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Objective Arteriovenous grafts (AVGs) are the second best option for haemodialysis access when native arteriovenous fistulae placement is not possible, because they have a lower patency owing to neointimal hyperplasia at the venous anastomosis. This review aimed to evaluate the effect of geometric graft modification to the graft–vein interface on AVG patency. Data sources The MEDLINE and Embase (OvidSP) databases were systematically searched for relevant studies analysing the effect of geometrically modified AVGs on graft patency and stenosis formation (last search July 2019). Review methods Data regarding AVG type, patency, and graft outlet stenosis was extracted for further evaluation. Data were pooled in a random effects model to estimate the relative risk of graft occlusion within one year. Follow up, number of patients, and relevant patient characteristics were extracted for the quality assessment of the included studies using Newcastle-Ottawa Scale and Cochrane Risk of Bias Tool. The quality of the evidence was determined according to the Grading of Recommendations, Assessment, Development and Evaluations (GRADE) system. Results Search strategies produced 2772 hits, of which eight articles met predetermined inclusion criteria. Overall, the included articles had low to moderate risk of bias. In total, 414 expanded polytetrafluoroethylene AVGs (232 geometrically modified and 182 standard) were analysed, comprising two modified AVG types: a prosthetic cuff design (Venaflo®) and grafts with a Tyrell vein patch. Overall, modified grafts did not show a statistically significantly higher one year primary (relative risk [RR] 0.86, 95% confidence interval [CI] 95% 0.64–1.16; GRADE: “low to very low”) or secondary patency (RR 0.57, 95% CI 0.32–1.02; GRADE: “low to very low”) when compared with standard AVGs. Analysis of prosthetic cuffed grafts (112 patients) separately demonstrated a statistically significantly higher one year primary (RR 0.75, 95% CI 0.61–0.91) and one year secondary patency (RR 0.47, 95% CI 0.30–0.75) compared with standard grafts (92 patients). The results on stenosis formation were inconclusive and inadmissible to quantitative analyses. Conclusion The meta-analysis showed that a prosthetic cuff design significantly improves AVG patency, while a venous cuff does not. Although the heterogeneity and low number of available studies limit the strength of the results, this review shows the potential of grafts with geometric modification to the graft–vein anastomosis and should stimulate further clinical and fundamental research on improving graft geometry to improve graft patency.

Compliance mismatch between an arteriovenous dialysis graft (AVG) and the connected vein is believed to result in disturbed haemodynamics around the graft–vein anastomosis and increased mechanical loading of the vein. Both phenomena are associated with neointimal hyperplasia development, which is the main reason for AVG patency loss. In this study, we use a patient-specific fluid structure interaction AVG model to assess whether AVG haemodynamics and mechanical loading can be optimised by using novel electrospun polyurethane (ePU) grafts, since their compliance can be better tuned to match that of the native veins, compared to gold standard, expanded polytetrafluoroethylene (ePTFE) grafts. It was observed that the magnitude of flow disturbances in the vein and the size of anastomotic areas exposed to highly oscillatory shear ($$\hbox {OSI} >0.25$$OSI>0.25) and very high wall shear stress ($$>40 \hbox { Pa}$$>40Pa) were largest for the ePTFE graft. Median strain and von Mises stress in the vein were similar for both graft types, whereas highest stress and strain were observed in the anastomosis of the ePU graft. Since haemodynamics were most favourable for the ePU graft simulation, AVG longevity might be improved by the use of ePU grafts.

The recommendations recently proposed by the European and American Vascular Societies in this new ‘Covid-19’ era regarding the triage of various vascular operations into urgent, emergent and programmed based on the nature of their pathology aim at reserving health care expenses and hospital staff towards managing the current unexpected worldwide pandemic to the highest possible degree. The suggestion for implementation of these changes into real-world practice, however, does not come without a cost. In particular, the recommendation for deferral of access creation in pre-dialysis patients, ethical, socio-economic and medico-legal issues arise which should be seriously taken into consideration. At the end of the day, vascular access creation is the lifeline of haemodialysis patients and the indication for surgery warrants patient-specific clinical judgement rather than ‘group labelling’.

Objective: Arteriovenous grafts (AVGs) typically lose patency within two years of creation due to venous neointimal hyperplasia, which is initiated by disturbed haemodynamics after AVG surgery. Haemodialysis needle flow can further disturb haemodynamics and thus impact AVG longevity. In this computational study it was assessed how dialysis flow and venous needle positioning impacts flow at the graft-vein anastomosis. Furthermore, it was studied how negative effects of dialysis needle flow could be mitigated.Methods: Non-physiological wall shear stress and disturbed blood flow were assessed in an AVG model with and without dialysis needle flow. Needle distance to the venous anastomosis was set to 6.5, 10.0, or 13.5 cm, whereas dialysis needle flow was set to 200, 300 or 400 mL/min. Intraluminal needle tip depth was varied between superficial, central, or deep. The detrimental effects of dialysis needle flow were summarised by a haemodynamic score (HS), ranging from 0 (minimal) to 5 (severe).Results: Dialysis needle flow resulted in increased disturbed flow and/or non-physiological wall shear stress in the venous peri-anastomotic region. Increasing cannulation distance from 6.5 to 13.5 cm reduced the HS by a factor 4.0, whereas a central rather than a deep or superficial needle tip depth reduced the HS by a maximum factor of 1.9. Lowering dialysis flow from 400 to 200 mL/min reduced the HS by a factor 7.4.Conclusion: Haemodialysis needle flow, cannulation location, and needle tip depth considerably increase the amount of disturbed flow and non-physiological wall shear stress in the venous anastomotic region of AVGs. Negative effects of haemodialysis needle flow could be minimised by more upstream cannulation, by lower dialysis flow and by ensuring a central needle tip depth. Since disturbed haemodynamics are associated with neointimal hyperplasia development, optimising dialysis flow and needle positioning during haemodialysis could play an important role in maintaining AVG patency.

Objective: The aim of the study was to observe the natural haemodynamic changes after arteriovenous fistula (AVF) creation in haemodialysis patients with and without a previous ipsilateral vascular access.Methods: This was a retrospective, single centre cohort study. Patient demographics were registered and preand post-operative vessel ultrasound examinations were performed at regular follow up intervals. Arteriovenous fistula outcomes in terms of vessel diameter and access flow enhancement were determined for radiocephalic, brachiocephalic, and brachiobasilic AVFs.Results: In total, 331 patients (median age 66 years, 60% male) with 366 new autologous AVFs were studied, of whom 112 patients had a previous ipsilateral vascular access (VA). Patients with a previous ipsilateral VA had a statistically significantly greater pre-operative brachial artery diameter (4.4 mm) and flow (106 mL/min), and basilic vein diameter (4.9 mm), compared with patients without a previous ipsilateral VA (4.0 mm, 54 mL/min, and 4.3 mm, respectively). For all AVF configurations these differences gradually disappeared over three months after AVF creation. The haemodynamic changes reached a plateau at three months, and were statistically significantly accelerated in patients with a previous ipsilateral VA. There were no differences in primary failure or high flow complications between both groups.Conclusion: Arteriovenous fistulae show haemodynamic and remodelling changes up to three months post-operatively. Previous ipsilateral VAs may initiate vessel preconditioning, and accelerate the observed haemodynamic changes after AVF creation. However, this preconditioning does not result in a beneficial or detrimental effect on VA function.

Objective: Chronic renal failure patients with arteriovenous hemodialysis access may exhibit pain and neurological complaints due to local nerve compression by the access conduit vessels of autogenous arteriovenous fistulas or the prosthesis of arteriovenous grafts. In this study, we have examined the results of surgical intervention for vascular access–related nerve compression in the upper extremity. Methods: A single center retrospective study was performed of all patients referred for persistent pain and neurological complaints after vascular access surgery for hemodialysis. There were four brachial-cephalic, three brachial-basilic upper arm arteriovenous fistulas, and three prosthetic arteriovenous grafts. All patients had pain and sensory deficits in a distinct nerve territory (median nerve: 6; median + ulnar nerve: 1; medial cutaneous nerve: 1), and two patients had additional motor deficits (median nerve). Results: A total of 10 patients (mean age: 59 years; range: 25–73 years; 2 men; 4 diabetics) were treated by surgical nerve release alone (2 patients) or in combination with access revision (8 patients). Mean follow-up was 23 months (range: 8–46 months). Direct complete relief of symptoms was achieved in six patients. Three patients had minor complaints, and one patient had a reoperation with good success. Conclusion: Vascular access–related nerve compression is an uncommon cause for pain, sensory and motor deficits after vascular access surgery. Surgical nerve release and access revision have good clinical outcome with relief of symptoms and maintenance of the access site in the majority of patients.

Interpreting evidence in the arteriovenous (AV) access literature is challenged by the heterogeneity in terminology and the lack of standardization in outcomes. Below some of the terms used in this guideline are listed and how they have been interpreted in the context of this document. Because guideline development necessarily relies on aggregate data from systematic reviews and other individual studies, we can only hope to provide the user with conceptual definitions for certain concepts and outcome domains. At present, there is insufficient consensus to go beyond that point and define specific outcome measures or measurements. [...]

Objective To determine the best operation technique, open versus laparoscopic, for insertion of a peritoneal dialysis (PD) catheter with regard to clinical success. Clinical success was defined as an adequate function of the catheter 2 – 4 weeks after insertion. Methods All patients with end-stage renal disease who were suitable for PD and gave informed consent were randomized for either open surgery or laparoscopic surgery. A previous laparotomy was not considered an exclusion criterion. Laparoscopic placement had the advantage of pre-peritoneal tunneling, the possibility for adhesiolysis, and placement of the catheter under direct vision. Catheter fixation techniques, omentopexy, or other adjunct procedures were not performed. Other measured parameters were in-hospital morbidity and mortality and post-operative infections. Results Between 2010 and 2016, 95 patients were randomized to this study protocol. After exclusion of 5 patients for various reasons, 44 patients received an open procedure and 46 patients a laparoscopic procedure. Gender, age, body mass index (BMI), hypertension, current hemodialysis, severe heart failure, and previous an abdominal operation were not significantly different between the groups. However, in the open surgery group, fewer patients had a previous median laparotomy compared with the laparoscopic group (6 vs 16 patients; p = 0.027). There was no statistically significant difference in mean operation time (36 ± 24 vs 38 ± 15 minutes) and hospital stay (2.1 ± 2.7 vs 3.1 ± 7.3 days) between the groups. In the open surgery group 77% of the patients had an adequate functioning catheter 2 – 4 weeks after insertion compared with 70% of patients in the laparoscopic group ( p = not significant [NS]). In the open surgery group there was 1 post- operative death (2%) compared with none in the laparoscopic group ( p = NS). The morbidity in both groups was low and not significantly different. In the open surgery group, 2 patients had an exit-site infection and 1 patient had a paramedian wound infection. In the laparoscopic group, 1 patient had a transient cardiac event, 1 patient had intraabdominal bleeding requiring reoperation, and 1 patient had fluid leakage that could be managed conservatively. The survival curve demonstrated a good long-term function of PD. Conclusion This randomized controlled trial (RCT) comparing open vs laparoscopic placement of PD catheters demonstrates equal clinical success rates between the 2 techniques. Advanced laparoscopic techniques such as catheter fixation techniques and omentopexy might further improve clinical outcome.

The potential impact of hemodynamic and vascular wall models on the diagnosis, treatment, and wellbeing of thousands of patients suffering from cardiovascular diseases, is tremendous. Despite the potential impact, it is not straightforward to use these models for individualized diagnosis and intervention planning (model predictive decision support). Major challenges are the adaptation of the models to patient-specific conditions and the necessary uncertainty assessment of the simulated outcome measures. In this manuscript, we will present our view on what is needed to make cardiovascular models suitable for clinical decision support. Hereto, we will first describe how an engineer might support clinical decisions. Secondly, we will give a description of the challenges faced by the engineers. Finally we will introduce an innovative approach in which model personalization is guided by sensitivity analysis, and in which the effect of input uncertainties and model assumptions (acknowledged model errors) on model predictions are considered during model corroboration. The approach is illustrated by two different vascular cases. Hopefully our view will be useful in bringing models from the pre-clinical phase to the clinical phase where they will actually be used for model predictive decision support. (C) 2017 Published by Elsevier B.V.

Objective. An arteriovenous fistula (AVF) needs to mature before it becomes suitable to cannulate for haemodialysis treatment. Maturation importantly depends on the post-operative flow increase. Unfortunately, 20-40% of AVFs fail to mature (FTM). A patient specific computational model that predicts immediate postoperative flow was developed, and it was hypothesised that providing information from this model for planning of fistula creation might reduce FTM rates.Methods: A multicentre, randomised controlled trial in nine Dutch hospitals was conducted in which patients with renal failure who were referred for AVF creation, were recruited. Patients were randomly assigned (1:1) to the control or computer simulation group. Both groups underwent a work up, with physical and duplex ultrasonography (DUS) examination. In the simulation group the data from the DUS examination were used for model simulations, and based on the immediate post-operative flow prediction, the ideal AVF configuration was recommended. The primary endpoint was AVF maturation defined as an AVF flow >= 500 mL/min and a vein inner diameter of >= 4 mm six weeks post-operatively. The secondary endpoint was model performance (i.e. comparisons between measured and predicted flows, and (multivariable) regression analysis for maturation probability with accompanying area under the receiver operator characteristic curve [AUC]).Results: A total of 236 patients were randomly assigned (116 in the control and 120 in the simulation group), of whom 205 (100 and 105 respectively) were analysed for the primary endpoint. There was no difference in FTM rates between the groups (29% and 32% respectively). Immediate post-operative flow prediction had an OR of 1.15 (1.06-1.26; p Conclusion: Providing pre-operative patient specific flow simulations during surgical planning does not result in improved maturation rates. Further study is needed to improve the predictive power of these simulations in order to render the computational model an adjunct to surgical planning.

Introduction Digital subtraction angiography (DSA) is the gold standard in diagnosis and treatment of central venous obstructions (CVOs) in hemodialysis access. However, growing data suggest that DSA might underestimate the degree and morphology of venous outflow stenosis. This could lead to inappropriate CVO management. Intravascular ultrasound (IVUS) has been shown to identify lesion characteristics remaining obscure with angiography. With the current study we suggest IVUS as an eminent imaging modality in CVO management. Methods Twelve patients (8 male, mean age 62.4 ± 9 years) were analyzed for suspicion of symptomatic CVO. Both angiography and IVUS evaluation were performed to determine the degree of obstruction before and after PTA. Stent placement was indicated when significant residual stenosis (>50% lumen reduction) was suspected. Results Conventional plain angiography determined 8 out of 12 central venous lesions significant. Secondary signs of obstruction, i.e., collateral filling, was present in all 12 cases. After PTA, persistent significant stenosis was observed in 3 out of 12 patients. IVUS showed significant lumen reduction in all 12 cases. Additionally, IVUS showed a median cross-sectional area of 24 ± 12 mm2 before PTA and 37 ± 23 mm2 after PTA (NS). Furthermore, IVUS showed signs of intraluminal fibrotic trabeculations in 9 patients. Stenting was performed in 10 patients with >50% lumen reduction on IVUS after PTA. Conclusions Conventional angiography seems unreliable to identify all significant aspects of a central venous outflow obstruction. Additional use of IVUS might aid in the decision-making process and select the optimal treatment strategy.

The autologous arteriovenous fistula (AVF) for hemodialysis burdens the cardiovascular system with increased cardiac output and pulmonary artery pressure, increasing cardiovascular risk. This article reviews literature on the benefits and drawbacks of a functioning AVF after kidney transplantation and discusses the cardiovascular effects of AVF closure. Several cohort studies demonstrate a significant cardiac burden of an AVF and improvement of cardiac dimensions after AVF ligation. However, no randomized trials have been conducted on routine AVF closure after successful kidney transplantation. Therefore, clinical trials are warranted to evaluate whether the cardiovascular benefits of routine AVF closure outweigh the potential harm for patients after successful kidney transplantation.

The European Society for Vascular Surgery (ESVS), in line with its mission, appointed the Vascular Access (VA) Writing Committee (WC) to write the current clinical practice guidelines document for surgeons and physicians who are involved in the care of patients with haemodialysis (HD) and VA. The goal of these Guidelines is to summarise and evaluate all the currently available evidence to assist physicians in selecting the best management strategies for all patients needing VA or for pathologies derived from a VA.

Objectives: Upper arm arteriovenous fistulas (AVF) occasionally develop high flow. Revision using distal inflow (RUDI) effectively reduces flow of high flow accesses (HFA) in the short-term and is also popularised for treatment of haemodialysis access induced distal ischaemia (HAIDI). The long-term efficacy is unknown. The study's aim was to report on 3 year RUDI patency and recurrence rates for HFA with and without HAIDI. Material and methods: This was a retrospective cohort study of patients with a HFA with or without HAIDI undergoing RUDI using greater saphenous vein (GSV) interposition between March 2011 and October 2017 at three facilities. AVFs were termed HFA if flow volumes exceeded 2 L/min on two consecutive measurements using dilution techniques. HAIDI was diagnosed as recommended. Following RUDI, follow up was not different from standard care in AVF patients. Data on post-operative flows and re-interventions were extracted from electronic patient files. Loss to follow up was avoided. Rates of patency and HFA recurrence were analysed. Results: During the observation period, 21 patients were studied (7 females, 54 years +/- 3). Fourteen had uncomplicated HFA whereas seven had additional HAIDI. Immediately post-operatively, flows decreased threefold (3120 mL/min +/- 171 vs. 1170 mL/min +/- 87, p

Purpose In the Netherlands, 86% of patients start renal replacement therapy with chronic intermittent hemodialysis (HD). Guidelines do indicate predialysis care and maintenance of a well-functioning vascular access (VA) as critical issues in the management of the renal failure patient. Referral to the surgeon and time to VA creation are important determinants of the type and success of the VA and HD treatment. Methods and Results Data from a national questionnaire showed that time from referral to the surgeon and actual access creation is 8 weeks in 27% of the centers. Pre-Operative ultrasonography and postoperative access flowmetry are the diagnostic methods in the majority of centers (98%). Most facilities perform rope-ladder cannulation with occasionally the buttonhole technique for selected patients in 87% of the dialysis units. Endovascular intervention for thrombosis is practiced by 13%, surgical thrombectomy by 21% and either endovascular or surgery by 66% of the centers. Weekly multidisciplinary meetings are organized in 57% of the units. Central vein catheters are inserted by radiologists (36%), nephrologists and surgeons (32%). Conclusions We conclude that guidelines implementation has been successful in particular regarding issues as pre-operative patient assessment for VA creation and postoperative surveillance in combination with (preemptive) endovascular intervention, leading to very acceptable VA thrombosis rates.

Objective: Although clinical guidelines on arteriovenous fistula (AVF) creation advocate minimum luminal arterial and venous diameters, assessed by duplex ultrasonography (DUS), the clinical value of routine DUS examination is under debate. DUS might be an insufficiently repeatable and/or reproducible imaging modality because of its operator dependency. The present study aimed to assess intra-and inter-observer agreement of DUS examination in support of AVF surgery planning.Methods: Ten end stage renal disease patients were included, to assess intra-and inter-observer agreement of pre-operative DUS measurements. All measurements were performed by two trained and experienced vascular technicians, blinded to measurement readings. From the routine DUS protocol, representative measurements (venous diameters, and arterial diameters and volume flow in the upper arm and forearm) were selected. For intra-observer agreement the measurements were performed in triplicate, with the probe released from the skin between each. Intraclass correlation coefficients were calculated for intra-and inter-observer agreement, and Bland-Altman plots used to graphically display mean measurement differences and limits of agreement.Results: Ten patients (6 male, 59.4 +/- 19.7 years) consented to participate, and all predefined measurements were obtained. Intraclass correlation coefficients for intra-observer agreement of diameter measurements were at least 0.90 (95% CI 0.74-0.97; radial artery). Inter-observer agreement was at least 0.83 (0.46-0.96; lateral diameter upper arm cephalic vein). The Bland-Altman plots showed acceptable mean measurement differences and limits of agreement.Conclusion: In experienced hands, excellent intra-and inter-observer agreement can be reached for the discrete pre-operative DUS measurements advocated in clinical guidelines. DUS is therefore a reliable imaging modality to support AVF surgery planning. The content of DUS protocols, however, needs further standardisation. (C) 2017 European Society for Vascular Surgery. Published by Elsevier Ltd. All rights reserved.

Introduction The arteriovenous fistula (AVF) is the preferred vascular access for hemodialysis patients. Unfortunately, 20-40% of all constructed AVFs fail to mature (FTM), and are therefore not usable for hemodialysis. AVF maturation importantly depends on postoperative blood volume flow. Predicting patient-specific immediate postoperative flow could therefore support surgical planning. A computational model predicting blood volume flow is available, but the effect of blood flow predictions on the clinical endpoint of maturation (at least 500 mL/min blood volume flow, diameter of the venous cannulation segment ≥4 mm) remains undetermined. Methods A multicenter randomized clinical trial will be conducted in which 372 patients will be randomized (1:1 allocation ratio) between conventional healthcare and computational model-aided decision making. All patients are extensively examined using duplex ultrasonography (DUS) during preoperative assessment (12 venous and 11 arterial diameter measurements; 3 arterial volume flow measurements). The computational model will predict patient-specific immediate postoperative blood volume flows based on this DUS examination. Using these predictions, the preferred AVF configuration is recommended for the individual patient (radiocephalic, brachiocephalic, or brachiobasilic). The primary endpoint is FTM rate at six weeks in both groups, secondary endpoints include AVF functionality and patency rates at 6 and 12 months postoperatively. Trial registration ClinicalTrials.gov (NCT02453412), and ToetsingOnline.nl (NL51610.068.14).

Background: Frequent hemodialysis (HD) may be associated with an increased risk of vascular access complications. Studies addressing vascular access outcomes in frequent HD show conflicting results. Methods: We searched Medline for trials looking at vascular access outcomes in frequent HD. Results: Nineteen studies met the inclusion criteria; only studies with a control group were included for analysis (n = 15). The vascular access event rate was higher in intensive HD as compared to conventional HD (difference of 6.7 events per 100 patient-years, p = 0.009). Overall event rates were not significantly different between conventional and intensive HD when stratified for access type, but were notably higher in the arteriovenous grafts and catheter group as compared to the arteriovenous fistula (AVF) group. Conclusion: Intensive HD is associated with an increased risk of vascular access complications. Overall reported event rates were lower in the AVF group. Further controlled studies should investigate whether a ‘fistula first' strategy may be recommended also for intensive HD.

Aims: To determine the incidence and risk factors for surgical site infections (SSI) after vascular surgery, to evaluate the Dutch safety bundle to reduce adverse complications and to analyze causative microorganisms of SSIs. Materials & methods: The 3.5-year study was divided into two periods: the control period (before bundle implementation) and intervention period (after implementation). Postdischarge surveillance was performed until 30 days after surgery. Causative microorganisms from in-hospital wound swabs were determined. SSI rates between both periods were compared and a risk analysis was carried out by performing a logistic regression. Results: The study included 1719 operations. The in-hospital SSI rate increased significantly over time. Out of 140 SSIs, 39% were diagnosed postdischarge. Risk factors were diabetes, age >60 years and operations classified as contaminated or dirty. Pseudomonas aeruginosa susceptibility was the highest for gentamicin (97%). All Staphylococcus aureus were methicillin susceptible. Conclusion: As patient demographics are important to determine the effectiveness of infection preventive measures, (postdischarge) surveillance is important for developing SSI interventions.

Objective: Hand ischemia may occur in the presence of a hemodialysis arteriovenous fistula (AVF), but its pathophysiology is partly unclear. The aim of this observational study was to investigate flow characteristics of forearm arteries in patients with a brachial artery-based AVF suffering from hemodialysis access-induced distal ischemia (HAIDI). Methods: A questionnaire scored hand ischemia in patients with HAIDI scheduled for revisional surgery (no symptoms of ischemia, 0 points; maximal ischemia, 500 points). Systolic index finger pressures (P-dig) and digital brachial index (DBI) were determined with open and compressed AVF. Blood flow direction and peak systolic velocity (PSV) were measured in radial and ulnar arteries using Doppler ultrasonography. Age-and sex-matched hemodialysis patients without HAIDI served as controls (CONT). Results: Questionnaire scores were 258 +/- 30 in patients with HAIDI (n = 10) compared with 31 +/- 16 in CONT (n = 10; P

Background The use of an arteriovenous fistula (AVF) for haemodialysis treatment may be associated with a high early failure rate, but usually good long-term patency, while using an arteriovenous graft (AVG) yields a lower early failure rate with worse long-term patency. The aim of this study was to calculate and compare the costs and outcome of AVF and AVG surgery in terms of early and long-term patencies. Methods A decision tree and a Markov model were constructed to calculate costs and performance of AVFs and AVGs. The model was populated with a retrospective cohort of HD patients receiving their first VA. The outcomes were determined probabilistically with a 5-year follow-up. Results AVFs were usable for a mean (95% CI) of 28.5 months (24.6–32.5 months), while AVGs showed a patency of 25.5 months (20.0–31.2 months). The use of AVFs was the dominant type of VA and €631 could be saved per patient/per month patency compared to AVG use. Regardless of the willingness to pay, the use of AVFs yielded a higher probability of being cost-effective compared to AVGs. Conclusions AVFs are more cost-effective than AVGs. Nonetheless, early failure rates significantly influence AVF performance and initiatives to reduce early failure can improve its cost-effectiveness.

Purpose The aim of this work was to establish the relationship between traditional blood vessel mapping for vascular access (VA) creation by B-mode ultrasound (US) and novel non contrast-enhanced magnetic resonance angiography (NCE-MRA), and to study the potential influence of the diameter assessment technique on the choice of hemodialysis vascular access. Methods A total of 27 end-stage renal-disease patients were included. They received routine US and a NCE-MRA examination of the upper extremity. Diameters were measured manually on US and semi-automatically on NCE-MRA. These measurements were statistically compared for the arteries and veins and for each measurement location. Furthermore, sensitivity and specificity of both modalities to predict VA location was investigated by comparison with an experienced surgeon. This analysis gave insight into the potential influence of vessel mapping modality on decision-making. Results Comparison of NCE-MRA with US for the arteries and veins, demonstrated a bias of 9% (limits −33%-78%) and 38% (limits −36%-198%), respectively. Statistically significant differences between the modalities on the individual locations were mainly found for the venous locations. The sensitivity and specificity for US to predict VA location was 1.0 and 0.74, respectively, while for NCE-MRA this was 0.88 and 0.39, respectively. Conclusions The results obtained indicate that extreme caution should be exercised when replacing one diameter measurement modality with the other. A further need exists to improve both vessel mapping protocols to obtain a geometric description of the upper extremity vasculature regardless of acquisition modality.

Prosthetic arteriovenous grafts (AVGs) are indicated for vascular access for long-term hemodialysis in patients in whom creation or maintenance of an arteriovenous fistula (AVF) has failed or is contraindicated. AVGs have an inferior long-term patency as compared to AVFs. To ameliorate patency rates of prosthetic AVGs, different strategies have emerged to improve graft materials. This review aims to describe current strategies and future perspectives on graft modification, by graft geometry, drug coatings and graft surface technology, to improve AVG patency.

OBJECTIVES: This study assessed the safety and efficacy of a novel implantable device therapy in resistant hypertension patients. BACKGROUND: Despite the availability of potent antihypertensive drugs, a substantial proportion of patients remain hypertensive. A new implantable device (Rheos system, CVRx, Inc., Minneapolis, Minnesota) that activates the carotid baroreflex may help these patients. METHODS: Forty-five subjects with systolic blood pressure ≥160 mm Hg or diastolic ≥90 mm Hg despite at least 3 antihypertensive drugs were enrolled in a prospective, nonrandomized feasibility study to assess whether Rheos therapy could safely lower blood pressure. Subjects were followed up for as long as 2 years. An external programmer was used to optimize and individualize efficacy. RESULTS: Baseline mean blood pressure was 179/105 mm Hg and heart rate was 80 beats/min, with a median of 5 antihypertensive drugs. After 3 months of device therapy, mean blood pressure was reduced by 21/12 mm Hg. This result was sustained in 17 subjects who completed 2 years of follow-up, with a mean reduction of 33/22 mm Hg. The device exhibited a favorable safety profile. CONCLUSIONS: The Rheos device sustainably reduces blood pressure in resistant hypertensive subjects with multiple comorbidities receiving numerous medications. This unique therapy offers a safe individualized treatment option for these high-risk subjects. This novel approach holds promise for patients with resistant hypertension and is currently under evaluation in a prospective, placebo-controlled clinical trial.

Background Central venous catheters (CVCs) are widely used to create a temporary or long-term access to the central venous system. A variety of treatments require a functional central venous access, including hemodialysis, administration of drugs, plasmapheresis and parenteral nutrition. The aim of this study was to evaluate the results of CVC placement performed by surgical trainees, according to a strict protocol of ultrasound-guided puncture and fluoroscopy-guided catheter insertion in a large teaching hospital in an outpatient setting. Methods Between 1 January 2006 and 31 December 2008, 539 CVCs were placed, of which 486 were primary inserted by surgical trainees. All placements were ultrasound- and fluoroscopy-guided. After every placement operators recorded type of catheter, type of anesthesia, subcutaneous tunneling, technique of insertion and complications. Results The study population consisted of 52% males. Access sites of CVCs were the internal jugular vein (91%), subclavian vein (5%) and other veins (3%). Technical success rate was 96.5%. Complication rate was 8.4%, of which 93% were arterial punctures. Pneumothorax occurred in three patients. Conclusions CVC placement by surgical trainees is a safe procedure when using a strict protocol of ultrasound-guided vessel puncture and fluoroscopic-guided catheter placement.

Nephrology Section, Department of Internal Medicine, University Hospital, Gent, Belgium, Nephrology, Dialysis and Intensive Care Unit, Lapeyronie University Hospital, Montpellier, France, Department of Renal Medicine, Royal Derby Hospital, Derby, UK, Nephrology, Cliniques Universitaires Saint-Luc, Universite Catholique de Louvain, Brussels, Belgium, Nephrology Department, Consorcio Hospital General Universitario, Valencia, Spain and Vascular Surgery, Department of Surgery, Maastricht University Medical Center, Maastricht, the Netherlands

Background: Maturation failure is the major obstacle to establishing functional arteriovenous fistulae (AVF) for haemodialysis treatment. Various endovascular and surgical techniques have been advocated to enhance fistula maturation and to increase the number of functional AVFs. This narrative review considers the available evidence of interventional techniques for treatment of AVF non-maturation. Results: Intra-operative vein dilation and anastomosis modification results in a clinical maturation rate of 74-92% and a 6 month cumulative AVF patency of 79-93%. Percutaneous transluminal angioplasty (PTA) with or without accessory vein obliteration is successful in 43-97% of patients. The long-term primary patency of PTA is rather low and multiple re-interventions are needed to achieve an acceptable cumulative fistula patency. The results of surgical revision exceed the results of endovascular intervention, with a mean primary one year patency of 73% (range 68-78%) compared with 49% (range 28-72%), respectively. The role of accessory vein obliteration remains unclear. Conclusion: Intervention for autologous arteriovenous fistula non-maturation is worthwhile and results in an increased number of functional fistulae. The outcome of surgical revision is better than endovascular and might be preferable in certain patient populations. (C) 2017 European Society for Vascular Surgery. Published by Elsevier Ltd. All rights reserved.

Objective Successful access cannulation is of utmost importance for adequate hemodialysis treatment. Upper arm fistulae, obesity and deep or tortuous veins may impair needling and can cause significant complications and inconvenience for the patient. In the ultimate case, cannulation problems lead to temporary central vein catheter use for dialysis or even to irreversible access loss. Surgical access revision may enhance successful cannulation. Methods A systematic literature review of all publications related to hemodialysis vascular access, cannulation complications and treatment was performed. Results A total of 384 publications were identified, of which only 17 were related to treatment of cannulation complications in large patient populations. The clinical success rate of surgical intervention with vein elevation or transposition ranges from 85% to 91%. The 1-year primary and secondary patencies are 60% and 71%, respectively. Lipectomy results in an initial success rate of 100% with a primary and secondary patency of 71% and 98%, respectively, after 1 year of follow-up. Conclusion Surgical revision to improve hemodialysis vascular access cannulation has a high clinical success rate with good long-term patency.

Item does not contain fulltext Increased understanding of the pathophysiology of ischemic acute kidney injury in renal transplantation may lead to novel therapies that improve early graft function. Therefore, we studied the renal microcirculation in ischemically injured kidneys from donors after cardiac death (DCD) and in living donor kidneys with minimal ischemia. During transplant surgery, peritubular capillaries were visualized by sidestream darkfield imaging. Despite a profound reduction in creatinine clearance, total renovascular resistance of DCD kidneys was similar to that of living donor kidneys. In contrast, renal microvascular perfusion in the early reperfusion period was 42% lower in DCD kidneys compared with living donor kidneys, which was accounted for by smaller blood vessel diameters in DCD kidneys. Furthermore, DCD kidneys were characterized by smaller red blood cell exclusion zones in peritubular capillaries and by greater production of syndecan-1 and heparan sulfate (main constituents of the endothelial glycocalyx) compared with living donor kidneys, providing strong evidence for glycocalyx degradation in these kidneys. We conclude that renal ischemia and reperfusion is associated with reduced capillary blood flow and loss of glycocalyx integrity. These findings form the basis for development of novel interventions to prevent ischemic acute kidney injury. 01 november 2010

Background. The rope-ladder puncture technique, with cannulation along the whole length of the vessel traject, has been very common in haemodialysis patients with autogenous arterio-venous fistula (AVF). Today’s dialysis population with AVF may exhibit difficult cannulation, because of a short vein length or a complicated cannulation route. An alternative needling possibility is the buttonhole (BH) technique, which inserts needles at exactly the same location during every dialysis session. The present study was conducted to investigate the effect of both cannulation techniques on the incidence of vascular access (VA) complications. Methods. A total of 75 prevalent haemodialysis patients with autogenous AVF using the BH technique were compared with 70 patients using the rope-ladder technique. The following parameters were registered: haematoma occurrence, redness, swelling, aneurysm formation, the use of sharp or dull needles, miscannulations, and interventions. Needling pain and fear of puncture were assessed using a verbal rating scale (VRS). The duration of the follow-up was 9 months. Results. Patients in the BH group had more unsuccessful cannulations, compared with the rope-ladder method (P

Background. The European Best Practice Guidelines on Vascular Access propose magnetic resonance angiography (MRA) of dysfunctional dialysis fistulae and grafts if visualization of the complete arterial inflow and outflow vessels is needed. In a prospective multi-centre study we determined the technical success rate of complete vascular access tree depiction by digital subtraction angiography (DSA) as an alternative to MRA. Instead of a more invasive brachial artery of femoral artery approach, we performed a retrograde catheterization of the venous outflow or graft, and stenoses were treated in connection with DSA. Methods. A catheter was advanced into the central arterial inflow after retrograde puncture of the venous outflow or graft for depiction of the complete inflow, access region and complete outflow. Access DSA through femoral artery puncture was done if the retrograde approach failed to depict the complete vascular access tree. Stenoses with a luminal diameter reduction >= 50% were treated, if possible, in connection with DSA. Results. A total of 116 dysfunctional haemodialysis fistulae and 50 grafts were included. Retrograde DSA depicted the complete vascular tree in 162 patients (97.6%). The arteriovenous anastomosis of four fistulae could not be negotiated by a catheter. DSA demonstrated 247 significant stenoses: 30, 128 and 89 were located in the arterial inflow (12.1%), AV anastomosis and graft region (51.8%) and venous outflow (36.0%), respectively. Ten patients (6.0%) had no stenosis. Eight (4.8%), 55 (33.1%) and 33 (19.9%) patients demonstrated stenoses in only inflow, access region or outflow, respectively. Stenoses in two or three vascular territories were present in 53 (31.9%) and 7 (4.2%) patients, respectively. A technically successful endovascular intervention was obtained in 135 of the 139 patients (97.1%) who underwent angioplasty and/or stent placement. Additional sheath insertion by antegrade outflow puncture was needed in 46 patients (33.1%) for the treatment of coexisting venous outflow stenoses, located downstream from the retrograde positioned sheath. Two minor complications were observed at DSA/angioplasty. Conclusion. As an alternative to MRA, full retrograde DSA is safe and effective for stenosis detection and stenosis treatment. However, access evaluation by a non-invasive imaging modality such as colour duplex ultrasound will be sufficient in most cases as proximal inflow stenoses are encountered in a minority of patients. Full retrograde DSA, including complete arterial inflow depiction, may then be reserved for cases with an unsuccessful outcome following endovascular intervention of stenoses depicted at ultrasound.

Purpose To determine prospectively the clinical value of contrast-enhanced magnetic resonance angiography (CE-MRA) for assessment of the arterial inflow and venous outflow prior to vascular access (VA) creation. Methods Seventy-three patients underwent duplex ultrasonography (DUS) and CE-MRA prior to VA creation for detection of stenoses and occlusions. Two observers read the CE-MRA images for determination of inter-observer agreement. A VA was considered functional if it could be used for successful two-needle hemodialysis therapy within 2 months after creation. Results CE-MRA detected 6 stenosed, 8 occluded arterial vessel segments and 12 stenosed and 41 occluded venous vessel segments in 70 patients. Inter-observer agreement for detection of upper extremity arterial and venous stenoses and occlusions with CE-MRA was substantial to almost perfect (kappa values 0.76–0.96). CE-MRA detected lesions, not detected by DUS, that were associated with VA early failure and non-maturation in 33% of patients (7/21). Accessory veins detected preoperatively were the cause of VA non-maturation in a substantial group of patients (47%: 7/15). Conclusion CE-MRA enables accurate detection of upper extremity arterial and venous stenosis and occlusions prior to VA creation. Preoperative CE-MRA identified arterial and venous stenoses, not detected by DUS that were associated with VA early failure and non-maturation. However, the use of gadolinium containing contrast media is currently contraindicated due the reported incidence of nephrogenic systemic fibrosis.

Background. This review describes the peritoneal dialysis (PD) catheter implantation techniques for the treatment of PD. The PD catheter-related complications still cause significant morbidity and mortality, resulting in the necessity to switch to haemodialysis (HD) treatment. Methods. Several catheter insertion techniques, using an open surgical approach, laparoscopic and percutaneous techniques have been employed, with their specific early and late complications and failure rates. Results. Despite the similar outcomes of open surgical versus laparoscopic techniques from randomized studies, the laparoscopic insertion has the major advantage of correct catheter positioning in the lower abdomen, with the possibility of adhesiolysis. The minimal invasive percutaneous insertion bears the risk of bowel perforation and catheter malpositioning, and the outcome of this technique is strongly related to the experience of the surgeon. The major complications of these implantation techniques, like bleeding, dialysate leakage and catheter malpositioning, and their management are discussed in our study. Late peritonitis remains the major drawback of PD treatment, with the need of temporary or permanent changeover to the HD treatment in 10% of the patients. Conclusions. Enrichment of the physician's interest and experience, along with a multidisciplinary approach to outline the optimal strategy of PD-catheter insertion and complication of the treatment, may improve the patients' survival and decrease the morbidity.

Background Autologous arteriovenous (AV) fistulas are the first choice for vascular access but have a high risk of non-maturation due to insufficient vessel adaptation, a process dependent on nitric oxide (NO)-signaling. Chronic kidney disease (CKD) is associated with oxidative stress that can disturb NO-signaling. Here, we evaluated the influence of CKD on AV fistula maturation and NO-signaling. Methods CKD was established in rats by a 5/6th nephrectomy and after 6 weeks, an AV fistula was created between the carotid artery and jugular vein, which was followed up at 3 weeks with ultrasound and flow assessments. Vessel wall histology was assessed afterwards and vasoreactivity of carotid arteries was studied in a wire myograph. The soluble guanylate cyclase (sGC) activator BAY 60-2770 was administered daily to CKD animals for 3 weeks to enhance fistula maturation. Results CKD animals showed lower flow rates, smaller fistula diameters and increased oxidative stress levels in the vessel wall. Endothelium-dependent relaxation was comparable but vasorelaxation after sodium nitroprusside was diminished in CKD vessels, indicating NO resistance of the NO-receptor sGC. This was confirmed by stimulation with BAY 60-2770 resulting in increased vasorelaxation in CKD vessels. Oral administration of BAY 60-2770 to CKD animals induced larger fistula diameters, however; flow was not significantly different from vehicle-treated CKD animals. Conclusions CKD induces oxidative stress resulting in NO resistance that can hamper AV fistula maturation. sGC activators like BAY 60-2770 could offer therapeutic potential to increase AV fistula maturation.

Purpose To determine if large caliber accessory veins are associated with radial-cephalic arteriovenous fistula (RC-AVF) non-maturation. Methods RC-AVFs were created in 15 consecutive patients (radial artery and cephalic vein diameter >2 mm, in the absence of arterial inflow or venous outflow stenoses or occlusions). Contrast-enhanced magnetic resonance angiography (CE-MRA) was performed preoperatively for the determination of vessel diameters, stenoses and occlusions. The location and caliber of accessory veins was determined. Vascular access (VA) function was monitored and all interventions required to obtain a functioning VA were recorded. Non-maturation was defined as a nonfunctional VA at 2 months after creation. The predictive value of accessory vein caliber for prediction of RC-AVF non-maturation was evaluated using receiver operating characteristic (ROC) analysis. Results Non-maturation occurred in 10 (67%) out of 15 RC-AVFs. Large caliber accessory veins (n=4), venous stenosis (n=3) or both (n=2) were associated with RC-AVF non-maturation. The presence of large caliber accessory veins was the only significant predictor for RC-AVF non-maturation (p=0.01). Preoperatively detected accessory veins with a diameter >70% of the cephalic vein diameter, had a sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of 80, 100, 100 and 91% for prediction of RC-AVF non-maturation on patient level. Accessory vein ligation and dilatation of venous stenosis resulted in an overall salvage success rate of 89% (8/9). Conclusion Large caliber accessory veins are associated with RC-AVF non-maturation. Ligation of large caliber accessory veins is a successful salvage procedure in a substantial group of patients. Furthermore, ligation of these accessory veins during initial RC-AVF creation can potentially reduce non-maturation rates; and therefore, preoperative assessment of accessory veins is recommended.

Background Creation of an arteriovenous fistula (AVF) may increase left ventricular hypertrophy in the hemodialysis population. Aim of this study was to compare the effects of a brachial-basilic (BB) AVF and the prosthetic brachial-antecubital forearm loop access (PTFE) on cardiac performance. Methods Patients were randomized to receive BB-AVF or prosthetic brachial-antecubital forearm loop access. Before and three months after AVF creation patients underwent an echocardiographic examination. Mann-Whitney U-test was used to compare relative increase between the measured cardiac parameters for the two groups. Results Twenty-seven patients participated in the study. The relative increase in left ventricular parameters was not significantly different between the two groups. Only left ventricular end-diastolic diameter tended to be of significance. Mean blood flow through the brachial artery was 1680±156 and 1450±221 mL/min three months after surgery for the PTFE and the BB-AVF group, respectively. Conclusion After three months of follow-up, changes in cardiac structure were comparable between patients with BB and PTFE AVFs. Also access flow was comparable at this time. In general, the effects of creation of a fistula on LV structure were limited. Longer follow up time may be needed to explore the long term effects of different vascular accesses on cardiac function.

A reduction in vascular access flow poses a risk for thrombosis. We present a new technique to measure vascular access flow during dialysis based on extracorporeal temperature gradients, and their changes, on reversing the extracorporeal bloodlines without having to inject an indicator. Fistula temperatures were measured by the blood temperature monitor with normal line position and after manual switching of the bloodlines using the same extracorporeal blood flow. The access flow by our temperature gradient method (TGM) was compared to access flow derived by saline dilution with measurements in the same patients repeated in subsequent weeks. In 70 pairs of TGM and saline dilution measurements in 35 patients, the repeatability of the TGM measurements was not significantly different from that of saline dilution. There was a highly significant correlation between the two techniques with an acceptable confidence level for limits of agreement for the difference between them. It took about 9 min to complete the TGM method and about 5 min for saline dilution. Our studies show that the novel TGM method showed excellent agreement and reproducibility with the saline dilution method without the need for indicator dilution.

A contrast-enhanced magnetic resonance angiography (CE-MRA) protocol for selective imaging of the entire upper extremity arterial and venous tree in a single exam has been developed. Twenty-five end-stage renal disease (ESRD) patients underwent CE-MRA and duplex ultrasonography (DUS) of the upper extremity prior to hemodialysis vascular access creation. Accuracy of CE-MRA arterial and venous diameter measurements were compared with DUS and intraoperative (IO) diameter measurements, the standard of reference. Upper extremity vasculature depiction was feasible with CE-MRA. CE-MRA forearm and upper arm arterial diameters were 2.94 +/- 0.67 mm and 4.05 +/- 0.84 mm, respectively. DUS arterial diameters were 2.80 +/- 0.48 mm and 4.38 +/- 1.24 mm; IO diameters were 3.00 +/- 0.35 mm and 3.55 +/- 0.51 mm. Forearm arterial diameters were accurately determined with both techniques. Both techniques overestimated upper arm arterial diameters significantly. Venous diameters were accurately determined with CE-MRA but not with DUS (forearm: CE-MRA: 2.64 +/- 0.61 mm; DUS: 2.50 +/- 0.44 mm, and IO: 3.40 +/- 0.22 mm; upper arm: CE-MRA: 4.09 +/- 0.71 mm; DUS: 3.02 +/- 1.65 mm, and IO: 4.30 +/- 0.78 mm). CE-MRA enables selective imaging of upper extremity vasculature in patients requiring hemodialysis access. Forearm arterial diameters can be assessed accurately by CE-MRA. Both CE-MRA and DUS slightly overestimate upper arm arterial diameters. In comparison to DUS, CE-MRA enables a more accurate determination of upper extremity venous diameters.

1. Evaluation of the patient1.1 Assessment of dry weight1.2 Measurement of blood pressure and heart rateduring dialysis1.3 Cardiac evaluation2. Lifestyle interventions2.1 Sodium restriction2.2 Food and caffeine intake during dialysis3. Factors relation to the dialysis treatment3.1 Manipulation of ultrafiltration3.1.1 Ultrafiltration profiling3.1.2 Blood volume controlled ultrafiltration3.2 Dialysate composition.3.2.1 High sodium dialysis and sodium profiling3.2.2 Dialysate buffer3.2.3 Dialysate calcium3.2.4 Other components of dialysate3.3 Dialysis membranes/contamination ofdialysate.3.4 Dialysate temperature.3.5 Convective techniques and isolatedultrafiltration.3.5.1 Convective techniques3.5.2 Isolated ultrafiltration3.6 Dialysis duration and frequency.3.7 Switch to peritoneal dialysis.4. Antihypertensive drugs and preventive medication4.1 Antihypertensive drugs4.2 Preventive vasoactive agents4.3 Carnitine5. Stratified approach to prevent IDH6. Treatment of IDH6.1 Trendelenburg position6.2 Stopping ultrafiltration6.3 Infusion fluids6.4 Protocol

Guideline 1. Prevalence of malnutrition and outcomeGuideline 2. Diagnosis and monitoring of malnutrition2.1. Diagnosis of malnutrition2.2. Monitoring and follow-up of nutritionalstatusGuideline 3. Recommendations for protein and energyintake3.1. Recommended protein intake3.2. Recommended energy intakeRecommendation 4. Recommendations for vitamins,minerals and trace elementsadministration in maintenancehaemodialysis patients.4.1. Vitamins4.2. Minerals4.3. Trace elementsGuideline 5. Treatment of malnutrition5.1. Dietary intervention5.2. Oral supplements and enteral feeding5.3. Intradialytic parenteral nutrition5.4. Anabolic agents5.5. Other interventions: daily dialysisGuideline 6. Metabolic acidosisAppendices

Department of Renal Medicine, St James’s University Hospital, Leeds, UK, Nephrology Department, Reina Sofia University Hospital, Cordoba, Spain, Division of Nephrology and Dialysis, Bolognini Hospital, Seriate, Italy, Department of Medicine, Division of Nephrology, Ege University Medical Faculty, Izmir, Turkey, Nephrology, Dialysis and Intensive Care Unit, Lapeyronie University Hospital, Montpellier, France, Departement de Nephrologie JE 2411 Denutrition des Maladies Chroniques, Hopital E Herriot, France, Department of Diagnostic and Interventional Radiology, Helios Klinikum Wuppertal, University Hospital Witten/Herdecke, Germany, Medical Faculty University of Cologne, Medicine Clinic I, Hospital Merheim, Germany (retired), Department of Internal Medicine, Division of Nephrology, University Hospital Maastricht, The Netherlands, Nephrology Unit, SM Annunziata Hospital, Florence, Italy, Department of Surgery, University Hospital Maastricht, The Netherlands, Department of Nephrology, Nutrition and Dietetics, Guy’s and St Thomas’ NHS Foundation Trust, London, UK (retired), Department of Medicine, Division of Nephrology, University Hospital, Wurzburg, Germany, Department of Nephrology, Institute for Cardiovascular Research, VU University Medical Center, Amsterdam, The Netherlands and Nephrology Section, Department of Internal Medicine, University Hospital, Ghent, Belgium

Objectives. To study incidence and severity of steal phenomena in hemodialysis patients and to investigate possible methods for its detection. Methods. A questionnaire was composed based on a literature search. A subgroup of patients having steal as identified by the questionnaire was studied using physical examination, arterial blood pressure, skin temperature, digital oxygenation, grip strength and plethysmography. Contralateral arms served as controls. Results. A cold hand was present in 50% of the patients with a brachiocephalic (BC) arteriovenous fistula (AVF, n ¼28) compared to 25% of prosthetic forearm loops (loop, n ¼27) and 12% of the radiocephalic (RC, n ¼ 65, p < 0.05) fistulas. Diabetics were at risk for steal (p < 0.001). Intensity of steal was not related to magnitude of access flow. Digital skin temperatures and grip strength were lower in steal hands (p < 0.02). Manual compression of the AVF normalised low digital pressures in steal hands (106 � 33 vs 154 � 25 mm Hg, p < 0.001, contralateral side 155 � 21 mm Hg). Conclusions. Mild to moderate steal symptoms are common in a hemodialysis patient. Individuals with a BC are at a higher risk for developing complaints associated with reduced hand circulation compared to patients with a RC or loop. Low finger pressures in the presence of steal symptoms are usually reversible.

ObjectivesDuplex ultrasonography assessment of superficial forearm veins is frequently used before a hemodialysis arteriovenous fistula (AVF) is created. There is, however, no standardized preoperative duplex ultrasonography protocol. This study assessed B-mode image analysis reproducibility and reproducibility of repeated forearm superficial venous diameter measurements on different days at different venous congestion pressures (VCPs).MethodsDiameters were determined using B-mode ultrasonography in 10 healthy male volunteers on days 1 and 14 at incremental VCP values (10 to 80 mm Hg). Intra- and interobserver agreement was assessed for B-mode image analysis by calculating interclass correlation coefficients (ICC). Reproducibility of repeated diameter measurements (maximum and minimum diameter at days 1 and 14), cross-sectional area size increase, and shape change due to incremental VCPs were determined by calculating ICC values.ResultsAnalysis of intraobserver agreement of B-mode image interpretation yielded ICC values of 0.97 (95% confidence interval [CI], 0.94 to 0.99) and 0.97 (95% CI, 0.96 to 0.99) for determination of maximum and minimum diameters, respectively. Interobserver agreement analysis yielded ICC values of 0.95 (95% CI, 0.92 to 0.97) and 0.96 (95% CI, 0.96 to 0.99) for determination of maximum and minimum diameters, respectively. Reproducibility of repeated diameter measurements on days 1 and 14 improved substantially at incremental VCP values, with best reproducibility at VCPs >40 mm Hg. Repeated determination of cross-sectional area size increase and shape change due to VCP increase from 10 to 80 mm Hg yielded ICC values of 0.49 (95% CI, 0.19 to 1.00) and 0.09 (95% CI, 0.00 to 0.92), respectively. Maximum and minimum diameters as well as cross-sectional area size increased significantly (P < .01) due to VCP increase during both sessions. Cross-sectional area shape changed significantly (P < .01) due to VCP increase during both sessions.ConclusionsDiameter measurements on B-mode images are largely observer independent. Superficial venous cross-sectional area shape is noncircular, and cross-sectional area size depends on VCP. Both maximum and minimum venous diameters should be determined at VCPs >40 mm Hg to attain the best reproducibility. Further studies are needed to determine whether a standardized preoperative vein mapping protocol can reduce AVF nonmaturation rates.

Periodical access flow measurements can predict the development and presence of vascular access flow-limiting stenosis and subsequent thrombosis. Access flow measurement has become a standard in vascular access care. Different techniques to measure access flow are available. The aim of this study was to compare an integrated access flow measurement device, based on thermodilution (Blood Temperature Monitor, BTM, Fresenius Medical Care, Bad Homburg, Germany), with the gold standard, the HD01 (Transonic Systems Inc., Ithaca, NY), whose technique is based on saline dilution.In 40 patients with end-stage renal disease, 40 vascular accesses were studied to determine the correlation between access flow measurements by both techniques. Reproducibility of access flow measurements by both techniques was assessed in 20 patients on a weekly interval.A total of 40 measurement series were performed. Average access flow measured with the saline technique and the thermodilution technique was 1053 (+/-495) ml/min and 1034 (+/-527) ml/min, respectively (p = ns) (n = 40). Correlation between access flow measurements by both techniques expressed in R was 0.79 (r = 0.89). Reproducibility of saline and thermodilution subsequent measurements with a weekly interval, expressed in relative difference (Delta xrel) was 13 (+/-11)% and 24 (+/-14)%, respectively (p < 0.01) (n = 20).BTM access flow measurements correlated well with the HD01 access flow measurements. However, the better reproducibility of HD01 and shorter measurement time compared with BTM access flow measurements should be considered when implementing access flow measurement to prevent vascular access failure.

The aim of our study is to investigate with computational fluid dynamics (CFD) whether different arterial anastomotic geometries result in a different hemodynamics at the arterial (AA) and venous anastomosis (VA) of hemodialysis vascular access grafts. We have studied a 6 mm graft (CD) and a 4–7 mm graft (TG). A validated three-dimensional CFD model is developed to simulate flow in the two graft types. Only the arterial anastomosis (AA) geometry differs. The boundary conditions applied are a periodic velocity signal at the arterial inlet and a periodic pressure wave at the venous outlet. Flow rate is set to 1000 ml/min. The time dependent Navier–Stokes equations are solved. Wall shear stress (WSS), wall shear stress gradient (WSSG) and pressure gradient (PG) are calculated. Anastomotic flow is asymmetric although the anastomosis geometry is symmetric. The hemodynamic parameters, WSS, WSSG and PG, values at the suture line of the arterial anastomosis of the TG are at least twice as much as in the CD. Comparing the parameters at the two AA indicate that little flow rate increase introduces the risk of hemolysis in the TG whereas the CD is completely free of hemolysis. The hemodynamic parameter values at the venous anastomosis of the CD are 24 till 35% higher compared to the values of the TG. WSS values (>3 Pa) in the VA are in the critical range for stenosis development in both graft geometries. The zones where the parameters reach extreme values correspond to the locations where intimal hyperplasia formation is reported in literature. In all anastomoses, the hemodynamic parameter levels are in the range where leucocytes and platelets get activated. Our simulations confirm clinical results where TG did not show a better outcome when compared to the CD.

Background Preoperative assessment of forearm superficial venous diameter may predict early failure of newly created arteriovenous fistulas for haemodialysis access. However, early failure and non-maturation rates remain high (up to 30%) and reported cut-off diameters are inconsistent. We hypothesize that this inconsistency is due to differences in the methods used to achieve venous dilatation prior to diameter measurements and daily variation in superficial venous diameter. We furthermore hypothesize that the use of a cuff will lead to a better inter-observer agreement since the applied pressure can be precisely determined. The purpose of this study was to determine inter-observer agreement of superficial venous diameter measurement under venous congestion by using either a graduated pressure cuff or tourniquet and furthermore, to determine daily variations in superficial venous diameter. Methods Diameter measurements were performed by two observers on days 1 and 3, in 21 end-stage renal disease patients using either a cuff (60 mmHg) or tourniquet. Measurements were carried out in random order and observers were blinded for each other's results. Inter-observer agreement was expressed as interclass correlation coefficients. Variance components analysis was used to determine possible causes of disagreement. Results Using a cuff, mean venous diameter was 1.8 mm (range, 0.7-3.3 mm). When a tourniquet was used, the mean diameter was 1.8 mm (range, 0.6-3.2 mm). Interclass correlation coefficients between observers were 0.76 and 0.74 for the use of a cuff and tourniquet, respectively. Diameter measurements were revealed to be observer independent. Variations in venous diameter were determined by the patient and the interaction of patient and day. Repeated assessment of venous diameter on different days revealed a variation coefficient of 26.4% when using a cuff, and 26.5% when using a tourniquet. Conclusions Venous diameter assessment is observer and congestion method independent. Daily variations in forearm superficial venous diameters should be taken into account when defining and using cut-off diameters prior to vascular access surgery.