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Concept: Renal replacement therapy

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BACKGROUND: Maintenance hemodialysis (HD) patients universally suffer from excess toxin load. Hemodiafiltration (HDF) has shown its potential in better removal of small as well as large sized toxins, but its efficacy is restricted by inter-compartmental clearance. Intra-dialytic exercise on the other hand is also found to be effective for removal of toxins; the augmented removal is apparently obtained by better perfusion of skeletal muscles and decreased inter-compartmental resistance. The aim of this trial is to compare the toxin removal outcome associated with intra-dialytic exercise in HD and with post-dilution HDF.Methods/designThe main hypothesis of this study is that intra-dialytic exercise enhances toxin removal by decreasing the inter-compartmental resistance, a major impediment for toxin removal. To compare the HDF and HD with exercise, the toxin rebound for urea, creatinine, phosphate, and beta2-microglobulin will be calculated after 2 hours of dialysis. Spent dialysate will also be collected to calculate the removed toxin mass. To quantify the decrease in inter-compartmental resistance, the recently developed regional blood flow model will be employed. The study will be single center, randomized, self-control, open-label prospective clinical research where 15 study subjects will undergo three dialysis protocols (a) high flux HD, (b) post-dilution HDF, © high flux HD with exercise. Multiple blood samples during each study session will be collected to estimate the unknown model parameters. DISCUSSION: This will be the first study to investigate the exercise induced physiological change(s) responsible for enhanced toxin removal, and compare the toxin removal outcome both for small and middle sized toxins in HD with exercise and HDF. Successful completion of this clinical research will give important insights into exercise effect on factors responsible for enhanced toxin removal. The knowledge will give confidence for implementing, sustaining, and optimizing the exercise in routine dialysis care. We anticipate that toxin removal outcomes from intra-dialytic exercise session will be comparable to that obtained by standalone HDF. These results will encourage clinicians to combine HDF with intra-dialytic exercise for significantly enhanced toxin removal.Trial registrationClinicalTrials.gov number, NCT01674153.

Concepts: Chronic kidney disease, Nephrology, Dialysis, Clinical trial, Effectiveness, Hemodialysis, Renal replacement therapy, Clinical research

165

Vascular access problems are a daily occurrence in hemodialysis units. Loss of patency of the vascular access limits hemodialysis delivery and may result in underdialysis that leads to increased morbidity and mortality. Despite the known superiority of autogenous fistulae over grafts, autogenous fistulae also suffer from frequent development of stenosis and subsequent thrombosis. International guidelines recommend programmes for detection of stenosis and consequent correction in an attempt to reduce the rate of thrombosis. Physical examination of autogenous fistulae has recently been revisited as an important element in the assessment of stenotic lesions. Prospective observational studies have consistently demonstrated that physical examination performed by trained physicians is an accurate method for the diagnosis of fistula stenosis and, therefore, should be part of all surveillance protocols of the vascular access. However, to optimize hemodialysis access surveillance, hemodialysis practitioners may need to improve their skills in performing physical examination. The purpose of this article is to review the basics and drawbacks of physical examination for dialysis arteriovenous fistulae and to provide the reader with its diagnostic accuracy in the detection of arteriovenous fistula dysfunction, based on current published literature.

Concepts: Chronic kidney disease, Dialysis, Hemodialysis, Renal replacement therapy, Arteriovenous fistula, Fistula, Cimino fistula

30

Retrospective studies suggest that online hemodiafiltration (OL-HDF) may reduce the risk of mortality compared with standard hemodialysis in patients with ESRD. We conducted a multicenter, open-label, randomized controlled trial in which we assigned 906 chronic hemodialysis patients either to continue hemodialysis (n=450) or to switch to high-efficiency postdilution OL-HDF (n=456). The primary outcome was all-cause mortality, and secondary outcomes included cardiovascular mortality, all-cause hospitalization, treatment tolerability, and laboratory data. Compared with patients who continued on hemodialysis, those assigned to OL-HDF had a 30% lower risk of all-cause mortality (hazard ratio [HR], 0.70; 95% confidence interval [95% CI], 0.53-0.92; P=0.01), a 33% lower risk of cardiovascular mortality (HR, 0.67; 95% CI, 0.44-1.02; P=0.06), and a 55% lower risk of infection-related mortality (HR, 0.45; 95% CI, 0.21-0.96; P=0.03). The estimated number needed to treat suggested that switching eight patients from hemodialysis to OL-HDF may prevent one annual death. The incidence rates of dialysis sessions complicated by hypotension and of all-cause hospitalization were lower in patients assigned to OL-HDF. In conclusion, high-efficiency postdilution OL-HDF reduces all-cause mortality compared with conventional hemodialysis.

Concepts: Dialysis, Epidemiology, Medical statistics, Randomized controlled trial, Hemodialysis, Renal replacement therapy, Outcome, Suggestion

28

In the continuing dispute about the superiority of either intermittent or continuous renal replacement therapy for the critically ill, hybrid methods such as sustained low-efficiency dialysis (SLED) combining the advantages of both modalities - that is, excellent hemodynamic stability and low costs - receive growing attention. The study by Schwenger and colleagues is the first randomized trial indicating that there may be no significant difference in survival at 90 days between patients treated with SLED as compared with those treated with continuous veno-venous hemofiltration.

Concepts: Nephrology, Hemodialysis, Renal replacement therapy

28

The optimal choice of modality for acute renal replacement therapy is unclear at present. Diffusive therapy (hemodialysis) removes small solutes mainly, whereas convective therapies (hemofiltration and hemodiafiltration) may also eliminate larger molecules such as myoglobin or cytokines. Conversely, convective therapies might predispose patients to filter clotting and thus increased costs. A systematic review and meta-analysis of clinical trials could not find evidence for clinical benefits of either modality. Thus, the decision on renal replacement therapy modality still is based on the clinical status of the individual patient, the expertise of the medical and nursing staff, and local circumstances and availability.

Concepts: Chronic kidney disease, Nephrology, Dialysis, Medicine, Systematic review, Hemodialysis, Renal replacement therapy, Hemofiltration

27

This proof of concept pilot study was performed to determine whether vibration can increase solute clearance when applied to an in vitro dialysis model. Urea, creatinine, gentamicin, and vancomycin transmembrane clearances were calculated at a blood flow rate of 200 ml/min, dialysate flow rates of 2 and 8 L/hr, and no concurrent ultrafiltration at various vibration intensities. Dialyzer integrity was determined by measuring transmembrane pressure, filter drop pressure, and albumin clearance, and by visually inspecting the dialysate. Comparing the highest vibration modality with no vibration, the median percentage increase in urea, creatinine, gentamicin, and vancomycin clearance was 18% (all p < 0.005). The transmembrane clearance of albumin was negligible for all experiments. When measuring transmembrane pressure and filter drop pressure, no significant differences were found between nonvibration and vibration dialysis. The addition of vibration during dialysis increased transmembrane clearance for solutes with molecular weights of 60-1450 Daltons.

Concepts: Chronic kidney disease, Nephrology, Dialysis, Chemistry, Hemodialysis, Ultrafiltration, Renal replacement therapy, Renal dialysis

26

Long life expectancy and wide development of therapies have increased the number of patients under artificial treatment for lost kidney function or dialysis. Different options for vascular access are suitable for receiving this therapy. The use of tunneled catheters has consequently increased complications related to its use. A difficult retrieval of catheters caused by a hard fibrin sheath along its trajectory is a common drawback. Herein, we report a woman with suspicion of hemodialysis catheter infection and an irretrievable Tesio catheter. A novel technique using a Fogarty arterial catheter allowed a successful retrieval and avoided an aggressive management.

Concepts: Chronic kidney disease, Nephrology, Dialysis, Hemodialysis, Renal replacement therapy, Catheters, Artificial kidney, Urinary catheterization

25

Vascular surgeons are essential in “lifeline” creation for hemodialysis patients and should be the central player in any multidisciplinary access service together with nephrologists, dialysis staff and interventional radiology. In this position, access surgeons are involved in complicated clinical decision making regarding primary and secondary access selection, which throughout the last decade has been largely aided, and influenced, by national and international guidelines as well as other initiatives. These recommendations, unanimously and appropriately, advocate the placement of native fistulas over synthetic grafts (the majority grafts from expanded polytetrafluoroethylene, ePTFE, herein referred to as PTFE) based on the superiority of fistulas with respect to complications such as infections and thrombosis. Nevertheless, the use of PTFE grafts for hemodialysis access is an accepted and firmly established alternative to native fistulas where data today reveal unwanted consequences to overinterpretation of established guidelines such as increased catheter use. This information highlights a need for an adjustment of access selection strategies based on patient-centered algorithms. Here, available results on PTFE graft performance in hemodialysis access is recapitulated, with respect to both conventional grafts and technical modifications, and conclude with a modified approach to primary access selection.

Concepts: Chronic kidney disease, Dialysis, Hemodialysis, Renal replacement therapy, Interventional radiology, Polytetrafluoroethylene, DuPont, Gore-Tex

6

In-centre haemodialysis (ICHD) is the most common dialysis method used by patients worldwide. However, quality of life and clinical outcomes in patients treated via ICHD have not improved for some time. ‘High-dose’ haemodialysis (HD) regimens - which are longer and/or more frequent than conventional regimens and are particularly suitable to delivery in the home - may offer a route to improved outcomes and quality of life. This survey aimed to determine nephrologists' views on the validity of alternatives to ICHD, particularly home HD and high-dose HD.

Concepts: Chronic kidney disease, Nephrology, Dialysis, Life, Hemodialysis, Renal replacement therapy

4

Persons receiving outpatient hemodialysis are at risk for bloodstream and vascular access infections. The Centers for Disease Control and Prevention conducts surveillance for these infections through the National Healthcare Safety Network. We summarize 2014 data submitted to National Healthcare Safety Network Dialysis Event Surveillance.

Concepts: Chronic kidney disease, Dialysis, Disease, Infection, Hemodialysis, Renal replacement therapy, Security, Renal dialysis