scholarly journals Combining Diffusion, Convection and Absorption: A Pilot Study of Polymethylmethacrylate versus Polysulfone Membranes in the Removal of P-Cresyl Sulfate by Postdilution On-Line Hemodiafiltration

2021 ◽  
Vol 1 (2) ◽  
pp. 121-134
Author(s):  
Pablo Molina ◽  
Julio Peiró ◽  
María A. Martínez-Gómez ◽  
Belén Vizcaíno ◽  
Cristina Esteller ◽  
...  
Keyword(s):  
Adsorptive Capacity ◽  
Dialysis Session ◽  
High Flux ◽  
Dialysis Dose ◽  
Polysulfone Membrane ◽  
Β2 Microglobulin ◽  
Urea Kinetics ◽  
On Line ◽  
Diffusion Convection ◽  
Polysulfone Membranes

Dialytic clearance of p-cresyl sulfate (pCS) and other protein-bound toxins is limited by diffusive and convective therapies, and only a few studies have examined how to improve their removal by adsorptive membranes. This study tested the hypothesis that high-flux polymethylmethacrylate (PMMA) dialysis membranes with adsorptive capacity increase pCS removal compared to polysulfone membranes, in a postdilution on-line hemodiafiltration (OL-HDF) session. Thirty-five stable hemodialysis patients randomly completed a single study of 4 h OL-HDF with PMMA (BG2.1U, Toray®, Tokyo, Japan) and polysulfone (TS2.1, Toray®) membranes. The primary endpoint was serum pCS reduction ratios (RRs) obtained with each dialyzer. Secondary outcomes included RRs of other solutes such as β2-microglobulin, the convective volume obtained after each dialysis session, and the dialysis dose estimated by ionic dialysance (Kt) and urea kinetics (Kt/V). The RRs for pCS were higher with the PMMA membrane than those obtained with polysulfone membrane (88.9% vs. 58.9%; p < 0.001), whereas the β2-microglobulin RRs (67.5% vs. 81.0%; p < 0.001), Kt (60.2 ± 8.7 vs. 65.5 ± 9.4 L; p = 0.01), Kt/V (1.9 ± 0.4 vs. 2.0 ± 0.5; p = 0.03), and the convection volume (18.8 ± 2.8 vs. 30.3 ± 7.8 L/session; p < 0.001) were significantly higher with polysulfone membrane. In conclusion, pCS removal by OL-HDF was superior with high-flux PMMA membranes, appearing to be a good dialysis strategy for improving dialytic clearance of pCS, enabling an acceptable clearance of β2-microglobulin and small solutes.

scholarly journals Multicenter clinical validation of an on-line monitor of dialysis adequacy.

1996 ◽  
Vol 7 (3) ◽  
pp. 464-471
Author(s):  
T A Depner ◽  
P R Keshaviah ◽  
J P Ebben ◽  
P F Emerson ◽  
A J Collins ◽  
...  
Keyword(s):  
Solute Concentration ◽  
Dialysis Dose ◽  
Dialysis Adequacy ◽  
Automated Method ◽  
Baxter Healthcare ◽  
Significant Difference ◽  
Urea Kinetics ◽  
Nitrogen Concentrations ◽  
On Line ◽  
Paired Analysis

Quantitation of hemodialysis by measuring changes in blood solute concentration requires careful timing when taking the postdialysis blood sample to avoid errors from postdialysis rebound and from recirculation of blood through the access device. It also requires complex mathematical interpretation to account for solute disequilibrium in the patient. To circumvent these problems, hemodialysis can be quantified and its adequacy assessed by direct measurement of the urea removed in the dialysate. Because total dialysate collection is impractical, an automated method was developed for measuring dialysate urea-nitrogen concentrations at frequent intervals during treatment. A multicenter clinical trial of the dialysate monitoring device, the Biostat 1000 (Baxter Healthcare Corporation, McGaw Park, IL) was conducted to validate the measurements of urea removed, the delivered dialysis dose (Kt/V), and net protein catabolism (PCR). The results were compared with a total dialysate collection in each patient. During 29 dialyses in 29 patients from three centers, the paired analysis of urea removed, as estimated by the dialysate monitor compared with the total dialysate collection, showed no significant difference (14.7 +/- 4.7 g versus 14.8 +/- 5.1 g). Similarly, measurements of Kt/V and PCR showed no significant difference (1.30 +/- 0.18 versus 1.28 +/- 0.19, respectively, for Kt/V and 42.3 +/- 15.7 g/day versus 52.2 +/- 17.4 g/day for PCR). When blood-side measurements during the same dialyses were analyzed with a single-compartment, variable-volume model of urea kinetics, Kt/V was consistently overestimated (1.49 +/- 0.29/dialysis, P < 0.001), most likely because of failure to consider urea disequilibrium. Because urea disequilibrium is difficult to quantitate during each treatment, dialysate measurements have obvious advantages. The dialysate monitor eliminated errors from dialysate bacterial contamination, simplified dialysate measurements, and proved to be a reliable method for quantifying and assuring dialysis adequacy.

scholarly journals Oxidative Status before and after Renal Replacement Therapy: Differences between Conventional High Flux Hemodialysis and on-Line Hemodiafiltration

Nutrients ◽  
2019 ◽  
Vol 11 (11) ◽  
pp. 2809 ◽  
Author(s):  
José Alberto Navarro-García ◽  
Elena Rodríguez-Sánchez ◽  
Jennifer Aceves-Ripoll ◽  
Judith Abarca-Zabalía ◽  
Andrea Susmozas-Sánchez ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Antioxidant Defense ◽  
Oxidized Ldl ◽  
Oxidative Status ◽  
Dialysis Session ◽  
High Flux ◽  
Oxidative Markers ◽  
Before And After ◽  
Total Antioxidant ◽  
On Line

Hemodialysis patients experience high oxidative stress because of systemic inflammation and depletion of antioxidants. Little is known about the global oxidative status during dialysis or whether it is linked to the type of dialysis. We investigated the oxidative status before (pre-) and after (post-) one dialysis session in patients subjected to high-flux dialysis (HFD) or on-line hemodiafiltration (OL-HDF). We analyzed carbonyls, oxidized LDL (oxLDL), 8-hydroxy-2′-deoxyguanosine, and xanthine oxidase (XOD) activity as oxidative markers, and total antioxidant capacity (TAC), catalase, and superoxide dismutase activities as measures of antioxidant defense. Indices of oxidative damage (OxyScore) and antioxidant defense (AntioxyScore) were computed and combined into a global DialysisOxyScore. Both dialysis modalities cleared all markers (p < 0.01) except carbonyls, which were unchanged, and oxLDL, which increased post-dialysis (p < 0.01). OxyScore increased post-dialysis (p < 0.001), whereas AntioxyScore decreased (p < 0.001). XOD and catalase activities decreased post-dialysis after OL-HDF (p < 0.01), and catalase activity was higher after OL-HDF than after HFD (p < 0.05). TAC decreased in both dialysis modalities (p < 0.01), but remained higher in OL-HDF than in HFD post-dialysis (p < 0.05), resulting in a lower overall DialysisOxyScore (p < 0.05). Thus, patients on OL-HDF maintain higher levels of antioxidant defense, which might balance the elevated oxidative stress during dialysis, although further longitudinal studies are needed.

Mathematical Modeling of Different Molecule Removal on On-Line Haemodiafiltration: Influence of Dialysis Duration and Infusion Flow

2015 ◽  
Vol 39 (4) ◽  
pp. 288-296 ◽  
Author(s):  
Francisco Maduell ◽  
Juan Sanchez ◽  
Marta Net ◽  
Miquel Gomez ◽  
Jose M. Gonzalez ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Treatment Time ◽  
Compartment Model ◽  
Dialysis Dose ◽  
Β2 Microglobulin ◽  
Dialysis Duration ◽  
Two Compartment Model ◽  
On Line ◽  
The Impact ◽  
Kinetics Of

Background: In a previous study on a nocturnal, every-other-day online haemodiafiltration scheme, different removal patterns were observed for urea, creatinine, β2-​microglobulin, myoglobin and prolactin. The aim of this study was to evaluate the influence of dialysis duration and infusion flow (Qi) on the removal of different molecular weight (MW) solutes, and to quantify the effect of the different treatments on the kinetics of the solutes by using a classical two-compartment model. Methods: This prospective, in-center study was carried out in 10 patients on a nocturnal, every-other-day online post-dilution haemodiafiltration program. Each patient received four dialysis sessions with different conditions, two 4-h sessions (with infusion flows of 50 or 100 ml/min) and two 8-h sessions (with infusion flows of 50 or 100 ml/min). To analyze the solute kinetics, blood samples were obtained hourly during the dialysis treatments and in the first 3 h post-dialysis. Results: Removal patterns differed in the molecules studied, which were quantified by means of the two-compartment mathematical model. The main results show the impact of dialysis duration on the removal of low molecular weight molecules (urea and creatinine), while the impact of Qi is clearly shown for high molecular weight molecules (myoglobin and prolactin). For middle molecular weight solutes, such as β2-microglobulin, both factors (duration and Qi) enhance the removal efficiency of the dialyzer. Conclusions: Our study evaluates experimentally and mathematically how treatment time and infusion flow affect the filtration of solutes of different MW during post-dilution haemodiafiltration. The results provided by the present study should help physicians to select and individualise the most appropriate schedules to deliver an optimum diffusive and convective dialysis dose for each patient.

scholarly journals P1082COMPARISON OF THE REMOVAL OF PROTEIN-BOUND TOXINS AND LARGE MIDDLE MOLECULES WITH HIGH-FLUX PMMA AND MEDIUM CUT-OFF DIALYZERS

2020 ◽  
Vol 35 (Supplement_3) ◽  
Author(s):  
Pablo Molina ◽  
Julio Peiró ◽  
María Amparo Martínez-Gómez ◽  
Belén Vizcaíno ◽  
Mercedes Gonzã¡lez Moya ◽  
...  
Keyword(s):  
Membrane Surface ◽  
Convective Transport ◽  
Reduction Ratio ◽  
Prospective Clinical Study ◽  
Dialysis Session ◽  
High Flux ◽  
Dialysate Flow ◽  
Middle Molecules ◽  
On Line ◽  
New Generation

Abstract Background and Aims Dialytic clearance of protein-bound toxins and large middle molecules is poor by diffusive treatment and limited by high-flux hemodialysis (HD) and on-line hemodiafiltration (OL-HDF), and only a few studies have examined how to improve their removal by other extracorporeal strategies. Since 2017, there is a new generation of polymethyl methacrylate (PMMA) membranes that suppress platelet adhesion on the membrane surface improving hemocompatibility and permeability, while also maintaining adsorption properties related to conventional PMMA membranes. Expanded HD (HDx) with medium cut-off (MCO) membranes has also recently been incorporated into clinical practice and may improve the removal of uremic toxins in HD treatments. The aim of this pilot study was to compare the efficacy of a new high-flux PMMA dialyzer (Filtryzer® NF-2.1H) in a post-dilution OL-HDF session with a new MCO membrane (Theranova® 400) in a HDx session. Method In an open, cross-over, single-center, controlled, prospective clinical study, 40 adult stable HD patients were assigned to be treated by post-dilution OL-HDF with the NF-2.1H dialyzer or by HDx with the Theranova 400 dialyzer. All other dialysis parameters, including blood and dialysate flow rates, length of dialysis session, and ultrafiltration rate remained unchanged during both sessions. P-cresyl sulfate (PCS), indoxyl sulfate (IS), and kappa (κ) and lambda( λ) free light chains (FLC) reduction rates were intraindividually compared for the two dialyzer types (primary outcomes). Secondary outcomes included the kt and the reduction ratio of blood urea nitrogen, phosphate and β2 -microglobulin (β 2-m). Results The reduction ratio of protein-bound toxins ranges from 60% to 67%, with no differences between membranes (Figure). PMMA membrane achieved greater FLC reduction ratios than MCO membrane, reaching significance for λFLC (56.6% vs. 77.4%; p &lt; 0.001). Conversely, β2M reduction ratio was slightly but significantly higher with MCO membrane (68.5 vs. 72.1%; p = 0.002). Small molecules removal including urea and phosphate were similar in both groups, achieving an optimal Kt with no differences between groups (61.3±9.2 Vs. 59.7±9.3; p=0.16). Albumin reduction ratio tended to be higher with PMMA membrane without reaching significance (10.1±5.9% Vs. 7.8±12.3%; p=0.17). The mean convective volume achieved with PMMA was 23.5±4.4 L. Conclusion This study suggested that new high-flux PMMA dialyzer in post-dilution OL-HDF mode might achieve better FLC reduction ratios than MCO dyalizer in HDx mode, whereas both techniques may equally remove protein-bound toxins. OL-HDF with new PMMA membranes could be a good dialysis strategy for adding convective transport to the well-known mechanisms of diffusion and absorption previously described with conventional PMMA membranes, enabling an adequate substitution volume.

On-Line Estimation and Prediction of Urea Kinetics during Hemodialysis: A Simulation Approach

1995 ◽  
Vol 18 (5) ◽  
pp. 245-253 ◽  
Author(s):  
G. Comai ◽  
A. Cappello ◽  
F. Grandi ◽  
G. Avanzolini
Keyword(s):  
Simulated Data ◽  
Volume Ratio ◽  
Initial Distribution ◽  
Urea Concentration ◽  
Dialysis Session ◽  
Large Set ◽  
Simulation Approach ◽  
Urea Kinetics ◽  
Pool Model ◽  
On Line

A new method for the on-line estimation of urea kinetic parameters from blood urea concentration (BUN) continuously measured during a dialysis session is proposed. The method, based on the variable-volume double-pool model, is evaluated through a simulation approach in order to easily consider a large set of well-controlled test conditions. The model is characterized by six parameters, knowledge of which enables early prediction of the end dialysis urea concentration and the dose of dialysis. The sensitivity of the model predicted BUN with respect to the parameters was first analyzed to investigate which can be reliably estimated from blood urea measurements taken at a suitable rate. This analysis showed that the model predicted BUN is highly sensitive to the initial blood urea concentration and to the dialyzer clearance, normalized with respect to the total initial distribution volume, while it is scarcely influenced by the normalized ultrafiltration and urea generation rates. The new on-line estimation technique keeps these two last parameters constant and takes advantage of an original analytic solution of the second order urea kinetics. The results of the estimation process on realistic simulated data showed that the proposed method provides early and reliable estimates of the normalized clearance and of the end dialysis concentration. The transcellular mass transfer coefficient and the intra-extra cellular volume ratio can also be estimated, although with less accuracy. Moreover, it was shown that the use of the single-pool model, instead of the double-pool one, provides systematic errors on the estimates.

High-Flux Dialysis: Clinical, Biochemical, and Proteomic Comparison with Low-Flux Dialysis and On-Line Hemodiafiltration

2017 ◽  
Vol 44 (2) ◽  
pp. 129-139 ◽  
Author(s):  
Carlo Donadio ◽  
Angeliki Kanaki ◽  
Nadia Sami ◽  
Danika Tognotti
Keyword(s):  
Proteomic Analysis ◽  
High Flux ◽  
Aged Patients ◽  
Efficient Treatment ◽  
Β2 Microglobulin ◽  
Small Proteins ◽  
On Line ◽  
Efficient Alternative ◽  
Proteomic Analyses

Hemodiafiltration on-line (on-line HDF) is a more efficient treatment than low-flux hemodialysis (HD). Unfortunately, it cannot be proposed to all patients. The aim of this study was to evaluate the safety, efficiency, and mechanisms of removal of toxins with high-flux HD vs. low-flux HD and on-line HDF. Randomized cross-over study designed to evaluate efficiency and tolerability of high-flux HD vs. low-flux HD in aged patients; to compare by means of biochemical and proteomic analyses the efficiency and mechanisms of removal of toxins with high-flux HD vs. on-line HDF. The removal of small toxins was similar with high-flux and low-flux HD. β2-microglobulin was removed only with high-flux HD, which had an excellent tolerability. The efficiency of high-flux HD was similar to on-line HDF. Proteomic analysis demonstrated that only high-flux membranes remove and adsorb small proteins. High-flux HD may be an efficient alternative to on-line HDF.

Technical and Clinical Evaluation of a New Asymmetric Polysulfone Membrane (Biosulfane®)

1993 ◽  
Vol 16 (8) ◽  
pp. 573-584 ◽  
Author(s):  
C. Ronco ◽  
A. Brendolan ◽  
C. Crepaldi ◽  
M.C. Bettini ◽  
M. Scabardi ◽  
...  
Keyword(s):  
Wall Thickness ◽  
Hydraulic Permeability ◽  
Dialysis Session ◽  
High Flux ◽  
Polysulfone Membrane ◽  
Diffusive Permeability ◽  
Wide Range ◽  
Beta 2 ◽  
Beta 2 Microglobulin

First generation asymmetric polysulfone membranes had high hydraulic permeability (kf=40 ml/h/mmHg/sqm) but a low diffusive permeability due to the hydrophobic nature and wall thickness of 75–100 microns. We have tested a new polysulfone membrane with a wall thickness of 40 microns in a series of in vitro and in vivo dialysis session experiments. The new “Biosulfane®” membrane presented a Kf of 45.8 with constant performance up to 240 mins. The koA was 760 and the clearance value at 350 ml/min of Qb in hemodiafiltration was 255 ml/min for urea, 210 for creatinine, 225 for phosphate, 76 for inulin. In high flux dialysis the clearances were similar except for inulin which was 32% lower due to the lower convection amount. Beta-2 microglobulin clearance was 22 ml/min in high flux dialysis and 37 in hemodiafiltration. Solute sieving coefficients were close to 1 for the majority of the studied solutes in a wide range of molecular weights and slight variations were observed for charged solutes due to Donnan's effect. The sieving for Inulin was 0.96 while that for Beta-2 microglobulin was not measurable due to a large molecule adsorption on the inner structure of the fibres. The good performances of this membrane are probably due to reduced wall thickness and a consequent improvement in diffusive permeability to small size solutes.

On-Line Urea Monitoring: A Further Step towards Adequate Dialysis Prescription and Delivery

1995 ◽  
Vol 18 (9) ◽  
pp. 534-543 ◽  
Author(s):  
C. Ronco ◽  
A. Brendolan ◽  
C. Crepaldi ◽  
P. Frisone ◽  
F. Ghiotto ◽  
...  
Keyword(s):  
Nitrogen Concentration ◽  
High Rate ◽  
Dialysis Session ◽  
New Device ◽  
Baxter Healthcare ◽  
Direct Measurements ◽  
Blood Drawing ◽  
Urea Kinetics ◽  
On Line ◽  
Spent Dialysate

The Aim Of This Study Is To Present A Clinical Experience Carried Out With A New Device Designed To Measure On-Line Urea Nitrogen Concentration In The Effluent Dialysate. The Biostat 1000® Urea Monitor (Baxter Healthcare, Dirfield, Iii, Usa) Was Utilized In The Present Study. The Monitor Is Based On The Principle That Multiple Urea Measurements In The Dialysate Effluent From The Dialyzer, Permit To Built A Double Exponential Regression Leading To The Urea Kinetic Parameters Of The Dialysis Session. Data Obtained With The Urea Monitor Were, In The Present Study, Compared With Those Obtained By Direct Measurements Carried Out In Blood And Dialysate And By The Collection Of The Whole Amount Of Spent Dialysate. The Monitor Provided An Accurate Value Of Predialysis Bun Without Any Blood Drawing. Urea Kinetics Were Established From Multiple Dialysate Measurements And No Blood Drawing Was Necessary. The Double Pool Kinetics Were Taken Into Account And Kt/V, Pcr And Sri° Obtained Were Comparable To Those Obtained From Direct Measurement. Since A Projected Value Of Kt/V Can Be Obtained, The Monitor Could Represent A Potential Source Of Information To Detect Possible Filter And Machine Dysfunction, As Well As High Rate Of Recirculation.

scholarly journals Simulating the effect of exercise on urea clearance in hemodialysis.

1998 ◽  
Vol 9 (1) ◽  
pp. 128-132
Author(s):  
S W Smye ◽  
E J Lindley ◽  
E J Will
Keyword(s):  
Experimental Studies ◽  
Compartment Model ◽  
Low Flow ◽  
Limiting Factor ◽  
Dialysis Session ◽  
Dialysis Dose ◽  
Blood Flows ◽  
Two Compartment Model ◽  
Urea Kinetics ◽  
Model Equations

A two-compartment model of urea kinetics during hemodialysis is used to predict the effect of exercise on hemodialysis dose. It is assumed that the two compartments represent tissues that are perfused by low and high blood flows (initially 1.1 L/min and 3.8 L/min). The effect of changing the distribution of flows between the compartments, emulating the effect of exercise, is simulated using the model equations for a range of dialyzer clearances. Compartmental volumes are assumed constant (33.4 L and 8.6 L for low- and high-flow compartments, respectively). The analysis identifies muscle perfusion as a rate-limiting factor during the later stages of hemodialysis and illustrates the benefit of exercise during this phase in increasing dialysis efficiency. The model suggests that the postdialysis rebound in the blood urea concentration is eliminated by increasing flow to the low-flow compartment from 1.1 L/min to 7.1 L/min and sustaining this for at least 30 min of a 150-min dialysis session, independent of the dialyzer clearance. Additional exercise will not increase the dialysis dose. Experimental studies are required to confirm the analysis.

scholarly journals Randomised trial on clinical performances and biocompatibility of four high-flux hemodialyzers in two mode treatments: hemodialysis vs post dilution hemodiafiltration

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Marion Morena ◽  
Caroline Creput ◽  
Mouloud Bouzernidj ◽  
Annie Rodriguez ◽  
Lotfi Chalabi ◽  
...  
Keyword(s):  
Primary Outcome ◽  
Randomised Trial ◽  
High Flux ◽  
Β2 Microglobulin ◽  
Inflammatory Parameters ◽  
Large Size ◽  
Significant Difference ◽  
Good Biocompatibility ◽  
Very High ◽  
Solute Clearance

AbstractThis prospective multicenter randomized comparative cross-over trial aimed at evaluating the influence of hemodialysis vs post-dilution hemodiafiltration with high-flux dialyzers in solute clearance and biocompatibility profile. 32 patients were sequentially dialyzed with Leoceed-21HX, Polypure-22S+, Rexsys-27H and VIE-21A. Primary outcome was β2-microglobulin removal. Secondary outcomes were (i) extraction of other uremic solutes (ii) parameters of inflammation and nutrition and (iii) comparative quantification of perdialytic albumin losses (using total ‘TDC’ vs partial ‘PDC’ collection of dialysate). Significant increases in removal rates of β2-microglobulin (84.7 ± 0.8 vs 71.6 ± 0.8 mg/L), myoglobin (65.9 ± 1.3 vs 38.6 ± 1.3 µg/L), free immunoglobulin light chains Kappa (74.9 ± 0.8 vs 55.6 ± 0.8 mg/L), β-trace protein (54.8 ± 1.3 vs 26.8 ± 1.4 mg/L) and orosomucoid (11.0 ± 1.1 vs 6.0 ± 1.1 g/L) but not myostatin (14.8 ± 1.5 vs 13.0 ± 1.5 ng/mL) were observed in HDF compared to HD when pooling all dialyzers. Rexsys and VIE-A use in both HD and HDF subgroups was associated to a better removal of middle/large-size molecules compared to Leoceed and Polypure, except β2-microglobulin for Rexsys. Inflammatory parameters were unchanged between dialyzers without any interaction with dialysis modality. Mean dialysate albumin loss was comparable between TDC and PDC (1.855 vs 1.826 g/session for TDC and PDC respectively). In addition, a significant difference in albumin loss was observed between dialyzers with the highest value (4.5 g/session) observed using Rexsys. Use of all dialyzers was associated with good removals of the large spectrum of uremic toxins tested and good biocompatibility profiles, with an additional gain in removal performances with HDF. Larger surface area, thinner wall and resultant very high ultrafiltration coefficient of Rexsys should be taken into account in its clear performance advantages.

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