Low Dialysate Flow Research Articles

#2567 Protein-bound uremic toxins are better removed with short-daily Home Haemodialysis using low dialysate flow rate: randomized clinical trial results

Abstract Background and Aims Short daily home hemodialysis (HDD) with low dialysate flow rate has been shown in recent years as an attractive alternative for portable dialysis home use. Although the effectiveness of the technique for volume control and elimination of small solutes and middle molecules has been demonstrated, data are scarce for the elimination of protein-bound uremic toxins. The aim of this study was to compare the reduction ratios (RRs) of p-cresol sulfate (pCS) and indoxyl sulfate (IS) in the Physidia HHD system with high-volume online-hemodiafiltration (OL-HDF) treatment. Methods In an open, randomized, cross-over, single-center, controlled study, 40 adult chronic HD patients were treated with a 2.5 h-length HD session with low dialysate flow rate with the Physidia HDD system, and a 4 h-length OL-HDF session in post-dilution mode during two successive weeks. During the sessions, pre-HD and post-HD plasma samples were collected and single and weekly RRs of pC and IS were intraindividually compared for the two dialysis types with linear mixed models. Results Whereas single-session RRs of p-CS and IS were similar in both groups, weekly RRs of both protein-bound uremic toxins were significantly higher with the short-daily HDD Physida system than those obtained with OL-HDF (Table 1). Conclusion The short-daily home hemodialysis using low dialysate flow rate with the Physidia system appears to be a potential technologic step ahead in terms of improved protein-bound uremic toxins removal for dialysis patients, and might contribute to a more adequate dialysis therapy than in-center high-volume online-hemodiafiltration (OL-HDF) treatment.

Quantitative monitoring and modelling of retrodialysis drug delivery in a brain phantom

A vast number of drug molecules are unable to cross the blood-brain barrier, which results in a loss of therapeutic opportunities when these molecules are administered by intravenous infusion. To circumvent the blood-brain barrier, local drug delivery devices have been developed over the past few decades such as reverse microdialysis. Reverse microdialysis (or retrodialysis) offers many advantages, such as a lack of net volume influx to the intracranial cavity and the ability to sample the tumour’s micro-environment. However, the translation of this technique to efficient drug delivery has not been systematically studied. In this work, we present an experimental platform to evaluate the performance of microdialysis devices in reverse mode in a brain tissue phantom. The mass of model drug delivered is measured by computing absorbance fields from optical images. Concentration maps are reconstructed using a modern and open-source implementation of the inverse Abel transform. To illustrate our method, we assess the capability of a commercial probe in delivering methylene blue to a gel phantom. We find that the delivery rate can be described by classical microdialysis theory, except at low dialysate flow rates where it is impacted by gravity, and high flow rates where significant convection to the gel occurs. We also show that the flow rate has an important impact not only on the overall size of the drug plume, but also on its shape. The numerical tools developed for this study have been made freely available to ensure that the method presented can be used to rapidly and inexpensively optimise probe design and protocol parameters before proceeding to more in-depth studies.

Removal of Uremic Solutes from Dialysate by Activated Carbon.

Adsorption of uremic solutes to activated carbon provides a potential means to limit dialysate volumes required for new dialysis systems. The ability of activated carbon to take up uremic solutes has, however, not been adequately assessed. Graded volumes of waste dialysate collected from clinical hemodialysis treatments were passed through activated carbon blocks. Metabolomic analysis assessed the adsorption by activated carbon of a wide range of uremic solutes. Additional experiments tested the ability of the activated carbon to increase the clearance of selected solutes at low dialysate flow rates. Activated carbon initially adsorbed the majority, but not all, of 264 uremic solutes examined. Solute adsorption fell, however, as increasing volumes of dialysate were processed. Moreover, activated carbon added some uremic solutes to the dialysate, including methylguanidine. Activated carbon was particularly effective in adsorbing uremic solutes that bind to plasma proteins. In vitro dialysis experiments showed that introduction of activated carbon into the dialysate stream increased the clearance of the protein-bound solutes indoxyl sulfate and p-cresol sulfate by 77%±12% (mean±SD) and 73%±12%, respectively, at a dialysate flow rate of 200 ml/min, but had a much lesser effect on the clearance of the unbound solute phenylacetylglutamine. Activated carbon adsorbs many but not all uremic solutes. Introduction of activated carbon into the dialysate stream increased the clearance of those solutes that it does adsorb.

MO661: Elimination of Middle and Large Uraemic Toxins in Short Daily Home Haemodialysis with Low Dialysate Volume: A Randomized Crossover Clinical Trial

Abstract BACKGROUND AND AIMS Portable haemodialysis (HD) systems with a low dialysate flow rate in a short frequent schedule have become an attractive option for patients on home HD (HHD). Although these systems have been demonstrated to be effective for removing low weight molecular uraemic toxins, there are few data on their removal ability of higher molecular weight toxins. This study assessed the uraemic toxin removal ability of the portable Physidia S3 Monitor in a short, frequent, 5 days/week, low-dialysate flux HHD versus 3 days/week, in centre online haemodiafiltration (OL-HDF). METHOD In an open, randomized, cross-over, single-centre, controlled, prospective study, 40 adult chronic HD patients were treated by a 2.5-h low flux dialysate HD session or a 4-h post-dilution OL-HDF. All other dialysis parameters including dialyzer (polysulfone high-flux dialyzer NS 1.8, Toray®) were kept constant in both the study arms. The weekly reduction rate (RR) and the weekly eliminated mass into dialysate (EM) of urea, creatinine, phosphate, β2-microglobulin, kappa (κFLC) and lambda (λFLC) free light chains and albumin, were intra-individually compared for the two dialysis types with linear mixed models. RESULTS There were no significant differences in the RR for urea, phosphate, κFLC and albumin, whereas the weekly RRs for creatinine and β2-microglobulin were significantly higher with the Physidia S3 system than those obtained with OL-HDF (Table). Only the λFLC RR was significantly higher with OL-HDF. Similar results were observed when weekly EMs were compared (data not shown). CONCLUSION This study demonstrates that treating patients with low flow dialysate HHD in a short frequent schedule with Physidia S3 system, instead of 3 days/week, in-centre OL-HDF, significantly increases the weekly elimination of β2-microglobulin, enabling an adequate clearance of small and large uraemic toxins.

Maintenance haemodialysis with low dialysate flow rates in Senegal

Introduction: The objective of the study reported here was to demonstrate that maintenance haemodialysis using a reduced dialysate flow rate of 300 mL/min (RQD) is not inferior to haemodialysis using the standard flow rate of 500 mL/min (SQD) in respect of the delivered dose of dialysis. Methods: A prospective, single-centre, sequential study was performed at the haemodialysis centre of Pikine Hospital in Dakar. Twenty patients were included. During the first week, three haemodialysis sessions were performed with SQD and during the second week three haemodialysis sessions were conducted with RQD for each patient. Results: For SQD, the mean eKt/V was 1.38 ± 0.58. There were 38 (63%) sessions with eKt/V greater than 1.2 and 16 patients (80%) had adequate dialysis, based on the average eKt/V. For RQD, the mean eKt/V was 1.2 ± 0.43 with 25 sessions (42%) having an eKt/V greater than 1.2. There were 11 patients (55%) with adequate dialysis. The dialysis dose was higher with the SQD prescription (P < 0.001). Ten patients with dry weight ≤60 kg had adequate dialysis with RQD. Cases of hypokalaemia were significantly higher with the SQD (P = 0.001). Conclusions: RQD appears to be inferior in terms of dialysis dose. However, for patients with dry weight ≤60 kg, adequate dialysis could be delivered with RQD, consequently allowing substantial saving of water in haemodialysis. Keywords: low flow dialysate rates, dialysis dose, dry weight, Senegal

Novel Use of Premixed Dialysate Bags during Water Supply Interruption in Acute Hospital Setting.

Patients on dialysis are exposed to large amounts of water during conventional intermittent hemodialysis; hence, there are strict regulations regarding the quality of water used to prepare dialysate. Occasionally, water systems fail due to natural disasters or structural supply issues, such as water-main breaks or unplanned changes in municipal or facility water quality. It is critical to regularly monitor and immediately recognize such a failure and take steps to avoid exposing the patients to contaminants. In addition to the recognition of the problem, the ability to pivot and continue to provide safe treatment to inpatients who are dependent on dialysis is essential, both from an ultrafiltration and a clearance standpoint. At our hospital, an unforeseen water disruption occurred and we were able to continue to provide KRT with premade, bagged dialysate to mitigate the effect on our patients on dialysis. This is a novel method using available machines and dialysate, which we normally stock for continuous KRT, for short dialysis sessions. The methodology is similar to that which has been widely used for short daily home hemodialysis with low dialysate flow rate. Because this situation occurred in the midst of the SARS-CoV-2 pandemic, we had to be mindful of dialysate volumes and staffing time. Here, we present our investigation into the cause of the water-system failure and how we quickly implemented the alternative dialysis method. Short dialysis with low-flow dialysate will not deliver the same Kt/V per session as standard dialysis; however, this method was successfully implemented and tailored with adjustments for patients requiring higher clearance for specific indications, such as severe hyperkalemia.

Optimizing serum total carbon dioxide concentration during short and nocturnal frequent hemodialysis using lactate as dialysate buffer base.

Definitive clinical studies to determine the optimal dialysate lactate concentration to prescribe during frequent hemodialysis when using the NxStage System One dialysis delivery system at low dialysate flow rates have not been reported. We used clinical data from patients who transferred from in-center thrice-weekly hemodialysis (ICHD) to daily home hemodialysis using the NxStage System One and the H+ mobilization model to calculate acid generation rates in patient sub-groups during the FREEDOM study. Assuming those acid generation rates were representative, we then predicted using the H+ mobilization model the effect of using dialysate lactate concentrations of 40 and 45 mEq/L on predialysis serum total carbon dioxide (tCO2 ) concentrations in patients who transfer from ICHD to short and nocturnal frequent hemodialysis prescriptions used in current clinical practice; the prescriptions evaluated varied by treatment frequency, dialysate volume per treatment, and treatment times. With frequencies of four to six treatments per week and treatment times of 170 to 210 minutes per treatment, the effect of dialysate lactate concentration was primarily dependent on weekly dialysate volume. For weekly dialysate volumes of 150 to 160 L per week, use of dialysate lactate concentrations of 45 mEq/L, but not 40 mEq/L, resulted in an increase of predialysis serum tCO2 concentration. When longer treatment times typical of nocturnal frequent hemodialysis were evaluated, model predictions showed that the use of dialysate lactate concentration of 45 mEq/L may not be appropriate for many patients because of excessive increases in predialysis serum tCO2 concentration. Reducing dialysate volume from 60 to 30 L may limit the increase in predialysis serum tCO2 concentration when patients transfer from ICHD to nocturnal frequent hemodialysis. Predictions from the H+ mobilization model show that dialysate lactate concentration and weekly dialysate volume are the primary prescription parameters for optimizing predialysis serum tCO2 concentration during short and nocturnal frequent hemodialysis.

P1051ASINGLE SESSION AND WEEKLY BETA 2 MICROGLOBULIN REMOVAL DURING SHORT FREQUENT HEMODIALYSIS USING PHYSIDIA TECHNOLOGY

Abstract Background and Aims S3 Physidia monitor is a dedicated system for short frequent hemodialysis at home based on push pull dialysis mode. Clinical data is provided to show the Beta 2 microglobulin elimination, used as a model for middle molecule removal. The aim of the study is to compare Beta 2 microglobulin removal between hemodialysis systems with low dialysate flow rate and conventional hemodialysis or hemodiafiltration. Method Analyzed data is collected during multicentric clinical study performed to evaluate the safety and performances level with S3 Physidia system. This clinical investigation has been conducted in accordance with the Good Clinical Practices (Helsinki Declaration), every patient was informed by the investigator and has signed the consent form prior to the completion of the study. The project has been approved by the local Committee and authorities. Anonymized data of 10 patients (age: 55.3 +/- 12.3 years, weight: 72.8 +/- 17.2 kg) is collected during 126 dialysis sessions (blood flow rate: 293 +/- 24 ml/min, dialysate flow rate: 190 +/- 14 ml/min). The convection volume (Ultrafiltration and back filtration generated by the push pull technique) is between 1 to 8 l per session (dialyzer used: Smartflux HFP190). For each session, Beta 2 microglobulin (β2M) removal rate is calculated by using pre and post dialysis β2M blood concentrations. Post concentration is corrected by using Bergström formula to take into account the hemoconcentration and rebound. Both single session (2hours) and weekly (12 hours/week) β2m removal rates were calculated. Single session and weekly β2m removal levels are compared to published data with conventional hemodialysis or post dilution hemodiafiltration. Weekly dialysis performance is evaluated according to the standardized Kt / V (sdt) according to the Gotch calculation method. Results Using S3 daily hemodialysis, weekly dialysis diffusive performance for urea (standardized Kt / V is 2.56 +/- 0.39, higher than KDIGO recommendations for frequent dialysis (min 2.1). β2M removal rate per session is 52.9 +/- 6.6 % with pre dialytic concentration average value of 25 mg/l corresponding to 73 mg of β2M removed per session. Calculated weekly β2M removal is 438 mg. These results are compared to β2M removal obtained by standard treatment procedures (ref1) and by short frequent hemodialysis using diffusive low dialysate flow (Nx Stage system One, ref 2). During conventional hemodialysis (4h, 3 sessions per week), the β2M removal rate is between 60 to 80 % corresponding to a removal of 300 to 380 mg/week (ref 1) During high volume post dilution hemofiltration (4h, 3 sessions per week, convection > 20 l per session), the average β2M removal rate is 80% corresponding to a removal of 380 mg/week (ref 1) With Nx Stage device, without convective component, single session β2M removal rate is between 40 and 50 % depending on blood flow rate (maximum obtained with blood flow rate 400 ml/min) (ref 2) Ref 1: J. Potier et al, Int J Artif Organs. 2016 Nov 11;39(9):460-470 Ref 2 : M. Leclerc et al, Blood Purif 2018;46:279–285 Conclusion β2M reduction rate obtained with the S3 Physidia system is greater than 50%, removing any dowry concerning the performance of a low dialysate flow rate system. The convective component, provided by the push pull technique, must be confirmed, but these initial results are encouraging (reduction rate > 50% despite a relatively low blood flow rate). Due to the frequency, the quantity of β2M weekly removed is higher than that obtained with conventional treatment methods.

82 The Effects of Low Dialysate Flow Rate on Hemodialysis Patients

82 The Effects of Low Dialysate Flow Rate on Hemodialysis Patients

Effect of dialysate potassium and lactate on serum potassium and bicarbonate concentrations during daily hemodialysis at low dialysate flow rates

BackgroundObservational studies of hemodialysis patients treated thrice weekly have shown that serum and dialysate potassium and bicarbonate concentrations are associated with patient outcomes. The effect of more frequent hemodialysis on serum potassium and bicarbonate concentrations has rarely been studied, especially for treatments at low dialysate flow rate.MethodsThese post-hoc analyses evaluated data from patients who transferred from in-center hemodialysis (HD) to daily HD at low dialysate flow rates during the FREEDOM Study. The primary outcomes were the change in predialysis serum potassium and bicarbonate concentrations after transfer from in-center HD (mean during the last 3 months) to daily HD (mean during the first 3 months).ResultsAfter transfer from in-center HD to daily HD (data from 345 patients, 51 ± 15 years of age, mean ± standard deviation), predialysis serum potassium decreased (P < 0.001) by approximately 0.4 mEq/L when dialysate potassium concentration during daily HD was 1 mEq/L; no change occurred when dialysate potassium concentration during daily HD was 2 mEq/L. After transfer from in-center HD to daily HD (data from 284 patients, 51 ± 15 years of age), predialysis serum bicarbonate concentration decreased (P = 0.0022) by 1.0 ± 3.3 mEq/L when dialysate lactate concentration was 40 mEq/L but increased (P < 0.001) by 2.5 ± 3.5 mEq/L when dialysate lactate concentration was 45 mEq/L. These relationships were dependent on serum potassium and bicarbonate concentrations during in-center HD.ConclusionsControl of serum potassium and bicarbonate concentrations during daily HD at low dialysate flow rates is readily achievable; the choice of dialysate potassium and lactate concentration can be informed when transfer is from in-center HD to daily HD.

Synthetic 2018 data report of the French Language Peritoneal Dialysis and Home Hemodialysis Registry (RDPLF)

The RDPLF was created in 1986 and collects the main data of peritoneal dialysis of French patients and of various French-speaking countries. The database is structured in several modules: a compulsory core module including a follow-up of comorbidities, assistance, infections, survival, transplantation, and optional modules following more specific aspects: nursing, catheter, anemia, nutrition, heart failure. In addition, since 2012 patients treated at home in hemodialysis are also followed. This article presents a summary of the main characteristics of patients in the RDPLF in 2018. It highlights important differences in practices and patient profiles between francophone countries. Daily low dialysate flow rate hemodialysis is predominant in the new centers and sometimes begins to appear as a transitional mode that allows home maintenance for patients who cannot continue on peritoneal dialysis.

Volume of urea cleared as a therapy dosing guide for more frequent hemodialysis.

With dialysis delivery systems that operate at low dialysate flow rates, prescriptions for more frequent hemodialysis (HD) employ dialysate volume as the primary parameter for small solute removal rather than blood-side urea dialyzer clearance (K). Such delivery systems, however, yield dialysate concentrations that almost completely saturate with blood (water), suggesting that the volume of urea cleared (the product of K and treatment time or Kt) can be readily estimated from the prescribed dialysate volume to target small solute removal. Methods For more frequent HD, we examined the volume of urea cleared per treatment required to achieve a minimal dose of small solute removal, comparing results based on body surface area (BSA) with those based on KDOQI clinical practice guidelines, that is, a weekly stdKt/V of 2.1. Estimates of the target volume of urea cleared were calculated for 4, 5, and 6 treatments per week, and compared for patients with different anthropometric estimates of total body water volume (Vant ). BSA was assumed proportional to Vant0.8 , and residual kidney function was neglected. Findings Whether based on BSA or weekly stdKt/V of 2.1, the target volume of urea cleared per treatment required to achieve a minimal dose of small solute removal was lower at higher treatment frequency. As with conventional thrice-weekly HD, target volumes of urea cleared for more frequent HD based on BSA were larger for patients with small Vant and smaller for patients with large Vant than those based on a weekly stdKt/V of 2.1. Discussion Prescription of more frequent HD using the volume of urea cleared per treatment, calculated from the prescribed dialysate volume, is simple in principle and can be readily implemented in clinical practice when using dialysis delivery systems that operate at low dialysate flow rates. Other aspects of dialysis adequacy require additional consideration.

Home hemodialysis : is there still room for high dialysis solution flow rate ?

Abstract&#x0D; The availability in France, for the last decade, of low dialysate flow rate hemodialysis monitors, specifically adapted for daily hemodialysis (5 to 6 sessions per week), is contemporary with a real renewal of home hemodialysis. The clinical benefits of daily hemodialysis with high dialysate flow and of thrice-weekly long nocturnal hemodialysis, which are two intensive hemodialysis modalities, have been demonstrated ; however they are less well demonstrated with low dialysate flow hemodialysis. Thus, some patients may still wish to use conventional hemodialysis monitors in order to limit the number of sessions (and therefore the number of vascular punctures) to 3 per week (or every other day) or wish to benefit from a modality of intensive hemodialysis.

Does the Blood Pump Flow Rate have an Impact on the Dialysis Dose During Low Dialysate Flow Rate Hemodialysis?

We conducted a prospective study to assess the impact of the blood pump flow rate (BFR) on the dialysis dose with a low dialysate flow rate. Seventeen patients were observed for 3 short hemodialysis sessions in which only the BFR was altered (300,350 and 450 mL/min). Kt/V urea increased from 0.54 ± 0.10 to 0.58 ± 0.08 and 0.61 ± 0.09 for BFR of 300, 400 and 450 mL/min. For the same BFR variations, the reduction ratio (RR) of β2microglobulin increased from 0.40 ± 0.07 to 0.45 ± 0.06 and 0.48 ± 0.06 and the RR phosphorus increased from 0.46 ± 0.1 to 0.48 ± 0.08 and 0.49 ± 0.07. In bivariate analysis accounting for repeated observations, an increasing BFR resulted in an increase in spKt/V (0.048 per 100 mL/min increment in BPR [p < 0.05, 95% CI (0.03–0.06)]) and an increase in the RR β2m (5% per 100 mL/min increment in BPR [p < 0.05, 95% CI (0.03–0.07)]). An increasing BFR with low dialysate improves the removal of urea and β2m but with a potentially limited clinical impact.

Severe carbamazepine intoxication unresponsive to albumin‐enhanced continuous venovenous hemodiafiltration with low dialysate flow

Carbamazepine (CBZ) intoxication can be associated with severe toxicity, including neurological and cardio-respiratory abnormalities. Highly protein-bound, CBZ is not removed efficiently through conventional hemodialysis. Charcoal hemoperfusion is the most effective extracorporeal elimination therapy for CBZ intoxication. Recent reports have indicated that continuous venovenous hemodiafiltration (CVVHDF), albumin-enhanced continuous venovenous hemodialysis, high-flux hemodialysis and plasma exchange can be as effective as charcoal hemoperfusion. In contrast to recent reports, which demonstrated the effectiveness of CVVHDF with high dialysate flow in CBZ intoxication, we observed that serum CBZ level was decreased minimally by albumin-enhanced CVVHDF with low dialysate flow. Therefore, albumin-enhanced CVVHDF with high dialysate flow should be considered in severe CBZ intoxication, if hemoperfusion is unavailable because of the lack of facilities or if it cannot be performed.

Comparison of urea clearance in low‐efficiency low‐flux vs. high‐efficiency high‐flux dialyzer membrane with reduced blood and dialysate flow: An in vitro analysis

Rapid removal of small molecules during hemodialysis places an acutely ill patient with kidney failure at an increased risk of hemodynamic instability and for dialysis disequilibrium syndrome. The use of high-flux, high-efficiency (HEF) dialyzers may increase this risk despite reductions in blood and dialysate flow. We performed in vitro experiments to compare urea clearance at low dialysate flow and various blood flows using a low-efficiency low-flux (LEF) and a HEF membrane. Compared to LEF, there was a significant increase in the clearance of urea at all blood flows with the HEF (all P values < 0.005). HEF dialyzer (F180NR) had higher urea clearance at a blood flow of 150 mL/min than LEF dialyzer (F5) at blood flow of 300 mL/min (144.1 ± 0.99 vs. 130.1 ± 0.001 mL/min for F180 vs. F5, respectively, P < 0.002). Our data suggest that use of HEF dialyzer are not as safe as LEF in high-risk acute dialysis patients since these are associated with more rapid removal of urea despite reduction in blood and dialysate flow as compared to LEF.

Electrolyte Management in Frequent Home Hemodialysis

Short daily hemodialysis (SDHD) and nocturnal home hemodialysis are modalities performed at home at shorter intervals than conventional hemodialysis. Because of their increased frequency, these alternative modalities create the potential for less inter-dialytic fluid gains and therefore fewer episodes of intra-dialytic hypotension. By more closely replicating normal renal physiology, they may also improve electrolyte management. In this article, we review published data on levels of calcium, phosphate, potassium, and bicarbonate levels using these home dialysis modalities. We also present our single-center experience with electrolyte management in patients maintained on SDHD using low dialysate flow rate, a modality of growing prevalence.

Dialyzer Clearances and Mass Transfer-Area Coefficients for Small Solutes at Low Dialysate Flow Rates

New daily hemodialysis therapies operate at low dialysate flow rates to minimize dialysate volume requirements; however, the dependence of dialyzer clearances and mass transfer-area coefficients for small solutes on dialysate flow rate under these conditions have not been studied extensively. We evaluated in vitro dialyzer clearances for urea and creatinine at dialysate flow rates of 40, 80, 120, 160, and 200 ml/min and ultrafiltration flow rates of 0, 1, and 2 l/h, using a dialyzer containing PUREMA membranes (NxStage Medical, Lawrence, MA). Clearances were measured directly across the dialyzer by perfusing bovine blood with added urea and creatinine single pass through the dialyzer at a nominal blood flow rate of 400 ml/min. Limited, additional studies were performed with the use of dialyzers containing PUREMA membranes at a blood flow rate of 200 ml/min and also with the use of other dialyzers containing polysulfone membranes (Optiflux 160NR, FMC-NA, Ogden, UT) and dialyzers containing Synphan membranes (NxStage Medical). For dialyzers containing PUREMA membranes, urea and creatinine clearances increased (p < 0.001) with increasing dialysate and ultrafiltration flow rates but were not different at blood flow rates of 200 and 400 ml/min. Dialysate saturation, defined as dialysate outlet concentration divided by blood water inlet concentration, for urea and creatinine was independent of blood and ultrafiltration flow rate but varied inversely (p < 0.001) with dialysate flow rate. Mass transfer-area coefficients for urea and creatinine were independent of blood and ultrafiltration flow rate but decreased (p < 0.001) with decreasing dialysate flow rate. Calculated mass transfer-area coefficients at low dialysate flow rates for all dialyzers tested were substantially lower than those reported by the manufacturers under conventional conditions. We conclude that dialyzers require specific characterization under relevant conditions if they are used in novel daily hemodialysis therapies at low dialysate flow rate.

Advantages of Tidal Peritoneal Dialysis

Tidal peritoneal dialysis (TPD) was introduced in 1990 in the hopes of improving dialysis efficiency. Studies comparing low dialysate flow rates show that tidal peritoneal dialysis has no clearance advantage over intermittent peritoneal dialysis (IPD). With high dialysate flow rates, TPD may be superior or similar to IPD in efficacy, but it is expensive because of the high volumes of dialysis solution used. However, it provides better fluid flow mechanics and more comfort to the patient owing to fewer alarms and less pain during inflow and outflow.

Tidal peritoneal dialysis for home-treated patients: should it be preferred?

Tidal peritoneal dialysis (TPD) was introduced to increase the efficacy of peritoneal dialysis. We measured peritoneal clearances of small solutes and beta2-microglobulin, peritoneal protein loss, and efficacy of ultrafiltration in 30 patients during TPD and intermittent peritoneal dialysis (IPD) with low-dialysate flow (1.7 L/h) and, in addition, in 17 of these patients using a high-dialysate flow (3 L/h). Using a low-dialysate flow, patients with low/low average peritoneal transport rates showed significantly better peritoneal creatinine and urea nitrogen clearances during IPD compared with TPD, whereas there was no difference between these two treatment modalities in high/high average transporters. With high-dialysate flow, peritoneal clearances of creatinine and urea nitrogen were similar between TPD and IPD independent of peritoneal transport type. Clearances of phosphate and beta2-microglobulin were similar between TPD and IPD independent of dialysate flow or peritoneal transport type. Increasing the dialysate flow rate led to a significant increase in small-solute clearances, but not beta2-microglobulin clearances, in both peritoneal transport types. Total peritoneal protein and albumin losses were similar between TPD and IPD only with low-dialysate flow. However, using a high-dialysate flow, total protein losses tended to increase in both transport types during IPD compared with TPD. In conclusion, up to a dialysate flow of 3 L/h, TPD did not provide better small-solute or middle-molecule clearances compared with IPD. Moreover, using a low-dialysate flow, IPD was superior to TPD in low/low average transporters.