Electrodialysis desalination: The impact of solution flowrate (or Reynolds number) on fluid dynamics throughout membrane spacers.

The incorporation of a spacer among membranes has a major influence on fluid dynamics and performance metrics. Spacers create feed channels and operate as turbulence promoters to increase mixing and reduce concentration/temperature polarization effects. However, spacer geometry remains unoptimized, and studies continue to investigate a wide range of commercial and custom-made spacer designs. The in-depth discussion of the present systematic review seeks to discover the influence of Reynolds number or solution flowrate on flow hydrodynamics throughout a spacer-filled channel. A fast-flowing solution sweeping one membrane's surface first, then the neighboring membrane's surface produces good mixing action, which does not happen commonly at laminar solution flowrates. A sufficient flowrate can suppress the polarization layer, which may normally require the utilization of a simple feed channel rather than complex spacer configurations. When a recirculation eddy occurs, it disrupts the continuous flow and effectively curves the linear fluid courses. The higher the flowrate, the better the membrane performance, the higher the critical flux (or recovery rate), and the lower the inherent limitations of spacer design, spacer shadow effect, poor channel hydrodynamics, and high concentration polarization. In fact, critical flow achieves an acceptable balance between improving flow dynamics and reducing the related trade-offs, such as pressure losses and the occurrence of concentration polarization throughout the cell. If the necessary technical flowrate is not used, the real concentration potential for transport is relatively limited at low velocities than would be predicted based on bulk concentrations. Electrodialysis stack therefore may suffer from the dissociation of water molecules. Next studies should consider that applying a higher flowrate results in greater process efficiency, increased mass transfer potential at the membrane interface, and reduced stack thermal and electrical resistance, where pressure drop should always be indicated as a consequence of the spacer and circumstances used, rather than a problem.

Inflamación y adecuación de la hemodiálisis: ¿están los niveles de proteína C reactiva influidos por la dosis de diálisis recibida? / Inflammation and hemodialysis adequacy: Are C-reactive protein levels influenced by dialysis dose?

Introducción : La inflamación crónica y la subyacente comorbilidad cardiovascular aún son problemas vigentes en los pacientes en hemodiálisis crónica. Existen pocos estudios que comparen la «dosis de diálisis» (Kt/V) con el grado de inflamación del paciente. Nuestro objetivo principal fue determinar si existe una relación entre los niveles séricos de proteína C reactiva (PCR) y el Kt/V utilizando la dialisancia iónica.Métodos : Estudio transversal multicéntrico. Se incluyeron 536 pacientes prevalentes en hemodiálisis crónica. Se recogieron los niveles de PCR, el índice neutrófilo-linfocito y el índice plaqueta-linfocito. Se obtuvo el Kt por dialisancia iónica y el volumen de distribución de la urea mediante la fórmula de Watson. Se dividió la muestra en 2 grupos tomando como punto de corte la mediana de PCR y se comparó la adecuación de diálisis en cada uno. Finalmente, se realizó un modelo de regresión logística para determinar las variables de mayor influencia.Resultados : La mediana de PCR fue 4,10mg/L (q25-q75: 1,67-10). El Kt/V medio fue de 1,48±0,308. El Kt/V fue menor en los pacientes incluidos en el grupo de inflamación alta (p=0,01). En la regresión logística multivariante, los niveles «altos» de PCR tuvieron una correlación directa con el Log índice neutrófilo-linfocito (p<0,001) e inversamente proporcional con los valores de albúmina sérica (p=0,014), Kt/V (p=0,037) y hierro sérico (p<0,001).Conclusión : La peor adecuación en términos de dosis de diálisis (valores de Kt/V más bajos) puede contribuir a un mayor grado de inflamación en los pacientes en hemodiálisis crónica. (AU)

Introduction : Chronic inflammation and the underlying cardiovascular comorbidity are still current problems in chronic hemodialysis patients. There are few studies comparing the “dialysis dose” (Kt/V) with the degree of inflammation in the patient. Our main objective was to determine whether there is a relationship between serum C-reactive protein (CRP) levels and the Kt/V using ionic dialysance.Methods : Multicenter cross-sectional study. A total of 536 prevalent chronic hemodialysis patients were included. CRP levels, neutrophil-lymphocyte ratio and platelet-lymphocyte ratio were collected. Kt was obtained by ionic dialysance and urea distribution volume was calculated from the Watson's formula. The sample was divided into 2 groups, taking the median CRP as the cut-off point. Dialysis adequacy obtained in each group was compared. Finally, a logistic regression model was carried out to determine the variables with the greatest influence.Results : Median CRP was 4.10mg/L (q25-q75: 1.67-10) and mean Kt/V was 1.48±0.308. Kt/V was lower in the patients included in the high inflammation group (P=.01). In the multivariate logistic regression, the “high” levels of CRP were directly correlated with the Log neutrophil-lymphocyte ratio (P<.001) and inversely proportional with serum albumin values (P=.014), Kt/V (P=.037) and serum iron (P<.001).Conclusion : The poorer adequacy in terms of dialysis doses (lower Kt/V values) may contribute to a higher degree of inflammation in chronic hemodialysis patients. (AU)

Validación del método inverso para la determinación del flujo de acceso con termodilución / Validation of the inverse method for the determination of the access flow with thermodilution

Introducción: La termodilución es un método ampliamente usado para la medición del flujo de acceso vascular (QA). Entre las posibilidades de la termodilución, el método inverso (MI) puede ser beneficioso en el tiempo de ejecución, sin repercusión en la eficacia dialítica (Kt). Sin embargo, no es una técnica lo suficientemente estudiada.MétodoEstudio transversal sobre 117 fístulas arteriovenosas. Se realizaron 2 mediciones de QA con el método descrito por el fabricante (MR) y otra con MI. El MI se basa en la obtención del registro de recirculación invertida al iniciar la sesión y una única medición posterior de recirculación con las líneas en posición normal. En el análisis de concordancia se utilizó el método Bland-Altman y el índice kappa de Cohen.ResultadosSe evidenció muy buena concordancia entre MR y MI para QA inferiores a 700ml/min, pero empeora a medida que aumenta el flujo. La variabilidad mediana entre las mediciones con MR (variabilidad intramétodo) fue del 3,4% (−17,13). Este valor no difirió de la variabilidad mediana generada entre MR y MI (variabilidad intermétodo), que fue del 2% (−14,12) (p=0,287). El grado de acuerdo entre ambos para identificar fístulas arteriovenosas susceptibles de intervención fue muy bueno (kappa=0,834). El tiempo empleado utilizando el MI fue significativamente menor (p=0,000), sin evidenciarse variaciones en el Kt de las sesiones de medida (p=0,201).ConclusionesEl MI de termodilución es válido para determinar el flujo del acceso vascular, especialmente en QA inferiores a 700ml/min, con gran ahorro de tiempo, simplificación del procedimiento y sin modificar la eficacia de diálisis. La variabilidad entre la medición por MR y MI es similar a la propia del MR. La concordancia entre métodos a la hora de identificar fístulas arteriovenosas potencialmente patológicas es muy buena. (AU)

Introduction: Thermodilution is a widely used method for measuring vascular access flow (QA). Among the possibilities of thermodilution, the reverse method (RM) can be beneficial in the execution time, without impact on the dialysis efficacy (Kt). However, it is not a sufficiently studied technique.MethodTransversal study of 117 arteriovenous fistulas. Two QA measurements were taken with the method described by the manufacturer (MR) and another with RM. RM is based on the obtention of an inverted recirculation registry at the beginning of the session and a single subsequent recirculation measurement with the lines in normal position. In the concordance analysis, the Bland-Altman method and Cohen's Kappa index were used.ResultsVery good concordance between MR and RM was evidenced for QA below 700ml/min, but it worsens as flow increases. The median variability between the MR measurements (intra-method variability) was 3.4% (−17.13). This value did not differ from the median variability generated between MR and RM (inter-method variability), which was 2% (−14,12) (P=.287). The degree of agreement between the 2 to identify arteriovenous fistulas susceptible to intervention was very good (Kappa=0.834). The time spent using the RM was significantly shorter (P=.000) without evidence of variations in the Kt of the measurement sessions (P=.201).ConclusionsThe thermodilution RM is valid to determine the flow of the vascular access, especially in QA lower than 700ml/min, with great time savings, simplification of the procedure and without modifying the dialysis efficiency. The variability between the measurement by MR and RM is similar to that of MR. The concordance between methods in identifying potentially pathological arteriovenous fistulas is very good. (AU)

Artificial liver support systems.

Artificial liver systems are used to bridge between transplantation or to allow a patient's liver to recover. They are used in patients with acute liver failure (ALF) and acute-on-chronic liver failure. There are five artificial systems currently in use: molecular adsorbent recirculating system (MARS), single-pass albumin dialysis (SPAD), Prometheus, selective plasma filtration therapy, and hemodiafiltration. The aim is to compare existing data on the efficiency of these devices. A literature search was conducted using online libraries. Inclusion criteria included randomized control trials or comparative human studies published after the year 2000. A systematic review was conducted for the five individual devices with a more detailed comparison of the biochemistry for the SPAD and MARS systems. Eighty-nine patients were involved in the review comparing SPAD and MARS. Results showed that there was an average reduction in bilirubin (-53 µmol/L in MARS and -50 µmol/L in SPAD), creatinine (-19.5 µmol/L in MARS and -7.5 µmol/L in SPAD), urea (-0.9 mmol/L in MARS and -0.75 mmol/L in SPAD), and gamma-glutamyl transferase (-0.215 µmol/L·s in MARS and -0.295 µmol/L·s in SPAD) in both SPAD and MARS. However, there was no significant difference between the changes in the two systems. This review demonstrated that both MARS and SPAD aid recovery of ALF. There is no difference between the efficiency of MARS and SPAD. Because of the limited data, there is a need for more randomized control trials. Evaluating cost and patient preference would aid in differentiating the systems.

The current and future landscape of dialysis.

The development of dialysis by early pioneers such as Willem Kolff and Belding Scribner set in motion several dramatic changes in the epidemiology, economics and ethical frameworks for the treatment of kidney failure. However, despite a rapid expansion in the provision of dialysis - particularly haemodialysis and most notably in high-income countries (HICs) - the rate of true patient-centred innovation has slowed. Current trends are particularly concerning from a global perspective: current costs are not sustainable, even for HICs, and globally, most people who develop kidney failure forego treatment, resulting in millions of deaths every year. Thus, there is an urgent need to develop new approaches and dialysis modalities that are cost-effective, accessible and offer improved patient outcomes. Nephrology researchers are increasingly engaging with patients to determine their priorities for meaningful outcomes that should be used to measure progress. The overarching message from this engagement is that while patients value longevity, reducing symptom burden and achieving maximal functional and social rehabilitation are prioritized more highly. In response, patients, payors, regulators and health-care systems are increasingly demanding improved value, which can only come about through true patient-centred innovation that supports high-quality, high-value care. Substantial efforts are now underway to support requisite transformative changes. These efforts need to be catalysed, promoted and fostered through international collaboration and harmonization.

Surgical management of catheter-related right atrial thrombus with superior vena cava syndrome A Case Report.

There are no consensus guidelines on the management of catheter-related right atrial thrombus. We present the case of a 29-year-old female with end-stage renal disease who was found to have a large right atrial thrombus associated with her tunneled dialysis catheter during preoperative workup for renal transplant. She exhibited signs and symptoms of superior vena cava syndrome and NYHA class III congestive heart failure. She was successfully treated with surgical thrombectomy and demonstrated rapid resolution of her symptoms postoperatively.

How Electrical Heterogeneity Parameters of Ion-Exchange Membrane Surface Affect the Mass Transfer and Water Splitting Rate in Electrodialysis.

Electrodialysis (ED) has been demonstrated as an effective membrane method for desalination, concentration, and separation. Electroconvection (EC) is a phenomenon which can essentially increase the mass transfer rate and reduce the undesirable water splitting effect. Efforts by a number of researchers are ongoing to create conditions for developing EC, in particular, through the formation of electrical heterogeneity on the membrane surface. We attempt, for the first time, to optimize the parameters of surface electrical heterogeneity for ion-exchange membranes used in a laboratory ED cell. Thirteen different patterns on the surface of two Neosepta anion-exchange membranes, AMX and AMX-Sb, were tested. Low-conductive fluoropolymer spots were formed on the membrane surface using the electrospinning technique. Spots in the form of squares, rectangles, and circles with different sizes and distances between them were applied. We found that the spots' shape did not have a visible effect. The best effect, i.e., the maximum mass transfer rate and the minimum water splitting rate, was found when the spots' size was close to that of the diffusion layer thickness, δ (about 250 µm in the experimental conditions), and the distance between the spots was slightly larger than δ, such that the fraction of the screened surface was about 20%.

Influence of acid/base activation treatment in the performance of recycled electromembrane for fresh water production by electrodialysis.

In this study, an activation treatment for recycled anion exchange membranes is proposed. Following the circular economy approach, these membranes were prepared by using end-of-life reverse osmosis membranes as mechanical support. The end-of-life membrane was previously used and discarded by desalination plants after overcoming its lifespan. The activation treatment was based on the subsequent immersion of the membranes in diluted acid and alkali solutions. This treatment promoted the complete dissociation of the functional groups in the membrane, making them more reactive to the counter ions. The effects of acid and alkali concentrations and exposition times on the electrochemical properties were studied and the best combination was selected. In such a way, a decrease of 37% in membrane electrical resistance was achieved. The performance of activated and non-activated membranes in brackish water desalination by electrodialysis was compared. The results showed that the proposed activation treatment increased the flux of fresh water more than four-fold (from 1.2 to 4.9 L h-1·m-2), with a considerable reduction of energy consumption (from 5.2 to 3.0 kWh·m-3) and a great improvement in current efficiency (from 38% to 71%). In conclusion, this work shows a simple and low cost methodology for the improvement of the electrochemical properties of recycled electromembranes and thus, their performance in electrodialysis.

Evaluation of the feasibility of short-term electrodialysis for separating naturally occurring fluoride from instant brick tea infusion.

BACKGROUND: Removing excessive naturally occurring fluoride from tea and/or infusions is difficult because the process has low efficiency and causes secondary pollution. In this study, a novel electrodialysis (ED) technology was developed. We examined the effect of crucial parameters (electrolyte concentration, operation voltage, ED duration and initial concentration of the tea infusion) on defluoridation performance using a highly efficient ion-exchange membrane with five-compartment cells. RESULTS: The most effective ED system results were obtained at an electrolyte concentration of 10 g kg-1 and operating voltage of 20 V. Moreover, the fluoride removal capacity (10.70-66.93%) was highly dependent on the ED duration (1-15 min) and initial concentration of the tea infusion (0.5-10 g kg-1 ). The longer the ED duration and the lower the initial concentration, the higher was the defluoridation performance. During ED, limited loss of the main inclusions (total polyphenols, catechins, caffeine and selected ions) was observed. Furthermore, the D201 anion resin-filled ED stack (0.5-5 g) and improvement of concentrate compartment electrolyte (≥5 times the dilute compartment electrolyte) in the ED system enhanced the defluoridation rate significantly. CONCLUSION: ED is a potentially effective method that can be used for defluoridation in the deep processing of tea products. © 2019 Society of Chemical Industry.

Isolating Urinary Extracellular Vesicles as Biomarkers for Diabetic Disease.

Extracellular vesicles are lipid bilayer enclosed structures secreted by all cell types. Their cargo includes proteins, lipids, RNAs, and DNA, which reflect the physiological state of their cells of origin. Recently, urinary extracellular vesicles have emerged as a valuable source of biomarkers for kidney and systemic disease.Unfortunately, all existing methods for extracellular vesicle isolation from urine are time consuming and/or expensive. Thus, they are not adaptable to large-scale studies and unsuitable for clinical use without special equipment in the laboratory. Recently, our group has devised a set of new, quick, simple, and inexpensive techniques, based on hydrostatic filtration dialysis (HFD) of urine extremely suitable for diagnostic purposes. This novel approach represents a great potential for new diagnostics and understanding disease biology in general and brings the biomarker detection to the scope of all laboratories.

Is dialysis water a safe component for hemodialysis treatment in São Paulo State, Brazil?

Failure on the water treatment poses hemodialysis patients at risk of injury and death. Identifying if the patients are exposed to water quality related microbiological risks is an important objective to reduce the mortality for chronic renal patients and is the main issue of this study. We evaluated the microbiological water quality used by 205 dialysis services in São Paulo State, Brazil between 2010 to 2016. The study included heterotrophic bacteria count, total coliforms research, and bacterial endotoxin determination in 1366 dialysis water samples. The number of unsatisfactory clinics for at least one microbiological parameter decreased 16.0% between 2010 to 2015 but increased 57.2% in 2016. In 2010, the most frequent unsatisfactory parameter was related to heterotrophic bacteria count (54.8%) followed by endotoxin determination (45.2%). However, in 2013 an opposite situation was observed: endotoxin determination as the parameter of the higher incidence of nonconformities. Total coliform was verified at a lower frequency. We highlighted the importance of regular monitoring of dialysis water quality to prevent infections caused by dialytic procedures and to ensure that the water is a safe component of the treatment.

Extraction, formulation and characterization of an in vitro and ex-vivo evaluation of Thymus serpyllum L. (Thymus oil) from topical preparations using dialysis cellulose membrane and natural rabbit skin.

Herbal remedies like the Thymus serpyllum L. is useful in traditional medicine for the treatment of many diseases especially congestion, and bronchitis. The purpose of this study was to formulate a micro-emulsion, a gel and an ointment containing the plant hydro distilled thymus oil extracted from Thymus serpyllum L. collected from Ziarat, Balochistan. The prepared formulations were subjected to in-vitro and ex vivo study release, High performance Liquid Chromatography (HPLC), Thin Layer Chromatography (TLC), to justify their suitability for topical use. The in-vitro and ex-Vivo release was studied using Franz Cells and using two different kinds of membrane synthetic dialysis cellulose membrane and natural rabbit skin and the amount of drug released was determined by HPLC at λ 274nm. The three formulations result obtained through dialysis cellulose membrane showed the faster release than the natural rabbit skin. However, the micro-emulsion, gel formulation showed the same release except ointment. The release from the above mentioned formulation can be arranged in the following descending order. micro-emulsion > Gel > Ointment. The best fit of release kinetics was achieved by Krosmeyer- Peppas, the TLC and HPLC identifies the Thymol, isolation and quantification of the marker. This study demonstrates that it is necessary to assess the impact of release and permeability pattern of different formulations. In vitro and ex-vivo diffusion cell experiments can be utilized to develop formulations of traditional medicines identifies.

Effects of Virtual Reality in Patients Undergoing Dialysis: Study Protocol.

Dialysis is often considered slow, repetitive, and with programmed intervals. Patients often perceive it as time taken from their lives with a sense of ineluctability and emptiness, engendering a negative emotional and cognitive perception of the world and one's place in it. Today, it is possible to improve the quality of life of patients during hemodialysis using virtual reality (VR). This creation of a true multisensory experience may absorb the patient's perceptions during hemodialysis, improving his/her quality of life. An Italian multicenter, longitudinal experimental study will be conducted with a randomized, pre-post test design, with balanced allocation 1:1, in parallel groups with a control group in the standard care of patients diagnosed with chronic renal failure who are, undergoing hemodialysis treatment. A sample of 186 patients calculated with sample size (power = 80%, ß = 0.2, α = 0.05) will be randomized into an experimental group exposed to VR, and a control group in standard care. The 2 groups will be studied over a period of 1 month, with 12 applications of VR and with measurements of the following outcomes: anxiety, fatigue, pruritus, arterial pressure, heart rate, respiration rate, and duration of the session at each hemodialysis session. This is the first international experimental protocol that examines the application of VR in patients undergoing hemodialysis. If the results show statistically and clinically significant differences, the VR could be an additional holistic intervention, which is evidence based, linked to the humanization of chronic, repetitive interventions, complementary to and synergistic with standard of care.

Fabrication and practical applications of molybdenum disulfide nanopores.

Among the different developed solid-state nanopores, nanopores constructed in a monolayer of molybdenum disulfide (MoS2) stand out as powerful devices for single-molecule analysis or osmotic power generation. Because the ionic current through a nanopore is inversely proportional to the thickness of the pore, ultrathin membranes have the advantage of providing relatively high ionic currents at very small pore sizes. This increases the signal generated during translocation of biomolecules and improves the nanopores' efficiency when used for desalination or reverse electrodialysis applications. The atomic thickness of MoS2 nanopores approaches the inter-base distance of DNA, creating a potential candidate for DNA sequencing. In terms of geometry, MoS2 nanopores have a well-defined vertical profile due to their atomic thickness, which eliminates any unwanted effects associated with uneven pore profiles observed in other materials. This protocol details all the necessary procedures for the fabrication of solid-state devices. We discuss different methods for transfer of monolayer MoS2, different approaches for the creation of nanopores, their applicability in detecting DNA translocations and the analysis of translocation data through open-source programming packages. We present anticipated results through the application of our nanopores in DNA translocations and osmotic power generation. The procedure comprises four parts: fabrication of devices (2-3 d), transfer of MoS2 and cleaning procedure (24 h), the creation of nanopores within MoS2 (30 min) and performing DNA translocations (2-3 h). We anticipate that our protocol will enable large-scale manufacturing of single-molecule-analysis devices as well as next-generation DNA sequencing.

Efficient Preparation of Xylonic Acid from Xylonate Fermentation Broth by Bipolar Membrane Electrodialysis.

Preparation of xylonic acid from xylonate fermentation broth was studied in a four-chamber bipolar membrane electrodialysis (BMED) setup. The effects of metal-ion size, current density, and xylonate concentration on BMED were evaluated principally with respect to acid yield and partially with respect to efficiency and energy consumption. Sodium xylonate was more successful than potassium xylonate because of its smaller size and easier membrane penetrability for BMDE. Efficient electrodialysis was achieved using 50 mA/cm2 current density for 14 min; thus, we obtained 92% xylonic acid from 100 g/L sodium xylonate fermentation broth. In conclusion, BMED can be used for producing xylonic acid from fermentation broth. Moreover, this study highlights ways of improving the efficiency of BMED.

Determination of inorganic anions in the whole blood by ion chromatography.

A fast, precise, and accurate method that can simultaneously determine 7 anions in whole blood was established by on line dialysis-double suppression ion chromatography. Performance parameters which could affect the determination of anions were optimized, including the selection of protein precipitant in samples, the amount of filtrate discarded, selection of eluent flow rate, influence of the Ag-Na column on experimental results, influence of ethylenediamines on ClO2-, and investigation of nitrogen drying. Finally, 3.6 mmol/L sodium carbonate was selected as eluent, with a flow rate of 0.8 mL/min, to separate the 7 anions. Blood and alcohol (v/v, 1:4) were used to precipitate the proteins in blood. The 7 anions reached an adequate recovery rate when the first 2 mL of filtrate from the C18 column was discarded. The recovery rate at LLOQ, low, medium, and high concentrations was 80-120%. The correlation coefficients (r2) of the calibration curves of the targeted anions ranged from 0.9975 to 0.9998. The limit of detection (LOD) was 0.309-7.71 µg/L. This method has simple pretreatment, high accuracy, and good reproducibility and selectivity, and is suitable for the separation and determination of anions in blood.

Incidents related to the Hickman® catheter: identification of damages.

OBJECTIVE: to identify damages resulting from incidents with the Hickman® catheter. METHOD: descriptive, retrospective, qualitative approach. The source of data were the notifications of incidents that occurred between January 2012 and May 2015, as well as the information available on the medical records of patients involved in incidents with the Hickman® catheter. RESULTS: the incidents related to the Hickman® catheter with the greatest impact on patient care were obstruction, fracture and traction. All incidents caused damage to patients, in a greater or lesser degree, in the dimensions of physical damage and subjective damage. FINAL CONSIDERATIONS: damage or potential risk of damage was present in all incidents analyzed. The need to revise cleaning and obstruction protocols for the maintenance of the permeability of Hickman® catheters was demonstrated.