Kinetic Modeling of “Go Slow” Dialysis in Acute Renal Failure

Go slow” dialysis is a gentle, intermittent hemodialysis therapy for acute renal failure patients, with advantages compared to slow, continuous therapies. It employs a recirculating closed dialysate circuit. A two-pool urea kinetic model is elaborated to determine kinetic parameters from blood and dialysate concentrations. This will allow quantification of the therapy. Variable clearance is included to accurately describe the kinetic process. The model is tested in an acute renal failure patient. Solute removals, as determined from direct dialysis quantification and by the model, are comparable. Variable clearance is not required to determine the kinetic parameters, because the constant mean clearance delivers equal results. The dialysis dose, as defined, allows comparison with chronic renal therapies. It requires solute removal determined from dialysate sampling and time-averaged concentration (TAC) from the urea kinetic modeling. In the test patient, dialysis dose is lower compared to standard thrice-weekly therapies because of its lower efficiency and higher TAC, a result of his highly catabolic state.     

Application of a recycle dialysis system in a reversed micellar reactor

A recycle dialysis stirred cell has been successfully used for integrating the reaction and product recovery of the lipase-catalyzed hydrolysis of olive oil in bis (2-ethylhexyl) sodium sulfosuccinate (AOT)-iso-octane reversed micelles. The resistance of membrane to reversed micelles was monitored by the water content and found to be 95.9% rejection after 24 h and 93.4% rejection after 48 h. The resistance of the membrane to free surfactants, by monitoring the UV absorption, was found to be 98.5% rejection after 10 h and 97.3% rejection after 24 h. Mathematical formulations involving the enzymatic reaction coupled with mass transfer were developed for predicting the performance of a membrane reactor. Theoretical predictions in terms of time course of oleic acid concentrations were found to be in agreement with the experimental results.     

Phosphate removal from aqueous solution by Donnan dialysis with anion-exchange membrane

The removal of phosphate from aqueous solution by Donnan dialysis with anion-exchange membrane was investigated.The results show that phosphate could be removed from aqueous solution without supplying external high pressure or electrical potential.Under the conditions of influent phosphate of 2.0 mg/L,counterion（Cl-） concentration of 0.1 mol/L,stirring speed of 500 r/min and phase temperature of 298 K,the removal of phosphate achieves 70.0%.Decreasing counterion concentration has little influence on the removal of phosphate,but phosphate amount in anion-exchange membrane increases significantly.With the increase of stirring speed and phase temperature,the removal efficiency of phosphate greatly is improved.Existing forms of phosphate in aqueous solution affected transport of phosphate and only strong acidic pH of feed solution （pH=3.0） decreases the removal of phosphate.Transport of phosphate is also accompanied by change of pH value of feed solution.In consequence,it might be a promise potential process for phosphate advanced wastewater treatment,especially in the area where high salted nature water can be utilized.     

Younger black patients have a higher risk of infection mortality that is mostly non‐dialysis related: A national study of cause‐specific mortality among U.S. maintenance dialysis patients

Introduction: While it has been well documented that in the U.S., black and Hispanic dialysis patients have overall lower risks of death than white dialysis patients, little is known whether their lower risks are observed in cause‐specific deaths. Additionally, recent research reported that younger black patients have a higher risk of death, but the source is unclear. Therefore, this study examined cause‐specific deaths among US dialysis patients by race/ethnicity and age. Methods: This national study included 1,255,640 incident dialysis patients between 1995 and 2010 in the United States Renal Data System. Five cause‐specific mortality rates, including cardiovascular (CVD), infection, malignancy, other known causes (miscellaneous), and unknown, were compared across blacks, Hispanics, and whites overall and stratified by age groups. Findings: After multiple adjustments, Hispanic patients had the lowest risk of mortality for every major cause in almost all ages. Compared with whites, blacks had a lower risk of death from CVD, malignancy and miscellaneous causes in most age groups, but not from infection. In fact, blacks had a higher risk of infection death than whites in ages 18–30 years (HR [95% CI] 1.94 [1.69–2.23]; P < 0.001), 31–40 years (HR 1.51 [1.40–1.63]; P < 0.001) and 41–50 years (HR 1.07 [1.02–1.12]; P = 0.009), which were partially attributed to their higher prevalence of AIDS nephropathy. For each race/ethnicity, more than two‐thirds of infection deaths were due to non‐dialysis related infections. Discussion: Hispanics had the lowest risk for each major cause of death. Blacks were less likely to die than whites from most causes, except infection. The previously reported higher overall mortality rate for younger blacks is attributed to their two‐fold higher infection mortality, which is mostly non‐dialysis related, suggesting a new direction to improve their overall health status. Research is greatly needed to determine social and biological factors that account for the survival gap in dialysis among different racial/ethnic groups.     

Fabrication of cation exchange membrane from polyvinyl alcohol using lignin sulfonic acid: Applications in diffusion dialysis process for alkali recovery

We report polyvinyl alcohol (PVA)-based hybrid membranes composed of salt of lignin sulfonic acid (LSA) and tetraethyl orthosilicate. The concentration of LSA with respect to PVA varied from 10% to 40%. The hybrid membranes showed water uptake (W_U) in the range of 122–210%, ion exchange capacities in the range of 0.32–0.75 mmol g^?1, dialysis coefficient (U_OH) from 0.0068 to 0.0119 m h^?1, and selectivity (S) from 15 to 26. The hybrid membranes also showed thermal and mechanical stability.     

类肝素聚乳酸微孔膜的血液相容性

通过在生物基聚乳酸(PLA)膜表面进行类肝素化修饰,得到了具有良好血液相容性的生物基聚合物膜。首先通过自由基聚合合成了聚(乙烯基吡咯烷酮–乙烯基三乙氧基硅烷)[P(VP–VTES)]预聚物,进一步通过其界面交联,将高含量的聚乙烯基吡咯烷酮固化到PLA膜表面,提高膜表面的亲水性和抗污性能。其次通过自由基聚合合成类肝素预聚物苯乙烯磺酸钠–乙烯基三乙氧基硅烷–丙烯酸三元共聚物[P(SSNa–VTES–AAH)],并利用预聚物中VTES链段的水解缩合反应将类肝素共聚物固定在PLA膜表面,从而提高膜的血液相容性。通过红外光谱确定了PLA膜表面亲水层P(VP–VTES)和P(SSNa–VTES–AAH)的分子结构。通过接触角测试表明类肝素分子修饰的PLA膜具有良好的亲水性,并可以抑制膜表面血小板的吸附和聚集。同时,凝血测试结果表明类肝素分子修饰的PLA膜表面具有良好的血液相容性。     

Application of diffusion dialysis for reduction of acidity of real pregnant leach solutions containing Ni and Co ions

ABSTRACT

Diffusion dialysis (DD) was proposed as a pretreatment step to reduce the acidity of real sulfate/chloride pregnant leach solutions containing cobalt(II) and nickel(II). Optimum DD conditions that enable reduction of acidity in the feed while maintaining a high rejection level of metal ions present in PLS were proposed, e.g. for 0.06 dm³/min flow of both aqueous phases H⁺ concentration in the dialysate reached 3.8 and 2.99 M for PLS1 and PLS2, respectively. Acid diffusion coefficients varied from 0.32 ?10 ^?6 to 3.15?10^?6 m/s and decreased with increasing phase flow rates. Moreover, dialysate neutralization was beneficial for the H⁺ reduction in the feed.     

Time trends in the association of ESRD incidence with area‐level poverty in the US population

The objective of this study was to examine the temporal trends of the association between area‐level poverty status and end‐stage renal disease (ESRD) incidence. We hypothesized that the association between area‐level poverty status and ESRD incidence has increased significantly over time. Patient data from the United States Renal Data System were linked with data from the 2000 and 2010 US census. Area‐level poverty was defined as living in a zip code‐defined area with ≥20% of households living below the federal poverty line. Negative binomial regression models were created to examine the association between area‐level poverty status and ESRD incidence by time period in the US adult population while simultaneously adjusting for the distribution of age, sex, and race/ethnicity within a zip code. Time was categorized as January 1, 1995 through December 31, 2004 (Period 1) and January 1, 2005 through December 31, 2010 (Period 2). The percentage of adults initiating dialysis with area‐level poverty increased from 27.4% during Period 1 to 34.0% in Period 2. After accounting for the distribution of age, sex, and race/ethnicity within a zip code, area‐level poverty status was associated with a 1.24 (95% confidence interval [CI] 1.22, 1.25)‐fold higher ESRD incidence. However, this association differed by time period with 1.04‐fold (95% CI 1.02, 1.05) higher ESRD incidence associated with poverty status for Period 2 compared with the association between ESRD and poverty status in Period 1. Area‐level poverty and its association with ESRD incidence is not static over time.     

Unusual cause of hypercalcaemia in end stage renal failure patients

Immobility‐induced hypercalcaemia is rarely considered in patients on dialysis and is a challenging diagnosis to make. This is especially so due to the lack of biomarkers as well as the notion that calcium metabolism is mostly related to chronic kidney disease‐metabolic bone disorder due to the role of iPTH. We present two cases of our dialysis patients, who were clinically unwell from hypercalcemia. We were initially uncertain of the cause of hypercalcemia as despite our attempts to adjust treatment based on their biochemical findings, we were unable to correct the hypercalcemia. We did not have appropriate bone turnover markers to guide us and out of desperation, anti‐resorptives—calcitonin and bisphosphonate were given with good clinical response. We concluded that the hypercalcemia was related to immobility‐induced hypercalcemia and the inappropriately low iPTH was a red herring. Immobility‐induced hypercalcaemia should be considered in patients with end stage renal failure on renal replacement therapy, especially in those with recent and significant immobility. In these patients, pamidronate can be considered should the hypercalcaemia persist.