Improved β2-Microglobulin and Phosphorous Removal with Expanded Hemodialysis and Online Hemodiafiltration versus High-Flux Hemodialysis: A Cross-Over Randomized Clinical Trial

INTRODUCTION

Expanded hemodialysis (HDx) is expected to provide enhanced permeability of medium-sized molecules, selective solute retention, and better internal retrofiltration. The primary objective of this study was to compare the efficiency for removal of β2-microglobulin with 3 different extracorporeal therapies (ETs): high-flux hemodialysis (HF), online hemodiafiltration (OL-HDF), and HDx. The secondary objective was to evaluate the efficiency of removal of other uremic toxins, including urea, phosphate, CRP, IL-6, IL-10, TNF-⍺, indoxyl sulfate, and p-cresol.

METHODS

This single-center, randomized, and cross-over study was performed. Patients were randomized to determine the initial modality of treatment, each period lasted 4 weeks and between one modality and another, there was a washout period of 1 week. Reduction ratios (RRs) of different-size molecules and albumin were calculated for the different ET.

RESULTS

Twenty-two patients were included, β2-microglobulin RR was greater during both OL-HDF and HDx as compared to HF (RR 62% vs. 73% vs. 27%, respectively, p = <0.0001), and there was no significant difference between HDx and OL-HDF (p = 0.09). A decrease in serum phosphate levels was observed in the HDx and OL-HDF periods, contrary to an increase in HF (-0.79 mg/dL vs. -1.02 mg/dL vs. + 0.11 mg/dL, respectively, p = <0.0001). There was no difference in RRs of other molecules (BUN, CRP, IL-6, IL-10, TNF-⍺, indoxyl sulfate, and p-Cresol). There was no decrease in serum albumin in any ET.

CONCLUSION

HDx provides enhanced removal of β2-microglobulin and phosphate as compared to HF, and similar efficacy as with OL-HDF. HDx should be considered an alternative to chronic convective therapies.

Efficacy and Safety of the Medium Cut-Off Elisio HX Dialyzer

INTRODUCTION

The medium cut-off Elisio HX dialyzer by Nipro became commercially available in Europe in 2021, but there are still no reports of in vivo data. This study aimed to evaluate the safety and efficacy of it compared with previously evaluated hemodialysis (HD), expanded HD (HDx), and postdilution hemodiafiltration (HDF) treatments.

METHODS

A prospective study was carried out on 18 patients who underwent 5 dialysis sessions: FX80 Cordiax in HD, Elisio H19 in HD, Elisio HX19 in HDx, Theranova 400 in HDx, and FX80 Cordiax in HDF. The reduction ratios of urea, creatinine, ß2-microglobulin, myoglobin, kappa FLC, prolactin, α1-microglobulin, α1-acid glycoprotein, lambda FLC, and albumin were compared. Dialysate albumin loss was measured.

RESULTS

The comparison between the different dialysis modalities revealed no difference for small molecules, but HDx and HDF were significantly more efficient than HD for medium and large molecule removal. The efficacy of Elisio HX19 dialyzer in HDx was similar to the Theranova 400, superior to both dialyzers in HD, and slightly lower than HDF. Albumin losses in dialysate with HD dialyzers were less than 1 g, but between 1.5 and 2.5 g in HDx and HDF. The global removal score (GRS) values with HDx treatments were statistically significantly higher than those with HD. The highest GRS was obtained with the helixone dialyzer in HDF.

CONCLUSIONS

The new MCO dialyzer, Elisio HX, performs with excellent behavior and tolerance. It represents an upgrade compared to their predecessor and is very close to the removal capacity of HDF treatment.

Use of regional citrate anticoagulation with medium cut-off membrane: pilot report

Background

Regional citrate anticoagulation during hemodialysis provides an immediate and complete anticoagulant effect, which is limited to the extracorporeal circuit. Citrate has become the standard anticoagulant in acute renal replacement therapy and is widely used in various intermittent hemodialysis modalities, especially for patients with contraindications for heparin. With the increased adoption of medium cut-off membranes, experience with regional citrate anticoagulation is needed. To our knowledge, this is the first report to assess the feasibility of regional citrate anticoagulation in expanded hemodialysis.

Methods

We prospectively analyzed 5 expanded hemodialysis procedures in 5 patients in which a medium cut-off membrane (Theranova®) was used. We followed our standard citrate protocol developed and tested for high-flux membrane. Anticoagulation was performed with a continuous infusion of 8% trisodium citrate into the arterial line and supplementation of 1 M calcium chloride into the venous line. We monitored ionized calcium and magnesium, sodium and blood gas analysis. Anticoagulation effectiveness was assessed by post-filter ionized calcium and by visual inspection of the anticoagulation in the circuit.

Results

There were no prematurely terminated procedures due to anticoagulation-related complications. With a blood flow of 250 mL/min and a dialysate flow of 500 mL/min, we were able to maintain serum ionized calcium in the range of 0.89–1.29 mmol/L and serum sodium in the range of 136–144 mmol/L. The mean pre- and post-dialysis arterial circuit pH was 7.42 (± 0.04) and 7.53 (± 0.23), respectively. The mean pre- and post-dialysis serum ionized magnesium was 0.54 (± 0.04) mmol/L and 0.43 (± 0.03) mmol/L, respectively (measurements were done on a point-of-care ionometer with a lower normal range for ionized magnesium).

Conclusion

We have shown that our standard citrate protocol for high-flux hemodialysis membrane could be successfully adopted for use in expanded hemodialysis with a medium cut-off membrane. Overall, electrolyte and acid-base balances were relatively well-controlled and anticoagulation effectiveness was excellent.

Trial registration

This is a pilot report with results taken from a larger ongoing trial (registered at ClinicalTrials.gov on October 25, 2019 under number NCT04139525) comparing citrate and heparin anticoagulation during expanded hemodialysis.

Effect of Expanded Hemodialysis with Theranova® in Patients with COVID-19

INTRODUCTION

Cytokine storm control is the main target for improving severe COVID-19 by using immunosuppressive treatment. Effective renal replacement therapy (RRT) could give us an advantage removing cytokines in patients with RRT requirements superimposed on COVID-19.

METHODS

This is a prospective observational study in COVID-19 patients who required hemodialysis (HD). Patients were assigned to online hemodiafiltration (OL-HDF) and expanded HD (HDx) according to Brescia group recommendations. We measured several cytokines, β2 microglobulin and albumin levels pre/post-dialysis and on 1st-2nd week. We compared levels among both techniques and control group (HD without COVID-19).

RESULTS

We included 26 patients: 18 with COVID-19 on RRT (5 of them had acute kidney injury [AKI]) and 8 controls. We confirm higher cytokine levels in COVID-19 patients than controls and even higher in patients with AKI than in those with chronic kidney disease. Most cytokines raised during HD session, except IL-10 and TNFα. IL-10 was eliminated by any dialysis technique, while clearance of TNFα was higher in the HDx group. HDx achieved a deeper normalization of cytokines and β2 microglobulin reduction. Mortality was higher in the OL-HDF group than the HDx group.

DISCUSSION

Not all cytokines behave equally along HD session. The following characteristics should be taken into account, such as intrinsic kinetic profile during a HD session. HDx seems to get better performance, probably due to the combination of different factors; however, we did not reach statistical significance due to the small sample size, dropout, and reduction of AKI incidence during the 2nd pandemic wave.

CONCLUSION

HDx appears to provide better clearance for TNFα and β2 microglobulin during HD session and associates lower mortality. We propose the HDx technique for COVID-19 patients with RRT requirements since it seems to be safe and more effective than OL-HDF. Further studies are still needed, but we hope that our preliminary data may help us in future pandemic waves of SARS-CoV-2 or other viruses still to come.

Flow Dynamic Analysis by Contrast-Enhanced Imaging Techniques of Medium Cutoff Membrane Hemodialyzer

INTRODUCTION

Medium cutoff (MCO) membranes represent an interesting innovation in the field of hemodialysis. Given the correlation between large (PM >25 kDa) middle molecules (LMM) and clinical outcomes, the possibility to broaden the spectrum of solutes removed in hemodialysis with MCO membranes introduces a new perspective for end-stage kidney disease patients. Due to low diffusion coefficients of LMM, the use of convection is required to maximize extracorporeal clearance. High convective rates are achieved with high-flux membranes in hemodiafiltration, a technique not available in the US. In case of the MCO membrane, remarkable clearances of LMM are achieved combining the permeability of the membrane with a significant amount of internal convection. The mechanism of filtration-backfiltration inside the dialyzer enables effective removal of LMM in a technique called expanded hemodialysis (HDx). Given such theoretical explanation, it is important to demonstrate the blood and ultrafiltration rheology inside the MCO dialyzer.

METHOD

This study for the first time describes flow dynamic parameters and internal cross-filtration, thanks to specific radiology and nuclear imaging techniques.

RESULTS

Flow dynamic analysis of the blood and dialysate compartment confirms excellent distribution of velocities and an excellent matching of blood and dialysate. Average blood flow velocity allows for wall shear rates adequate to avoid protein stagnation at the blood membrane interface and increase in blood viscosity. Cross-filtration analysis demonstrates a remarkable filtration/backfiltration flux reaching values >30 mL/min at a blood flow of 300 mL/min and zero net filtration.

CONCLUSION

The MCO dialyzer Theranova 400 appears to have a design optimized to perform expanded hemodialysis (HDx).

Expanded Hemodialysis and Its Effects on Hospitalizations and Medication Usage: A Cohort Study

INTRODUCTION

Expanded hemodialysis (HDx) effectively removes large middle molecular uremic toxins (>25 kDa) while still retaining albumin, potentially reducing their adverse effects. We compare the clinical laboratory parameters, hospitalization rates, and medication use in a cohort of patients switched from high-flux HD to HDx.

METHODS

This is a multicenter, observational cohort study of 81 adult patients, across 3 clinics, with end-stage kidney disease (ESKD) on chronic hemodialysis (HD). Patients received high-flux HD for at least 1 year and then switched to HDx and were followed up for 1 year. Patients were excluded if they discontinued therapy, changed provider, underwent kidney transplant, recovered kidney function, or changed to peritoneal dialysis, another dialyzer, or renal clinic.

RESULTS

Twelve months after switching to HDx, the rate of hospitalization events per patient-year decreased from 0.77 (95% CI: 0.60-0.98, 61 events) to 0.71 (95% CI: 0.55-0.92, 57 events) (p = 0.6987). The hospital day rate per patient-year was significantly reduced from 5.94 days in the year prior to switching compared with 4.41 days after switching (p = 0.0001). The mean dose of erythropoiesis-stimulating agent (SC epoetin-α) and intravenous iron also significantly decreased (p = 0.0361 and p = 0.0003, respectively).

CONCLUSION

Switching to HDx was associated with reductions in hospital day rate and medication use, suggesting HDx has the potential to reduce the burden of ESKD on patients and healthcare systems.

Effects of medium cut-off dialysis membranes on inflammation and oxidative stress in patients on maintenance hemodialysis

PURPOSE

Medium cut-off membranes were developed for providing increased clearance of larger middle-molecule uremic toxins. We compared the effect of low-flux, medium cut-off, and high-flux membranes on chronic inflammation and oxidative stress in patients with maintenance hemodialysis.

METHODS

A total of 42 patients were enrolled in this study. Total antioxidant status, total oxidant status, paraoxonase-1, ischemia-modified albumin, total Thiol, disulfide bond, and native Thiol were measured to determine oxidative stress. C-reactive protein was measured to define inflammation.

RESULTS

37% of the total patients were females, and the mean age was 52.9 ± 16 years. Serum albumin and Kt/V were similar between groups during the study period. We did not find any significant difference at baseline in the 3rd and 6th months of the study when we compared the inflammatory marker and oxidative indicator levels between three hemodialysis membranes in the whole study group. In the subgroup analysis of 19 patients with a high C-reactive protein level, we found that the medium cut-off membrane significantly reduced serum C-reactive protein level, when compared to low-flux and high-flux membrane [2.8 mg/L vs. 13.7 mg/L and 6.1 mg/L, respectively, p = 0.05]. However, we did not find a significant change in oxidative stress indicators in patients with high C-reactive protein levels between the three dialysers.

CONCLUSION

The medium cut-off membrane has favorable effects on inflammation in patients with maintenance hemodialysis. However, this positive effect could not be demonstrated in oxidative stress.