Decreased hemodialysis circuit pressures indicating postpump tubing kinks: a retrospective investigation of hemolysis in five patients

The source of hemolysis during hemodialysis must be quickly identified to avoid life-threatening complications. At a single clinic, over a 10-day period in which 550 treatments were performed, 5 case-patients were retrospectively identified for experiencing acute hemolysis (4 deaths) from an unknown origin. The investigation focused on the postpump arterial tubing as the pressure was not monitored in this region, and the segment was shorter than required and could kink if overly stressed at bend points (i.e., tubing support clips, dialyzer inlet). To determine whether the circuit pressures indicated kinked tubing, a relative comparison between each case-patient's recorded arterial (prepump) and venous circuit pressures throughout their adverse event treatment and their immediately preceding treatment was conducted. Treatment pressure-time traces showed that sustained, significant decreases (>25 mmHg) in both of the circuit pressures occurred only on the hemolytic event dates. While direct observations of kinked tubing were not reported, the circuit pressure decreases could only be explained by severe postpump tube kinking causing a decrease in the blood flow rate. While postpump obstructions and hemolysis can occur without causing noticeable changes to the prepump arterial and venous blood line pressures (due to the highly occlusive setting of the roller blood pump), recognizing sudden and/or sustained decreases in the circuit pressures during treatment may help to prevent adverse patient events. This analysis reinforces the importance of regularly checking the blood tubing set for kinks and for monitoring the circuit pressures for atypical trends within and between treatments.     

Blood access in daily hemodialysis

Frequent dialyses are sometimes perceived as increasing the risk of blood access malfunction and decreased longevity. This review of the literature, however, indicates that the failure rates and overall fistula survival appear to be better with more frequent dialyses than with routine dialysis frequency, although the reasons for this phenomenon are not clear. One of the possible explanations is that frequent dialyses are associated with fewer intradialytic hypotensive episodes, which are very detrimental to the blood access. Another possible explanation is the generally lower blood flow used with more frequent hemodialyses, particularly long nocturnal hemodialysis. Finally, a decreased clotting tendency and decreased rates of hematoma formation at the puncture sites are additional possible explanations. Complication rates with bridge grafts are not higher with more frequent compared to routine thrice‐weekly hemodialysis sessions. No such comparative data are available, however, for central‐vein catheters. This lack of comparisons seems to stem from the intuitive assumption by nephrologists that hemodialyses that are more frequent should not adversely impact catheter complication rates and survival. No data at all are available on the use of the Dialock® hemodialysis system (Biolink Corp., Norwell, MA, USA) and LifeSite® hemodialysis access system (Vasca, Inc., Tewksbury, MA, USA), two newer forms of hybrid access in patients undergoing frequent hemodialyses. Current evidence shows that the perceived risk of blood access malfunction and decreased longevity when patients undergo more frequent hemodialysis is not supported by the current literature.     

Fallacies of High‐Speed Hemodialysis

Chronic hemodialysis sessions, as developed in Seattle in the 1960s, were long procedures with minimal intra‐ and interdialytic symptoms. Financial and logistical pressures related to the overwhelming number of patients requiring hemodialysis created an incentive to shorten dialysis time to four, three, and even two hours per session in a thrice weekly schedule. This method spread rapidly, particularly in the United States, after the National Cooperative Dialysis Study suggested that time of dialysis is of minor importance as long as urea clearance multiplied by dialysis time and scaled to total body water (Kt/V_urea) equals 0.95–1.0. This number was later increased to 1.3, but the assumption remained unchanged that hemodialysis time is of minimal importance as long as it is compensated by increased urea clearance. Patients accepted short dialysis as a godsend, believing that it would not be detrimental to their well‐being and longevity. However, Kt/V_urea measures only removal of low molecular weight substances and does not consider removal of larger molecules. Besides, it does not correlate with the other important function of hemodialysis, namely ultrafiltration. Whereas patients with substantial residual renal function may tolerate short dialysis sessions, the patients with little or no urine output tolerate short dialyses poorly because the ultrafiltration rate at the same interdialytic weight gain is inversely proportional to dialysis time. Rapid ultrafiltration is associated with cramps, nausea, vomiting, headache, fatigue, hypotensive episodes during dialysis, and hangover after dialysis; patients remain fluid overloaded with subsequent poor blood pressure control, left ventricular hypertrophy, diastolic dysfunction, and high cardiovascular mortality. Short, high‐efficiency dialysis requires high blood flow, which increases demands on blood access. The classic wrist arteriovenous fistula, the access with the best longevity and lowest complication rates, provides “insufficient” blood flow and is replaced with an arteriovenous graft fistula or an intravenous catheter. Moreover, to achieve high blood flows, large diameter intravenous catheters are used; these fit veins “too tightly,” so predispose the patient to central‐vein thrombosis. Longer hemodialysis sessions (5–8 hrs, thrice weekly), as practiced in some centers, are associated with lower complication rates and better outcomes. Frequent dialyses (four or more sessions per week) provide better clinical results, but are associated with increased cost. It is my strong belief that a wide acceptance of longer, gentler dialysis sessions, even in a thrice weekly schedule, would improve overall hemodialysis results and decrease access complications, hospitalizations, and mortality, particularly in anuric patients.     

Role of bicarbonate dialysis in prevention of serious arrhythmias in high‐risk cardiac patients undergoing regular hemodialysis

Background: Cardiac arrhythmias are considered as one of the most important causes of mortality in patients on hemodialysis. Arrhythmias frequently occur in patients with chronic renal failure on regular hemodialysis with reported incidences varying from 30–48% of patients. These abnormalities can span from supraventricular to severe ventricular arrhythmia. There is an increased frequency of occurrence and clustering of arrhythmias around the dialysis time. Aim of the study: To detect the difference between acetate and bicarbonate dialysis as regard to the type and frequency of arrhythmia in those patients. Study design: This study was done on 20 male patients age 51–73, all have history of heart disease. Patients were divided into 2 equal groups using acetate in group 1 and bicarbonate in group 2. All patients were on regular hemodialysis (4 hours, thrice weekly). Careful history and clinical examination were done. Pre‐dialysis investigations included serum creatinine, blood urea nitrogen, serum sodium, potassium, calcium and phosphorus, serum albumin, hemoglobin, and arterial blood gases. Post‐dialysis serum potassium and arterial blood gases were measured. ECG and forty‐eight hours ambulatory monitor (Holter monitor)(before, during, and after hemodialysis, till the end of the dialysis day and throughout the following day) were performed. Results: Group 1 showed significantly less post‐dialysis supraventricular arrhythmias than in dialysis day (210.9 ± 236 and 62.3 ± 14.4), respectively. Significantly less ventricular arrhythmias in post‐dialysis than in dialysis day (30.7 ± 50.4, and 106.2 ± 128.4), respectively. While in Group 2 there were insignificant differences regarding supraventricular arrhythmias (21.9 ± 28.9 and 16.6 ± 36.3) and ventricular arrhythmias (22.9 + 7.8 and 29.6 + 12.8) in dialysis day than in post‐dialysis day. There was significantly higher frequency of supraventricular and ventricular arrhythmias in the dialysis day in acetate hemodialysis in comparison to bicarbonate hemodialysis. Conclusion: Bicarbonate hemodialysis is less arrhythmogenic in comparison to acetate hemodialysis and has better effect on the blood pH and greater degree of base repletion. Continuous ambulatory ECG recording (Holter) is a useful tool in detecting arrhythmias in dialysis patients.     

Development of a gamma compensated boron lined ionisation chamber for reactor safety and control applications

Boron lined ionisation chambers with an overall diameter of 85 mm and maximum length of 165 mm have been developed and tested. The chamber consists of 34 numbers of parallel plate aluminium electrodes spaced at a distance of 2 mm and mounted on SS rods and radiation resistant polyetheretherketone (PEEK) spacers. One surface of the signal electrode and both the surfaces of the +HT electrodes are dip coated with boron. It is filled with nitrogen gas at a pressure of 128 cm of Hg. Tests at the ⁶⁰Co source facility at gamma fields ranging from 200 R/h to 830 kR/h showed that the chamber required 500 V to obtain 90% of the saturation current at 830 kR/h. The gamma compensation factor was measured as 0.12–7% for various gamma fields for polarising voltages of +400 and −350 V. Neutron measurements at the Apsara Thermal Column showed that the linearity of the chamber response as a function of reactor power was within 2%. The neutron sensitivity was measured as 3.9 fA/nv.     

高压扭转对GW83K镁合金耐腐蚀性能的影响

采用高压扭转(HPT)工艺对Mg-8Gd-3Y-0.4Zr(GW83K)合金进行剧烈塑性变形加工,通过显微组织观察、物相分析、显微硬度测定、开路电位测试、动极化曲线测试、交流阻抗谱及扫描开尔文探针分析,对比研究了HPT前后GW83K合金的显微组织和耐蚀性。结果表明:经5圈高压扭转后,GW83K合金的晶粒细化不显著,物相结构亦无变化,晶粒中出现大量孪晶和位错,试样中心区域和边缘区域的晶粒尺寸无明显差异,但边缘区域硬度远高于中心区域。HPT后镁合金在空气中伏打电位较低,在3.5%(质量分数)NaCl溶液中浸泡时开路电位迅速稳定(约1h)但稳定值较负,腐蚀电流密度较大,电化学阻抗较小且随浸泡时间延长而减少,其耐蚀性不及未HPT加工的初始态合金。在0.1mol/L NaOH溶液中,浸泡初期初始态和HPT态合金开路电位较接近,交流阻抗相差不大,浸泡6h后初始态的电化学阻抗容抗弧直径则明显大于HPT态样品。极化曲线显示HPT态合金在碱性溶液中的维钝区间减小,维钝电流密度增大,初次击穿电压负移。HPT加工虽有助于镁合金表面快速形成钝化膜(不能有效保护基体),却使镁基体更活泼(溶解加速),GW83K镁合金耐蚀性下降。     

Warm forming limits of rare earth-magnesium alloy ZEK100 sheet

Forming limit curves were developed for a rare earth-magnesium alloy, ZEK100-F, at temperatures between 25 and 350 °C in both the rolling (RD) and transverse directions (TD) of the sheet. ZEK100-F contains additions of zirconium (Zr) as a grain refining alloying element and a rare earth addition, neodymium (Nd), that promotes a weakened basal texture allowing enhanced slip activity at lower temperatures. Warm formability measurements were also performed on non-rare earth containing AZ31B-O to examine the relative performance of these two alloys. The ZEK100 material exhibited significantly better room temperature formability over AZ31B-O with a limiting dome height of 29 mm for ZEK100 compared to only 12 mm for the AZ31B-O. At elevated temperatures (250 °C) the difference in formability between the two alloys becomes less pronounced with a LDH of 40 and 36 mm for ZEK100 and AZ31B-O, respectively. What is particularly striking is the pronounced benefit of the rare earth alloyed material at intermediate temperatures, with an LDH of 37 mm at 150 °C which equals the LDH of AZ31B at 250 °C. Similar trends were determined in the measured forming limit curves reported here for the two alloys. The relative performance of the two alloys is largely attributed their initial textures. ZEK100-F also exhibits strongly anisotropic formability (RD versus TD) which can again be attributed to its’ initial texture.     

Microstructure,Phase Composition,and Thermal Stability of Two Zirconium Alloys Subjected to High‐Pressure Torsion at Different Temperatures

The structure, phase composition, and thermal stability of the industrial zirconium alloys, namely, E110 (Zr–1% Nb) and E635 (Zr–1% Nb–0.3% Fe–1.2% Sn), which are subjected to high‐pressure torsion (HPT) at room temperature (RT), 200, and 400 °С have been studied. HPT of Zr‐alloys at RT (10 revolutions) leads to the formation of grain–subgrain nano‐sized structure and to increase the microhardness by 2.1…2.8 times. The increase in the HPT temperature to 200–400 °С leads to the increase in the structural‐element average size. The structural‐element size in the complexly alloyed E635 alloy in all cases is lower compared with the E110 alloy. The hardening of the alloys after HPT at RT and 200 °С is close, and at 400 °С is much less. HPT initiates the α‐Zr → (ω‐Zr + β‐Zr) transformation, which is the main factor for alloys hardening. The α‐Zr → (ω‐Zr + β‐Zr) transformation in the E635 alloy occurs less quickly. The maximum amount (ω‐Zr + β‐Zr) phase in the structure of the alloys is observed after HPT at RT and 200 °C, and the minimum ? at 400 °C. During heating, the alloys undergo the reverse (ω‐Zr + β‐Zr) → α transformation which depends on both the alloy composition and HPT temperature.

     

The Middle Molecule Hypothesis Revisited. Should Short,Three Times Weekly Hemodialysis Be Abandoned?

When the middle molecule (MM) hypothesis was formulated in 1975, no MM had yet been identified as a uremic toxin. Meanwhile, the birth and implementation of the Kt/V_urea concept gained wide acceptance and has remained the world standard for assessing dialysis adequacy. However, over the past 20 years, accumulating evidence has made it clear that MM's are important uremic toxins, and that the dose of dialysis based on removal of small molecular substances does not protect against excessive hemodialysis mortality, morbidity, or the presence of uremic signs and symptoms. These poor results are, in one way or another, linked to the accumulation of MM's and other substances behaving like MM's, such as phosphate. Dialysis schedules yielding the best clinical results, such as longer dialysis and more frequent dialysis, favor increased removal of middle molecular substances. The observation that short daily dialysis is giving results similar to long nocturnal quotidian dialysis supports early observations that the volume from which middle molecular substances are extracted mainly by hemodialysis is small (about as large as the extracellular volume), and that transfer of MM's from cells to extracellular fluid is very slow. This behavior of MM's is markedly different from that of small molecular substances, which are more rapidly transferred from intracellular to extracellular compartments and are more readily extracted from total body water during hemodialysis. In order to achieve even minimum adequate dialysis, it is now scientifically validated that toxic MM's must be removed in larger amounts than currently attained. This can only be accomplished by long dialysis sessions with a 3‐times per week schedule or more frequent dialyses. Five hours 3 times per week represents the absolute minimum treatment. Dialy sis 6 to 7 times per week is the ideal schedule for patients who are willing to commit the time and effort in exchange for maximum well‐being and long survival.     

Successful Long-Term Central Venous Access

Daily home hemodialysis (DHHD) requires simple, vascular access to minimize patients' discomfort but also to guarantee tolerance and long-term efficiency. The arteriovenous fistula is not ideal for DHHD because of the double puncture required every day; in addition, the rate of dysfunction is probably greater because of the more frequent use. Central venous catheters may be a good alternative to the arteriovenous fistula as long-term vascular access for DHHD. In this study we report our experience with the internal jugular vein two-catheter access for long-term dialysis and evaluate its possible use for DHHD. Since 1988, Tesio's twin catheters have been positioned in 908 patients with exhausted peripheral vascular bed. In all patients hemodialysis could be performed a few minutes after the surgical procedure. The survival rate of catheters, in a selected group of 46 patients, at 1, 2, and 5 years was, respectively, 92%, 87%, and 82%. The mean blood flow was 282±29 mL/min at 1 month, 286±36 mL/min at 1 year, and 274±37 mL/min at 5 years. Venous pressure in the inlet side was 102±31 mm Hg at 1 month, 126±36 mm Hg at 1 year, and 132±58 mm Hg at 5 years. Catheter clotting was treated either with thrombolytic agents or with catheter (one or both) replacement. Sepsis was treated with systemic antibiotic therapy or catheter removal. Data support the potential role of the internal jugular vein two-catheter system for DHHD.     

Intracranial arterial calcification is highly prevalent in hemodialysis patients but does not associate with acute ischemic stroke

Intracranial arterial calcification (IAC) is associated with ischemic stroke in the general population but this relationship has not been examined in hemodialysis patients. We examined the factors associated with IAC and its relationship with acute ischemic stroke in this population. We retrospectively studied 490 head computed tomographic scans from 2225 hemodialysis patients presenting with neurological symptoms at our center (October 2005-May 2009). Intracranial arterial calcification was graded using a validated scoring system. Multivariate regression was used to examine the factors associated with the presence of IAC, its severity, and its ability to predict acute ischemic stroke. Weibull's survival models analyzed the relationship between IAC severity and survival. Ninety-five percent of patients with ischemic stroke had IAC vs. 83% in the nonstroke group (P=0.02). Intracranial arterial calcification severity increased with age (P<0.001), hemodialysis vintage (P<0.001), serum phosphate (P<0.05), and major comorbidities. In patients with multiple computed tomographic scans during the study period, increased IAC severity at baseline was predictive of acute ischemic stroke (P=0.05) on logistic regression analysis. High-grade and not low-grade IAC was associated with worse survival (P=0.008). Intracranial arterial calcification is highly prevalent in hemodialysis patients, especially in those with acute ischemic stroke. Its severity is prognostically significant and associated with risk factors for vascular calcification and may confer a greater risk of acute ischemic stroke. The mechanisms underlying the high incidence of ischemic stroke in this patient group require further comprehensive study.     

Beyond ultrapure hemodialysis: A necessary and achievable goal

Survival of chronic hemodialysis patients is worse than that of many patients with cancers or severe infections. An important cause of chronic inflammation is impurities infused into patients during dialysis. Definitions of dialysis purity have been narrow and focused on metals in dialysate water and on bacterial contaminants. There is no standard for priming fluids or toxins released directly into blood from inside the extracorporeal circuit. We propose a much broader standard of dialysis purity that also includes phthalate metabolites, bisphenols, spalled particles, and other contaminants from dialysis machines, filters, and bloodlines. Standards must include new methods for measuring bacteriological contaminants in addition to colony‐forming units and endotoxin determinations. These include the sensitive silkworm larva plasma test that detects peptidoglycan that is missed by endotoxin tests and standards for newly detected small molecular bacterial detritus. Current levels for “standard” bacteriological contaminants are woefully inadequate and should be increased. New standards for contamination with plasticizers and spallation are also necessary. Studies with ultrapure dialysis have shown almost immediate patient benefits with increased well‐being and stabilization of the cardiovascular system during and between dialyses. Intermediate effects include lower C‐reactive protein levels, better response to erythropoietin, increased appetite, and improved nutrition. Over the years, amyloidosis and carpal tunnel syndrome have become less common and cardiovascular deaths have decreased. Standards for dialysis purity must be sharpened and expanded and this becomes even more urgent with daily and long nightly hemodialysis. All contaminants received by patients, whether biological, chemical, or physical, must be considered.     

Impact of hypertension guideline implementation on blood pressure control and drug use in primary care clinics

BACKGROUND: A worsening of blood pressure control has occurred in the 1990s despite the availability of sophisticated technologic, pharmacologic, and educational advances applicable to hypertension care. Clinical guidelines that are intended to improve hypertension care by making specific recommendations on drug use, frequency of follow-up care, and target levels of blood pressure have been developed. METHODS: The Institute for Clinical Systems Integration's (ICSI's; Minneapolis) Hypertension Treatment Guideline was developed in 1994 and is updated annually. This study employed a quasi-experimental, before-and-after design at two medical groups to assess changes in the care provided to patients 18 years of age and older with identified hypertension (International Classification of Diseases-9 codes 401.0, 401.1, or 401.9). RESULTS: Among adults with hypertension, the proportion meeting the blood pressure goal of < 140/90 mm Hg increased from 36.8% (of 685 patients) preguideline to 50.3% (of 928 patients) postguideline (chi-square = 29.4, p < 0.001); the mean arterial pressure decreased from 102.7 mm Hg to 99.4 mm Hg (t = 5.45, p < 0.001). Cohort analysis of patients enrolled at both points in time confirmed these findings and showed an increase in the number of office visits from 5.4 to 6.7 visits per patient per year after guideline implementation (F = 10.9, p = 0.001). The use of a guideline-recommended medication for treatment of blood pressure was 35.9% preguideline and 36.2% postguideline. CONCLUSIONS: Implementation of a hypertension treatment guideline in primary care clinics was related to significantly improved hypertension control. Identification, tracking, and active outreach to patients with hypertension were used by all clinics.     

Consolidation of Cu-based amorphous alloy powders by high-pressure torsion

We applied high-pressure torsion (HPT) for consolidation of gas-atomized metallic glass Cu₅₄Zr₂₂Ti₁₈Ni₆ powders into high-density bulk disks. The effects of the number of revolutions (N = 1–5 turns), applied pressure (2.5–10 GPa), and temperature (298–473 K) on densification and structural changes were investigated. The consolidated glassy disks showed an excellent hardness of ~5.2 GPa although a mechanical softening effect along with fragmentation in the center of HPT disks occurred at N > 3 by a couple of branching cracks. The HPT process at higher applied pressures improved the bulk density and inter-particulate bonding, resulting in higher hardness. Increasing the temperature of HPT processing enhanced the densification and deep drawability of the consolidated metallic glass. Although the HPT process did not change the crystallization temperature of the metallic glass powders, it increased the crystallization enthalpy, suggesting the free volume increase and inhibition of a significant nanocrystallization during the HPT process.     

High-pressure torsion for fabrication of high-strength and high-electrical conductivity Al micro-wires

Iron (Fe) is commonly found in aluminum (Al), but its contents are usually kept as low as possible, because the formation of intermetallic phases may induce fracture. In this study, high-pressure torsion (HPT) was used to control the microstructure in an Al-2 %Fe alloy in conjunction with wire drawing and an aging treatment, in order to improve not only their mechanical properties but also the electrical conductivity. It is shown that HPT processing of ring-shaped samples produced ultrafine grains with a size of ~150 nm in the matrix, while intermetallic phases were fragmented to nanosizes with some Fe fraction dissolved in the matrix. Semi-rings were extracted from the HPT-processed samples and swaged to a round section with 0.4-mm diameter. The HPT-processed sample was successfully drawn to a final diameter of 0.08 mm (25:1 ratio, 96 % reduction in area), whereas the sample without HPT processing failed after drawing to 0.117-mm diameter (12:1 ratio, 91 % reduction in area). The electrical conductivity increased to ~65 IACS % in the HPT-processed rings and to ~54 IACS % in the wires by aging for 1 h after the drawing.     

The ideal home hemodialysis machine

Daily home hemodialysis (HD) patients have a much superior survival rate than patients on regular, 3 times a week in-center HD or on peritoneal dialysis. Present-day HD machines are unsuitable for use at home by patients. We present our concept of the ideal home HD machine that allows daily short and long HD, does all the work preparing for and cleaning up after dialysis, has an intravenous infusion system controlled by the patient, needs no systemic anticoagulation, and teaches and interacts with the patient during dialysis. To fulfill these functionalities, the dialyzer and blood tubing must be integrated with the machine and replaced less often than monthly, the machine must be capable of at least 200 L/week of hemodiafiltration, prepare all fluids necessary between and during dialyses, and all the components and fluids must be much beyond ultrapure.     

Allotropic phase transformation of pure zirconium by high-pressure torsion

Pure Zr is processed by high-pressure torsion (HPT) at pressures in the range of 1–40 GPa. A phase transformation occurs from α to ω phase during HPT at pressures above 4 GPa while the total fraction of ω phase increases with straining and saturates to a constant level at higher strain. This phase transformation leads to microstructural refinement, hardness and strength enhancement and ductility reduction. Lattice parameter measurements confirm that c for α phase is expanded about 0.6% by the presence of ω phase. The temperature for reverse transformation from ω to α phase increases with straining and thus, straining under high pressure increases thermal stability of ω phase. The ω phase obtained by HPT is stable for more than 400 days at room temperature.     

A new safety device for hemodialysis

Accidental venous needle dislodgement during hemodialysis may cause serious bleeding including a sometimes fatal outcome. The venous pressure gauge of the dialysis monitor does not react when dislodgement occurs. A sensor patch put as an adhesive over the venous needle puncture site connected to an alarm unit by an optic fiber has been clinically tested in 5 dialysis departments. A small amount of blood on the sensor activates a light and sound alarm. A simple questionnaire was filled out by the nurses at each dialysis concerning their feeling of safety when the new device was used. Forty-one patients, mean age 65 years, have tested the new safety device. Two hundred test dialyses were studied, after exclusion of 13 tests. One hundred seventy-nine tests reacted positively on blood. In another 6 dialyses, a warning light appeared on the alarm unit indicating a failure in the sensor patch. Thus, the alarm functioned in 92.5% of all tests. After a small modification of the sensor patches there were only 2 dialyses (2/71) without an activated alarm on blood, i.e., 97.2% positive alarm reactions. The answers of the nurses indicated that they had an increased feeling of safety when using the new safety device, with a mean value of 3.4 points on a visual scale from 0 to 5 where 5 meant very much increased safety. In a situation when the dialysis monitors today do not react on bleedings from venous needle dislodgements, the new alarm safety device fulfils a known shortage in routine dialysis safety. In situations where supervision during a dialysis session may be insufficient as, for example, in home hemodialysis and self-care dialysis or in other situations when the patient is sleeping, the device may be life saving.     

106 Patient‐years experience with the Aksys PHD System for quotidian home hemodialysis

The Aksys PHD System, designed to utilize ultrapure dialyzate for quotidian hemodialysis at home, uses mechanical cleaning and hot water sanitization of the blood, dialysate, and water flow‐paths from inlet to outlet. Since January 2000, it has been used by 110 US patients and 8 UK patients for a total of 106 patient years and more than 30,000 dialyses runs. Of those treated, 75 patients were male and 43 female; mean age was 52 ± 25 (range 22–82) years; 65% were white, 25% black, and 10% other; mean weight was 78 ± 20 (44–125) kg; the cause of renal failure was primary renal disease (50%), hypertension (24%), diabetes (19%), and other (4%). Dialysis access included fistula (61%), graft (25%), and catheter (14%). Patients had been on ESRD therapy on average of 6 ± 7 (0–32) years when starting on PHD dialysis. As of August 2004, patients had dialyzed 11 ± 8 (1–52) months on the PHD. Of those, 78 patients remained on the PHD, 12 were transplanted, 10 died, 7 returned to conventional dialysis at the end of the original study for the FDA and 7 for medical or social reasons, 2 returned to quotidian dialysis on other equipment, and 2 stopped during home dialysis training. Patients dialyzed an average of 145 ± 27 min, 5.6 ± 0.6 dialyses/week with a QB of 376 ± 45 ml/min and a QD of 545 ± 170 ml/min. eKt/V was 0.68 ± 0.20 and weekly stdKt/V was 2.61 ± 0.52. Mean dialyser reuse was 17 ± 14 times without significant decline in urea clearance. 23/118 patients (19%) who came to the PHD from quotidian dialysis on other equipment thought the PHD twice as easy to use and experienced only half as many episodes hypotension, cramps, headache, backache, nausea, and arrhythmias (all p < 0.02). They were hospitalized only half as many days on the PHD. Cumulative patient survival was 60% at 4 years, with 94 deaths/1,000 patient years, relative risk 0.56 compared with age‐matched patients from the USRDS database. Conclusion: This large clinical experience shows the PHD System is easier to use and delivers smoother dialysis with better cardiovascular stability than conventional dialysis machines. It easily fulfills the DOQI guidelines for adequacy of dialysis, economizes on use of dialyzers, tubing, and dialysate, results in less hospitalization, and appears to result in superior patient survival.     

Switch from calcitriol to paricalcitol in secondary hyperparathyroidism of hemodialysis patients: Responsiveness is related to parathyroid gland size

Paricalcitol is more effective than calcitriol in hemodialysis patients (HD) with secondary hyperparathyroidism (SHPT), but it is not effective in some of them. We have investigated the relationship between paricalcitol responsiveness and parathyroid gland (PTG) size. Thirty HD with SHPT treated previously with calcitriol for at least 6 months were switched to paricalcitol (1:4 conversion ratio). Parathyroid gland number and size (maximum longitudinal diameter [MLD] of largest PTG) was measured by ultrasonography. Patients were divided into 2 groups: group A (MLD ≤9.0 mm [17 HD]); and group B (MLD >9.0 mm [13 HD]). They were defined responder if both the last 2 monthly determinations of inhibit parathyroid hormone (iPTH) were within the target (<300 pg/mL) according to National Kidney Foundation Kidney Disease Outcomes Quality Initiative recommendations. Twenty‐six and 20 HD completed 6‐month and 12‐month paricalcitol therapy, respectively. After 6 months of paricalcitol treatment, 23.5% HD of group A and 7.7% of group B were responders. At 12 months, 41.2 % of group A and 7.7% of group B were responders. Throughout paricalcitol therapy, serum calcium and phosphorus concentrations slightly increased in all HD but more significantly in group B. The baseline iPTH and MLD of the largest PTG were significantly correlated with final iPTH levels. Paricalcitol is more effective than calcitriol in SHPT, but the responsiveness to paricalcitol and hypercalcemia are related to PTG size. The measurement of MLD by ultrasonography may be useful for predicting responsiveness to paricalcitol, avoiding an unnecessary and expensive therapy.