of substitution fluids thus can be by-products. They are potentially able to cross ultrafil- considered microbiologically safe. tration and dialysis membranes and stimulate immuno- competent blood cells to synthesize cytokines. In turn, cytokine induction causes acute symptoms and has been incriminated in the long-term complications of Introduction haemodialysis patients. Infusion of large volumes of substitution fluids following ultrafiltration of micro- Dialysis fluids, as well as their components, purified bially contaminated dialysis fluids may place patients water and dialysis concentrates, are subject to micro- on on-line therapies at particular risk. bial contamination. Indeed, poor microbiological qual- Methods. In this study we evaluated 30 machines with ity is evident in hydraulic dialysis systems, as recent a two-stage ultrafiltration system in routine clinical surveys have revealed high levels of micro-organisms haemodiafiltration settings in six centres for 6 months. in water and dialysis fluids (1-3). In turn, contamina- Microbiological safety was assessed monthly and tion with bacteria has been demonstrated to be associ- at the last use of the filters by determining micro- ated with the presence of soluble, pyrogenic (pro- bial counts, endotoxin concentration and cytokine- inflammatory cytokine-inducing) by-products, which inducing activity. are potentially able to penetrate low- and high-flux Results. No pyrogenic episodes were observed during dialysis membranes alike (4,5). As a consequence, the study period. Double-filtration of standard dialysis haemodialysis (HD) patients exhibit chronic inflam- fluid (range, <1-895 cfu/ml, 0.0028-4.6822 IU/ml ) mation, an increasingly unravelled factor of long-term resulted in sterile substitution fluids with endotoxin morbidity and mortality (6-9). In addition, acute concentrations well below the Ph.Eur. standard for febrile reactions may be triggered by excessive trans- haemofiltration solutions (range, 0.0014-0.0281 vs 0.25 membrane passage of cytokine-inducing substances IU/ml ). Moreover, they did not differ from commercial (10,11). haemofiltration solutions and depyrogenated saline. Highly convective therapies in their most practical Likewise, there was no difference in the cytokine- and cost-effective form include a large volume substitu- inducing activity between the solutions tested. The tion with on-line prepared infusates. Substitution with high microbiological quality of the ultrafiltered dialysis fluid prepared from contaminated dialysate, however, fluid, which was in the same range as substitution may place patients at particular risk with respect to fluid, translates into both the absence of cytokine pyrogen exposure. The high retention capabilities of induction by dialyser back-transport and a redundant ultrafilters to micro-organisms and endotoxins in the safety mode of the on-line system by a second filtra- laboratory or clinical setting suggest the micro- tion step.

/pdf/can-sterile-and-pyrogen-free-on-line-substitution-fluid-be-4dpbg7h92y.pdf

Can sterile and pyrogen-free on-line substitution fluid be routinely delivered? A multicentric study on the microbiological safety of on-line haemodiafiltration.

: Background: On-line hemodiafiltration (HDF) represents the supreme blood purification modality for end-stage renal disease (ESRD) patients. Large-volume infusion of on-line prepared substitution fluid may, however, expose patients to inflammatory contaminants. As a result, on-line HDF might aggravate chronic inflammation, which correlates with malnutrition, cardiovascular disease, and mortality among ESRD patients. Methods: In a multicenter cross-over study, 27 ESRD patients were randomly assigned to treatment with on-line HDF and low-flux hemodialysis (HD). After 6 months, patients were crossed to the other treatment modality, and treatment continued for another 6 months. Both on-line HDF and low-flux HD were conducted with polysulfone membranes and ultrapure dialysis fluid. Samples were drawn at the end of each treatment period. Results: Inflammatory parameters were elevated in the study population when compared to healthy controls. Induction of interleukin-1 receptor antagonist (IL-1Ra) and tumor necrosis factor α (TNF-α) was comparable for on-line HDF and low-flux HD, and there was no intradialytic increase in cytokine production. As a result, interleukin-6 (IL-6) plasma levels did not differ significantly between the two treatment modalities. Similarly, no difference between on-line HDF and low-flux HD was observed for C-reactive protein (CRP) and albumin. Markers of endothelial cell activation (soluble intercellular and vascular cell adhesion molecules sICAM-1 and sVCAM-1) as well as the cardiovascular risk marker cardiac troponin T (cTnT) remained elevated compared to healthy subjects, but showed no difference between the two treatment modalities. Conclusions: On-line HDF, as the most effective renal replacement therapy, does not provoke inflammatory response and is both safe and highly biocompatible.

On‐line Hemodiafiltration Does Not Induce Inflammatory Response in End‐stage Renal Disease Patients: Results From a Multicenter Cross‐over Study

Cost reduction and quality improvement seem to be conflicting issues. However, online hemodiafiltration (oHDF) with new automatic functions offers a cost-efficient therapy compared to hemodialysis (HD). Seven dialysis centers conducted a randomized clinical trial with cross-over design: high-flux HD vs. postdilutional oHDF with functions coupling both dialysate and substitution flow rates to blood flow rates. During the 6 weeks of the study, all treatment parameters remained unchanged for HD and oHDF, apart from dialysate and substitution flow rate. Treatment data were recorded during each treatment, and predialytic and postdialytic concentrations of urea were recorded at the end of each study phase. The analysis involved 956 treatments of 54 patients. The mean dialysate consumption was 123.2 ± 6.4 l for HD and 113.4 ± 14.9 l for oHDF (p < 0.0001), the mean dialysis dose was 1.42 ± 0.23 for HD and 1.47 ± 0.26 for oHDF (p < 0.0001); oHDF resulted in a lower dialysate consumption (8.0% less) and a slightly increased dialysis dose (Kt/V 3.5% higher) compared to HD. oHDF with the investigated automatic functions offers substantial savings in dialysate consumption without decreasing dialysis dose.

Lajos Major

Papers

On-Line Haemodiafiltration versus Haemodialysis: Stable Haematocrit with Less Erythropoietin and Improvement of Other Relevant Blood Parameters

Can sterile and pyrogen-free on-line substitution fluid be routinely delivered? A multicentric study on the microbiological safety of on-line haemodiafiltration.

On‐line Hemodiafiltration Does Not Induce Inflammatory Response in End‐stage Renal Disease Patients: Results From a Multicenter Cross‐over Study

Dialysate saving by automated control of flow rates: comparison between individualized online hemodiafiltration and standard hemodialysis.