Conventional Hemodialysis Treatment Research Articles

Closed Loop Ultrafiltration Feedback Control in Hemodialysis: A Narrative Review.

While life-sustaining, hemodialysis is a non-physiological treatment modality that exerts stress on the patient, primarily due to fluid shifts during ultrafiltration. Automated feedback control systems, integrated with sensors that continuously monitor bio-signals such as blood volume, can adjust hemodialysis treatment parameters, e.g., ultrafiltration rate, in real-time. These systems hold promise to mitigate hemodynamic stress, prevent intradialytic hypotension, and improve the removal of water and electrolytes in chronic hemodialysis patients. However, robust evidence supporting their clinical application remains limited. Based on an extensive literature research, we assess feedback-controlled ultrafiltration systems that have emerged over the past three decades in comparison to conventional hemodialysis treatment. We identified 28 clinical studies. Closed loop ultrafiltration control demonstrated effectiveness in 23 of them. No adverse effects of closed loop ultrafiltration control were reported across all trials. Closed loop ultrafiltration control represents an important advancement towards more physiological hemodialysis. Its development is driven by innovations in real-time bio-signals monitoring, advancement in control theory, and artificial intelligence. We expect these innovations will lead to the prevalent adoption of ultrafiltration control in the future, provided its clinical value is substantiated in adequately randomized controlled trials.

Non-invasive intradialytic percutaneous perfusion monitoring: a view to the heart through the skin.

The life-sustaining treatment of hemodialysis (HD) induces recurrent and cumulative systemic circulatory stress resulting in cardiovascular injury. These recurrent insults compound preexisting cardiovascular sequalae leading to the development of myocardial injury and resulting in extremely high morbidity/mortality. This is largely a consequence of challenged microcirculatory flow within the myocardium (evidenced by detailed imaging-based studies). Currently, monitoring during HD is performed at the macrovascular level. Non-invasive monitoring of organ perfusion would allow the detection and therapeutic amelioration of this pathophysiological response to HD. Non-invasive percutaneous perfusion monitoring of the skin (using photoplethysmography-PPG) has been shown to be predictive of HD-induced myocardial stunning (a consequence of segmental ischemia). In this study, we extended these observations to include a dynamic assessment of skin perfusion during HD compared with directly measured myocardial perfusion during dialysis and cardiac contractile function. We evaluated the intradialytic microcirculatory response in 12 patients receiving conventional HD treatments using continuous percutaneous perfusion monitoring throughout HD. Cardiac echocardiography was performed prior to the initiation of HD, and again at peak-HD stress, to assess the development of regional wall motion abnormalities (RWMAs). Myocardial perfusion imaging was obtained at the same timepoints (pre-HD and peak-HD stress), utilizing intravenous administered contrast and a computerized tomography (CT)-based method. Intradialytic changes in pulse strength (derived from PPG) were compared with the development of HD-induced RWMAs (indicative of myocardial stunning) and changes in myocardial perfusion. We found an association between the lowest pulse strength reduction (PPG) and the development of RWMAs (p = 0.03) and also with changes in global myocardial perfusion (CT) (p = 0.05). Ultrafiltration rate (mL/kg/hour) was a significant driver of HD-induced circulatory stress [(associated with the greatest pulse strength reduction (p = 0.01), a reduction in global myocardial perfusion (p = 0.001), and the development of RWMAs (p = 0.03)]. Percutaneous perfusion monitoring using PPG is a useful method of assessing intradialytic hemodynamic stability and HD-induced circulatory stress. The information generated at the microcirculatory level of the skin is reflective of direct measures of myocardial perfusion and the development of HD-induced myocardial stunning. This approach for the detection and management of HD-induced cardiac injury warrants additional evaluation.

Strategies for optimizing urea removal to enable portable kidney dialysis: A reappraisal.

Portable hemodialysis has the potential to improve health outcomes and quality of life for patients with kidney failure at reduced costs. Urea removal, required for dialysate regeneration, is a central function of any existing/potential portable dialysis device. Urea in the spent dialysate coexists with non-urea uremic toxins, nutrients, and electrolytes, all of which will interfere with the urea removal efficiency, regardless of whether the underlying urea removal mechanism is based on urease conversion, direct urea adsorption, or oxidation. The aim of the current review is to identify the amount of the most prevalent chemicals being removed during a single dialysis session and evaluate the potential benefits of an urea-selective membrane for portable dialysis. We have performed a literature search using Web of Science and PubMed databases to find available articles reporting (or be able to calculate from blood plasma concentration)>5mg of individually quantified solutes removed during thrice-weekly hemodialysis sessions. If multiple reports of the same solute were available, the reported values were averaged, and the geometric mean of standard deviations was taken. Further critical literature analysis of reported dialysate regeneration methods was performed using Web of Science and PubMed databases. On average, 46.0g uremic retention solutes are removed in a single conventional dialysis session, out of which urea is only 23.6g. For both urease- and sorbent-based urea removal mechanisms, amino acids, with 7.7g removal per session, could potentially interfere with urea removal efficiency. Additionally for the oxidation-based urea removal system, plentiful nutrients such as glucose (24.0g) will interfere with urea removal by competition. Using a nanofiltration membrane between dialysate and oxidation unit with a molecular weight cutoff (MWCO) of ~200Da, 67.6g of non-electrolyte species will be removed in a single dialysis session, out of which 44.0g are non-urea molecules. If the membrane MWCO is further decreased to 120Da, the mass of non-electrolyte non-urea species will drop to 9.3g. Reverse osmosis membranes have been shown to be both effective at blocking the transport of non-urea species (creatinine for example with ~90% rejection ratio), and permissive for urea transport (~20% rejection ratio), making them a promising urea selective membrane to increase the efficiency of the oxidative urea removal system. Compiled are quantified solute removal amounts greater than 5mg per session during conventional hemodialysis treatments, to act as a guide for portable dialysis system design. Analysis shows that multiple chemical species in the dialysate interfere with all proposed portable urea removal systems. This suggests the need for an additional protective dialysate loop coupled to urea removal system and an urea-selective membrane.

In vitro Evaluation of Solute Removal Characteristics in Intermittent Infusion Hemodiafiltration

Background: In a typical hemodialysis (HD) session, excessive water removal sometimes induces peripheral circulatory failure and a rapid drop in blood pressure. Intermittent infusion hemodiafiltration (I-HDF), a new modality of dialysis therapy, has been developed to improve peripheral circulation by repeated intermittent infusion of dialysate during an HD session. In a typical I-HDF session, we infuse a volume of 200 mL of ultrapure dialysate by backfiltration at 150 mL/min every 30 min. The same volume is alternately removed from the patient’s blood by filtration at a constant rate after each infusion. However, solute removal characteristics in I-HDF have not been clarified previously. We therefore conducted an in vitro study to investigate the characteristics of solute removal and the factors affecting such removal. Summary: We used human plasma to evaluate the effects of filtration (QF)/infusion (QI) flow rates on solute clearance (CL) and to estimate the time-averaged solute CL (TACL) values. The CL values for all solutes decreased with increasing QI. For small molecules such as urea, the CL values predominantly decreased with increasing QI because of decreasing diffusive transport. For medium and large solutes such as β2 microglobulin or larger, CL values predominantly increased with increasing QF because of increasing convective transport. However, the effects of these changes on TACL values were small compared with the CL value in a typical HD session because of the alternate filtration and infusion in I-HDF. Key Messages: Solute removal characteristics in I-HDF do not differ significantly from those in conventional HD treatment.

Hemodialysis-induced changes in hematocrit, hemoglobin and total protein: Implications for relative blood volume monitoring.

BackgroundRelative blood volume (RBV) changes during hemodialysis (HD) are typically estimated based on online measurements of hematocrit, hemoglobin or total blood protein. The aim of this study was to assess changes in the above parameters during HD in order to compare the potential differences in the RBV changes estimated by individual methods.Methods25 anuric maintenance HD patients were monitored during a 1-week conventional HD treatment. Blood samples were collected from the arterial dialysis blood line at the beginning and at the end of each HD session. The analysis of blood samples was performed using the hematology analyzer Advia 2120 and clinical chemistry analyzer Advia 1800 (Siemens Healthcare).ResultsDuring the analyzed 30 HD sessions with ultrafiltration in the range 0.7–4.0 L (2.5 ± 0.8 L) hematocrit (HCT) increased by 9.1 ± 7.0% (mean ± SD), hemoglobin (HGB) increased by 10.6 ± 6.3%, total plasma protein (TPP) increased by 15.6 ± 9.5%, total blood protein (TBP) increased by 10.4 ± 5.8%, red blood cell count (RBC) increased by 10.8 ± 7.1%, while mean corpuscular red cell volume (MCV) decreased by 1.5 ± 1.1% (all changes statistically significant, p < 0.001). HGB increased on average by 1.5% more than HCT (p < 0.001). The difference between HGB and TBP increase was insignificant (p = 0.16).ConclusionsTracking HGB or TBP can be treated as equivalent for the purpose of estimating RBV changes during HD. Due to the reduction of MCV, the HCT-based estimate of RBV changes may underestimate the actual blood volume changes.

Hemodiafiltration versus conventional hemodialysis: Should "conventional" be redefined?

In the 1980s, conventional hemodialysis was considered as dialysis with acetate dialysate, dialysis machines without volumetric control, low blood flow and low-flux dialyzers; in the 1990s, the concept of conventional hemodialysis changed due to technological advances in dialysis machines, control of ultrafiltration and the widespread use of bicarbonate dialysate, which allowed an increase in blood flow and the use of synthetic high-flux dialyzers. To avoid backfiltration-induced adverse reactions, exogenous replacement fluid was promoted but its adoption was limited for technical and financial reasons. This scenario changed in 1995 with the development of on-line hemodiafiltration (HDF) techniques using the dialysis fluid itself as a replacement fluid. Dialysis machines were modified to perform on-line HDF, incorporating safety filters to ensure the quality of this replacement fluid (ultrapure dialysate). After more than two decades of clinical experience and technological development with high-volume HDF, the present article discusses whether HDF can currently be considered as the standard conventional treatment for chronic hemodialysis patients. A review of the evidence indicates that the time has come to consider HDF as the conventional hemodialysis treatment for the following reasons: first, technological development in water treatment and advances in dialysis machines, as well as the widespread use of synthetic high-flux dialyzers has made it a feasible proposition. Second, there is an absence of published literature showing any undesirable effects. Finally, scientific evidence is available showing the superiority of HDF over hemodialysis in overall and cardiovascular mortality in both prevalent and incident patients.

Short, frequent, 5-days-per-week, in-center hemodialysis versus 3-days-per week treatment: a randomized crossover pilot trial through the Midwest Pediatric Nephrology Consortium.

No controlled trials in children with end-stage kidney disease have assessed the benefits of more frequently administered hemodialysis (HD). We conducted a multicenter, crossover pilot trial to determine if short, more frequent (5days per week) in-center HD was feasible and associated with improvements in blood pressure compared with three conventional HD treatments per week. Because adult studies have not controlled for the weekly duration of dialysis, we fixed the total treatment time at 12 h a week of dialysis during two 3-month study periods; only frequency varied from 5 to 3days per week between study periods. Eight children (median age 16.7years) consented at three children's hospitals. The prespecified primary composite outcome was a sustained 10% decrease in systolic blood pressure and/or a decrease in antihypertensive medications relative to each study period's baseline. Among the six patients completing both study periods, five (83.3%) experienced the primary outcome during HD performed 5days per week but not 3days per week; one of the six (16.7%) achieved that outcome during 3-day but not 5-day (p = 0.22) per week HD. During 5-day HD, all patients had significantly more treatments during which their pre-HD systolic (p = 0.01) or diastolic (p = 0.01) blood pressure was 10% lower than baseline. We observed that more frequent HD sessions per week was feasible and associated with improved blood pressure control, but barriers to changing thrice-weekly standard of care include financial reimbursement and the time demands associated with more frequent treatments.

Extended-hours hemodialysis is associated with lower mortality risk in patients with end-stage renal disease

Extended-hours hemodialysis offers substantially longer treatment time compared to conventional hemodialysis schedules and is associated with improved fluid and electrolyte control and favorable cardiac remodeling. However, whether extended-hours hemodialysis improves survival remains unclear. Therefore, we determined the association between extended-hours compared to conventional hemodialysis and the risk of all-cause mortality in a nationally representative cohort of patients initiating maintenance dialysis in the United States from 2007 to 2011. Survival analyses using causal inference modeling with marginal structural models were performed to compare mortality risk among 1206 individuals undergoing thrice weekly extended-hours hemodialysis or 111,707 patients receiving conventional hemodialysis treatments. The average treatment time per session for extended-hours hemodialysis was 399 minutes compared to 211 minutes for conventional therapy. The crude mortality rate with extended-hours hemodialysis was 6.4 deaths per 100 patient-years compared with 14.7 deaths per 100 patient-years for conventional hemodialysis. In the primary analysis, patients treated with extended-hours hemodialysis had a 33% lower adjusted risk of death compared to those who were treated with a conventional regimen (95% confidence interval: 7% to 51%). Additional analyses accounting for analytical assumptions regarding exposure and outcome, facility-level confounders, and prior modality history were similar. Thus, in this large nationally representative cohort, treatment with extended-hours hemodialysis was associated with a lower risk for mortality compared to treatment with conventional in-center therapy. Adequately powered randomized clinical trials comparing extended-hours to conventional hemodialysis are required to confirm these findings.

Acute Hemodynamic Response and Uremic Toxin Removal in Conventional and Extended Hemodialysis and Hemodiafiltration: A Randomized Crossover Study

Intensive hemodialysis (HD) may have significant benefits. Recently, the role of extended hemodiafiltration (HDF) has gained interest. The aim of this study was to evaluate the acute effects of extended HD and HDF on hemodynamic response and solute removal. Randomized crossover trial. Stable patients with end-stage renal disease undergoing conventional HD. 13 patients randomly completed a single study of 4-hour HD (HD4), 4-hour HDF (HDF4), 8-hour HD (HD8), and 8-hour HDF (HDF8), with a 2-week interval between study sessions. Between study sessions, patients received routine conventional HD treatments. Acute hemodynamic effects and uremic toxin clearance. Blood pressure and heart rate, pulse wave analysis, cardiac output, and microvascular density by sublingual capillaroscopy, as well as relative blood volume and thermal variables, were measured. Clearance and removal of uremic toxins also were studied. Long treatments showed more stability of peripheral systolic blood pressure (change during HD4, -21.7±15.6 mm Hg; during HDF4, -23.3±20.8 mm Hg; during HD8, -6.7±15.2 mm Hg [P=0.04 vs. HD4; P=0.08 vs. HDF4]; and during HDF8, -0.5±14.4 mm Hg [P=0.004 vs. HD4; P=0.008 vs. HDF4]). A similar observation was found for peripheral diastolic and central blood pressures. Cardiac output remained more stable in extended sessions (change during HD4, -1.4±1.5 L/min; during HDF4, -1.6±1.0 L/min; during HD8, -0.4±0.9 L/min [P=0.02 vs. HDF4]; and during HDF8, -0.5±0.8 L/min [P=0.06 vs. HD4; P=0.03 vs. HDF4), in line with the decreased relative blood volume slope in long dialysis. No differences in microvascular density were found. Energy transfer rates were comparable (HD4, 13.3±4.7 W; HDF4, 16.2±5.6 W; HD8, 14.2±6.0 W; and HDF8, 14.5±4.3 W). Small-molecule and phosphate removal were superior during long treatments. β2-Microglobulin and fibroblast growth factor 23 (FGF-23) reduction ratios were highest in HDF8. Small sample size, only acute effects were studied. Treatment time, and not modality, was the determinant for the hemodynamic response. HDF significantly improved removal of middle molecules, with superior results in extended HDF.

Elimination of Large Uremic Toxins by a Dialyzer Specifically Designed for High-Volume Convective Therapies

Background: Unlike conventional hemodialysis treatments, which rely almost solely on diffusion-related mechanisms for solute removal, hemodiafiltration (HDF) allows more efficient removal of higher molecular weight toxins due to convective transport mechanisms. To facilitate the removal of these toxins in HDF treatment modalities, dialyzers with highly efficient high-flux membranes are necessary. This study assessed the large uremic toxin removal ability of a high-flux dialyzer (FX CorDiax 60) specifically designed to facilitate convective therapies compared with a standard high-flux dialyzer (FX 60). Methods: In an open, randomized, cross-over, single-center, controlled, prospective clinical study, 30 adult chronic hemodialysis patients were treated by post-dilution online HDF with the FX 60 or the FX CorDiax 60 dialyzer. All other dialysis parameters were kept constant in both study arms. The reduction rate (RR) of blood urea nitrogen, phosphate, β₂-microglobulin (β₂-m), myoglobin, prolactin, α₁-microglobulin, α₁-acid glycoprotein, albumin and total protein as well as the elimination into dialysate was intraindividually compared for the two dialyzer types. Results: For FX CorDiax 60 versus FX 60, the RR was significantly higher for blood urea nitrogen (86.23 ± 4.14 vs. 84.89 ± 4.59%, p = 0.015), β₂-m (84.67 ± 3.79 vs. 81.30 ± 4.82%, p < 0.0001), myoglobin (75.23 ± 10.48 vs. 58.60 ± 12.1%, p < 0.0001), prolactin (72.96 ± 9.68 vs. 56.91 ± 13.01%, p < 0.0001) and α₁-microglobulin (20.89 ± 18.27 vs. 13.60 ± 12.50%, p = 0.016). There were no significant differences in the RR for phosphate, α₁-acid glycoprotein, albumin and total protein. Mass removal was significantly higher with the FX CorDiax 60 than with the FX 60 for β₂-m (0.26 ± 0.09 vs. 0.24 ± 0.09 g, p = 0.0006), myoglobin (1.83 ± 0.89 vs. 1.51 ± 0.76 mg, p = 0.0017), prolactin (0.17 ± 0.13 vs. 0.14 ± 0.08 mg, p = 0.02) and albumin (4.25 ± 3.49 vs. 3.01 ± 2.37 g, p = 0.03). Conclusions: This study demonstrates that treating patients with an FX CorDiax 60 instead of an FX 60 dialyzer in post-dilution HDF mode significantly increases the elimination of middle molecules.

Fabrication of zeolite-polymer composite nanofibers for removal of uremic toxins from kidney failure patients.

There is a need to develop a simple, cheap, and accessible method of treating patients with kidney failure, especially in resource-limited environments such as disaster areas and the developing world due to the inaccessibility of conventional hemodialysis treatments. In this study, we develop a zeolite-polymer composite nanofiber mesh to remove uremic toxins for blood purification. The nanofiber is composed of blood compatible poly(ethylene-co-vinyl alcohol) (EVOH) as the primary matrix polymer and zeolites which are capable of selectively adsorbing uremic toxins such as creatinine. The composite fiber meshes were produced by a cost-effective electrospinning method: electrospinning composite solutions of EVOH and zeolites. Scanning electron microscope (SEM) images revealed that the 7 w/v% EVOH solution produced non-woven fibers with a continuous and smooth morphology. The SEM also showed that over 90% of zeolites in the solution were successfully incorporated into the EVOH nanofibers. Although the barrier properties of the EVOH matrix lowered the creatinine adsorption capacity of the zeolites in the fiber when compared with adsorption to free zeolites, their adsorption capacity was still 67% of the free zeolites. The proposed composite fibers have the potential to be utilized as a new approach to removing nitrogenous waste products from the bloodstream without the requirement of specialized equipment.

Pulmonary Congestion in Hemodialysis

It is well documented that pulmonary congestion is common among patients undergoing treatment with hemodialysis, and recent evidence suggests a strong association with mortality ([1][1]–[4][2]). The cyclical, and very predictable, nature of each hemodialysis session carries several major risks

Novel Dialysis Modalities: Do We Need New Metrics to Optimize Treatment?

Delivered dose of hemodialysis has long been an important predictor of mortality. The limitations of conventional hemodialysis treatments have led to a renewed interest in more frequent and longer hemodialysis treatments. As alternative hemodialysis schedules have become more prevalent, a need for modified metrics to measure adequacy has emerged. In addition, there is an interest in finding measures of hemodialysis adequacy that are more reliable in certain subgroups of patients, such as women, ethnic minority groups, or people with small body size. Finally, extended hemodialysis schedules suggest a need for metrics that can measure the clearance of solutes other than urea, such as middle-size molecules, and solutes for which clearance depends on intercompartmental transport across membranes. New metrics to quantify clearance in extended and alternate hemodialysis schedules are needed. As new metrics are developed, it is anticipated that they will also contribute to more accurate assessments of associations between clinical outcomes and delivered dose of dialysis in more intensive, nontraditional hemodialysis schedules. This review provides a historical prospective of dialysis dose and adequacy and describes the need for new metrics from both solute type and dialysis dose prospective as alternative hemodialysis schedules have emerged and become more prevalent.

Kinetic Model of Phosphorus Mobilization during and after Short and Conventional Hemodialysis

The kinetics of plasma phosphorus (inorganic phosphorus or phosphate) during hemodialysis treatments cannot be explained by conventional one- or two-compartment models; previous approaches have been limited by assuming that the distribution of phosphorus is confined to classical intracellular and extracellular fluid compartments. In this study a novel pseudo one-compartment model, including phosphorus mobilization from a large second compartment, was proposed and evaluated. Clinical data were obtained during a crossover study where 22 chronic hemodialysis patients underwent both short (2-hour) and conventional (4-hour) hemodialysis sessions. The model estimated two patient-specific parameters, phosphorus mobilization clearance and phosphorus central distribution volume, by fitting frequent intradialytic and postdialytic plasma phosphorus concentrations using nonlinear regression. Phosphorus mobilization clearances varied among patients (45 to 208 ml/min), but estimates during short (98 ± 44 ml/min, mean ± SD) and conventional (99 ± 47 ml/min) sessions were not different (P = 0.74) and correlated with each other (concordance correlation coefficient ρ(c) of 0.85). Phosphorus central distribution volumes for each patient (short: 11.0 ± 4.2 L and conventional: 11.9 ± 3.8 L) were also correlated (ρ(c) of 0.45). The reproducibility of patient-specific parameters during short and conventional hemodialysis treatments suggests that a pseudo one-compartment model is robust and can describe plasma phosphorus kinetics under conditions of clinical interest.

Effect of High-Flux Hemodialysis on Delayed Hepatitis B Virus Vaccination Response in Hemodialysis Patients

Objectives: The aim of the study was to evaluate the effect of high-flux (HF) hemodialysis (HD) on delayed protective hepatitis B virus (HBV) antibody seroconversion in HD patients who had no response to the classic third dose of HBV vaccination. Methods: We performed a prospective cohort study. Forty-two patients who did not respond within 6 months after the third dose of the vaccination were enrolled in the study. The patients were randomized to either an HF HD treatment group (n =19) or a conventional HD treatment group (n = 23). Patients' serum hepatitis B surface antibody levels were followed monthly. Results: After 6 months of follow-up, there were 15 (78.9%) patients in HF group and 7 (30.4%) patients in the control group showing delayed HBV vaccination response. The level of antibody titer of HBV vaccination responders was 103.6 ± 48.3 mIU/mL in the HF group and 23.5 ± 15.7 mIU/mL in the control group. The antibody titer did not correlate with sex, age, serum albumin, or hemoglobin in either group. Four patients in control group lost HBV vaccination response > 2 times after 3 months of follow-up, whereas no patients in the HF group lost HBV vaccination response. Conclusion: Hemodialysis patients who do not respond to the classic third dose of HBV vaccination could reobtain a delayed higher protective HBV antibody seroconversion rate by HF HD without other intervention.

Prediction of Intradialytic Hypotension Using Photoplethysmography

Intradialytic hypotension is the most common acute complication during conventional hemodialysis treatment. Prediction of such events is highly desirable in clinical routine for prevention. This paper presents a novel prediction method of acute symptomatic hypotension in which the photoplethysmographic signal is analyzed with respect to changes in amplitude, reflecting vasoconstriction, and cardiac output. The method is based on a statistical model in which the noise is assumed to have Laplacian amplitude distribution. The performance is evaluated on 11 hypotension-prone patients who underwent hemodialysis treatment, resulting in seven events with acute symptomatic hypotension and 17 without. The photoplethysmographic signal was continuously acquired during treatment as was information on blood pressure and oxygen saturation. Using leave-one-out cross validation, the proposed method predicted six out of seven hypotensive events, while producing 1 false prediction out of 17 possible. The performance was achieved when the prediction threshold was chosen to be in the range 57%-65% of the photoplethysmographic envelope at treatment onset.

Application of sodium profile combined with ultrafiltration profile in preventing intradialytic hypotension

Objective To study the efficacy of sodium profile combined with ultrafiltration profile in preventing intradialytic hypotension and changes of the sodium level in blood plasma after hemodialysis. Methods 10 patients with maintenance hemodialysis were chosen randomly. Every patient underwent with conventional hemodialysis treatment and sodium profile combined with ultrafiltration profile treatment 5 times alternatively. And then the blood pressure changes. HR changes, ultrafiltration volume changes and clinical symptoms were observed during treatments. And also after HD, the sodium level in blood plasma was observed. Results The blood pressure decrease of sodium profile combined with ultrafiltration profile evidently reduced the conventional HD treatments( P＜0.01 ).Ultrafiltration volume of the former evidently increased compared with that of the latter(P＜0.01 ). The sodium level in blood plasma after HD was not significantly changed compared with before HD(P＞0.05). Conclnsion Sodium profile combined with ultrafiltration profile diminishes the episodes of hypotension evidently and increases the ability to endure sufferirgs to patients and does not increase the sodium level in blood plasma. So it is an effective medical treatment. Key words: Hemodiafiltration; Hypotension; Sodium

An Electrocardiogram-Based Method for Early Detection of Abrupt Changes in Blood Pressure during Hemodialysis

Clinical techniques for early detection of acute hypotension during conventional hemodialysis treatment are lacking, even though intradialytic hypotension is the most common acute complication. In this article, intradialytic hypotension is identified by means of signal analysis of data recorded at two clinics. The database consists of 30 treatments with concurrently acquired signals: the 12-lead electrocardiogram, continuous blood pressure, hematocrit, oxygen saturation, relative blood volume, and important hemodialysis variables. This article presents two characteristics, a heart rate turbulence (HRT) measure called turbulence slope (TS), and the LF/HF ratio, which provide information, at the beginning of hemodialysis treatment, on the patient's propensity to hypotension (TS: p = 0.0038, and LF/HF ratio: p = 0.0028). The authors also present a novel dynamic echocardiography-based method for detecting intradialytic hypotension using complementary information on heart rate variability (HRV) and ectopic beat patterns. These two types of information reflect different mechanisms of cardiac activity. It is essential that both types are used for the detection of hypotension, because HRV analysis is inappropriate when several ectopic beats are present. The proposed dynamic echocardiography-based method offers early identification of the cases with acute intradialytic hypotension of the database.

Kinetics of urea and β2-microglobulin during and after short hemodialysis treatments

Daily short hemodialysis (HD) is often prescribed by simply doubling treatment frequency and halving treatment time; however, the effect of this prescription approach on the equilibrated HD dose (urea eKt/V) and whole body clearance for beta(2)-microglobulin has not been established. We compared urea and beta(2)-microglobulin kinetics during and 60 minutes after a short HD treatment and a conventional HD treatment in a crossover study on 22 maintenance HD patients: 16 male and 6 female, 61 +/- 18 (mean +/- standard deviation) years of age. One patient in each treatment modality was excluded from certain analyses because of missing data. Short and conventional HD treatments were essentially identical, except for treatment times, which were 116 +/- 14 and 241 +/- 27 minutes, respectively. Blood samples were collected at regular intervals during and after treatments, and additional blood and dialysate samples were collected at 60 minutes of treatment to evaluate dialyzer clearances. Plasma water urea clearances measured directly across the dialyzer during short and conventional HD treatments were not different (255 +/- 23 mL/min and 255 +/- 28 mL/min, respectively). The 60-minute postdialysis blood urea nitrogen concentration rebounded more (P < 0.01) after short HD than conventional HD (5.9 +/- 3.1 vs. 4.0 +/- 1.5 mg/dL, respectively). Calculated urea eKt/V values using the Daugirdas-Schneditz rate equation were not different from those measured during conventional HD using the 60-minute postdialysis concentration but significantly overestimated measured urea eKt/V values during short HD. Postdialysis rebound of beta(2)-microglobulin concentrations was variable but similar after short and conventional HD treatments (0.1 +/- 3.4 vs. 0.7 +/- 1.8 mg/L, respectively). Whole body clearances of beta(2)-microglobulin calculated from predialysis and immediate (10-second) postdialysis serum concentrations during short and conventional HD treatments were not different from each other (42.9 +/- 24.1 vs. 41.9 +/- 22.4 mL/min, respectively). These observations show that the Daugirdas-Schneditz rate equation is accurate in predicting urea eKt/V during conventional, but not during short, HD. In contrast, whole body clearances of beta(2)-microglobulin during short and conventional HD treatments were similar. We conclude that calculation of accurate estimates of urea eKt/V, but not clearances of beta(2)-microglobulin, differ during short and conventional HD treatments.

Advanced Glycation end Products: Specific Fluorescence Changes of Pentosidine-Like Compounds during Short Daily Hemodialysis

Advanced glycation end products (AGE) accumulate in uremia and represent an important etiopathogenetic cause of morbidity in dialyzed patients. Conventional hemodialysis treatment seems to be ineffective in lowering AGE levels. We wished to investigate whether daily hemodialysis (DHD), a treatment that seems to result in better clinical condition in end-stage renal disease patients, is effective in the reduction of these compounds. We evaluated 10 non-diabetic patients on standard hemodialysis (SHD = 3 x 4 h/week) for more than 6 months by a crossover study. These patients were assigned randomly to 6 months of DHD (6 x 2 h/week) or 6 months of SHD. Then, they were switched to 6 months of the alternative treatment. At the end of these two periods, we studied pentosidine-like AGE compounds by measuring the total fluorescence at a wavelength characteristic for these substances: Ex: 335nm/Em:385nm; we also measured protein-linked pentosidine at the same time points. Finally, we determined the AGE-related total fluorescence in the deproteinized serum of 13 uremic patients on peritoneal dialysis (CAPD) and of 10 healthy controls. Pre-HD AGE-related total fluorescence obtained after 6 months of DHD was significantly lower than that obtained with standard HD (DHD = 201.3 +/- 36.4 AU/ml vs. SHD = 267.5 +/- 141.4 AU/ml, p = 0.03). The extraction rate per minute of dialysis was slightly, but not significantly higher during DHD than SHD (0.29 +/- 0.11% vs. 0.23 +/- 0.04, p = 0.07). AGE-related total fluorescence pre-HD values in patients treated by SHD and DHD were about 20-fold higher than in control subjects. They did not differ from CAPD patients. The pre-dialysis level of protein-linked pentosidine was significantly lower in DHD than in SHD (DHD = 16.12 +/- 4.71 pmol/mg protein, SHD = 22.64 +/- 6.86 pmol/mg protein, p < 0.01). DHD showed a reduction in AGE-related total fluorescence, although the mean value remained higher than in control subjects. DHD is also accompanied by a decrease in protein-linked pentosidine.