Erratum: Preoperative assessment for percutaneous and open surgical arteriovenous fistula creation in patients for haemodialysis.

[This corrects the article DOI: 10.1093/ckj/sfz121.][This corrects the article DOI: 10.1093/ckj/sfz121.].

Preoperative assessment for percutaneous and open surgical arteriovenous fistula creation in patients for haemodialysis.

Preoperative assessment prior to surgical arteriovenous fistulas (AVFs) including ultrasound-guided mapping has been shown to have beneficial effects on their immediate success as well as early outcomes. This has led to their wide acceptance and adoption however clinical practice criteria is variable and is reflected in variabilities in practice. When transposing this to percutaneously created endovascular AVFs (endoAVFs), variable preoperative assessment criteria could equally result in variable practice and potentially subsequent and expectant outcomes. We aimed to review literature on reported validated methodologies and workflows of preoperative assessment for surgical AVF creation as reported in highest levels of available evidence, specifically randomized controlled trials. Published practice recommendations and guidelines on best clinical practice as well as systematic reviews and meta-analyses of published studies were also reviewed. Data on practice methodology from identified trial publications and protocols was collated and a summative narrative synthesis was carried out which compared these methodologies to additional assessments that may be required when targeting assessment for percutaneous endoAVF formation, based on our units experience as part of an international multicentre trial. In this review we present a brief overview of published literature and guidelines and propose a unified and uniform workflow for preoperative assessment for surgical AVFs and endoAVFs to aide clinical and imaging practice.

Recipient and allograft survival following donation after circulatory death versus donation after brain death for renal transplantation: A systematic review and meta-analysis.

BACKGROUND-OBJECTIVES: Current evidence based on retrospective and prospective studies demonstrates that donation after circulatory death (DCD) grafts are more susceptible to delayed graft function (DGF) than donation after brain death (DBD) grafts. The short- and long-term survival outcomes of the two cohorts are unclear. Therefore, we performed a systematic review and meta-analysis to estimate the patient and allograft survival outcomes for DCD and DBD in renal transplant surgery. METHODS: Systematic literature searches were conducted by searching various databases. Fixed and random effects models were used to assess the accumulation of evidence over time. RESULTS: The five-year patient survival rate was significantly better in the DBD than in the DCD cohort. Non-significant differences were observed in 1-, 3- and 10-year patient survival and in the 1-, 3-, 5-, and 10-year graft survival rates between the two cohorts. The acute rejection rate was lower in the DCD cohort than in the DBD cohort. Extended criteria of donor status, delayed graft function and primary non-function were significantly higher in the DCD cohort than in the DBD cohort. CONCLUSIONS: This study demonstrates that the short- and long-term survival graft and patient benefits are similar between DCD and DBD kidney transplants. Therefore, large, controlled DCD kidney programmes are urgently needed worldwide in order to increase the number of kidney transplants.

Quality improvement in vascular access: The role of patient-reported outcome measures.

Quality improvement initiatives should be aimed to enhance clinical outcomes, service delivery and quality of life for patients. For patients reliant on haemodialysis, vascular access is a lifeline. Survival differences relating to the type of vascular access are evident and many initiatives have focussed on increasing absolute rates of arteriovenous fistulas and/or decreasing central venous catheter use. While these have achieved some success quantitatively, the qualitative effects are less obvious. The aims of this review article are to explore the concepts of quality of care in vascular access. There is a paucity of studies into the effects of vascular access on the quality of life of dialysis patients, and where studies have been performed, generalised patient-reported outcome measures have been used. To facilitate the implementation of quality improvement programmes specifically for vascular access requires suitable tools. While existing patient-reported outcome measures may be applicable to vascular access, it is likely that these will require further evaluation, and the development of vascular access-specific patient-reported outcome measures may be required.

Early experience and observations in endovascular dialysis fistula re-intervention.

In recent years, new emerging technology has allowed the endovascular creation of dialysis fistulas in the proximal forearm without the need for open surgery. Two such systems currently exist, and evidence to date has demonstrated high rates of technical success in fistula creation, high rates of dialysis functionality, and low rates of re-intervention using both systems. Whilst early trial data has demonstrated lower rates of re-intervention to maintain patency compared to surgical fistulas, endovascular re-interventions are still required to maintain functionality. The endovascular fistula (endoAVF) typically exhibits a shared drainage pattern and is morphologically distinct from the surgical fistula and patterns of failure observed often differ to what has been traditionally encountered. A fresh approach and understanding is therefore required and here we share our observations and experience of endovascular re-intervention in endoAVF created with the Wavelinq system.

Recipient Outcomes From Nondirected Live Kidney Donors: A UK-based Cohort Study.

BACKGROUND: Increasing numbers of patients with end-stage renal failure are receiving kidneys from nondirected kidney donors (NKDs), also known as altruistic donors. Transplant outcomes for recipients of such kidneys are largely inferred from studies on specified kidney donors (SKDs), which may be inaccurate due to differences in donor, recipient and transplant specific factors. We report the outcomes for recipients of NKD in the United Kingdom. METHODS: Outcomes for 6861 patients receiving a living donor kidney transplant between January 2007 and December 2014 were analyzed using both the National Health Service Blood and Transplant and the UK Renal Registry datasets. Graft and patient outcomes were compared for patients receiving NKD and SKD organs using univariable and multivariable analyses. RESULTS: There was significant discordance between the NKD and SKD donors and recipients. These included increased donor age (median, 58 years vs 47 years; P < 0.001) and higher rates of hemodialysis and previous transplants in the NKD group (both P < 0.001). Despite such markers of increased risk among both donors and recipients of NKD kidneys, there was no difference in graft survival on univariable (hazard ratio, 1.20; 95% confidence interval, 0.77-1.86; P = 0.419) or multivariable analysis (hazard ratio, 1.13; 95% confidence interval, 0.65-1.95; P = 0.665). CONCLUSIONS: Despite some markers of transplant complexity, nondirected kidney donor organs are an excellent source of organs for transplantation.

The impact of donor body mass index on outcomes after deceased kidney transplantation - a national population-cohort study.

The aim of this study was to determine the effect of donor body mass index (BMI) on deceased donor kidney transplant outcomes. Data were collected from the UK Transplant Registry for all deceased donor kidney transplant recipients between January 2003 and January 2015. Univariable and multivariable analyses were undertaken to assess the impact of donor BMI on a range of outcomes. Donor BMI (kg/m2 ) was stratified as <18.5 (n = 380), 18.5-25.0 (n = 6890), 25.1-30.0 (n = 6669), 30.1-35.0 (n = 2503) and >35.0 (n = 1148). The prevalence of delayed graft function increased significantly with donor BMI (P < 0.001), with an adjusted odds ratio of 1.38 (95% CI: 1.16-1.63) for the >35.0 vs. 18.5-25.0 groups. However, there was no significant association between donor BMI and 12-month creatinine (P = 0.550), or patient (P = 0.109) or graft (P = 0.590) survival. In overweight patients, increasing donor BMI was associated with a significant increase in warm ischaemia time and functional warm ischaemia time, by an average of 4.6% (P = 0.043) and 5.2% (P = 0.013) per 10.0 kg/m2 . However, rising warm ischaemic time and functional warm ischaemic time was not significantly associated with delayed graft function, 12-month creatinine levels, graft loss or patient death. In this population cohort study, we identified no significant association between donor BMI and long-term clinical outcomes in deceased donor kidney transplantation.

Arterial stiffness alone does not explain arteriovenous fistula outcomes.

INTRODUCTION: Marked arterial adaptation is critical in permitting and sustaining the increased blood flow within an arteriovenous fistula (AVF). The aim of this investigation was to evaluate markers of arterial disease and their association with the early post-operative AVF outcomes. METHODS: We included all patients in whom an AVF had been performed after enrolment to the Renal Impairment In Secondary Care (RIISC) study. Primary AVF failure (PFL) was defined as thrombosis at six-week review. All patients underwent BP Tru and Vicorder pulse wave analysis assessments and also had assays of advanced glycation end-products prior to AVF formation. These were correlated with the short-term AVF outcomes. RESULTS: One hundred and eight AVFs were created in 86 patients. The primary patency (PPT) group were found to have significantly higher body mass index (BMI) (p = 0.01). Intraluminal vein diameter was significantly greater in the PPT group than the PFL group (p≤0.01). Mean augmentation index and augmentation index 75 was significantly higher in the PPT group than the PFL group (p = 0.03 and 0.03, respectively). Aortic pulse wave velocity was slower in the PPT group at 10.2 m/s than the PFL group at 10.8 m/s (p = 0.32). Advanced glycation end-product measurements did not vary significantly between the PPT and PFL groups (p = 0.4). Logistic regression analysis provided a predictive model, which demonstrated a predictive value of 78.1% for AVF patency at 6 weeks. CONCLUSIONS: All patients in this end-stage renal disease cohort have significant aortic stiffness. The results for pulse wave velocity were slower in the PPT group suggesting a tendency towards stiffer vessels and PFL.

Systematic review of drug eluting balloon angioplasty for arteriovenous haemodialysis access stenosis.

BACKGROUND: Native or prosthetic arteriovenous (AV) fistulas are preferred for permanent haemodialysis (HD) access. These are marked with circuit steno-occlusive disease leading to dysfunction or even failure. Late failure rates have been reported as high as 50%. Standard angioplasty balloons are an established percutaneous intervention for HD access stenosis. Reported restenosis rates remain high and practice guidelines recommend a wide 6-month primary patency (PP) of at least 50% for any intervention. Neointimal hyperplasia is one of the main causes for access circuit stenosis. Drug eluting balloon (DeB) angioplasty has been proposed as an alternative intervention to reduce restenosis by local drug delivery and possible inhibition of this process. PURPOSE: To systematically assess the reported efficacy and safety of DeB angioplasty in percutaneous management of prosthetic and autologous HD access stenosis. METHODS: Protocol for the review was developed following the PRISMA-P 2015 statement. An electronic database (Medline, EMBASE, Clinical Trials.gov and Cochrane CENTRAL) search was conducted to identify articles reporting on the use of DeB intervention in HD AV access. Backward and forward citation search as well as grey literature search was performed. The MOOSE statement and PRISMA 2009 statement were followed for the reporting of results. Data from the included studies comparing DeBs with non-DeBs were pooled using a random effects meta-analysis model and reported separately on randomised and non-randomised studies. RESULTS: Six studies reported on 254 interventions in 162 participants (mean 27 ± 10 SD). The pooled mean and median duration of follow-up was 12 and 13 months (range 6-24 months). These comprised two randomised control trials (RCTs) and four cohort studies. Participant's mean age was 64 ± 5 years and 61% were male. Target lesions (TLs) ranged from under 2 mm to 5.9 mm and 51 were reported as de novo stenosis. Device failure described as wasting of the DeB was reported in two studies (55% and 92.8%). At 6 months TL PP was reported between 70% to 97% for DeBs in the RCTs and cohort studies, and 0% to 26% for non-DeBs. TLs treated with DeBs were associated with a higher primary patency at 6 months as compared to non-DeB balloons (RCTs: odds ratio [OR] 0.25, 95% CI 0.08 to 0.77 and I2 = 19%, cohort studies: OR 0.10, 95% CI 0.03 to 0.31 and an I2 = 20%). No procedure-related major or minor complications were reported. CONCLUSIONS: Current literature reports DeBs as being safe and may convey some benefit in terms of improved rate of restenosis when used to treat AV access disease. However, this body of evidence is small and clinically heterogeneous. A large multicentre RCT may help to clarify the role of DeBs in the percutaneous treatment of AV HD access stenosis.

Arteriovenous fistula outcomes in the elderly.

OBJECTIVE: Over several decades, there has been an increase in the number of elderly patients requiring hemodialysis. These older patients typically have an increased incidence of comorbidities including diabetes, hypertension, and peripheral vascular disease. We undertook a systematic review of the current literature to assess outcomes of arteriovenous fistula (AVF) formation in the elderly and to compare the results of radiocephalic AVFs vs brachiocephalic AVFs in older patients. METHODS: A literature search was performed using MEDLINE, Embase, PubMed, and the Cochrane Library. All retrieved articles published before December 31, 2014 (and in English) primarily describing the creation of hemodialysis vascular access for elderly patients were considered for inclusion. We report pooled AVF patency rates and a comparison of radiocephalic vs brachiocephalic AVF patency rates using odds ratios (ORs). RESULTS: Of 199 relevant articles reviewed, 15 were deemed eligible for the review. The pooled 12-month primary and secondary AVF patency rates were 53.6% (95% confidence interval [CI], 47.3-59.9) and 71.6% (95% CI, 59.2-82.7), respectively. Comparison of radiocephalic vs brachiocephalic AVF patency rates demonstrated that radiocephalic AVFs have inferior primary (OR, 0.72; 95% CI, 0.55-0.93; P = .01) and secondary (OR, 0.76; 95% CI, 0.58-1.00; P = .05) patency rates. CONCLUSIONS: This meta-analysis confirms that adequate 12-month primary and secondary AVF patency rates can be achieved in elderly patients. Brachiocephalic AVFs have both superior primary and secondary patency rates at 12 months compared with radiocephalic AVFs. These important data can inform clinicians' and patients' decision-making about suitability of attempting AVF formation in older persons.

Revisiting the risks of MRI with Gadolinium based contrast agents-review of literature and guidelines.

UNLABELLED: Gadolinium based contrast agents (GBCA) have been linked to the occurrence of nephrogenic systemic fibrosis (NSF) in renal impaired patients. The exact interaction between the various different available formulations and occurrence of NSF is not completely understood, but has been postulated. This association has triggered public health advisory bodies to issue guidelines and best practice recommendations on its use. As a result, the reported incidence of NSF, as well as the published use of GBCA-enhanced magnetic resonance imaging in renal impairment, has seen a decline. Understanding of the events that led to these recommendations can increase clinical awareness and the implications of their usage. We present a review of published literature and a brief overview of practice recommendations, guidelines and manuals on contrast safety to aide everyday imaging practice. TEACHING POINTS: • Low risk gadolinium based contrast agents should be the choice in renal insufficiency. • Higher doses have been linked to NSF development. Doses should be as low as possible. • Clear documentation of date, dose and type of formulation used should be noted. • Post-scan dialysis should be arranged as soon as possible and feasible. • Pre- existing inflammatory state is a risk factor; liver insufficiency is not a contraindication.

Current tools for prediction of arteriovenous fistula outcomes.

It remains challenging to accurately predict whether an individual arteriovenous fistula (AVF) will mature and be useable for haemodialysis vascular access. Current best practice involves the use of routine clinical assessment and ultrasonography complemented by selective venography and magnetic resonance imaging. The purpose of this literature review is to describe current practices in relation to pre-operative assessment prior to AVF formation and highlight potential areas for future research to improve the clinical prediction of AVF outcomes.

Long-term results of biological grafts for haemodialysis vascular access.

The quest for suitable conduits for dialysis access has continued since the first patients were dialysed. Whilst synthetic grafts made from expanded polytetrafluoroethylene (ePTFE) have been the main definitive option after autologous arteriovenous fistulas they have a number of drawbacks, which has led to the use and development of biological grafts such as autografts, homografts or xenografts. Technology continues to improve and currently biosynthetic options are available which may combine the benefits of a readily available product without the drawbacks of PTFE. The history and evidence of biological options for haemodialysis access are discussed.

Patient survival following arteriovenous fistula formation.

PURPOSE: Efforts to promote arteriovenous fistulas (AVFs) have been successful in increasing the prevalence of AVF use as the primary vascular access for haemodialysis (HD). Sustained preference for AVF use may not be the most appropriate vascular access choice for all patient groups. Arteriovenous grafts (AVGs) offer advantages of earlier use and lower primary failure rates compared to AVFs so may be preferable for patients where short-term vascular access is needed. This study was designed to assess comparative mortality in different age groups following AVF formation. METHODS: A prospective cohort of patients having AVF creation was recruited. Patients were subdivided into three age groups: Group A: <50 years; Group B: 50-74 years and Group C: ≥75 years. Survival curves and Cox regression analysis were performed on each of these groups. RESULTS: One hundred and thirty-four patients (n = 134) were recruited into the study. The prevalence of diabetes increased significantly with age. As expected, mortality was higher in older age groups (log rank (Mantel-Cox) 19.227; p = 0.0001). Mortality rates at 1 year were 0% in group A, 12.5% in group B and 29.1% in group C. Medium-term mortality at 4 years was 7.9% in group A, 39.1% in group B and 54.8% in group C. CONCLUSIONS: We found a significantly higher mortality rate in patients ≥75 years in comparison to those <75 years. The choice of vascular access modality should be tailored to the individual with particular reference to the patient's expected survival.

Metabolomic analysis of perfusate during hypothermic machine perfusion of human cadaveric kidneys.

BACKGROUND: The metabolic processes occurring within the preserved kidney during hypothermic machine perfusion (HMP) are not well characterized. The aim of this study was to use nuclear magnetic resonance (NMR) spectroscopy to examine the metabolomic profile of HMP perfusate from human cadaveric kidneys awaiting transplantation and to identify possible discriminators between the profiles of kidneys with delayed graft function (DGF) and immediate graft function (IGF). METHODS: Perfusates from HMP kidneys were sampled at 45 min and 4 hr of preservation with the LifePort Kidney Transporter 1.0 (Organ Recovery Systems, Chicago, IL) using KPS-1. Prepared samples underwent 1-D Proton-NMR spectroscopy, and resultant spectra were analyzed. Clinical parameters were collected prospectively. RESULTS: Perfusate of 26 transplanted cadaveric kidneys was analyzed; 19(73%) with IGF and 7(27%) with DGF. Glucose concentrations were significantly lower in DGF kidneys compared to those with IGF at both 45 min (7.772 vs. 9.459 mM, P = 0.006) and 4 hr (8.202 vs. 10.235 mM, P = 0.003). Concentrations of inosine and leucine were significantly different between DGF and IGF kidneys at 45 min (0.002 vs. 0.013 mM, P = 0.009 and 0.011 vs. 0.006 mM, P = 0.036), and gluconate levels were also significantly different between DGF and IGF kidneys at 4 hr (49.099 vs. 59.513 mM, P = 0.009). CONCLUSION: Significant metabolic activity may be occurring in kidneys during HMP. The NMR spectroscopy of the perfusate can identify differences in the metabolomic profiles of DGF and IGF kidneys that might have a predictive role in viability assessment. Modification of harmful metabolic processes may improve outcomes for HMP kidneys.

Metabolomic perfusate analysis during kidney machine perfusion: the pig provides an appropriate model for human studies.

INTRODUCTION: Hypothermic machine perfusion offers great promise in kidney transplantation and experimental studies are needed to establish the optimal conditions for this to occur. Pig kidneys are considered to be a good model for this purpose and share many properties with human organs. However it is not established whether the metabolism of pig kidneys in such hypothermic hypoxic conditions is comparable to human organs. METHODS: Standard criteria human (n = 12) and porcine (n = 10) kidneys underwent HMP using the LifePort Kidney Transporter 1.0 (Organ Recovery Systems) using KPS-1 solution. Perfusate was sampled at 45 minutes and 4 hours of perfusion and metabolomic analysis performed using 1-D 1H-NMR spectroscopy. RESULTS: There was no inter-species difference in the number of metabolites identified. Of the 30 metabolites analysed, 16 (53.3%) were present in comparable concentrations in the pig and human kidney perfusates. The rate of change of concentration for 3-Hydroxybutyrate was greater for human kidneys (p<0.001). For the other 29 metabolites (96.7%), there was no difference in the rate of change of concentration between pig and human samples. CONCLUSIONS: Whilst there are some differences between pig and human kidneys during HMP they appear to be metabolically similar and the pig seems to be a valid model for human studies.

Preserving arteriovenous fistula outcomes during surgical training.

PURPOSE: Arteriovenous fistulae (AVFs) are the preferred option for vascular access, as they are associated with lower mortality in hemodialysis patients than in those patients with arteriovenous grafts (AVGs) or central venous catheters (CVCs). We sought to assess whether vascular access outcomes for surgical trainees are comparable to fully trained surgeons. METHODS: A prospectively collected database of patients was created and information recorded regarding patient demographics, past medical history, preoperative investigations, grade of operating surgeon, type of AVF formed, primary AVF function, cumulative AVF survival and functional patency. RESULTS: One hundred and sixty-two patients were identified as having had vascular access procedures during the 6 month study period and 143 were included in the final analysis. Secondary AVF patency was established in 123 (86%) of these AVFs and 89 (62.2%) were used for dialysis. There was no significant difference in survival of AVFs according to training status of surgeon (log rank x2 0.506 p=0.477) or type of AVF (log rank x2 0.341 p=0.559). Patency rates of successful AVFs at 1 and 2 years were 60.9% and 47.9%, respectively. CONCLUSION: We have demonstrated in this prospective study that there are no significant differences in outcomes of primary AVFs formed by fully trained surgeons versus surgical trainees. Creation of a primary AVF represents an excellent training platform for intermediate stage surgeons across general and vascular surgical specialties.