Kidney Dial., Volume 1, Issue 2 (December 2021) – 13 articles

As the Medical Director of this new dialysis facility, I recommend a fixed sodium dialysate (Na_dial) concentration at 138 mEq/L. This relates to my former experience in the Tassin unit in France and the fear of sodium as a powerful uremic toxin. I realize that, according to the Na⁺ set-point theory, a fixed value of the Na_dial may create a plasma–dialysate (P–D) gradient and may favor intradialytic plasma Na⁺ changes. In cases where this is associated with signs of negative Na⁺ balance (bad session tolerance/quality of life) or positive Na⁺ balance (high interdialytic weight gain or high blood pressure), individualization of the Na_dial to reduce the P–D gradient and change in plasma Na⁺ concentration may be useful, even though evidence remains scarce. I look forward to the possibility of using new dialysis machines that allow for the evaluation of sodium balance and tailoring of the sodium diffusion process. Full article

The optimal dialysate sodium concentration for chronic hemodialysis patients remains controversial. Conflicting data from small observational studies and large cohort study data have not convinced nephrologists to choose either a high or low sodium dialysate. Despite a lack of evidence, I would prescribe individualized dialysate sodium concentrations for patients with a risk of hypertension or volume overload, aligning the dialysate sodium concentration with patients’ predialysis serum sodium level. The concentration of dialysate sodium would usually be 0–2 mEq/L below the patient’s serum sodium concentration. I believe that this strategy would help improve hypertension, intradialytic weight gain, cardiac outcomes, and deliver precision medicine. Full article

In haemodialysis, sodium and fluid balance (where intake matches loss) is achieved by ultrafiltration and by diffusion between the plasma water and dialysate. If a patient’s sodium intake does not change, any reduction in fluid gain obtained by lowering dialysate sodium concentration will result in less sodium removal by ultrafiltration. The corresponding change in diffusion to achieve balance may mean the benefit of lower fluid gain is offset by morbidity caused by a fall in serum sodium during dialysis. The standard dialysate sodium should minimise harm caused by both high ultrafiltration rates and osmotic disequilibrium. For most units, this is likely to be 138 to 140 mmol/L. Full article

With advances in hemodialysis technology and the desire to achieve cardiovascular stability during dialysis, prescribed dialysate sodium concentration has gradually increased over the years. Short-term trials suggest low dialysate sodium (<138 mEq/L) is beneficial in reducing interdialytic weight gain, pre- and post-dialysis BP, and predialysis serum sodium; but it increases intradialytic hypotensive episodes. We believe dialysate sodium prescription cannot be considered in isolation. Our approach is to use patient symptoms, meticulous fluid volume management and low temperature dialysate in conjunction with neutral dialysate sodium in managing our dialysis patients. Long-term trials are needed to inform optimum dialysate sodium prescription. Full article

The principal aim of dialysis in relation to sodium is that dialysate sodium should not be low enough to cause intradialytic hypotension and cramps, and should not be high enough to cause interdialytic weight gain and hypertension. Dialysis sodium at 138 meq/L is supposed to be neutral and for most patients, this remains the standard sodium level for regular long-term dialysis. In my opinion, sodium should be changed temporarily from this level to 142 meq/L in selected patients only for a few dialysis sessions, where the cause of intradialytic hypotension is not obvious. In patients who regularly go into intradialytic hypotension and whose cause of intradialytic hypotension is unclear or cannot be corrected, sodium profiling should be used for maintenance dialysis. There is no consensus on the level of sodium, although I think 142 meq/L for the initial hour followed by a decrease to 138 meq/L in the last hour is sensible. Full article

Restoring sodium and fluid homeostasis in hemodialysis (HD) patients is a crucial aim to reduce cardiovascular burden and improve global outcome. This crucial target is achieved at maximum in one quarter of HD patients according to a recent study. Sodium and fluid balance relies on a multitarget approach involving dietary salt restriction, dialysis salt mass removal and eventually residual kidney function. Salt mass removal in hemodialysis relies on ultrafiltration (convective sodium), the dialysate–plasma sodium gradient (diffusive sodium) and total treatment time. Manual dialysate sodium prescription has three major aims: dialysate–plasma sodium gradient; sodium mass removal target; hemodialysis tolerance and patient risks. In the future, automated dialysate sodium adjustment by HD machine will facilitate this aim. Full article

The best evidence available to guide a policy for prescribing the dialysate sodium concentration, [DNa], comes from large randomly selected observational studies, such as the Dialysis Outcomes and Practice Patterns Study (DOPPS). These show that, after adjustment for differences in demographics and comorbidity, using a [DNa] lower than 140 mEq/L is associated with patients taking longer to recover after a dialysis treatment, worse symptoms of kidney failure, a higher score for the burden of kidney disease and worse mental and physical health-related quality of life. It is also associated with greater risks of being admitted to hospital and dying. These outcomes are more important than any medically determined surrogate outcome, such as the control of blood pressure or interdialytic weight gain. The most appropriate policy for prescribing the dialysate sodium concentration is to use a [DNa] of 140 mEq/L for the majority of patients. Full article

Background: Monitoring of vascular access outflow (VAO) in dialysis is based on the indicator dilution method by ultrasound (UD). The role of arterial needle orientation in VAO measurement is not clear. We compared the impact of the retrograde (RET) versus the antegrade orientation (ANT) in terms of (a) VAO (UD) and (b) dialysis adequacy. Moreover, we compared VAO (UD ANT and RET orientation) with VAO measured by Doppler ultrasound. Methods: 22 patients participated in the study. Inclusion criteria: Dialysis > 6 months with a functioning AVF, no stenosis, no active infection, EF > 45% and informed consent. 4 flow measurements were taken on the same dialysis day (4 consecutive weeks). To account for blood pressure variation, we “corrected” VAO for a mean arterial pressure of 100 mmHg. Doppler VAO was measured just before dialysis. Means were compared by the paired t-test. For correlation and agreement, linear regression and Bland-Altman analysis were performed respectively. Results: Mean VAO (UD) was higher in the (ANT) versus the (RET) orientation: 1286.17 mL/min (SD = 455.78, 95%CI = 1084–1488) versus 1189.96 mL/min (SD = 401.05, 95%CI = 1012–1368) (p = 0.013) with a mean difference of 96.21 mL/min (5.66%). Mean Kt/V (RET orientation) was 1.57 (SD = 0.10, 95%CI = 1.52–1.61) versus 1,55 (SD = 0.10, 95%CI = 1.50–1.60) (ANT) orientation (p = 0.062). Recirculation was always 0%. The mean VAO (Doppler) was 1079.54 mL/min (SD = 356.04, 95%CI = 922–1237), 16% lower than VAO measured by UD with (ANT) orientation (p = 0.009) and 9.3% lower than the VAO in the (RET) orientation (p = 0.113). Linear regression analysis showed that VA flows (ANT versus RET) orientation of the needle correlates well between them (r = 0.93, p < 0.001) but show poor agreement (Bland–Altman analysis). Conclusion: VAO (UD) in the RET orientation was significantly lower than VAO in the ANT orientation and more consistent with VAO assessed by Doppler without influencing dialysis adequacy. Therefore, when using UD for VAO surveillance, the RET orientation should be used. Full article

The role of medical director of a hemodialysis unit has become increasingly complex. Among the many roles it encompasses, the delivery of safe and effective dialysis treatments requires constant review, synthesis, and interpretation of the medical literature. Despite decades of experience with hemodialysis, the evidence base for dialysate prescription is relatively limited, with the choice of dialysate sodium being a prime example. The ask of this exercise was to imagine ourselves as the medical director of a new hemodialysis unit and to consider factors influencing the choice of dialysate sodium. While fiscal considerations are indeed important, one hopes that these align with the delivery of clinical care to improve patient well-being. Therefore, my approach was to focus on exploring the clinical responsibilities of a medical director in the choice of dialysate sodium. As such, after reviewing the evidence to date, my ‘default’ dialysate sodium prescription would be 140 mmol/L, but I would retain the option of individualizing treatment for certain patients until further evidence becomes available. Full article

Dialytic clearance of p-cresyl sulfate (pCS) and other protein-bound toxins is limited by diffusive and convective therapies, and only a few studies have examined how to improve their removal by adsorptive membranes. This study tested the hypothesis that high-flux polymethylmethacrylate (PMMA) dialysis membranes with adsorptive capacity increase pCS removal compared to polysulfone membranes, in a postdilution on-line hemodiafiltration (OL-HDF) session. Thirty-five stable hemodialysis patients randomly completed a single study of 4 h OL-HDF with PMMA (BG2.1U, Toray^®, Tokyo, Japan) and polysulfone (TS2.1, Toray^®) membranes. The primary endpoint was serum pCS reduction ratios (RRs) obtained with each dialyzer. Secondary outcomes included RRs of other solutes such as β2-microglobulin, the convective volume obtained after each dialysis session, and the dialysis dose estimated by ionic dialysance (Kt) and urea kinetics (Kt/V). The RRs for pCS were higher with the PMMA membrane than those obtained with polysulfone membrane (88.9% vs. 58.9%; p < 0.001), whereas the β2-microglobulin RRs (67.5% vs. 81.0%; p < 0.001), Kt (60.2 ± 8.7 vs. 65.5 ± 9.4 L; p = 0.01), Kt/V (1.9 ± 0.4 vs. 2.0 ± 0.5; p = 0.03), and the convection volume (18.8 ± 2.8 vs. 30.3 ± 7.8 L/session; p < 0.001) were significantly higher with polysulfone membrane. In conclusion, pCS removal by OL-HDF was superior with high-flux PMMA membranes, appearing to be a good dialysis strategy for improving dialytic clearance of pCS, enabling an acceptable clearance of β2-microglobulin and small solutes. Full article

Weight gain within the first year of kidney transplantation is associated with adverse outcomes. This narrative systematic review and meta-analysis examines the effect of exercise, physical activity, dietary, and/or combined interventions on body weight and body mass index (BMI) within the first year of kidney transplantation. Seven databases were searched from January 1985 to April 2021 (Prospero ID: CRD42019140865), using a ‘Population, Intervention, Controls, Outcome’ (PICO) framework. The risk-of-bias was assessed by two reviewers. A random-effects meta-analysis was conducted on randomized controlled trials (RCTs) that included post-intervention body weight or BMI values. Of the 1197 articles screened, sixteen met the search criteria. Ten were RCTs, and six were quasi-experimental studies, including a total of 1821 new kidney transplant recipients. The sample sizes ranged from 8 to 452. Interventions (duration and type) were variable. Random-effects meta-analysis revealed no significant difference in post-intervention body weight (−2.5 kg, 95% CI −5.22 to 0.22) or BMI (−0.4 kg/m², 95% CI −1.33 to 0.54). Despite methodological variance, statistical heterogeneity was not significant. Sensitivity analysis suggests combined interventions warrant further investigation. Five RCTs were classified as ‘high-risk’, one as ‘some-concerns’, and four as ‘low-risk’ for bias. We did not find evidence that dietary, exercise, or combined interventions led to significant changes in body weight or BMI post kidney transplantation. The number and quality of intervention studies are low. Higher quality RCTs are needed to evaluate the immediate and longer-term effects of combined interventions on body weight in new kidney transplant recipients. Full article

The arteriovenous fistula (AVF) has long been considered the optimal vascular access. However, the evolving characteristics of the ageing dialysis population limit the creation of an AVF in all patients. Thus, more patients start hemodialysis (HD) with a central venous catheter (CVC) rather than an AVF, and the supremacy of the AVF has recently been questioned. The aim of this study was to analyze the incidence and rate of access complications in 100 patients between 2010 and 2015. A total of 63 patients started HD with an AVF, while 37 began HD with a CVC. We found no differences in patient survival according to the vascular access in use at the beginning of dialysis, but patients were more likely to die while undergoing dialysis by means of a CVC than an AVF. Patients started on dialysis with a CVC had more cardiovascular disease, while patients who began dialysis with an AVF presented more hypertension. Fistulas presented a longer survival time despite more hospital admissions, but CVCs bore a higher risk of infections. Our results suggest that starting dialysis with a CVC does not confer a greater risk of death. Full article

Sustainable vascular or peritoneal access for dialysis is very important for patients undergoing dialysis therapy, and access trouble is occasionally involved with unexpected occurrence of complications. Once access trouble occurs, dialysis therapy might be discontinued and be followed by a life-threatening state of patients with end-stage kidney disease. Bacterial infection, massive bleeding, and thrombosis in patients undergoing hemodialysis and acute infectious peritonitis and chronic encapsulating peritoneal sclerosis in patients undergoing peritoneal dialysis are important clinical issues. Preemptive kidney transplantation prior to dialysis has several advantages over transplantation after exposure to dialysis therapy. One of the notable advantages is the lack of necessity of dialysis access, which avoids access operations before transplantation. However, some transplant recipients may need short-term dialysis therapy due to the unexpected progression of chronic renal dysfunction. Dialysis access is required in a short preoperative period for preconditioning. The selection of renal replacement therapy without complications in a short-term dialysis before transplant surgery is important for the success of kidney transplantation. Appropriate preparation of short-term dialysis therapy and access is a key to success of preemptive kidney transplantation. Full article