High Ultrafiltration Research Articles

Peritoneal Dialysis Tailored to Pediatric Needs

Consideration of specific pediatric aspects is essential to achieve adequate peritoneal dialysis (PD) treatment in children. These are first of all the rapid growth, in particular during infancy and puberty, which must be accompanied by a positive calcium balance, and the age dependent changes in body composition. The high total body water content and the high ultrafiltration rates required in anuric infants for adequate nutrition predispose to overshooting convective sodium losses and severe hypotension. Tissue fragility and rapid increases in intraabdominal fat mass predispose to hernia and dialysate leaks. Peritoneal equilibration tests should repeatedly been performed to optimize individual dwell time. Intraperitoneal pressure measurements give an objective measure of intraperitoneal filling, which allow for an optimized dwell volume, that is, increased dialysis efficiency without increasing the risk of hernias, leaks, and retrofiltration. We present the concept of adapted PD, that is, the combination of short dwells with low fill volume to promote ultrafiltration and long dwells with a high fill volume to improve purification within one PD session. The use of PD solutions with low glucose degradation product content is recommended in children, but unfortunately still not feasible in many countries.

Characterization of chromophoric organic matter in effluent from Vitamin C wastewater anaerobic-aerobic treatment

Chroma is not effectively removed from Vitamin C (VC) wastewater by traditional anaerobic-aerobic treatment. This means current treatment does not meet the strict new discharge standard for VC wastewater in China. However, to date, no studies have investigated the removal of chroma from VC wastewater, or characterized the chromophoric organic matter in wastewater. In this study, choromophoric organic matter in effluent from anaerobic-aerobic treatment of Vitamin C wastewater was characterized using high performance gel permeation chromatography (HPGPC), ultrafiltration, and infrared (IR) and ultraviolet-visible (UV/Vis) spectroscopy. Routine water-quality indices were determined, and indicated that the organic matter in the effluent contained nitrogen. The molecular weight of most organic matter in this effluent was below 1000 Da, while the remainder was between 1000–3000 Da. These compounds are likely biodegradation products of high molecular weight organic matter in the effluent, which are raw materials and byproducts from VC production. IR spectra indicated that the low molecular weight (<1000 Da) organic matter and higher molecular weight (1000–3000 Da) organic matter contain similar major functional groups, including -OH, -NH2, -CO-NH2, -C=O-, and -COO−. The effluent was treated using electrolysis, and UV/Vis spectra of this effluent before and after electrolysis indicated that -C=O is an important chroma group in this effluent. Electrolysis can easily break -C=O, and provides a feasible technology for the advanced treatment of anaerobic-aerobic effluent from VC wastewater treatment.

Permeability performance of different molecular weight cellulose acetate hemodialysis membrane

Dialysis membranes were casted from solutions containing 20 wt.% cellulose acetate (CA), various concentrations of monosodium glutamate (MSG) and formic acid. Effect of MSG and different molecular weights of cellulose acetate on membrane permeability was investigated. As the MSG concentration increased from 2 wt.% to 6 wt.%, the uremic toxins permeability was enhanced, but further increase beyond this point did not improve the permeability performance. Similar separation trend was observed regardless of the CA molecular weight used, but membranes produced form high molecular weight CA membrane exhibit better uremic toxic permeability. SEM images illustrated that MSG influences the membrane thickness and macrovoids formation, while high molecular weight CA tends to suppress the size of the macrovoids. MSG also tends to reduce the membrane resistance promoting the formation of porous structure and thus explained for high ultrafiltration rate (UFR). In order to gain more insight on the influence of both MSG and molecular weight of CA on membrane properties, the membrane surfaces were analysed using Attenuated Total Reflection Fourier Transform Infrared (ATR-FTIR), contact angle measurement (CAM), atomic force measurement (AFM). In addition, mechanical test and thermal stability studies were performed in this study to evaluate the strength of the membranes. In short, MSG and high molecular weight CA played crucial roles in enhancing the separation performance.

Study of the pilot production process of long-circulating and pH-sensitive liposomes containing cisplatin

Long-circulating and pH-sensitive liposomes, containing cisplatin (SpHL-CDDP), have been developed as an alternative aimed at avoiding severe side effects as well as the appearance of resistance, which can limit the use of free cisplatin. However, physical (i.e., aggregation/fusion) and chemical instabilities limit the use of these drug carriers as pharmaceutical products. The preparation of freeze-dried pharmaceuticals has proven to be a successful strategy implemented to improve the stability of these formulations. In addition, the development of an economically feasible, reproducible process of liposome production, on a large scale, has also become necessary. A pilot production process, using three stages (i.e., reverse-phase evaporation, homogenization under high pressure, and ultrafiltration), was used to prepare SpHL-CDDP. The optimization of factors related to the homonogenization under high pressure (i.e., pressure and number of cycles), ultrafiltration (i.e., number of cycles), and storage stability at 4°C were assessed by means of particle size, zeta potential, and encapsulation percentage. A 500-bar pressure and 9 cycles were adopted as measures for the production of SpHL-CDDP, which presented a mean diameter of 99.0 ± 3.9 nm and an encapsulation percentage of 12.9 ± 2.3. The use of trehalose as a cryoprotectant was investigated, regarding its effective ability to control the vesicle diameter and retain encapsulated CDDP after the freeze-drying/rehydration step. After 135 days of storage, freeze-dried or liquid SpHL-CDDP showed no significant change in mean diameter. However, the freeze-dried SpHL-CDDP proved to be more efficient, in terms of CDDP retention, than did the liposomal liquid dispersion.

A comparative study of the performance behaviour of adsorbent materials used for the treatment of Spent Cutting Fluids

The high cost ultra-filtration methods normally employed for the treatment of Spent Cutting Fluids (SCFs) has forced to develop effective technology for environmental pollution management. The authors have proposed the use of agro based products such as arhar stem (cajanus cazan), rice husk, bagasse and saw dust in modified and unmodified form as adsorbents for removal of oil from water based SCFs, replacing costly activated carbon. Analytical Hierarchy Process (AHP) was applied and the results were used to select and grade the adsorbents. The results have also been compared with the experimental results of the batch adsorption studies.

Sodium Profiling, But Not Cool Dialysate, Increases the Absolute Plasma Refill Rate During Hemodialysis

Intradialytic hypotension is often caused by a discrepancy between ultrafiltration and plasma refilling. Increasing the plasma refill rate could therefore reduce intradialytic hypotension. We used a recently developed method to measure the effect of cool dialysate and sodium (Na) profiling on refill during hemodialysis (HD). Using a Gambro AK200 with blood volume (BV) sensor plus computer-guided external pump, a high ultrafiltration rate quickly induced a preset BV reduction. A software feedback mechanism subsequently adjusted the ultrafiltration rate continuously to maintain BV between very narrow preset boundaries. The continuously changing, software-generated ultrafiltration rate then quantitatively equalled refill. Absolute plasma refill rate was measured in six stable patients without intradialytic hypotension, undergoing HD without intervention, with cool dialysate (1 degrees C below core temperature), and with Na profiling (gradually declining from 150 to 140 mmol/l). Baseline refill rate was 20.1 + or - 4.0 ml/min (mean + or - SD). Although cool dialysate did not affect refill (22.2 + or - 4.1 ml/min, p = 0.27 vs. baseline), Na profiling induced a significant improvement (26.8 + or - 3.7 ml/min, p = 0.006 vs. baseline). Using our method to measure absolute plasma refill rate during HD, we demonstrated that Na profiling indeed improves the plasma refill rate. A potential effect of cool dialysate could not be established.

Effects of acute variation of dialysate calcium concentrations on arterial stiffness and aortic pressure waveform

Background. Abnormal mineral metabolism in chronic kidney disease plays a critical role in vascular calcification and arterial stiffness. The impact of presently used dialysis calcium concentration (DCa) on arterial stiffness and aortic pressure waveform has never been studied. The aim of the present study is to evaluate, in haemodialysis (HD) patients, the impact of acute modification of DCa on arterial stiffness and central pulse wave profile (cPWP).Method. A randomized Latin square cross-over study was used to evaluate the three different concentrations of DCa (1.00, 1.25 and 1.50 mmol/L) during the second HD of the week for 3 consecutive weeks. Subjects returned to their baseline DCa for the following two treatments, allowing for a 7-day washout period between each experimental HD. cPWP, carotido-radial (c-r) and carotido-femoral (c-f) pulse wave velocities (PWV), plasma level of ionized calcium (iCa) and intact parathyroid hormone (PTH) were measured prior to and immediately after each experimental HD session. Data were analysed by the general linear model for repeated measures and by the general linear mixed model.Results. Eighteen patients with a mean age of 48.9 ± 18 years and a median duration of HD of 8.7 months (range 1–87 months) completed the study. In post-HD, iCa decreased with DCa of 1.00 mmol/L (−0.14 ± 0.04 mmol/L, P < 0.001), increased with a DCa of 1.50 mmol/L (0.10 ± 0.06 mmol/L, P < 0.001) but did not change with a DCa of 1.25 mmol/L. Tests of within-subject contrast showed a linear relationship between higher DCa and a higher post-HD Δc-f PWV, Δc-r PWV and Δmean BP (P < 0.001, P = 0.008 and P = 0.002, respectively). Heart rate-adjusted central augmentation index (AIx) decreased significantly after HD, but was not related to DCa. The timing of wave refection (Tr) occurred earlier after dialysis resulting in a linear relationship between higher DCa and post-HD earlier Tr (P < 0.044). In a multivariate linear-mixed model for repeated measures, the percentage increase in c-f PWV and c-r PWV was significantly associated with the increasing level of iCa, whereas the increasing level of ΔMBP was not significant. In contrast, the percentage decrease in Tr (earlier wave reflection) was determined by higher ΔMBP and higher ultrafiltration, whereas the relative change in AIx was inversely determined by the variation in the heart rate and directly by ΔMBP.Conclusion. We conclude that Dca and acute changes in the serum iCa concentration, even within physiological range, are associated with detectable changes of arterial stiffness and cPWP. Long-term studies are necessary to evaluate the long-term effects of DCa modulation on arterial stiffness.

Sustained Low Efficiency Dialysis in the Continuous Mode (C-SLED)

Oliguric, hypotensive patients who require large amounts of fluids may benefit from sustained low-efficiency dialysis performed continuously (C-SLED). C-SLED through higher clearance may improve survival, or through greater nutritional loss may worsen survival. No studies have assessed survival on C-SLED. The objective was to examine patient outcomes and survival predictors on C-SLED. The data of 199 consecutive cancer patients treated with C-SLED were analyzed. The median duration of C-SLED was 50 h. With 48 h of C-SLED, the blood urea nitrogen (BUN) and serum creatinine levels had decreased by 80% and 73%, respectively. The mean arterial pressure (MAP) was maintained despite higher ultrafiltration and reduced vasopressor use. The 30-d mortality rate was 65%. Despite excellent dialysis, the sequential organ failure assessment (SOFA) score remained predictive of mortality. In the univariate model, higher SOFA scores and lower values for MAP, blood pH, and serum albumin and creatinine levels were associated with higher mortality. Administration of total parenteral nutrition (TPN) was, however, associated with lower mortality. In the multivariate model, the higher SOFA score and lower blood pH, MAP and C-SLED duration were associated with higher mortality. In a subset analysis of 129 patients who received C-SLED for at least 48 h, those with higher BUN levels, which were associated with higher TPN infusion, had a lower mortality risk. This first detailed report on C-SLED indicates that C-SLED can be effective and suggests a link between nutrition and survival.

Middle-Molecule Clearance in CRRT: In Vitro Convection, Diffusion and Dialyzer Area

Several studies have attempted to compare different doses and modes of therapy in continuous renal replacement therapies in critically ill patients. It is commonly asserted in the literature that convective therapies can achieve higher clearance of middle molecules than achieved by dialysis alone. However, regardless of the actual prescription, most therapies will actually contain a mixture of both diffusive and convective clearance. Molecular transport in purely convective prescriptions may be hindered by clotting and protein interactions with the dialyser. We measured middle molecule clearance using a tracer molecule, Ficoll, in citrated bovine blood. Using a 2 x 2 factorial design, we examined the impact of prescription [postdilution continuous venovenous hemofiltration (CVVH) vs. continuous venovenous hemodialysis (CVVHD)] and membrane area (0.4 m2 vs. 2.0 m2) on blood-side and dialysate-side middle-molecule clearance. In large dialysers, convective and diffusive prescriptions resulted in nearly identical middle molecule clearance from 10 to 100 kDa molecular weight. In the smaller dialyser, middle molecule clearance was higher when a diffusive therapy (CVVHD) was prescribed versus a convective therapy (postdilution CVVH). We hypothesized that high ultrafiltration rates in the smaller dialyzer resulted in a concentration polarization at the membrane that formed a prefilter, limiting middle-molecule clearance. This effect has implications for design and analysis of clinical trials of continuous renal replacement therapy (CRRT).

L’hémofiltration en cascade : principe, premières données expérimentales

High-volume hemofiltration has been suggested as an adjuvant treatment of septic shock (renal support and immunomodulation of the host response via the removal of middle molecular weight molecules such as cytokines). Nevertheless, high-volume hemofiltration presents some important drawbacks, such as the depletion of low molecular weight molecules (nutriments, vitamins, trace elements and antibiotics) due to the high ultrafiltration rate, or the significant financial cost and nursing workload. We describe cascade hemofiltration, a new high-volume hemofiltration system, which has been developed to limit these drawbacks by using a special extracorporeal circuit. Results of the first experimental study using this prototype are also reported. They demonstrate the technical feasibility, security and safety of the cascade system although other experimental and clinical studies are needed to continue evaluating this system.

How Does Higher Ultrafiltration within the Conventional Clinical Range Impact the Volume Status of Hemodialysis Patients?

Aims: The higher ultrafiltration (UF) induces poor outcomes. The impact of higher UF on the volume status was investigated. Methods: 60 hemodialysis (HD) patients were divided into three groups according to the ratio of total UF to post-dialysis body weight (TUF/PDW) (<3%, 3–5%, ≥5%). ANP, the ratio of extracellular water to total body water and excess fluid mass (ExF/PDW) by bioimpedance spectroscopy, inferior vena cava diameter by ultrasound were measured at the end of HD. The ratio of post-HD blood volume to pre-HD (BVpost/BVpre) and standardized filtration coefficients (Lpst) of the microvasculature in the vicinity of PDW were calculated. Results: Only Lpst and BVpost/BVpre showed significant differences among the three groups. A stepwise multiple linear regression model revealed that BVpost/BVpre was correlated with TUF/PDW, ExF/PDW and Lpst (R = 0.778, p < 0.001), independently. Conclusion: Higher UF causes decreases in BVpost/BVpre and Lpst. BVpost/BVpre was determined by TUF/PDW, ExF/PDW and Lpst.

Hemofiltration With the Cascade System in an Experimental Porcine Model of Septic Shock

High-volume hemofiltration (HVHF) has been suggested as an adjuvant treatment of septic shock because of its capacities to remove inflammatory mediators from blood. Nevertheless, HVHF presents some important drawbacks, such as the depletion of low molecular weight molecules (nutriments, vitamins, trace elements and antibiotics) due to the high ultrafiltration rate, or the significant financial cost and nursing workload due to the frequent changes of large amounts of expensive sterile substitution fluids. A new hemofiltration system called "Cascade" has been developed, allowing very high ultrafiltration rates (120 mL/kg/h) limiting these drawbacks by using a special extracorporeal circuit. The objective of this study was to assess the technical feasibility of the Cascade system and to compare its hemodynamic impact to that of the standard HVHF system. Twenty sepsis-induced pigs were randomized in two groups: one group was hemofiltered with the standard HVHF system and the other with the Cascade system during a six-hour session. No technical problems were observed with the Cascade system during the experiment. At the end of the experiment, colloid requirements (989 +/- 355 mL vs. 1913 +/- 538 mL, P = 0.006), epinephrine requirements (0.82 +/- 0.42 mg vs. 3.27 +/- 3.02 mg, P < 0.001), lactic acidosis (pH = 7.33 +/- 0.08 vs. 7.10 +/- 0.07, P < 0.001) and mean pulmonary arterial pressure were less pronounced in the Cascade group. These results suggest that Cascade hemofiltration is technically feasible and safe. Moreover, compared with standard HVHF, it can reduce the severity of porcine septic shock.

Dialysis Unphysiology and Sodium Balance

Dialysis unphysiology was first discussed by Carl Kjellstrand in 1975 for the possible negative effects of the unphysiology of intermittent dialysis treatment. Current hemodialysis practices are still unphysiologic because they cannot keep blood chemistries within normal limits, both before and after dialysis. In addition, the discontinuous nature of hemodialysis causes saw-tooth volume fluctuations, and the extracellular fluid volume expansion during the interdialytic period may lead to hypertension and adverse cardiovascular consequences. Sodium, which is accumulated over the interdialytic period, may be divided into two fractions. The one is the fraction of osmotically active sodium which is mainly confined to the extracellular space, and the other is that of water-free (osmotically inactive) sodium which diffuses into the intracellular space. Both contribute to the pathogenesis of hypertension because the former may act to expand extracellular fluid volume and the latter may cause vasoconstriction in the long run by increasing cytosolic concentration of calcium in the vascular smooth muscle cells. Even in intensive hemodialysis, it may take several weeks to months for water-free sodium storage in the vascular smooth muscle cells to be relieved. This may be an explanation for the lag phenomenon, i.e., the delay of blood pressure decrease after normalization of extracellular fluid volume shown in the Tassin experience. Modest restriction of dietary sodium intake, the dialytic session length long enough to maintain a high ultrafiltration volume, and the reasonably low dialysate sodium concentration are required to avoid unphysiology of positive sodium balance in current hemodialysis practice.

Coagulation pretreatment for a large-scale ultrafiltration process treating water from the Taihu River

A large-scale ultrafiltration (UF) system integrated with coagulation was applied to produce drinking water from the highly turbid Taihu River. This UF installation could produce 10,000 m 3 drinking water per day. In this study, the effect of FeCl 3 coagulant on the performance of the UF system was evaluated. Results showed that with the integration of coagulation, not only qualified drinking water was obtained from the high turbidity raw water, but also high UF specific flux was maintained, ca.190 200 L/m 2·hr·bar, and the chemical cleaning period was largely prolonged. The natural organic matter removal mechanism by coagulation was also discussed.

Association of higher ultrafiltration rates and increased creatinine levels during ultrafiltration in decompensated heart failure

Association of higher ultrafiltration rates and increased creatinine levels during ultrafiltration in decompensated heart failure

In vitro bicarbonate and urea kinetics during hemodialysis and online hemodiafiltration

Hemodiafiltration (HDF) associates the diffusive toxin removal of hemodialysis (HD) with the convective transfer toxins at a high ultrafiltration flow rate which is more efficient for large molecul...

Toxic metal ion separation by cellulose acetate/sulfonated poly(ether imide) blend membranes: Effect of polymer composition and additive

Toxic heavy metal ion removal from industrial effluents are gaining increased visibility owing to environmental concern and saving precious materials. In this work, an attempt has been made to remove the valuable metal ions using modified ultrafiltration (UF) blend membranes based on cellulose acetate (CA) and sulfonated poly(ether imide) (SPEI) were prepared in the presence and absence of additive, poly(ethylene glycol) 600 (PEG600) in various compositions. Prepared membranes were characterized in terms of pure water flux (PWF), water content and membrane hydraulic resistance. High flux UF membranes were obtained in the range of 15–25 wt% SPEI and 2.5–10 wt% PEG600 in the polymer blend. The molecular weight cut-off (MWCO) of the blend membranes were determined using protein separation studies found to vary from 20 to greater than 69 kDa. Surface morphology of the blend membranes were analysed with scanning electron microscopy. Studies were carried out to find the rejection and permeate flux of metal ions such as Cu(II), Ni(II), Zn(II) and Cd(II) using polyethyleneimine as the chelating ligand. On increasing the composition of SPEI and PEG600, the rejection of metal ions is decreasing while the permeate flux has an increasing trend. These effects are due to the increased pore formation in the CA/SPEI blend membranes because of the hydrophilic SPEI and polymeric additive PEG600. In general, it was found that CA/SPEI blend membranes displayed higher permeate flux and lower rejection compared to pure CA membranes. The extent of separation of metal ions depends on the affinity of metal ions to polyethyleneimine to form macromolecular complexes and the stability of the formed complexes.

Femoral Localization and Higher Ultrafiltration Rate but Not Concentration of Heparin Used for Canal Locking of Hemodialysis Catheter Are Negative Predictors for Its Malfunction

Background/Aim: Non-tunneled, temporal hemodialysis (HD) catheters are commonly used as short-term vascular access for the HD procedure. One of their late complications is thrombotic occlusion of the catheter ensuing in their malfunction. A heparin lock is conventionally used for maintaining the patency of the catheter. The aim of the study was to evaluate the influence of heparin concentration used for locking the catheter canals (5,000 vs. 2,500 IU/ml) and some other clinical and laboratory variables at the time of temporal HD catheter functioning. Methods: Catheter malfunction was defined as the inability to attain and maintain a blood flow of at least 150 ml/min. 174 consecutive HD catheters inserted into jugular or femoral veins (114 patients) were followed up and remained in use for a total of 3,284 days. Results: Catheter thrombosis occurred in 53 cases (30.5%) during the study period, giving an overall rate of 16 episodes per 1,000 catheter-days at risk. In univariate Cox proportional hazard analysis, predictors of catheter dysfunction were: femoral localization (HR 4.92, 95% CI 4.30–5.50), acute renal failure (HR 1.75, 95% CI 1.18–2.32), higher mean ultrafiltration (UF) (HR 1.31, 95% CI 0.99–1.63) and higher concentration of hemoglobin (HR 1.15, 95% CI 0.99–1.33). The concentration of heparin used for canal locking did not influence the time of catheter functioning (HR 1.1, p = 0.7). In multivariate Cox proportional hazard analysis (χ² = 38.5, d.f. = 4, p < 0.0001) the remaining statistically independent predictors of catheter malfunction were: femoral localization (HR 5.94, 95% CI 5.27–6.61, p < 0.0001) and higher UF (HR 1.60, 95% CI 1.24–1.94, p < 0.01). Conclusions: A lower concentration of heparin (2,500 IU/ml) prevents catheter thrombosis as effectively as a standard one (5,000 IU/ml). Femoral localization of HD catheters and higher UF during the HD procedure are the factors predisposing for catheter malfunction.

Icodextrin produces higher ultrafiltration in diabetic than in non-diabetic patients on continuous cyclic peritoneal dialysis

A preliminary report from our unit previously suggested that diabetic patients on continuous cyclic peritoneal dialysis (CCPD) have higher ultrafiltration (UF) with icodextrin than non-diabetic patients. To confirm this observation, we did a retrospective analysis of our patients (17 diabetic and 23 non-diabetic) who were on stable CCPD prescription using a long-day dwell with icodextrin. We collected daily UF data from these patients' records for 30 days. The two groups showed no significant difference with respect to age, gender, hemoglobin, serum albumin, peritoneal dialysis and icodextrin vintage, peritoneal membrane characteristics, CCPD prescription, and peritoneal and residual renal clearance. The overnight net UF achieved with the cycler with standard glucose dialysate was similar in the two groups (850+/-379 in diabetic vs 713+/-484 ml/day in non-diabetic, P=0.34). However, UF with icodextrin during the day dwell (14.8+/-0.8 h) was significantly higher in diabetics than non-diabetics (348+/-198 vs 137+/-311 ml/day, P=0.02). Our results show that icodextrin produces significantly higher UF in long-day dwell in diabetic ESRD patients on CCPD than in non-diabetic patients. The reason for this difference is not clear.

Association between high ultrafiltration rates and mortality in uraemic patients on regular haemodialysis. A 5-year prospective observational multicentre study

High ultrafiltration rate on haemodialysis (HD) stresses the cardiovascular system and could have a negative effect on survival. The effect of ultrafiltration rate (UFR; ml/h/kg BW) on mortality was prospectively evaluated in a cohort of 287 prevalent uraemic patients in regular HD from 1 January 2000 to 31 December 2005. 165 men and 122 women, age 66 +/- 13 years, on regular HD for at least 6 months, median: 48 months (range 6-372 months). Mean UFR was 12.7 +/- 3.5 ml/h/kg BW, Kt/V: 1.27 +/- 0.13, body weight (BW): 62 +/- 13 kg, PCRn: 1.11 +/- 0.20 g/kg/day, duration of dialysis: median 240 min (range 180-300 min), mean arterial blood pressure (MAP) 99 +/- 9 mm/Hg. One hundred and forty nine patients (52%) died, mainly for cardiovascular reasons (69%). Multivariate Cox regression analysis was utilized to evaluate the effect on mortality of UFR, age, sex, dialytic vintage, cardiovascular disease (CVD), diabetes, dialysis modality, duration of HD, BW, interdialytic weight gain (IWG), body mass index (BMI), MAP, pulse pressure (PP), Kt/V, PCRn. Age (HR 1.06; CI 1.04-1.08; P < 0.0001), PCRn (HR 0.17, CI 0.07-0.43; P < 0.0001), diabetes (HR 1.81, CI 1.24-2.47; P = 0.007), CVD (HR 1.86; CI 1.32-2.62; P = 0.007) and UFR (HR 1.22; CI 1.16-1.28; P < 0.0001) were identified as factors independently correlated to survival. We estimated the discrimination potential of UFR, evaluated at baseline, in predicting death at 5 years, calculating the relative receiver operating characteristic (ROC) curves and the cut-off that minimizes the absolute difference between sensitivity and specificity. High UFRs are independently associated with increased mortality risk in HD patients. Better survival was observed with UFR < 12.37 ml/h/kg BW. For patients with higher UFRs, longer or more frequent dialysis sessions should be considered in order to prevent the deleterious consequences of excessive UFR.