Uremic Toxins: Removal with Different Therapies

A convenient way to classify uremic solutes is to subdivide them according to the physicochemical characteristics influencing their dialytic removal into small water‐soluble compounds (<500 Da), protein‐bound compounds, and middle molecules (>500 Da). The prototype of small water‐soluble solutes remains urea although the proof of its toxicity is scanty. Only a few other water‐soluble compounds exert toxicity (e.g., the guanidines, the purines), but most of these are characterized by an intra‐dialytic behavior, which is different from that of urea. In addition, the protein‐bound compounds and the middle molecules behave in a different way from urea, due to their protein binding and their molecular weights, respectively. Because of these specific removal patterns, it is suggested that new approaches of influencing uremic solute concentration should be explored, such as specific adsorptive systems, alternative dialytic timeframes, removal by intestinal adsorption, modification of toxin, or general metabolism by drug administration. Middle molecule removal has been improved by the introduction of large pore, high‐flux membranes, but this approach seems to have come close to its maximal removal capacity, whereas multicompartmental behavior might become an additional factor hampering attempts to decrease toxin concentration. Hence, further enhancement of uremic toxin removal should be pursued by the introduction of alternative concepts of elimination.     

Assessment of subjective and hemodynamic tolerance of different high‐ and low‐flux dialysis membranes in patients undergoing chronic intermittent hemodialysis: A randomized controlled trial

Clinical experience and experimental data suggest that intradialytic hemodynamic profiles could be influenced by the characteristics of the dialysis membranes. Even within the worldwide used polysulfone family, intolerance to specific membranes was occasionally evoked. The aim of this study was to compare hemodynamically some of the commonly used polysulfone dialyzers in Switzerland. We performed an open‐label, randomized, cross‐over trial, including 25 hemodialysis patients. Four polysulfone dialyzers, A (Revaclear high‐flux, Gambro, Stockholm, Sweden), B (Helixone high‐flux, Fresenius), C (Xevonta high‐flux, BBraun, Melsungen, Germany), and D (Helixone low‐flux, Fresenius, Bad Homburg vor der Höhe, Germany), were compared. The hemodynamic profile was assessed and patients were asked to provide tolerance feedback. The mean score (±SD) subjectively assigned to dialysis quality on a 1–10 scale was A 8.4 ± 1.3, B 8.6 ± 1.3, C 8.5 ± 1.6, D 8.5 ± 1.5. Kt/V was A 1.58 ± 0.30, B 1.67 ± 0.33, C 1.62 ± 0.32, D 1.45 ± 0.31. The low‐ compared with the high‐flux membranes, correlated to higher systolic (128.1 ± 13.1 vs. 125.6 ± 12.1 mmHg, P < 0.01) and diastolic (76.8 ± 8.7 vs. 75.3 ± 9.0 mmHg; P < 0.05) pressures, higher peripheral resistance (1.44 ± 0.19 vs. 1.40 ± 0.18 s × mmHg/mL; P < 0.05) and lower cardiac output (3.76 ± 0.62 vs. 3.82 ± 0.59 L/min; P < 0.05). Hypotension events (decrease in systolic blood pressure by >20 mmHg) were 70 with A, 87 with B, 73 with C, and 75 with D (P < 0.01 B vs. A, 0.05 B vs. C and 0.07 B vs. D). The low‐flux membrane correlated to higher blood pressure levels compared with the high‐flux ones. The Helixone high‐flux membrane ensured the best efficiency. Unfortunately, the very same dialyzer correlated to a higher incidence of hypotensive episodes.     

Dialysis disequilibrium syndrome and other treatment complications of extreme uremia: a rare occurrence yet not vanished

Severe uremia is now a rare occurrence in most developed nations, and yet is still present in many countries of the world. It includes clinical manifestations such as calciphylaxis and uremic frost, which are now rarely seen. Patients with extremely high levels of blood urea nitrogen (above 175 mg/dL) are at a higher risk of experiencing first-time hemodialysis-related complications, in particular dialysis disequilibrium syndrome (DDS). DDS is a central nervous disorder characterized by a wide variety of neurological symptoms that range from nausea and vomiting to even death due to cerebral edema. There are 2 main theories to explain its pathophysiology: the reverse urea effect, which considers that the shift of urea between brain intracellular space and plasma is not immediate, causing a higher concentration of urea within the brain and leading to cerebral edema. The second theory considers that after hemodialysis, patients have transient paradoxical metabolic acidosis within the central nervous system, displacing Na(+) and K(+) from organic anions, making them osmotically active and again leading to cerebral edema. The main goal is to prevent the occurrence of DDS, for which there are several proposed measures including continuous renal replacement therapies. Once established, treatment should be focused on supportive therapy. Another uncommon phenomenon described in patients who initiate hemodialysis is transient pulmonary leukocyte margination, which in conjunction with an inflammatory milieu, may lead to non-cardiogenic pulmonary edema. We present the case of a young adult with severe uremia who, despite application of recommended measures, developed DDS and non-cardiogenic pulmonary edema.     

Obstructive sleep apnea in incremental hemodialysis: Determinants,consequences, and impact on survival

Sleep disorders are common in hemodialysis patients, although causes and consequences remain unclear. We sought to establish prevalence, determinants, and outcomes of sleep disturbances in patients receiving incremental dialysis. One hundred two unselected patients undergoing incremental high‐flux hemodialysis or hemodiafiltration underwent limited overnight sleep study. Large subsets underwent echocardiography, interdialytic ambulatory blood pressure monitoring, and brain natriuretic peptide measurements. Patients were followed up to 44 months. Full sleep data were obtained in 91 patients. All had sleep disturbance as evidenced by an apnea–hypopnea index >5/min. We defined major obstructive sleep apnea (MOSA) as an apnea–hypopnea index ≥15, together with either significant oxygen desaturation or symptoms of daytime sleepiness. Forty patients met these criteria. Significant independent predictors of MOSA were age <65 years, male gender, has diabetes, and has a brain natriuretic peptide >2500 pg/mL. Mean ambulatory blood pressure and left ventricular mass index were significantly higher in these patients. In a model controlling for body mass index, high C‐reactive protein, and the presence of cancer, MOSA was associated with a twofold increased risk of mortality, although this did not reach statistical significance. MOSA was common, and was associated with hypertension and high left ventricular mass index. Whether obstructive sleep apnea contributes to the high mortality remains to be firmly established.     

高速高压低温温度传感器的试验研究

简要介绍了高速高压低温条件下温度传感器的试验研究方法。试验研究的着重点是尽量利用现有的设备、试验条件和有关的氢氧发动机研制过程中的试验，对传感器进行一些针对性试验，以取得可靠的试验数据。通过对试验数据的分析和研究，验证考核传感器的性能。主要给出了强度试验、动态特性试验和恢复系数试验的模拟试验方案和方法及搭载试验方法，给出了某传感器进行上述试验的试验结果，结果表明，这种试验研究方法是可行且可靠的。     

Inherent Errors in the Quantitation of Dialysis Delivery: Implications For CAPD and Daily Hemodialysis

When compared to intermittent dialysis, the theoretical advantages of continuous dialysis may be less important than its practical disadvantage: the inability to accurately quantify dialysis. With intermittent dialysis the change in blood urea nitrogen over the course of the treatment allows the ratio of K (urea clearance) to V (volume of distribution of urea or total body water) to be determined, hence an accurate Kt/V. In continuous dialysis this approach cannot be used due to the steady-state nature of blood urea levels. Instead, V is estimated, generally from the Watson equations. This estimate has sufficient inaccuracy to result in substantial unrecognized underdialysis in many patients.     

大线能量焊接条件下低合金高强度钢针状铁素体形核影响因素及形核机理研究

综述了大线能量焊接条件下低合金高强度钢中针状铁素体形成的研究进展,概述了针状铁素体显微组织结构特点及其在低合金高强度钢中的主要性能,具体讨论了针状铁素体具有良好强韧性和抗断裂性等力学性能的原因,重点分析了大线能量焊接条件下影响焊接热影响区中针状铁素体形核长大的因素,包括合金元素及夹杂物的种类和尺寸,得出针状铁素体的形核机理是多种机理联合作用的结果。     

Comparison of Preventive Care Provided to Dialysis Patients by Nephrologists and to Patients Followed in General Medical Clinics: Compliance with American College of Physicians Guidelines

Most end‐stage renal disease (ESRD) patients do not have primary‐care providers, and preventive medicine often is provided by their nephrologists. Little has been written about their success in providing this care. We studied all patients on dialysis at our hospital and compared their preventive care to a control group followed in the general medical clinic. The general medical group showed higher compliance with Pap smears (89% vs 48%), mammography (87% vs 62%), fecal occult blood testing (75% vs 50%), and pneumococcal vaccination (55% vs 28%). The ESRD group had better compliance with influenza vaccination (70% vs 55%) and lipid profile (100% vs 75%). When the subgroup of patients on hemodialysis (HD) was compared with patients on peritoneal dialysis (PD), it was shown that HD patients were more likely than PD patients to receive preventive care. We also compared diabetes‐specific care. The ESRD group had a higher rate of HbA _1C (100% vs 78%) and lipid monitoring (100% vs 76%), diabetes education (100% vs 84%), and podiatry visits (70% vs 38%). There was no difference in ophthalmologic examination or influenza vaccination. We found that nephrologists provide preventive care to ESRD patients with success approximately equal to primary‐care physicians in our institution, although in different parameters. Ready access to dialysis patients and their blood and unit‐specific policies contribute to compliance that is above national averages. Further improvements can be made by additional preventative measures policies, by physician and patient education, and by monitoring primary‐care compliance in the chart.     

Cellulose Acetate and Polyetherimide Blend Ultrafiltration Membranes, I: Preparation, Characterization, and Application

Ultrafiltration (UF) techniques have particular advantages for simultaneous purification, concentration, and fractionation of macromolecules. In this study, polymeric blend ultrafiltration membranes based on cellulose acetate and polyetherimide were prepared by phase inversion technique and characterized in terms of compaction time, pure water flux (PWF), water content, membrane hydraulic resistance, and scanning electron microscopy (SEM). The blend membranes prepared were subjected to the separation of macromolecular proteins such as bovine serum albumin (BSA), egg albumin (EA), pepsin, and trypsin. The molecular weight cut-off (MWCO) of blend membranes obtained from the protein separation studies is also presented. Toxic heavy metal ions such as copper, nickel, zinc, and cadmium were subjected to separation by the blend membranes by complexing them with the polymeric ligand polyethyleneimine. The separation and permeate flux efficiencies of the blend membranes are compared with those of pure cellulose acetate membranes.     

Early,Frequent, and Efficient Hemodialysis: A New Trend or Déjà Vu From the 1970s?

After more than a quarter century of dialysis, two factors are still present in dialysis treatment of chronic renal failure patients: inadequacy of technology (the artificial kidney acts as an artificial glomerulus) and inadequate use of technology in terms of dialysis initiation and frequency. This paper presents the results of two less unphysiological dialysis programs, introduced in Bologna at the beginning of the 1960s, which proved their clinical value and are now becoming trendy, at the end of this century. Features of these programs are twofold: (1) daily dialysis, which aims at making treatment more biologically suited to the patient; its validity relies on lower intra- and interdialytic osmotic fluctuations; (2) early dialysis, which aims at making the patient more biologically suited to the treatment. After more than 25 years it is evident that this treatment has fulfilled its original expectations versus late dialysis. There is a 40% improvement in survival, a 35% decrease in morbidity, and a 24% improvement in the cost/benefit ratio. This report is based on a retrospective analysis of our overall experience and clinical results of chronic hemodialysis carried out in 224 patients on early dialysis and 1210 patients on late dialysis in Bologna from 1967 to 1997. Based on this experience, the following should be regarded as particularly important indications for early dialysis: adequate dialysis facilities; symptomatic patients despite renal creatinine clearances between 15 and 20 mL/min; patients unable to comply with dietary measures; children, to allow for adequate development; patients with diabetes mellitus; candidates for renal transplantation.     

Superamphiphobic Coatings with High Transmittance: Structure,Fabrication, and Perspective

In recent years, superamphiphobic coatings have attracted world‐wide interest. In particular, those with high transmittance are of great interest as they significantly expand the range of applications of superamphiphobic coatings. This article reviews the recent development in the design and fabrication of superamphiphobic coatings with high transmittance, and clarifies technological challenges facing their practical applications. Finally, an outlook is made toward their future prospects.     

高精度低冲击加速度校准装置研究

基于ISO国际标准设计了碰撞式高精度低冲击加速度校准装置,在冲击加速度峰值20～10000 m/s2,冲击脉宽0.5～10 ms范围内实现产生半正弦波形的冲击加速度传感器的高精度校准.介绍了校准装置的构成和工作原理,通过与冲击加速度国家基准的比对,结果表明本装置可实现0.5％(k=2)的冲击加速度校准不确定度.本装置提...     

High Throughput Methods in the Synthesis,Characterization, and Optimization of Porous Materials

Porous materials are widely employed in a large range of applications, in particular, for storage, separation, and catalysis of fine chemicals. Synthesis, characterization, and pre- and post-synthetic computer simulations are mostly carried out in a piecemeal and ad hoc manner. Whilst high throughput approaches have been used for more than 30 years in the porous material fields, routine integration of experimental and computational processes is only now becoming more established. Herein, important developments are highlighted and emerging challenges for the community identified, including the need to work toward more integrated workflows.     

A Learning Community of University Freshman Design,Freshman Graphics,and High School Technology Students: Description,Projects, and Assessment

A learning community was developed to enhance the teamwork and communication components of a freshman design course. The learning community was comprised of students from a freshman design course, a freshman graphics course, and a high school technology course. Design teams were formed by combining three to four students from each of these courses. These teams were required to research, design, build, and test a specified product. The high school and university students communicated only using e‐mails and Internet conferencing. This paper outlines how the learning community is implemented, describes three design projects, and presents the assessment methods. Assessment reveals that university students who participate in the learning community have a better understanding and confidence in the technical aspects of the design project than the students who do not participate in the learning community. It also reveals that high school participants display notable interest in the engineering design process.     

Discrepancy in responses to the surprise question between hemodialysis nurses and physicians,with focus on patient clinical characteristics: A comparative study

Introduction

The surprise question (SQ) “Would I be surprised if this patient died within the next xx months” can be used by different professions to foresee the need of serious illness conversations in patients approaching end of life. However, little is known about the different perspectives of nurses and physicians in responses to the SQ and factors influencing their appraisals. The aim was to explore nurses' and physicians' responses to the SQ regarding patients on hemodialysis, and to investigate how these answers were associated with patient clinical characteristics.

Methods

This comparative cross-sectional study included 361 patients for whom 112 nurses and 15 physicians responded to the SQ regarding 6 and 12 months. Patient characteristics, performance status, and comorbidities were obtained. Cohen's kappa was used to analyze the interrater agreement between nurses and physicians in their responses to the SQ and multivariable logistic regression was applied to reveal the independent association to patient clinical characteristics.

Findings

Proportions of nurses and physicians responding to the SQ with “no, not surprised” was similar regarding 6 and 12 months. However, there was a substantial difference concerning which specific patient the nurses and physicians responded “no, not surprised”, within 6 (κ = 0.366, p < 0.001, 95% CI = 0.288–0.474) and 12 months (κ = 0.379, p < 0.001, 95% CI = 0.281–0.477). There were also differences in the patient clinical characteristics associated with nurses' and physicians' responses to the SQ.

Discussion

Nurses and physicians have different perspectives in their appraisal when responding to the SQ for patients on hemodialysis. This may reinforce the need for communication and discussion between nurses and physicians to identify the need of serious illness conversations in patients approaching the end of life, in order to adapt hemodialysis care to patient preferences and needs.