Impact of needle type on substitution volume during online hemodiafiltration: plastic cannulae versus metal needles

BACKGROUND

Plastic cannulae have attracted increasing interest as an alternative to traditional metal needles with the aim of reducing cannulation-related complications. We investigated whether the substitution volumes during hemodiafiltration differ using these two types of needles in dialysis patients.

METHODS

An intervention study involving 26 hemodialysis patients was conducted in Korea between March and September in 2021. Patients first received online hemodiafiltration using traditional metal needles, and thereafter plastic cannulae were used in a stepwise protocol. Repeated-measures design and linear mixed-effect models were used to compare substitution volumes between the two needle types with the same inner diameter.

RESULTS

The mean patient age was 62.7 years, and their mean dialysis vintage was 95.2 months. Most patients (92.3%) had an arteriovenous fistula as the vascular access. The substitution volume increased as blood flow and needle size increased for both plastic cannulae and metal needles. The substitution volume was significantly higher with 17-gauge (G) plastic cannulae than with 16-G metal needles at blood flow rates of 280, 300, and 330 mL/min. Similar results were obtained for 15-G metal needles and 16-G plastic cannulae at a blood flow rate of 330 mL/min. However, the patient ratings of pain on a visual analogue scale were higher for plastic cannulae.

CONCLUSION

Higher substitution volumes were obtained at the same prescribed blood flow rate with plastic cannulae than with metal needles during online hemodiafiltration. Plastic cannulae are an option for achieving high-volume hemodiafiltration for patients with low blood flow rates.

Supportive Effects of Online Hemodiafiltration Therapy on the Nutritional State and Lipid Profile in Very Elderly Dialysis Patients

INTRODUCTION

Online hemodiafiltration (HDF) therapy has been recognized as one of the potential dialysis modalities. However, the long-term effects of online HDF therapy on very elderly dialysis patients older than 75 years have yet to be fully elucidated.

METHODS

Seventy-four very elderly patients older than 75 years undergoing maintenance dialysis therapy were studied retrospectively. Twenty-four (mean ± SE, 81.5 ± 1.0 years) were treated by predilution online HDF, and fifty (81.2 ± 0.6 years) were treated by conventional hemodialysis (HD) for 3 years. Laboratory data related to the nutritional state and lipid profile were collected. Body composition was measured by a bioelectrical impedance method.

RESULTS

Dry weight and body mass index decreased in HD patients (2.9%, p = 0.003 and 3.1%, p = 0.001, respectively), while no significant changes were found in online HDF patients. Serum albumin levels reduced in both HD and online HDF groups (3.5%, p = 0.003 and 2.9%, p = 0.026, respectively). The geriatric nutritional risk index decreased in HD patients (3.0%, p < 0.001), while no significant change was shown in online HDF patients. Body composition analysis demonstrated a significant decrease in intracellular water and increases in extracellular water and edema ratio in both groups. Fat mass and %fat showed significant decreases in HD patients (8.1%, p = 0.003 and 7.3%, p = 0.003, respectively), but no significant changes in online HDF patients. Among laboratory data, serum high-density lipoprotein cholesterol levels did not change in HD patients. However, the levels elevated significantly (10.6%, p = 0.03) in online HDF patients.

DISCUSSION/CONCLUSION

These results indicated that the time-dependent deterioration of the nutritional state in very elderly dialysis patients was inevitable; however, such deterioration was not prominent in online HDF patients. Moreover, the lipid profile showed unique changes in online HDF patients. In order to treat very elderly dialysis patients, online HDF should preferentially be taken into consideration because the maintenance of general condition seems to be a practical goal against the natural time-dependent deterioration.

Changes in practice patterns in Japan from before to after JSDT 2013 guidelines on hemodialysis prescriptions: results from the JDOPPS

BACKGROUND

The Japanese Society for Dialysis Therapy (JSDT) published in 2013 inaugural hemodialysis (HD) guidelines. Specific targets include 1.4 for single-pool Kt/V (spKt/V) with a minimum dose of 1.2, minimum dialysis session length of 4 hours, minimum blood flow rate (BFR) of 200 mL/min, fluid removal rate no more than 15 mL/kg/hr, and hemodiafiltration (HDF) therapy for certain identified symptoms. We evaluated the effect of these guidelines on actual practice in the years spanning 2005 - 2018.

METHODS

Analyses were carried out to describe trends in the above HD prescription practices from December 2005 to April 2013 (before guideline publication) to August 2018 based on prevalent patient cross-sections from approximately 60 randomly selected HD facilities participating in the Japan Dialysis Outcomes and Practice Patterns Study.

RESULTS

From April 2006 to August 2017 continual rises occurred in mean spKt/V (from 1.35 to 1.49), and percent of patients having spKt/V>1.2 (71% to 85%). Mean BFR increased with time from 198.3 mL/min (April 2006) to 218.4 mL/min (August 2017) , along with percent of patients with BFR >200 ml/min (65% to 85%). HDF use increased slightly from 6% (April 2006 and August 2009) to 8% by April 2013, but increased greatly thereafter to 23% by August 2017. In contrast, mean HD treatment time showed little change from 2006-2017, whereas mean UFR declined from 11.3 in 2006 to 8.4 mL/Kg/hour in 2017.

CONCLUSIONS

From 2006 - 2018 Japanese HD patients experienced marked improvement in reaching the spKt/V target specified by the 2013 JSDT guidelines. This may have been due to moderate increase in mean BFR even though mean HD session length did not change much. In addition, HDF use increased dramatically in this time period. Other HD delivery changes during this time, such as increased use of super high flux dialyzers, also merit study. While we cannot definitively conclude a causal relationship between the publication of the guidelines and the subsequent practice changes in Japan, those changes moved practice closer to the recommendations of the guidelines.

Mixed versus predilution hemodiafiltration effects on convection volume and small and middle molecule clearance in hemodialysis patients: a prospective randomized controlled trial

Background

The use of newly developed mixed-dilution hemodiafiltration (HDF) can supplement the weaknesses of pre- and postdilution HDF. However, it is unclear whether mixed-HDF performs well compared to predilution HDF.

Methods

We conducted a prospective, open-labeled, randomized controlled trial from two hemodialysis centers in Korea. Between January 2017 and September 2019, 60 patients who underwent chronic hemodialysis were randomly assigned at a 1:1 ratio to receive either predilution HDF (n = 30) or mixed-HDF (n = 30) for 6 months. We compared convection volume, changes in small- and medium-sized molecule clearance, high-sensitive C-reactive protein (hs-CRP) level, and dialysis-related parameters between the two dialysis modalities.

Results

A mean effective convection volume of 41.0 ± 10.3 L/session in the predilution HDF group and 51.5 ± 9.0 L/session in the mixed-HDF group was obtained by averaging values of three time-points. The difference in effective convection volume between the groups was 10.5 ± 1.3 L/session. This met the preset noninferiority criteria, suggesting that mixed-HDF was noninferior to predilution HDF. Moreover, the β2-microglobulin reduction rate was greater in the mixed-HDF group than in the predilution HDF group, while mixed-HDF provided greater transmembrane pressure. There were no significant between-group differences in Kt/V urea levels, changes in predialysis hs-CRP levels, proportions of overhydration, or blood pressure values. Symptomatic intradialytic hypotension episodes and other adverse events occurred similarly in the two groups.

Conclusion

Use of mixed-HDF was comparable to predilution HDF in terms of delivered convection volume and clinical parameters. Moreover, mixed-HDF provided better β2-microglobulin clearance than predilution HDF.

Stepwise achievement of high convection volume in post-dilution hemodiafiltration: A prospective observational study

High-volume online hemodiafiltration (HDF) has been reported to reduce the patient's mortality. However, achieving a high convection volume is challenging. In this prospective study, we investigated the feasibility of achieving high-volume HDF with ≥21 L substitution volume via modification of blood flow rate (BFR), needle size, and dialysis membrane. In 30 patients undergoing hemodialysis, we followed a stepwise protocol and gradually increased the BFR (280→300→330 ml/min; steps 1, 2, and 3) and needle size (16→15 G; step 4). After changing dialyzer surface area (1.8 m² →2.5 m² ), the BFR and needle size were similarly increased stepwise (steps 5, 6, 7, and 8). The mean substitution volume was 18.7 ± 2.2 L at step 1 and it significantly increased to 25.1 ± 2.6 L by step 8. A substitution volume of 21 L was achieved by 13.3% of patients in step 1 and by 96.7% after step 8. The substitution volume was higher for the dialyzer with a large surface area and for the larger needle (15 G). Between steps 1 and 8, the Kt/V and β₂ microglobulin reduction ratios also improved significantly. High-volume HDF is feasible through a stepwise increase in the BFR, needle size, and surface area of the dialysis membrane.

Online hemodiafiltration and mortality risk in end-stage renal disease patients: A critical appraisal of current evidence

The life expectancy of end-stage renal disease patients undergoing regular hemodialysis (HD) remains significantly lower than in the general population. Reducing excess mortality by improving renal replacement options is an unmet medical need. Online post-dilution hemodiafiltration (HDF) has been promoted as the gold standard, offering improved clinical outcomes, based on numerous observational studies that suggest a reduced mortality risk and lower morbidity with HDF compared with standard HD. However, most randomized controlled trials (RCTs) have failed to demonstrate a significant beneficial effect of HDF on all-cause mortality. The effects on secondary outcomes were often negligible or absent. Unfortunately, these RCTs were characterized by a moderate to high risk of bias. In post-hoc analyses of the largest RCTs and meta-analysis of individual participant data from four RCTs, HDF patients receiving the highest convection volume consistently and dose-dependently saw superior outcomes. However, as these studies were not designed a priori to clarify this issue, and there are no indisputable mechanisms underlying reduced mortality risks, we cannot exclude the possibility that the health status of patients (with vascular access as a proxy) may affect outcomes more than the convective technique itself. There is currently insufficient evidence to support the contention that high-volume HDF confers relevant benefits to patients over standard HD. The conflicting data of published RCTs reduce confidence in the superiority of high-volume convective therapy. Hopefully, ongoing large RCTs (for example, CONVINCE) may supply an indisputable answer to the crucial question of high-volume HDF.

Effect of online hemodiafiltration compared with hemodialysis on quality of life in patients with ESRD: A systematic review and meta-analysis of randomized trials

Background

End-stage renal disease (ESRD) is related to high morbidity, mortality, and impaired health-related quality of life. While hemodialysis (HD) is the current life-saving standard of treatment for patients with ESRD, their quality of life (QoL) remains far from desirable. Online HDF (OL-HDF), due to its convenience, could improve the QoL of patients with ESRD, however, this remains uncertain.

Objective

We aimed to assess the body of evidence of OL-HDF compared to HD regarding QoL in patients with ESRD.

Methods

We comprehensively searched in multiple data bases from their inception to February 2018. Reviewers working independently and in duplicate appraised the quality and included randomized controlled trials (RCTs) that evaluated, in patients with ESRD and HD or OL-HDF, QoL (Short Form Health Survey with 36 questions (SF-36) with physical component score (PCS) and mental component score (MCS) as well as scores about social activity, fatigue, and emotion). A meta-analysis of each outcome of interest was performed using a random-effects model.

Results

Six moderate quality RCTs met the inclusion criteria. Meta-analysis of 4 RCTs including a total of 1,209 patients showed that OL-HDF was associated with a lower yet non-significant score of PCS: MD (mean difference) -0.77 (95% CI -1.94 to 0.41, p = 0.20), and MCS: MD -1.25 (95% CI -3.10 to 0.59, p = 0.18); indicating a poorer QoL in patients on OL-HDF. Meta-analysis of 4 RCTs including a total of 845 patients showed OL-HDF was associated with a significant increase in the score of social activity compared to HD: SMD (standardized mean difference): 1.95 (95% CI 0.05 to 3.86, p = 0.04), indicating a better QoL in patients on OL-HDF; but regarding fatigue and emotion, there was no significant improvement when compared to HD by meta-analysis of 3 RCTs (133 patients).

Conclusions

The body of evidence suggests that OL-HDF does not improve QoL in patients with ESRD when compared to HD.

Hemodiafiltration to Address Unmet Medical Needs ESKD Patients

Hemodiafiltration combines diffusive and convective solute removal in a single therapy by ultrafiltering 20% or more of the blood volume processed using a high-flux hemodialyzer and maintaining fluid balance by infusing sterile nonpyrogenic replacement fluid directly into the patient's blood. In online hemodiafiltration, the large volumes of replacement fluid required are obtained by online filtration of standard dialysate through a series of bacteria- and endotoxin-retaining filters. Currently available systems for online hemodiafiltration are on the basis of conventional dialysis machines with added features to safely prepare and infuse replacement fluid and closely control fluid balance. Hemodiafiltration provides greater removal of higher molecular weight uremic retention solutes than conventional high-flux hemodialysis, and recently completed randomized, controlled clinical trials suggest better patient survival with online hemodiafiltration compared with standard high-flux hemodialysis when a high convection volume is delivered. Hemodiafiltration is also associated with improvements in other clinical outcomes, such as a reduction in intradialytic hypotension, and it is now used routinely to treat >100,000 patients, mainly in Europe and Japan.

Multicentre cross-sectional study for bone-articular lesions associated with dialysis related amyloidosis in Japan

AIM

Dialysis-related amyloidosis (DRA) exhibits multiple bone-articular lesions, such as carpal tunnel syndrome (CTS), trigger finger (TF), spinal canal stenosis (SCS), destructive spondyloarthropathy (DSA), bone cysts, and joint pains. DRA leads to a decrease in activities of daily living (ADL). We investigated the initiation of CTS and TF, and evaluated the relationship between walking disturbances and bone-articular lesions or joint pains.

METHODS

A multicentre cross-sectional study was performed. Eighty-two patients with clinical DRA from 20 hospitals in Japan were evaluated.

RESULTS

Of the 82 patients, the first symptom of DRA was CTS in 39 patients (47.6%) and TF in 21 (25.6%). The mean new-onset vintages of 21 earlier cases in the CTS and TF groups were 86.1 ± 36.3 and 133.2 ± 56.4 (mean ± SD) months, respectively (P = 0.0091). The development of SCS and DSA appeared to be later than CTS and TF. Multiple regression analysis revealed that knee joint pain was a significant contributor to walking disturbances.

CONCLUSION

Carpal tunnel syndrome appeared significantly earlier than TF since the initiation of dialysis. In the advanced phase, knee joint pain was a major cause of decreased ADL in patients with clinical DRA.

The Diet and Haemodialysis Dyad: Three Eras, Four Open Questions and Four Paradoxes. A Narrative Review, Towards a Personalized, Patient-Centered Approach

The history of dialysis and diet can be viewed as a series of battles waged against potential threats to patients' lives. In the early years of dialysis, potassium was identified as "the killer", and the lists patients were given of forbidden foods included most plant-derived nourishment. As soon as dialysis became more efficient and survival increased, hyperphosphatemia, was identified as the enemy, generating an even longer list of banned aliments. Conversely, the "third era" finds us combating protein-energy wasting. This review discusses four questions and four paradoxes, regarding the diet-dialysis dyad: are the "magic numbers" of nutritional requirements (calories: 30-35 kcal/kg; proteins > 1.2 g/kg) still valid? Are the guidelines based on the metabolic needs of patients on "conventional" thrice-weekly bicarbonate dialysis applicable to different dialysis schedules, including daily dialysis or haemodiafiltration? The quantity of phosphate and potassium contained in processed and preserved foods may be significantly different from those in untreated foods: what are we eating? Is malnutrition one condition or a combination of conditions? The paradoxes: obesity is associated with higher survival in dialysis, losing weight is associated with mortality, but high BMI is a contraindication for kidney transplantation; it is difficult to limit phosphate intake when a patient is on a high-protein diet, such as the ones usually prescribed on dialysis; low serum albumin is associated with low dialysis efficiency and reduced survival, but on haemodiafiltration, high efficiency is coupled with albumin losses; banning plant derived food may limit consumption of "vascular healthy" food in a vulnerable population. Tailored approaches and agreed practices are needed so that we can identify attainable goals and pursue them in our fragile haemodialysis populations.

Cost-effectiveness analysis of online hemodiafiltration versus high-flux hemodialysis

Background

Clinical studies suggest that hemodiafiltration (HDF) may lead to better clinical outcomes than high-flux hemodialysis (HF-HD), but concerns have been raised about the cost-effectiveness of HDF versus HF-HD. Aim of this study was to investigate whether clinical benefits, in terms of longer survival and better health-related quality of life, are worth the possibly higher costs of HDF compared to HF-HD.

Methods

The analysis comprised a simulation based on the combined results of previous published studies, with the following steps: 1) estimation of the survival function of HF-HD patients from a clinical trial and of HDF patients using the risk reduction estimated in a meta-analysis; 2) simulation of the survival of the same sample of patients as if allocated to HF-HD or HDF using three-state Markov models; and 3) application of state-specific health-related quality of life coefficients and differential costs derived from the literature. Several Monte Carlo simulations were performed, including simulations for patients with different risk profiles, for example, by age (patients aged 40, 50, and 60 years), sex, and diabetic status. Scatter plots of simulations in the cost-effectiveness plane were produced, incremental cost-effectiveness ratios were estimated, and cost-effectiveness acceptability curves were computed.

Results

An incremental cost-effectiveness ratio of €6,982/quality-adjusted life years (QALY) was estimated for the baseline cohort of 50-year-old male patients. Given the commonly accepted threshold of €40,000/QALY, HDF is cost-effective. The probabilistic sensitivity analysis showed that HDF is cost-effective with a probability of ~81% at a threshold of €40,000/QALY. It is fundamental to measure the outcome also in terms of quality of life. HDF is more cost-effective for younger patients.

Conclusion

HDF can be considered cost-effective compared to HF-HD.

Confronting Practical Problems for Initiation of On-line Hemodiafiltration Therapy

Conventional hemodialysis, which is based on the diffusive transport of solutes, is the most widely used renal replacement therapy. It effectively removes small solutes such as urea and corrects fluid, electrolyte and acid-base imbalance. However, solute diffusion coefficients decreased rapidly as molecular size increased. Because of this, middle and large molecules are not removed effectively and clinical problem such as dialysis amyloidosis might occur. Online hemodiafiltration which is combined by diffusive and convective therapies can overcome such problems by removing effectively middle and large solutes. Online hemodiafiltration is safe, very effective, economically affordable, improving session tolerance and may improve the mortality superior to high flux hemodialysis. However, there might be some potential limitations for setting up online hemodiafiltaration. In this article, we review the uremic toxins associated with dialysis, definition of hemodiafiltration, indication and prescription of hemodiafiltration and the limitations of setting up hemodiafiltration.