Ultrafiltration Profiles Research Articles

Vascular refilling in hemodialysis using feedback-controlled ultrafiltration profile.

The rate and the duration of ultrafiltration (UF) are considered the most important factors to affect vascular refilling. The aim of the study was to investigate whether a UF profile could improve the vascular refilling. Dialysis was delivered by a machine providing feedback control of ultrafiltration rates. Absolute blood volume (BV) was measured by dialysate bolus method. Vascular refilling volume (Vref) was calculated as UF volume - Δ absolute BV. In 40 patients, refilling fraction (Vref/UF volume) was 30.5% in the first hour. Thereafter, refilling fraction steeply increased and reached maximum values in the third and fourth hour at about 95%. The cumulative refilling fraction was 68.5 ± 9.4% at the end. In 14 patients, refilling data from the feedback-controlled UF profile were compared to dialysis sessions with constant UF rates. In 12 of 14 patients, refilling fraction was significantly (p = 0.013) higher in sessions with UF profile (71.6% vs 64.4%).There was a significant negative correlation (r = -0.606; p = 0.002) between the blood volume to extracellular volume ratio and the refilling fraction. The sum of this ratio and the refilling fraction was 1.01 ± 0.06. Despite significant differences, a feedback-controlled UF profile has no advantage over the previous refilling studies with regard to the refilling fraction because vascular refilling seems to depend mainly on the ratio of BV to ECV. This would explain the different results in studies using BV guided UF feedback programs.

#2570 Non-invasive blood pressure monitoring in dialysis patients using pulse wave velocity

Abstract Background and Aims Dialysis patients are at high risk of circulatory dysregulation and hypotension during treatment. Intradialytic hypotension (IDH) is a potentially life-threatening complication. The main causes are high ultrafiltration volumes and high ultrafiltration rates when patients tend to gain a lot of weight between dialysis treatments. A lack of patient compliance with regard to drinking volumes and a lack of residual diuresis are risk factors for this. Close circulatory monitoring and therapy settings to avoid absolute or relatively high UF rates to prevent IDH are frequently used. These are primarily the frequent non-invasive measurement of blood pressure using cuffs, the measurement of relative blood volume and the adjustment of ultrafiltration rates to these values. Prophylactically, the dialysis time can be extended, ultrafiltration profiles or ultrafiltration breaks can be planned, the dialysate temperature can be lowered and the composition of the dialysate can be adjusted. Despite all attempts, however, the incidence of IDH in everyday clinical practice is too high. The non-invasive measurements with cuffs are not carried out frequently enough, the measurement of the relative blood volume only covers a partial range, sudden changes in vascular tension or cardiac output are not recorded. Method The pulse wave velocity (PWV) is a well-known parameter for describing the propagation of the pressure wave after ejection of the heart beat volume in the arteries. The PWV is dependent on blood pressure, vessel wall tension and cardiac output. Changes in blood pressure can therefore be recognised by measuring the PWV. With the help of a measuring device (PESAS) for the ECG signal and peripheral pulse plethysmography, PWV can be measured non-invasively, continuously, for every heartbeat and, above all, hardly noticed by the patient. The PESAS allows the time-synchronised measurement of ECG and peripheral plethysmography curves and thus the determination of PWV. It is an experimental device. We would like to present a study showing the use of a measuring device (PESAS) in 15 prevalent dialysis patients for the detection of IDH. All study participants were examined during 3 dialysis treatments. Results The measurement of PWV in chronic dialysis patients during treatment is technically feasible. The measurement is tolerated by the patients. Changes in PWV could be detected in the patients during the course of dialysis; these were also dependent on the ultrafiltration rates. Individual patient reactions to volume withdrawal varied, with both increases and decreases in PWV being demonstrated. An acute change in PWV was usually associated with a drop in blood pressure. Continuous measurement allowed IDH events to be detected earlier than intermittent blood pressure measurement with cuffs. Sudden drops in blood pressure could be detected better and earlier with the PESAS system than by measuring the relative blood volume. Conclusion The PESAS system is suitable for monitoring dialysis patients to prevent IDH. Further adjustments and optimisation of the evaluation algorithms are necessary.

Impact of Ultrafiltration Profiling Compared to Conventional Methods on Blood Pressure Regulation Among Hemodialysis Patients

Background: Standard hemodialysis sessions pose challenges for patients due to fluctuations in blood pressure. Alternative strategies, such as ultrafiltration profiling, have been proposed as potentially more effective treatments. Objectives: This study aimed to evaluate the effects of ultrafiltration profiling compared to the conventional method on blood pressure regulation among hemodialysis patients. Methods: This study employed a pre-test and post-test design, involving a single group of 30 hemodialysis patients undergoing treatment at Shahid Beheshti Hospital in Hamadan in 2022. The sampling method used was simple random sampling. The intervention consisted of three sessions using the routine method, followed by three sessions utilizing the ultrafiltration profile method, which employed an interval with a negative slope. Demographic and clinical information about the patients was recorded on a checklist. Systolic and diastolic blood pressure measurements were taken before the commencement of hemodialysis, at 1-, 2-, and 3-hour intervals post-treatment initiation, and again 15 minutes after completing hemodialysis. Results: The mean blood pressure changes observed during dialysis stages increased with both methods; however, there was a significant difference between the methods (P < 0.001). Specifically, patients receiving the ultrafiltration profile method experienced significantly lower increases in blood pressure compared to those receiving the routine method. Conclusions: Based on the research results, integrating ultrafiltration profiling into hemodialysis can be regarded as an effective and viable strategy for enhancing blood pressure regulation in patients undergoing hemodialysis treatment. Therefore, it is recommended that this approach be considered in hemodialysis programs as well.

Combination of sodium and ultrafiltration profiles for prevention of intradialytic hypotension and related symptoms

Combination of sodium and ultrafiltration profiles for prevention of intradialytic hypotension and related symptoms

The Effect of Dialysis Solution Temperature and Stepwise Ultrafiltration Profile on Dialysis Adequacy and Pruritus in Hemodialysis Patients: A Quasi-experimental Study

Background: Patients with renal insufficiency who receive hemodialysis should be continuously monitored to avoid possible complications, as they are at increased risk of several problems, including pruritus, as one of the most annoying problems. It seems that dialysis adequacy affects the pruritus of hemodialysis patients. Objective: The current study aimed to investigate the effect of dialysis solution temperature and stepwise ultrafiltration profile on dialysis adequacy and pruritus of hemodialysis patients. Methods: Following a single group quasi-experimental design, 34 eligible hemodialysis patients admitted to the hemodialysis ward of Zahedan Medical Center (Iran) in 2020 were recruited using the convenience sampling technique. All patients attended three standard dialysis sessions (at a temperature of 37°C) and three cold dialysis sessions (36°C) with a stepwise dialysis ultrafiltration profile. Dialysis adequacy was measured at the end of each session, and Yosipovitch’s Pruritus Severity Scale (PSS) was filled before and after each dialysis session. Data were summarized using descriptive statistics (i.e., frequency, mean, and standard deviation). Mean scores before and after dialysis were paired by t-test using SPSS version 22. Statistical significance was considered when P-value < 0.05. Results: The mean and standard deviation of dialysis adequacy in both standard dialysis and cold dialysis techniques with stepwise ultrafiltration profile were 1.18 ± 0.36 and 1.44 ± 0.48, respectively, indicating that dialysis adequacy of the cold dialysis method with stepwise ultrafiltration profile was significantly higher (P = 0.001). Besides, the mean pruritus scores in the standard dialysis and cold dialysis methods with stepwise ultrafiltration profile were -0.73 ± 0.80 and -1.73 ± 1.16, respectively, showing a significant difference (P = 0.001). Conclusions: Cold hemodialysis with a stepwise ultrafiltration profile can be used as a simple and low-cost technique to improve both dialysis adequacy and relieve pruritus in hemodialysis patients.

Hemodialysis crossover study using a relative blood volume change-guided ultrafiltration control compared with standard hemodialysis: the BV-UFC study

BackgroundIt has been difficult to sufficiently achieve body-fluid management using blood volume (BV) monitor during hemodialysis (HD) with constant ultrafiltration (UF) rate. Recently, a relative BV change-guided UF control (BV-UFC) system was developed by combining the concepts of an automatic feedback system that could control the UF rate and profile with real- time monitoring of relative changes in BV (%ΔBV). However, this system has limited application in the clinical setting. Therefore, in this study, we aimed to perform the crossover study on HD with BV-UFC compared to standard HD in terms of hemodynamic stability during HD.MethodsForty-eight patients entered an 8-week crossover period of standard HD or HD with BV-UFC. Prevalence of intradialytic hypotension (IDH) as a primary outcome and changes in blood pressure (BP), differences in %ΔBV, and achievement of the target ultrafiltration volume as secondary outcomes were compared. IDH was defined as a reduction in systolic BP ≥20 mmHg from the baseline value at 10 min after HD initiation.ResultsNo significant differences were found in the prevalence of IDH, frequency of intervention for symptomatic IDH, and achievement of the target ultrafiltration volume between the groups. The %ΔBV was significantly fewer (-12.1 ± 4.8% vs. -14.4 ± 5.2%, p <0.001) in the HD with BV-UFC than that in the standard HD.ConclusionsHD with BV-UFC did not reduce the prevalence of IDH compared with standard HD. The relief of a relative BV reduction at the end of HD may be beneficial in patients undergoing HD with BV-UFC.Trial RegistrationUMIN, UMIN000024670. Registered on December 1, 2016.

Integrated strategies to prevent intradialytic hypotension: research protocol of the DialHypot study, a prospective randomised clinical trial in hypotension-prone haemodialysis patients

IntroductionIn patients on maintenance haemodialysis (HD), intradialytic hypotension (IDH) is a clinical problem that nephrologists and dialysis nurses face daily in their clinical routine. Despite the technological advances in the...

Investigation of the Effects of Stepwise Sodium and Ultrafiltration Profile on Dialysis Adequacy

Background: One of the leading causes of disability and mortality among patients receiving hemodialysis (HD) is HD inadequacy. Enhancing HD adequacy can improve the prognosis for these patients. Objectives: This study sought to investigate the effects of stepwise sodium and ultrafiltration profile on HD adequacy. Patients and Methods: This crossover clinical trial was conducted on 30 patients, who were receiving HD in two HD centers, affiliated to Isfahan University of Medical Sciences, Isfahan, Iran. Each participant received HD in four routine HD sessions and four stepwise sodium and ultrafiltration profile sessions. Hemodialysis adequacy was calculated online by a software installed on the HD machines. The data were analyzed by conducting the paired-samples t test. Results: The mean of dialyzer urea clearance multiplied by time, divided by volume of distribution of urea (Kt/V) ratio in the routine HD and the stepwise sodium and ultrafiltration profile groups were 1.237 and 1.395, respectively. This difference was statistically significant (P < 0.05). Conclusions: Sodium and ultrafiltration profile maintain hemodynamic stability through adjusting sodium concentration and ultrafiltration and, therefore, they improve HD adequacy, as well as patients’ tolerance to HD. Consequently, replacing routine HD techniques with this technique is recommended.

A physiologically based model of vascular refilling during ultrafiltration in hemodialysis

An assessment of fluid status can be obtained by monitoring relative blood volume (RBV) during hemodialysis (HD) treatment. The dynamics of RBV is determined by fluid removal from the intravascular compartment by ultrafiltration (UF) and vascular refill from the interstitium. To characterize this dynamics, a two-compartment model describing the short-term dynamics of vascular refilling and UF is developed. Fluid movement between the compartments is governed by lymphatic and microvascular fluid shifts. Further, protein flux is described by convection, diffusion and the lymphatic protein flux. Patient specific parameters are identified based on hematocrit (Hct) measurements by the Crit-Line monitor (CLM). Different measurement frequencies and UF profiles are compared to determine data fidelity and influence on the quality of parameter estimates. This relevant information can be used to assess the (patho)physiological status of hemodialysis patients and could aid in individualizing therapy.

Hydrodynamic Analysis of the Miniaturized Hemofilter for a Wearable Ultrafiltration Device

Background/Aims: Using a small wearable hemofiltration device, heart failure (HF) patients may have the possibility of eliminating acute hemodynamic changes and the freedom from spending many hours attached to a large stationary treatment system. Methods: We developed a miniaturized hemofilter for a vest-type wearable ultrafiltration device for the treatment of overhydration and congestive HF. In this study, we investigated the feasibility of the newly developed hemofilter based on dynamic CT imaging and in vitro evaluation of hydrodynamic properties. Results: The dynamic CT imaging technique showed development of uniform flow distribution and effective bubble removal in the hemofilter. Hydrodynamic performance of the hemofilter was also acceptable with a stable pressure drop in the blood compartment and ultrafiltration profiles in the intended operating ranges for the treatment of congestive HF patients. Conclusions: The newly developed miniaturized hemofilter for a wearable ultrafiltration device meets the technical requirements of wearable medical devices and its structural design enables uniform blood flow distribution and stable hydrodynamics during operation.

Numerical Investigation of Ultrafiltration Profiles in Peritoneal Dialysis with Residual Icodextrin in Blood

Icodextrin (ICO) has better biocompatibility and an improved ultrafiltration profile in long-dwell peritoneal dialysis compared to those of glucose. However, the long-term repeated use of a single ICO osmotic agent may cause a change in the peritoneal transport characteristics, leading to a reduction in the ultrafiltration profile. Many studies have shown that such a reduction can be quite significant in some patients. In this study, the factors responsible for this decline are investigated via a series of numerical simulations. The peritoneal transport characteristics and ultrafiltration profile are predicted using a three-pore model. To account for the continuous absorption of ICO from the abdominal cavity during peritoneal dialysis, the three-pore model is modified to accommodate a non-constant concentration of ICO in blood. The simulation results show that the presence of residual ICO in blood results in poorer ultrafiltration behavior. Long-duration and repeated use and exposure to ICO result in a residual concentration of TCO in blood, which changes the mesothelial tissue around the blood capillaries in the peritoneal membrane and causes a reduction in ultrafiltration performance.

Isonatric dialysis biofeedback in hemodiafiltration with online regeneration of ultrafiltrate (HFR): rationale and study protocol for a randomized controlled study

Dialysate sodium prescription has major implications for hemodialysis tolerance but also for dialyzed patients' cardiovascular morbidity as a determinant factor of blood pressure. Biofeedback systems have been developed to drive dialysate conductivity in order to reach a prescribed serum sodium concentration, indirectly evaluated by a dialysate or an ultrafiltrate conductivity measurement. A biofeedback system using hemodiafiltration with online regeneration of ultrafiltrate (HFR) has been specially developed with an isonatric mode maintaining an equal serum sodium concentration between start and end of the dialysis session, combined with ultrafiltration and conductivity profiles. We hypothesized that using this biofeedback in an isonatric mode would have a beneficial effect on blood pressure and dialysis tolerance. The study protocol has been approved by our ethics committee and is presented herein.

Automatic Adaptive System Dialysis for Hemodialysis-Associated Hypotension and Intolerance: A Noncontrolled Multicenter Trial

Hemodialysis is complicated by a high incidence of intradialytic hypotension and disequilibrium symptoms caused by hypovolemia and a decrease in extracellular osmolarity. Automatic adaptive system dialysis (AASD) is a proprietary dialysis system that provides automated elaboration of dialysate and ultrafiltration profiles based on the prescribed decrease in body weight and sodium content. A noncontrolled (single arm), multicenter, prospective, clinical trial. 55 patients with intradialytic hypotension or disequilibrium syndrome in 15 dialysis units were studied over a 1-month interval using standard treatment (642 sessions) followed by 6 months using AASD (2,376 sessions). AASD (bicarbonate dialysis with dialysate sodium concentration and ultrafiltration rate profiles determined by the automated procedure). Primary and major secondary outcomes were the frequency of intradialytic hypotension and symptoms (hypotensive events, headache, nausea, vomiting, and cramps), respectively. More stable intradialytic systolic and diastolic blood pressures with lower heart rate were found using AASD compared with standard treatment. Sessions complicated by hypotension decreased from 58.7% ± 7.3% to 0.9% ± 0.6% (P < 0.001). The incidence of other disequilibrium syndrome symptoms was lower in patients receiving AASD. There were no differences in end-session body weight, interdialytic weight gain, or presession natremia between the standard and AASD treatment periods. A noncontrolled (single arm) study, no crossover from AASD to standard treatment. This study shows the long-term clinical efficacy of AASD for intradialytic hypotension and disequilibrium symptoms in a large number of patients and dialysis sessions.

The Beginning of Icodextrin

Correspondence to: C.D. Mistry, Peterborough District Hospital, Thorpe Road, Peterborough PE3 6DA United Kingdom. chandra.mistry@btopenworld.com Received 27 October 2009; accepted 9 September 2010. In the history of peritoneal dialysis (PD), 1976 marked a significant step forward when Popovich and Moncrief revolutionized the practice by introducing the concept of equilibration PD and extending the duration of dwell time to 4 – 10 hours (1). Despite this fundamental change in the practice of PD, the basic principle used to generate osmotic forces across the peritoneum remained unaltered. This principle relied on the traditional concept of osmotic flow across an “ideal” semipermeable membrane, necessitating making dialysis solution hypertonic to plasma with the addition of glucose as osmotic agent. Unfortunately, not being an “ideal” semipermeable membrane but being partially permeable to solutes, the peritoneum allows rapid absorption of glucose with progressive dissipation of the osmotic gradient and ultrafiltration of short duration. While this is of little significance during short dwell exchanges (30 – 60 minutes’ dwell in intermittent PD), it is not the case for long exchanges, such as in continuous ambulatory PD (CAPD) and automated PD, where reabsorption of initially ultrafiltered peritoneal fluid occurs. In addition, the continuous daily absorption of glucose aggravates longterm metabolic complications, including hyperlipidemia and obesity (2,3). Even as early as the 1980s there was clear recognition for an alternative osmotic agent that would minimize metabolic derangements and provide the ultrafiltration profile to suit long dwell exchanges. A range of different macromolecules was evaluated based on the simplistic concept that large molecular weight (MW) agents are less readily absorbed through the peritoneum and are likely to produce sustained ultrafiltration while reducing metabolic complications. Early investigations clearly identified the problems associated with use of nonphysiological hyperviscous macromolecules and defined the need for a neutral substance that is soluble, nonallergenic, and readily metabolized (3). Glucose polymer (GP), derived from hydrolyzed cornstarch, seemed a natural contender and several groups already held patents of diverse MW fractions. Among them, the Abbott group led the way by studying a narrow MW fraction (MW 1000 Da) in both animals (4) and humans (5). In Manchester, we were well placed to explore the potential of this novel agent as considerable experience had been developed while investigating GP (Caloreen) as an intravenous high-energy nutrient source in the management of patients with renal (6) and hepatic failure (7). We worked closely in collaboration with Jerry Milner, the holder of the patent for Caloreen, Fisons Pharmaceutical, who had established expertise in fractionating GP technology, and J. Fox, Department of Biochemistry, University of Birmingham, who had extensive experience in methods of carbohydrate analysis. For the initial clinical studies carried out in July 1983, we utilized a readily available dextrin formulation (Caloreen) with a bimodal MW distribution consisting of a 67% “low” MW fraction (chain length 12 glucose units); weight average MW (Mw) was 7000 Da and number average MW (Mn) was 960 Da. In contrast to glucose solution, predicting osmotic performance of a polydisperse GP sample with a relatively unknown peritoneal permselectivity proved difficult. Our preliminary studies suggested that 5% (52 mmol/L) and 10% (104 mmol/L) GP solutions were probably comparable to 1.36% (76 mmol/L) and 3.86% (214 mmol/L) glucose respectively (8). The first formal Phase 1 study, using solutions containing 5% (52 mmol/L) and 10% (104 mmol/L) of this GP formulation over a 6-hour dwell, was exciting and

A numerical simulation for mass transfer through the porous membrane of parallel straight channels

In this paper, by adopting a “half-channel” model, a mass exchange process (presented in the therapy of hemodialysis) between two opposite running flows is numerically simulated. The flows are confined inside channels and separated by intercalary porous membranes. In the simulation, two types of flows, channel flow and ultra-filtration flow, are physically described, respectively, by Navier–Stokes equations and Kedem–Katchalsky (K–K) equations. By further adopting “SimpleR” algorithm, the velocity fields inside the channels are determined, meanwhile, solute mass distributions are predicted by concentration equation. The solid computation in this paper perfectly explored the process of hemodialysis, its results: (1) displayed the flow and solute distribution patterns inside channels; (2) described the ultra-filtration profiles along the surface of the porous membrane; and (3) disclosed an existent nano-scale reverse osmosis problem.

Changes in Red Blood Cell Size and Red Cell Fragmentation during Hemodialysis

Intradialytic hypotension remains the commonest complication for outpatient hemodialysis. The majority of relative blood volume (RBV) monitoring techniques monitor changes in hematocrit. As hematocrit can potentially be affected by changes in red cell size and hemolysis we studied the change in red blood cell size (MCV) during dialysis and hemolysis. MCV was prospectively measured in 176 stable regular adult hemodialysis outpatients (56% male, 27.8% diabetic, mean age 59.5 ±16.2 years) dialyzing against a range of dialysate sodiums (136-145 mmol/L), with cooled dialysate (35-36°C), containing 1 g/L glucose, with constant ultrafiltration profiles. Red cell fragmentation was studied in 41 of the cohort. Logistical regression analysis showed that the absolute change in MCV was related to the change in hematocrit (F=4.92, β=0.111, p=0.031), and inversely with red cell shrinkage associated with predialysis osmolality (F=5.06, β=0.83, p=0.029), and dialysate sodium (F=4.7, β=0.34, p=0.035). There was no significant increase in red cell fragments during the dialysis sessions. Indirect assessment of RBV based upon the relative change in hematocrit, depends not only upon the change in plasma water and red blood cell numbers, but also upon MCV. Changes in MCV may theoretically lead to potential effects on RBV measurements.

The Variability in Ultrafiltration Achieved with Icodextrin, Possibly Explained

A recent study by Jeloka et al. (Perit Dial Int 2006; 26:336-40) highlighted the high variability in maximum ultrafiltered volume (UF(max)) and the corresponding dwell time (t(max)) obtained using 7.5% icodextrin solution. We aimed to pinpoint the possible sources of this phenomenon by simulating the icodextrin ultrafiltration (UF) profiles according to the three-pore model of peritoneal transport. The individual UF time courses observed in the study by Jeloka et al. (n = 29) were first characterized by linear and quadratic regression. We were then able to identify four main patterns. These were then adapted to UF profiles generated by the three-pore model by systematically altering the values of some model parameters, namely, the mass transfer area coefficient (MTAC or PS) for icodextrin/glucose, the peritoneal UF coefficient (LpS), the plasma colloid osmotic pressure gradient (DeltaPi), and the macromolecular clearance out of the peritoneal cavity (Cl(LF)). Modifications in the PS values caused only marginal variations in UF(max) and t(max), while more significant changes were produced by altering LpS and Cl(LF). However, far more evident was the importance of changes in DeltaPi. In fact, lowering DeltaPi to 14 mmHg caused a steady increase in UF with 10 - 14 hour dwells. On the contrary, the UF profiles became nearly "flat" when DeltaPi was increased to 30 mmHg. The parallel shifts induced by altering icodextrin metabolite concentrations did not markedly influence UF(max) or t(max). The UF pattern in icodextrin dwells seem to be mainly determined by the plasma colloid osmotic pressure, while only moderate changes can be seen with alterations in LpS and Cl(LF). The result is not completely unexpected considering that icodextrin acts by inducing a strong colloid osmotic gradient. A number of clinical studies would be needed, however, in order to prove this hypothesis.

An approximate analytical solution to the ultra-filtration profile in a hemodialysis process between parallel porous plates

In a hemodialysis process, the blood that runs through straight channels exchanges substances with the dialysate through a semi-permeable membrane. The waste products, such as urea and creatinine, are therefore removed from the plasma by the membrane. In the analysis of this process, determination of the ultra-filtration profile along the porous membrane surface remains a difficult problem. In this work, an analytical solution to the derivation of such a profile was detailed, and the feasibility of this solution was discussed. The ultra-filtration profile was found to be in a cosine shape.

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

Evaluating methods for improving ultrafiltration in pediatric hemodialysis

Adequate ultrafiltration (UF) is necessary for good health, but it can be hindered by the development of intradialytic symptoms and hypotension. To determine whether sodium ramping, UF profiles and mannitol could improve UF in children, we instituted a standardized prescription for chronic hemodialysis in our unit. We prospectively analyzed 506 treatments from ten patients. Ultrafiltration volumes up to 9.7% of dry weight were obtained with an overall mean of 5.4%. Mannitol reduced the risk of intradialytic symptoms by 64% (p < 0.05) with a mean UF volume of 6.2%. Step sodium ramping from 148-138 mmol/l reduced the odds of intradialytic symptoms (p = 0.1) and hypotension (p < 0.05) with no difference in the mean UF compared with linear profiles. All UF profiles were associated with an increased risk of intradialytic symptoms, but the effect was only statistically significant with profile 2 (stepwise UF reduction). Overall intradialytic morbidity occurred in 10% of the treatments. Notwithstanding the study limitations, UF volumes higher than traditional recommendations of 5% of the dry weight were achieved with the use of mannitol and 148-138 mmol/l sodium ramping. Despite this, the desired dry weight was not achieved in 66% of our treatments. No clear benefit was seen with UF profiles.