Comparison of the effects of predilution and postdilution hemodiafiltration on neutrophils, lymphocytes and platelets

Comparison of the pre-dilution and post-dilution methods for online hemodiafiltration

Online hemodiafiltration (OL-HDF) is a treatment modality using diffusion and ultrafiltration. There are two types of dilution methods in OL-HDF: pre-dilution, which is commonly provided in Japan, and post-dilution, which is commonly provided in Europe. The optimal OL-HDF method for individual patients is not well studied. In this study, we compared the clinical symptoms, laboratory data, spent dialysate, and adverse events of pre- and post-dilution OL-HDF. We conducted a prospective study of 20 patients who underwent OL-HDF between January 1, 2019 and October 30, 2019. Their clinical symptoms and dialysis efficacy were evaluated. All patients underwent OL-HDF every 3 months in the following sequence: first pre-dilution, post-dilution, and second pre-dilution. We evaluated 18 patients for the clinical study and 6 for the spent dialysate study. No significant differences in spent dialysates regarding small and large solutes, blood pressure, recovery time, and clinical symptoms were observed between the pre- and post-dilution methods. However, the serum α1-microglobulin level in post-dilution OL-HDF was lower than that in pre-dilution OL-HDF (first pre-dilution: 124.8 ± 14.3 mg/L; post-dilution: 116.6 ± 13.9 mg/L; second pre-dilution: 125.8 ± 13.0 mg/L; first pre-dilution vs. post-dilution, post-dilution vs. second pre-dilution, and first pre-dilution vs. second pre-dilution: p = 0.001, p < 0.001, and p = 1.000, respectively). The most common adverse event was an increase in transmembrane pressure in the post-dilution period. Compared to pre-dilution, the post-dilution method decreased the α1-microglobulin level; however, there were no significant differences in clinical symptoms or laboratory data.

Removal performance of pre- and post-dilution online hemodiafiltration using identical hemodiafilters in the same patients

Online hemodiafiltration (OHDF) for renal replacement therapy has two modes: pre- (pre-OHDF) and post-dilution OHDF (post-OHDF). To elucidate the precise differences between the two modes, a clinical study was performed using the same polysulfone hemodiafilters in the same patients. Eight patients were treated with ABH™-22PA for 6 weeks: 3 weeks of pre-OHDF (with substitution volumes of 24, 36, and 48 L) and 3 weeks of post-OHDF (6, 8, and 10 L). The reduction ratios of urea, uric acid (UA), creatinine (CRE), inorganic phosphorus (iP), beta-2-microglobulin (β2-MG), and alpha-1-microglobulin (α1-MG) were evaluated. The removal amounts of β2-MG, α1-MG, and albumin were also evaluated by analyzing the spent dialysis fluids. The types and numbers of adverse events (AEs) and device malfunctions were recorded. The reduction ratios of urea, UA, CRE, iP, and β2-MG were comparable among all conditions, while that of α1-MG tended to be slightly higher in post-OHDF than in pre-OHDF. The removal amounts of α1-MG and albumin in pre-OHDF and post-OHDF were significantly greater with the maximum substitution volume than with the minimum volume. However, the selective removal indices, which were obtained by dividing the amount of α1-MG removed by the albumin level, tended to be slightly higher in pre- than in post-OHDF. No device-related AEs or device malfunctions occurred in either mode. No significant differences in inflammatory responses, evaluated by high-sensitivity C-reactive protein and interleukin-6, were observed. This study provides removal performance and safety data regarding the application of ABH-22PA for pre- and post-OHDF.

Comparison of the effects of pre-dilution and post-dilution online hemodiafiltration on the levels of inflammatory markers, lymphocytes, and platelets

Online hemodiafiltration (OL-HDF) is a blood purification therapy based on diffusion and ultrafiltration and is classified into two types according to the mode of addition of the substitution fluid: pre-dilution OL-HDF (pre-HDF) and post-dilution OL-HDF (post-HDF); we previously reported that pre-HDF is more biocompatible. However, we used lower blood and substitution flow rates in that study and may not have accurately simulated the treatment conditions used in Europe. In this study, we compared the biocompatibilities of the treatment conditions of pre-HDF, commonly used in Japan, and post-HDF, commonly used in Europe, to determine the most biocompatible treatment conditions. We compared the biocompatibilities of pre-HDF and post-HDF using high blood flow rates and high substitution fluid volumes, and also compared the results with those of our previous study. We enrolled six stable patients undergoing maintenance dialysis at our clinic for this study. After the patients underwent hemodialysis (HD), post-HDF, and pre-HDF treatment, the biocompatibilities (based on the serum levels of high-sensitivity C-reactive protein, interleukin-6, pentraxin-3, β-thromboglobulin, and soluble P-selectin, and the results of the lymphocyte blastogenesis test using phytohemagglutinin and concanavalin A as mitogens) and removal performances (removal performance for urea, creatinine, β₂-microglubulin [MG], and α₁-MG, and albumin leakage) were determined. There were no significant differences in the biocompatibility parameters evaluated among the three treatment modes. Post-HDF was associated with significantly higher removal rates of β₂-MG than HD. Post-HDF was associated with significantly higher removal rate of α₁-MG, and also significantly higher albumin leakage, than HD and pre-HDF.

Evaluation of low-volume post-dilution online hemodiafiltration with Japanese high-performance hemodiafilters

Purpose

To assess the removal performance of low-volume post-hemodiafiltration (HDF) with Japanese hemodiafilters and the removal performance with 20 % reduction in the total dialysate flow rate (Q_dtotal).

Methods

Subjects were 8 patients undergoing pre-HDF. Study 1: Post-HDF was performed at a blood flow rate (Q_b) of 250 mL/min and a total volume of substitution fluid (Vs) of 12 L/session(s) for 4 hrs using Fineflux-210Seco (FIX), ABH-21PA (ABH), and NVF-21H (NVF). We assessed removal efficiency of small molecular solutes, low-molecular-weight-proteins and the amount of albumin loss. Study 2: Post-HDF was performed at Vs of 12 L/s under G-1, Q_dtotal of 500 and Q_b of 250 mL/min; G-2, Q_dtotal of 400 and Q_b of 250 mL/min; and G-3, Q_dtotal of 400 and Q_b of 300 mL/min. Removal efficiency was compared and analyzed between these conditions.

Results

Study 1: The results using FIX, ABH and NVF are shown in order. The Kt/V were 1.8, 1.9 and 1.8. The β₂-Microglobulin (MG) removal rate (RR) (%) were 81.2, 83.1 and 82.8, and the α₁-MG RR were 37.4, 40.2 and 38.5, respectively. Study 2: The results in G-1, 2 and 3 are shown in order. The Kt/V and the RR of small solutes, were significantly higher in G-3. The β₂-MG RR (%) were 81.2, 80.1 and 81.0, and the α₁-MG RR were 37.4, 37.5 and 38.0, respectively.

Conclusions

Low-volume post-HDF performed at Q_b of 250 mL/min with Japanese high-performance hemodiafilters exhibited favorable removal efficiency for all solutes. Even with 20 % reduction in Q_dtotal, the removal performance was also favorable.

Acute non-heparin-induced thrombocytopenia during hemodiafiltration in a patient with multiple myeloma

This report demonstrates that not only heparin-induced thrombocytopenia, but also hemodialysis conditions (platelet activation due to hemodiafiltration and heparin underdosing) may markedly reduce the platelet count and cause clotting in the hemodialysis circuit in patients in a hypercoagulable state. The clot prevention effects of bortezomib are therefore of great importance.

The effect of high-flux hemodialysis and post-dilution hemodiafiltration on platelet closure time in patients with end stage renal disease

INTRODUCTION

We aimed to compare prospectively the effect of high-flux hemodialysis and post-dilution hemodiafiltration on platelets.

METHODS

Twenty-two hemodialysis patients were treated with one high-flux hemodialysis and one post-dilution hemodiafiltration procedure. PFA-100 closure times (collagen/epinephrine-CEPI and collagen/adenosine diphosphate-CADP) were measured before and after the procedure, as well as platelet count, hemoglobin, hematocrit, and red blood cell count. All pre-dialysis and post-dialysis samples were taken from the afferent line.

FINDINGS

The platelet count after vs. before hemodialysis did not change significantly (229.3 ± 55.0 x10⁹ /L vs. 233.6 ± 55.8 × 10⁹ /L; P = 0.269), but was significantly lower after post-dilution hemodiafiltration (215.5 ± 51.7 × 10⁹ /L vs. 245.3 ± 59.9 × 10⁹ /L; P < 0.0001). CEPI after vs. before hemodialysis was not significantly prolonged (192.9 ± 60.8 s vs. 173.4 ± 52.5 s; P = 0.147), and the same applied to CADP (143.6 ± 40.3 s vs. 142.6 ± 38.4 s; P = 0.897). CEPI after vs. before post-dilution hemodiafiltration was significantly prolonged (268.3 ± 41.3 s vs. 176.4 ± 54.0 s; P < 0.0001) as was CADP (221.0 ± 53.9 s vs.133.9 ± 31.1 s; P < 0.0001).

DISCUSSION

Only after post-dilution hemodiafiltration, we found a lower platelet count and prolonged platelet closure times.

Acute effects of haemodialysis on circulating microparticles

Background

Microparticles (MPs) are small cell membrane-derived vesicles regarded as both biomarkers and mediators of biological effects. Elevated levels of MPs have previously been associated with endothelial dysfunction and predict cardiovascular death in patients with end-stage renal disease. The objective of this study was to measure change in MP concentrations in contemporary haemodialysis (HD).

Methods

Blood was sampled from 20 consecutive HD patients before and 1 h into the HD session. MPs were measured by flow cytometry and phenotyped based on surface markers.

Results

Concentrations of platelet (CD41⁺) (P = 0.039), endothelial (CD62E⁺) (P = 0.004) and monocyte-derived MPs (CD14⁺) (P < 0.001) significantly increased during HD. Similarly, endothelial- (P = 0.007) and monocyte-derived MPs (P = 0.001) expressing tissue factor (TF) significantly increased as well as MPs expressing Klotho (P = 0.003) and receptor for advanced glycation end products (RAGE) (P = 0.009). Furthermore, MPs expressing platelet activation markers P-selectin (P = 0.009) and CD40L (P = 0.045) also significantly increased. The increase of endothelial (P = 0.034), monocyte (P = 0.014) and RAGE⁺ MPs (P = 0.032) as well as TF⁺ platelet-derived MPs (P = 0.043) was significantly higher in patients treated with low-flux compared with high-flux dialysers.

Conclusion

Dialysis triggers release of MPs of various origins with marked differences between high-flux and low-flux dialysers. The MPs carry surface molecules that could possibly influence coagulation, inflammation, oxidative stress and endothelial dysfunction. The clinical impact of these findings remains to be established in future studies.

Evaluation of pre- and post-dilution continuous veno-venous hemofiltration on leukocyte and platelet function in patients with sepsis

OBJECTIVE:

We investigated the differences in biocompatibility pre- and post-dilution during continuous veno-venous hemofiltration in patients with sepsis, focusing on leukocyte and platelet function.

PATIENTS AND METHODS:

Subjects were 12 patients with septic shock who underwent veno-venous hemofiltration for acute kidney injury between March 2016 and September 2017. The first six patients received pre-dilution veno-venous hemofiltration, and the next six patients received post-dilution veno-venous hemofiltration. The blood flow rate and filtration flow rate for veno-venous hemofiltration using a polysulfone hemofilter were set to 150 and 35 mL/min, respectively. Leukocyte and platelet counts were determined at 0 and 24 h after veno-venous hemofiltration commencement. Serum interleukin-6 and interleukin-10 levels, the induction rates of regulatory T cells, the expression rate of monocyte HLA-DR, neutrophil phagocytic and sterilizing ability, and platelet P-selectin expression rate were determined at 0, 6, and 24 h after veno-venous hemofiltration commencement.

RESULTS:

There were no significant differences in patient characteristics between the two groups. Serum interleukin-6 decreased over time during pre- and post-dilution veno-venous hemofiltration. Serum interleukin-10 levels decreased during pre-dilution veno-venous hemofiltration, but remained unchanged during post-dilution veno-venous hemofiltration. The Treg and platelet P-selectin expression rates significantly increased at 24 h compared to 0 h during post-dilution veno-venous hemofiltration. Neutrophil phagocytic ability at 24 h was significantly decreased compared to that at 0 h during post-dilution veno-venous hemofiltration. No significant changes in leukocyte and platelet function were observed during pre-dilution veno-venous hemofiltration.

CONCLUSION:

Pre-dilution veno-venous hemofiltration demonstrates superior biocompatibility in terms of decreased leukocyte function and platelet activation in septic shock patients with acute kidney injury.

Current approaches to middle molecule removal: room for innovation

Aggressive removal of middle molecules or larger low-molecular-weight proteins (LMWPs) has been a growing concern following studies on their harmful effects on the mortality and morbidity of chronic dialysis patients. To remove larger LMWPs and some protein-bound uremic toxins (PBUTs), high- and medium-cutoff (HCOs and MCOs, respectively) membranes, convective therapy and protein adsorptive membranes are available. When we use HCO or MCO membranes for convective therapy, we have to take care to avoid massive albumin leakage during a dialysis session. Convection volume is an important element to increase middle molecule removal; however, a larger convection volume has a risk of larger leakage of albumin. Predilution hemodiafiltration is a useful measurement to increase larger LMWPs without massive albumin leakage. β2-microglobulin (B2M), α1-microglobulin (A1M) and albumin leakage during a dialysis session are useful parameters for assessing middle-molecule removal. Reduction ratios of B2M >80% and of A1M >35% are favorable to improve severe dialysis-related symptoms. The efficacy of middle molecule removal should be evaluated in comparison with clinical outcomes, mortality, morbidity and the improvement of dialysis-related symptoms. Recently some dialysis-related symptoms such as sleep disturbance, skin itchiness and dialysis hypotension have been recognized as good surrogate makers for mortality. Further studies to evaluate the relationship between middle molecule or PBUTs removal and the improvement of patient symptoms should be performed in well-designed randomized controlled trials.

Experimental and Clinical Evaluation of Predilution and Postdilution Continuous Venovenous Hemofiltration on Clearance Characteristics

We compared the clearance characteristics of low-to-high molecular weight substances during pre-and postdilution continuous venovenous hemofiltration (CVVH) in experimental and clinical conditions. Experimental circuits for pre- and postdilution CVVH were prepared using a test solution containing creatinine (110 Da), inulin (5,000 Da), interleukin (IL)-8 (8,000 Da), IL-6 (22,000 Da), and tumor necrosis factor (TNF)-α (51,000 Da). Quantity of test solution flow and filtration flow (QF) were set to 150 ml/min and 10, 20, and 35 ml/min, respectively. Clinical CVVH settings were blood flow (QB): 150 ml/min and QF: 35 ml/min. Samples were obtained from pre- and posthemofilters, and clearance of target substances was determined during pre- and postdilution CVVH in experimental and clinical conditions. Clearance changed according to QF during both pre- and postdilution CVVH in the experiment. Clearance of creatinine, inulin (experiment only), and IL-8 during postdilution CVVH was superior to that during predilution CVVH. Few differences were seen in clearance of IL-6 and TNF-α between dilution methods in the experiment and clinical practice. Clearance of IL-8 and IL-6 decreased during postdilution CVVH over 24 hr but did not change during predilution CVVH in clinical practice. Predilution CVVH is useful for stable cytokine clearance in septic patients with acute kidney injury.

Evaluation of the Biocompatibility of Dialysis Membranes

BACKGROUND

Improvements in the biocompatibility of dialysis membranes have reduced biological responses elicited by blood-membrane interactions. In this article, recent technological developments in dialysis membranes with regard to biocompatibility and recent progress in the evaluation of the biocompatibility of dialysis membranes are reviewed.

SUMMARY

The focus of investigation into dialysis membranes in recent years has focused on not only membrane materials, but also their surface textures, which have been changed, for example, by coating with vitamin E or by changing the amount and type of hydrophilizing agents used. Research and development is directed at altering the chemical and physical properties of membrane surfaces to suppress biological responses that are particularly elicited as a result of platelet activation. To develop membranes with excellent biocompatibility, biocompatibility should be evaluated on a like-for-like basis under conditions that are similar to those in clinical settings. Evaluation using actual dialyzers can be performed using porcine blood, platelet-rich plasma isolated from porcine blood (and platelet-rich plasma with leukocytes), or suspension of neutrophils isolated from porcine blood or cultured human monocytes.

KEY MESSAGES

Highly biocompatible dialysis membranes can be developed when the overall correlations among biological reactions are examined by integrating all data on biological responses elicited by blood-membrane interactions or mutual interactions among blood cells.

Extracellular Vesicles in Renal Diseases: More than Novel Biomarkers?

Extracellular vesicles from the urine and circulation have gained significant interest as potential diagnostic biomarkers in renal diseases. Urinary extracellular vesicles contain proteins from all sections of the nephron, whereas most studied circulating extracellular vesicles are derived from platelets, immune cells, and the endothelium. In addition to their diagnostic role as markers of kidney and vascular damage, extracellular vesicles may have functional significance in renal health and disease by facilitating communication between cells and protecting against kidney injury and bacterial infection in the urinary tract. However, the current understanding of extracellular vesicles has derived mostly from studies with very small numbers of patients or in vitro data. Moreover, accurate assessment of these vesicles remains a challenge, in part because of a lack of consensus in the methodologies to measure extracellular vesicles and the inability of most techniques to capture the entire size range of these vesicles. However, newer techniques and standardized protocols to improve the detection of extracellular vesicles are in development. A clearer understanding of the composition and biology of extracellular vesicles will provide insights into their pathophysiologic, diagnostic, and therapeutic roles.

Performance evaluation of developed polysulfone membrane hemodiafilters, ABH-F and ABH-P, in post- and pre-dilution hemodiafiltration

ABH-F and ABH-P have been developed for hemodiafiltration (HDF) therapy. In this study, we evaluated the solute removal characteristics of the hemodiafilters in a bovine blood in vitro study. The hemodiafilters were examined for 120 min at various filtration flow rates (Q F) (31.2-250 mL/min) under a constant blood flow rate of 250 mL/min and constant dialysate flow rates of 500/250 mL/min in pre-dilution HDF (pre-HDF) and post-dilution HDF (post-HDF). Creatinine clearance in pre-HDF was approximately 85% of that in post-HDF because it was removed by molecular diffusion dominantly. The initial clearances of β2-microglobulin and α1-microglobulin increased with Q F and these values slightly and steeply decreased with time due to membrane fouling. Under a same Q F of 62.5 mL/min, higher clearance values in post-HDF were obtained compared with those in pre-HDF. All clearance values of ABH-P were higher than those of ABH-F under the same Q F. It seems that the ABH-P has a larger pore size of membrane than that in ABH-F. The creatinine and α1-microglobulin clearance values were obtained as highest at post-Q F62.5, the β2-microglobulin clearance values and transmembrane pressure were obtained as highest at pre-Q F250. Large solute clearances such as α1-microglobulin and albumin decreased with time in all HDF experiments. Time decay of large solute clearance values was observed in the HDF modality that had a higher clearance of the solute at 5 min later after the start of experiment.