Is Routine Preoperative Ultrasonographic Mapping for Arteriovenous Fistula Creation Necessary in Patients with Favorable Physical Examination Findings? Results of a Randomized Controlled Trial

Preoperative mapping and multidisciplinary team are the key to success of arteriovenous access for hemodialysis

INTRODUCTION AND OBJECTIVES

Functional and durable vascular access is needed for adequate hemodialysis. Arteriovenous fistula is preferred over prosthetic grafts or central venous catheters, but it is associated with high rates of primary failure and maturation failure. Preoperative mapping of arm vessels with color Doppler ultrasound (CDU) has been shown to be helpful in achieving better short and long-term outcomes. Unfortunately, is more time-consuming than a physical examination and requires an experienced examiner and special equipment; some authors defend that CDU should not be part of the routine preoperative assessment. We reported our experience in preoperative vessel mapping using color Doppler ultrasound to purpose a vascular access to the surgical team, surveillance of vascular access, and evaluation of main outcomes (primary failure, maturation failure, and patency).

METHODS

This is a single-center retrospective study that includes patients who attended a specific appointment for vascular access planning consultation between January 2019 and December 2021. A nephrologist performed the physical exam and vascular mapping and proposed to the vascular surgeon team a specific type and location of vascular access. Patients were followed until one month after the first hemodialysis through functioning vascular access.

RESULTS

In this study, 167 patients were evaluated (114 incident patients - chronic kidney disease stage 4 or 5 - and 53 prevalent patients - under hemodialysis through central venous catheter). The vascular accesses proposed by nephrologist were radial-cephalic arteriovenous fistula in 70 patients (41.9%), brachio-cephalic arteriovenous fistula in 50 patients (29.9%), brachio-basilic arteriovenous fistula in 34 patients (20.4%), arteriovenous graft in 8 patients (4.8%) and central venous catheter in 2 patients (1.2%). Vascular access was constructed in 141 patients: distal arteriovenous fistula in 57 patients (40.4%), brachio-cephalic arteriovenous fistula in 54 patients (38.3%), brachio-basilic AVF in 27 patients (19.1%), and arteriovenous graft in 3 patients (2.1%). The created access corresponds to the proposed access in 129 patients (91.5%). Twenty-two (15.6%) primary failures were registered. Distal arteriovenous fistulas and diabetes mellitus were associated with a higher risk of primary failure (OR=3.929 (1.485-10.392), p=0.004; OR=3.867 (1.235-12.113), p=0.014, respectively). The incidence of maturation failure at eight weeks was 4.8%. The primary patency at 6, 12 and 24 months was 76.3%, 70.4% and 49.2%. Primary assisted patency was 84.8% at 6 and 12 months and 81.3% at 24 months.

CONCLUSIONS

This study demonstrates that the study of the entire vascular territory performed with color Doppler ultrasound, within a multidisciplinary team of nephrologists and vascular surgeons, is associated with high rates of autologous access and very low rates of primary failure and maturation failure (almost unprecedented in the literature).

Pre-operative ultrasound mapping before arteriovenous fistula formation: an updated systematic review and meta-analysis

BACKGROUND

Arteriovenous fistula represents the preferred vascular access for patients with kidney failure requiring hemodialysis. Surgeons have traditionally used physical examination to identify the most suitable vessels. This meta-analysis aims to evaluate whether ultrasound mapping should be routinely performed before arteriovenous fistula creation.

METHODS

Medline, Scopus, Web of Science and CENTRAL were systematically searched from inception to November 1, 2022. Randomized controlled trials and cohort studies comparing routine ultrasound mapping to physical examination in terms of arteriovenous fistula patency were included. Meta-analysis was performed by fitting random-effects models. The study protocol has been prospectively registered in PROSPERO (CRD42023402390).

RESULTS

Overall, 18 studies were included, comprising 3655 participants. Routine pre-operative ultrasound mapping was associated with significantly lower rates of primary arteriovenous fistula failure (Risk Ratio-RR: 0.56, 95% confidence intervals-CI: 0.37-0.84, low certainty). A significant outcome was observed by separately pooling randomized controlled trials (RR: 0.37, 95% CI: 0.25-0.54). Routine ultrasound mapping was also associated with significantly higher rates of 1-year primary arteriovenous fistula patency (RR: 1.33, 95% CI: 1.19-1.47, moderate certainty). This effect remained significant in the analysis of randomized controlled trials (RR: 1.26, 95% CI: 1.02-1.56).

CONCLUSIONS

Implementing routine pre-operative ultrasound mapping of vessels is associated with significantly better outcomes in terms of early arteriovenous fistula failure and primary patency rates at 12 months. Further research should confirm the long-term benefits of routine ultrasound examination and evaluate its cost-effectiveness in different populations.

Contemporary review of management techniques for cephalic arch stenosis in hemodialysis

The type of hemodialysis access and its preservation impact the quality of life and survival of patients undergoing hemodialysis. Vascular access complications are among the top causes of morbidity, hospitalization, and catheter use, with significant economic burden. Poor maturation and stenosis continue to be key impediments to upper arm arteriovenous fistula feasibility. Cephalic arch is a common location for vascular access dysfunction due to its distinctive anatomy, complex valves, and biochemical alterations attributable to renal failure. Understanding cephalic arch stenosis is critical due to its high prevalence and treatment failure. The appropriate management option is highly debatable and mostly dependent on patient characteristics and interventionist's preference. Current options include, percutaneous transluminal balloon angioplasty, stent grafts, bare metal stents, cutting balloon angioplasty, endovascular banding, and surgical procedures. This article discusses the etiologies of cephalic arch stenosis as well as currents trends in management including endovascular and surgical options.

Predictors of arteriovenous fistula maturation in hemodialysis patients: a prospective cohort from an ambulatory surgical center in Joinville, Brazil

INTRODUCTION

The high rate of arteriovenous fistula maturation failure is a concern in a scenario of growing numbers of patients on hemodialysis. Non-vascular factors tied to maturation success have not been fully discussed.

METHODS

This prospective observational cohort study included patients with CKD on dialysis or pre-dialysis prescribed arteriovenous fistula creation for the first time in an ambulatory surgical center in Joinville, Brazil, from January 2021 to July 2021. Anthropometric aspects, sociodemographic characteristics, comorbidities, and vascular parameters observed in Doppler ultrasound were analyzed. Variables associated with maturation were analyzed in multivariate models by logistic regression.

RESULTS

Eighty-eight of 145 participants (60.1%) were males. Included patients had a median age of 59 years. Successful arteriovenous fistula maturation occurred in 113 (77.9%) patients. Factors such as increased BMI, hematocrit, arm circumference, and skinfold thickness were associated with lower chances of arteriovenous fistula maturation in univariate analysis. On the other hand, larger vein and artery diameter and fistulas in the more proximal portion of the arm were associated with higher maturation success. In multivariate analysis, smoking and larger skinfold and arm circumference were associated with lower chances of successful maturation. Increased systolic blood pressure and vein diameter were associated with greater chance of success.

CONCLUSION

In addition to the vascular parameters assessed in Doppler ultrasonography, factors related to obesity and/or nutritional aspects may influence arteriovenous fistula maturation.

Preditores da maturação de fístula arteriovenosa de pacientes em hemodiálise: coorte prospectiva de um centro cirúrgico ambulatorial, Joinville, Brasil

Resumo Introdução: A alta taxa de falha na maturação da fístula arteriovenosa é motivo de preocupação para o crescente número de pacientes em hemodiálise. Os fatores não vasculares não foram totalmente estudados em relação ao sucesso da maturação. Métodos: Estudo de coorte prospectivo, observacional de pacientes com DRC diálise ou pré-diálise encaminhados para a primeira criação de fístula arteriovenosa em um centro cirúrgico ambulatorial de Joinville, Brasil, de janeiro de 2021 a julho de 2021. Aspectos antropométricos, características sociodemográficas, comorbidades, além de fatores vasculares verificados pelo ultrassom Doppler. As variáveis associadas à maturação foram analisadas em modelos multivariados por regressão logística. Resultados: Dos 145 pacientes participantes, 88 (60,1%) eram homens, com idade mediana de 59 anos. Houve sucesso na maturação da fístula arteriovenosa em 113 (77,9%) pacientes. Fatores como aumento do IMC, hematócrito, circunferência do braço e valor das dobras cutâneas foram associados a menor chance de maturação da fístula arteriovenosa na análise univariada. Por outro lado, o maior diâmetro da veia e da artéria e fístulas na porção mais proximal do membro superior foram associados a maior sucesso de maturação. Na análise multivariada, tabagismo, maior dobra cutânea e circunferência do braço foram associados a menor chance de sucesso da maturação. O aumento da pressão arterial sistólica e o do diâmetro da veia foram associados a maior chance de sucesso. Conclusão: Além dos aspectos vasculares avaliados pela ultrassonografia Doppler, fatores relacionados à obesidade e/ou a aspectos nutricionais podem influenciar a maturação da fístula arteriovenosa.

Association of preoperative vein mapping with hemodialysis access characteristics and outcomes in the Vascular Quality Initiative

BACKGROUND

Preoperative vein mapping before arteriovenous fistula (AVF) or arteriovenous graft (AVG) placement has been debated as a possible method of improving hemodialysis access outcomes for patients. However, high-quality national studies that have addressed this relationship are lacking. Thus, we assessed the association of preoperative vein mapping with hemodialysis access configuration and outcomes.

METHODS

In the present cohort study, we analyzed all patients who had undergone AVF or AVG placement with data captured in the Vascular Quality Initiative hemodialysis access dataset from August 2011 to September 2019. The patients were stratified by whether they had undergone preoperative vein mapping. The primary (configuration) outcomes were access type (AVF vs AVG) and location (upper arm vs forearm). The secondary (longitudinal) outcomes were the successful initiation of hemodialysis, maintenance of secondary patency, and the need for reintervention 1 year after the index operation.

RESULTS

Overall, 85.6% of the 46,010 included patients had undergone preoperative vein mapping. Of the 46,010 patients, 76.1% and 23.9% had undergone AVF and AVG creation, respectively. AVF creation (77.6% vs 67.3%) and forearm location (54.6% vs 47.3%) were more frequent for the patients who had undergone preoperative vein mapping than for those who had not (P < .001). After adjusting for baseline differences between the groups, preoperative vein mapping was associated with increased odds of receiving an AVF vs AVG (adjusted odds ratio, 1.64; 95% confidence interval [CI], 1.55-1.75) and forearm vs upper arm access (adjusted odds ratio, 1.22; 95% CI, 1.16-1.30). The incidence of the loss of secondary patency was lower for patients with preoperative vein mapping (P < .001), and persisted after risk adjustment (adjusted hazard ratio, 0.81; 95% CI, 0.75-0.88).

CONCLUSIONS

Preoperative vein mapping was associated with favorable hemodialysis access configurations and outcomes in real-world practice. These data suggest that the use of preoperative vein mapping could improve the likelihood of favorable outcomes for patients requiring hemodialysis access.

Outcomes and predictors of failure of arteriovenous fistulae for hemodialysis

Purpose

Arteriovenous fistula(AVF) is preferred vascular access for hemodialysis but has primary failure in 20–60%. Studying predictors of AVF failure would help plan appropriate management.We studied AVF outcomes, clinical and vascular factors predicting their failure in patients requiring hemodialysis.

Methods

Retrospective study of patients with AVF creation from January 2017 to December 2018. Outcomes studied were immediate (< 72 h), primary (3 months) AVF failure, six-month/one-year patency, analyzed for predictive clinical, vascular factors as assessed using Pre-operative Doppler Ultrasound(DUS).

Results

Of 530 AVFs in 460 patients, DUS was done in 426/530 (80.4%), 349/460 (75.8%) were males, mean age was 53.10 ± 14.54 (18–91), 215/460(46.7%) had Diabetes mellitus(DM), 423/460(92%) hypertension. AVFs were radiocephalic in 79/530 (14.9%), brachiocephalic 418/530 (78.9%), brachiobasilic 33/530 (6.2%). AVF Immediate/Primary failure was seen in 64/530 (12.1%), 90/352 (25.6%); Patency at six months/one year in 253/352(71.8%),191/305 (62.6%), respectively. Older age had less immediate failures (AOR 0.97, CI 0.95–0.99, p 0.03). Feeding arterial diameter predicted immediate and primary failure on univariate analysis [OR 0.64 (95% CI 0.49–0.83), 0.62 (95% CI 0.47–0.89), respectively], but not multivariate. Artery diameter of > 4.0 mm had less failures [immediate (p 0.01), primary (p 0.02)], < 2.0 mm had specificity 95.9% and 95.4% for immediate, primary failure respectively.

Conclusion

AVF failure is 12.1%, immediately; 25.6% three months after construction, Patency at 6 months is 71.8%, one year 62.6%. Immediate failures decrease with age. Artery diameters > 4.0 mm had less, < 2.0 mm had more failures.

Reliability of preoperative venous mapping ultrasonography in predicting for autogenous arteriovenous fistula maturation

BACKGROUND

Autogenous arteriovenous fistula creation is the preferred route for vascular access for hemodialysis. Although preoperative venous mapping ultrasonography has been advocated as an operative planning adjunct and recently incorporated into the Society for Vascular Surgery clinical guidelines, controversy remains regarding its usefulness for predicting access success. The purpose of the present retrospective clinical study was to test the hypothesis that vein size measured on routine preoperative venous mapping is a poor predictor of primary fistula maturation.

METHODS

Consecutive upper extremity autogenous arteriovenous fistulas created by three dedicated vascular surgeons were retrospectively reviewed. The demographic characteristics, preoperative venous mapping, functional maturation, and patency were analyzed. The clinically relevant variables were tested for predictive significance using a logistic regression model.

RESULTS

A total of 199 upper extremity autogenous arteriovenous fistulas had been created during a 5-year period. Patients were aged 70 ± 16 years (range, 20-96 years), and 62% were men. Most had already been undergoing dialysis before fistula creation (83%), usually via a tunneled central venous catheter (62%). Radial-cephalic, brachial-cephalic, and brachial-basilic arteriovenous fistulas had been created in 82 patients (41%), 76 patients (38%), and 10 patients (5%), respectively. Fistula maturation, defined as a palpable thrill and/or successful cannulation of the fistula with the ability to deliver a flow rate of 400 mL/min, was achieved in 67% of the patients. A higher body mass index was associated with nonmaturation on both univariate and multivariate analyses (success, 28.6 ± 7.7 kg/m²; vs failed, 31.6 ± 9.4 kg/m²; P = .029; odds ratio [OR], 1.06; 95% confidence interval [CI], 1.02-1.10; P < .01). On univariate analysis, the maximum target vein diameter assessed by preoperative venous mapping was slightly larger in the group achieving successful maturation (2.9 ± 1.1 mm vs 2.6 ± 0.9 mm; P = .014). However, neither the maximum target vein diameter nor a target vein size >3 mm was significantly predictive of maturation on multivariate analysis (maximum vein diameter: OR, 0.65; 95% CI, 0.35-1.22; P = .176; vein size >3 mm: OR, 0.91; 95% CI, 0.32-2.60; P = .857). After a median follow-up of 15 months (interquartile range, 26 months), the primary functional patency, primary-assisted patency, and secondary patency rates were 39.1% ± 0.6%, 94.5% ± 0.6%, and 97.9% ± 0.5%. No association of vein diameter with long-term patency was found.

CONCLUSIONS

Despite the national fistula-first initiatives, most patients still undergo access via catheter at the initiation of hemodialysis. The use of routine preoperative venous mapping does not predict successful primary maturation. Also, no clinically useful predictor of fistula maturation was identified in the present study.

Randomised clinical study of the impact of routine preoperative Doppler ultrasound for the outcome of autologous arteriovenous fistulas for haemodialysis

Background:

Arteriovenous fistulas are the gold standard of vascular accesses in haemodialysis; however, they have a considerable primary failure rate. This study evaluated the comparative reliability of routine preoperative Doppler ultrasound with an isolated physical examination of autologous arteriovenous fistulas within the Single Health System of Brazil and analysed the potential clinical benefit, improvement in primary failure rates and its economic impact.

Methods:

A non-blind randomised clinical study group of patients undergoing a vessel mapping with preoperative Doppler ultrasound (ultrasound group) and a control group who had undergone only a physical examination (clinical group) before the vascular procedures was performed. The role of the arteriovenous fistula in dialysis and possible alterations was evaluated in both the groups and followed up for 6 months.

Results:

Of the initial 248 eligible patients, there was a randomisation of 230 patients, 228 of whom were submitted for surgery, 114 in each group. In the clinical group, a significantly higher rate of primary failure was recorded, with 13.6% versus 4.4% in the ultrasound group (p = 0.002). The Kaplan–Meier curve with log-rank analysis showed a significantly higher primary patency in the ultrasound group (p = 0.042). Regarding the cost-effectiveness of the use of Doppler ultrasound, there was no increase in the final cost compared to the physical examination (US$1.28/fistula day × US$1.29/fistula day).

Conclusion:

It was concluded that Doppler ultrasound contributed to the reduction of primary failure, leading to a significantly superior primary patency of arteriovenous fistulas, and no increase in the final cost. This justifies its routine preoperative use in the Single Health System. Registration number RBR-474xhn (http://www.ensaiosclinicos.gov.br).

The influence of a doppler ultrasound in arteriovenous fistula for dialysis failure related to some risk factors

INTRODUCTION

The increasing prevalence of chronic kidney disease has increased the demand for arteriovenous fistula (AVF) care. The objective of this study was to assess the relationship between some risk factors for AVF failure (advanced age, female sex, diabetes, obesity, central venous catheter, previous fistula, and hospitalization) and having a Doppler ultrasound performed preoperatively.

METHODS

A prospective study was performed with 228 dialysis patients from Imperatriz, Maranhão. Half of the sample was randomly selected to receive preoperative Doppler ultrasound and the other half did not, from the period of October 2016 to September 2018.

RESULTS

There were 53 total failures corresponding to 23.2% of our sample, which is almost double that of the patients in the clinical group. Considering the failures and risk factors associated with the overall sample, there was a statistically significant association between a central venous catheter on the same side of the AVF with P = 0.04 (Odds Ratio 1.24) and obesity with P = 0.05 (Odds Ratio 1.36), which was not repeated in the Doppler ultrasound group individually. There was no statistically significant difference between the Doppler group and clinical group with respect to the amount of days of previous AVF hospitalization and failure.

CONCLUSIONS

We concluded that the reduction of failures with an introduction of the Doppler was statistically significant in the overall sample, but establishing a relationship between specific risk factors and failure was only possible with two of the risk factors in the study - obesity and central venous catheter on the same side of the AVF.

KDOQI Clinical Practice Guideline for Vascular Access: 2019 Update

The National Kidney Foundation's Kidney Disease Outcomes Quality Initiative (KDOQI) has provided evidence-based guidelines for hemodialysis vascular access since 1996. Since the last update in 2006, there has been a great accumulation of new evidence and sophistication in the guidelines process. The 2019 update to the KDOQI Clinical Practice Guideline for Vascular Access is a comprehensive document intended to assist multidisciplinary practitioners care for chronic kidney disease patients and their vascular access. New topics include the end-stage kidney disease "Life-Plan" and related concepts, guidance on vascular access choice, new targets for arteriovenous access (fistulas and grafts) and central venous catheters, management of specific complications, and renewed approaches to some older topics. Appraisal of the quality of the evidence was independently conducted by using a Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach, and interpretation and application followed the GRADE Evidence to Decision frameworks. As applicable, each guideline statement is accompanied by rationale/background information, a detailed justification, monitoring and evaluation guidance, implementation considerations, special discussions, and recommendations for future research.

High low-density lipoprotein cholesterol level is the independent risk factor of primary patency rate of arteriovenous fistula

OBJECTIVES

An arteriovenous fistula is the first choice of vascular access in dialysis patients. However, the correlations between patient factors and the arteriovenous fistula patency rate remain unclear. Therefore, we examined the effect of dialysis patient factors on arteriovenous fistula patency rate.

METHODS

This study included 101 patients who received maintenance dialysis and used arteriovenous fistula for vascular access at Atami Hospital, International University of Health and Welfare in July 2018. A retrospective review was performed from the time of arteriovenous fistula creation to July 2018, and the primary and secondary arteriovenous fistula patency rates were investigated. The patency rate was calculated using the Kaplan-Meier method, and risk factor analysis was performed using Cox proportional hazards regression analysis.

RESULTS

The primary patency rate of arteriovenous fistula was 71.2% at one year and 43.0% at five years, and the secondary patency rate was 92.7% at one year and 79.8% at five years. In the multivariate analysis, high low-density lipoprotein cholesterol (LDL-C) level and a history of diabetes were considered significant risk factors (HR 1.023, p value <0.01 and HR 2.550, p value <0.01, respectively). A log rank test was conducted on the groups of patients with LDL <90 mg/dl and LDL ≥90 mg/dl, and the <90 mg/dl group resulted in a good primary patency rate (p value 0.0327).

CONCLUSIONS

High LDL-C level was considered the independent risk factors of arteriovenous fistula primary patency rate.

Upper limb vascular mapping with Doppler ultrasound: Technique precision evaluated in healthy volunteers

Introduction

Doppler ultrasound is recommended by international societies for preoperative vascular mapping in vascular access surgery. Literature is scarce regarding data on Doppler ultrasound-associated errors.

Objectives

Our aim was to evaluate Doppler ultrasound precision for upper limb vascular mapping.

Methods

Fifty-two adult healthy volunteers were evaluated for superficial vein diameter, brachial artery flow and diameter in the lower third of non-dominant arm by a dedicated vascular access radiologist blinded for the identification of the participants. Each participant was scheduled for three evaluations one week apart. Friedman test and multivariate analysis of variance for repeated measures were used.

Results

There were no statistical differences within subjects across the three weeks except for brachial artery flow in participants who had basilic vein as the dominant vein.

Discussion

Repeated anatomical and haemodynamic parameters measured by Doppler ultrasound performed by an experienced medical sonographer, according to our protocol, did not show statistical differences within subjects, independently of age, gender and body mass index.

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.

Evaluation of upper limb superficial venous percussion as a sign of anatomical location and venous permeability. A comparative study of superficial venous percussion to ultrasound findings on non-renal patients and on chronic kidney disease patients

METHODS

An analytical cross-sectional study with 70 individuals divided into two groups. Group A consisted of 35 volunteers who were being preoperatively prepared for the construction of arteriovenous fistula. Group B consisted of 35 non-renal patients selected by convenience. Each participant underwent physical examination, including venous percussion, of the dominant upper limb and then ultrasound. Interobserver agreement was assessed between a trained vascular surgeon performing percussion and fourth-year medical student. Accuracy, sensitivity, specificity, positive predictive value and negative predictive value of percussion were determined in relation to ultrasound. The agreement between the methods, venous percussion and venous duplex ultrasound was also evaluated by the Kappa index.

RESULTS

The overall interobserver agreement for the percussion was 0.74 (95% CI 0.632 to 0.851). It was observed that the results were more favorable in the cephalic vein than in the basilic vein, emphasizing that the cephalic is more used in venous punctures, because of its anatomical location and visibility, and in fistula construction. The 35 percussions of the cephalic forearm vein in Group A resulted in a sensitivity of 1.0 (95% CI 0.63 to 1.00), specificity of 0.96 (95% CI 0.81 to 1.00), a positive predictive value of 0.89(95% CI 0.52 to 1.00) and a negative predictive value of 1.00 (95% CI 0.87 to 1.00), with an accuracy of 0.97 (95% CI 0.85 to 1.00) and Kappa index of 0.92 (95% CI 0.77 to 1.00) in relation to ultrasound. Overall, when all venous segments were analyzed in group A, the Kappa index of agreement between the percussion and the ultrasonography reached 0.56 (95% CI 0.401 to 0.72). All venous segments in Group A had a sensitivity of 0.54 (95% CI 0.37 to 0.70) and a specificity of 0.96 (95% CI 0.90 to 0.99). When all venous segments were analyzed in group B, the Kappa index of agreement between the percussion and the ultrasonography reached 0.48 (95% CI 0.34 to 0.62). All venous segments in Group B had a sensitivity of 0.70 (95% CI 0.59 to 0.79) and a specificity of 0.82 (95% CI 0.69 to 0.91).

CONCLUSION

Venous percussion of the upper limbs has a high positive predictive value and high specificity, when compared to ultrasound as a way to evaluate the patency and adequacy of the cephalic vein. Although there is not enough evidence to preclude ultrasound, percussion should definitely be included in the traditional physical exam evaluation of upper limbs superficial veins.

Validation of the failure to maturation equation and proposal for a novel scoring system for arteriovenous fistula maturation in multiethnic Asian haemodialysis patients

INTRODUCTION

A successful arteriovenous fistula is essential for effective haemodialysis. We aim to validate the existing failure to maturation equation and to propose a new clinical scoring system by evaluating arteriovenous fistula success predictors.

METHODS

Data of end-stage renal disease patients initiated on haemodialysis from January 2010 to December 2012 were retrospectively obtained from medical records with follow-up until 1 January 2014. Application of the failure to maturation equation was evaluated. A nomogram was developed using arteriovenous fistula success predictors and was calibrated with a bootstrapping technique.

RESULTS

A total of 694 patients were included with mean duration of follow-up of 2.3 years. Arteriovenous fistula maturation was achieved by 542 patients (78%). Comparing our cohort with the failure to maturation cohort, there were statistically significant differences in mean age, ethnicity and presence of diabetes mellitus. The failure to maturation equation failed to predict arteriovenous fistula outcomes with area under the curve performance of 0.519 on a receiver operating characteristic curve. Multivariate logistic regression showed that Malay patients (odds ratio = 0.628; 95% confidence interval = 0.403-0.978; p < 0.05) and patients requiring preoperative vein mapping (odds ratio = 0.601; 95% confidence interval = 0.410-0.883; p < 0.01) had a lower chance of arteriovenous fistula success, whereas male gender (odds ratio = 1.526; 95% confidence interval = 1.040-2.241; p < 0.05) and presence of postoperative good thrill (odds ratio = 3.137; 95% confidence interval = 2.127-4.625; p < 0.0001) had a higher chance of arteriovenous fistula success. The derived nomogram predicted arteriovenous fistula success (odds ratio = 1.030; 95% confidence interval = 1.022-1.038; p < 0.0001) with the area under the curve of 0.695 on a receiver operating characteristic curve and an adequacy index of 99.86% (p < 0.0001).

CONCLUSION

The failure to maturation equation was not validated in our cohort. The clinical utility of our proposed arteriovenous fistula scoring system requires external validation in larger studies.

Reliability and accuracy of duplex ultrasound vein mapping for dialysis access

BACKGROUND

Duplex ultrasound vein mapping (DUVM) may increase autogenous dialysis access procedures but has not been universally adopted by surgeons.

METHODS

We determined reliability and accuracy of arm vein measurements on physical examination (PE) and DUVM, compared to direct measurements in the operating room (OR, gold standard). Operative plans were developed from each set of measurements and we evaluated which approach identified more options for autogenous procedures.

RESULTS

Vein diameters measured on DUVM correlated well with OR measurements but those made on PE did not. Autogenous access options were identified in 34.8% of patients based on PE and in 96.6% based on their DUVM. The 6-month primary-patency was 86.4%; assisted primary-patency was 89.8%.

CONCLUSIONS

Duplex ultrasound vein mapping is more reliable and accurate for assessing arm vein anatomy than physical examination. It identifies more autogenous options than physical-examination alone. It is essential for the preoperative evaluation for dialysis access.

Influence of intraoperative findings on immediate flow through radial-cephalic arteriovenous wrist fistulas for hemodialysis access

Background

Adequate flow through a newly created arteriovenous fistula depends on multiple characteristics of the vessels and patient comorbidities. Several studies have related preoperative findings to failure, but few have analyzed the influence of intraoperative findings.

Objectives

To evaluate the predictive value of intraoperative findings on the immediate outcome of radial-cephalic arteriovenous wrist fistulas (RCAVF) by collecting data that are easily measured intraoperatively.

Methods

We designed a cross-sectional study, in which a single surgeon performed 101 RCAVF in 100 patients at a single center. We analyzed the immediate postoperative flow, assessed by thrill intensity immediately after fistula creation, against patient demographics and intraoperative data. The following variables were analyzed: age, sex, comorbidities, length of vein visible at preoperative examination, macroscopic arterial calcification, maximum vein diameter, and length of stenosis-free vein, measured by cannulation with a urethral catheter during the procedure. The chi-square test was used both to eliminate possible bias introduced by side of venous access (left or right), and to determine predictive values of immediate thrill.

Results

Side of access was not associated with any significant differences in variables. Absence of macroscopic arterial calcification, successful venous catheterization using a 6 French catheter or larger, and ability to advance it more than 10 centimeters along the lumen of the proximal vein were correlated with adequate immediate postoperative thrill (p = 0.004, p < 0.001, and p = 0.005, respectively).

Conclusions

In this series of 101 RCAVF, both the diameter of the catheter and its progress through the proximal vein and also absence of arterial calcification had positive predictive value for achieving adequate immediate thrill after vascular access construction.

Spanish Clinical Guidelines on Vascular Access for Haemodialysis

Vascular access for haemodialysis is key in renal patients both due to its associated morbidity and mortality and due to its impact on quality of life. The process, from the creation and maintenance of vascular access to the treatment of its complications, represents a challenge when it comes to decision-making, due to the complexity of the existing disease and the diversity of the specialities involved. With a view to finding a common approach, the Spanish Multidisciplinary Group on Vascular Access (GEMAV), which includes experts from the five scientific societies involved (nephrology [S.E.N.], vascular surgery [SEACV], vascular and interventional radiology [SERAM-SERVEI], infectious diseases [SEIMC] and nephrology nursing [SEDEN]), along with the methodological support of the Cochrane Center, has updated the Guidelines on Vascular Access for Haemodialysis, published in 2005. These guidelines maintain a similar structure, in that they review the evidence without compromising the educational aspects. However, on one hand, they provide an update to methodology development following the guidelines of the GRADE system in order to translate this systematic review of evidence into recommendations that facilitate decision-making in routine clinical practice, and, on the other hand, the guidelines establish quality indicators which make it possible to monitor the quality of healthcare.

Improving haemodialysis fistula maturation following early ultrasound vascular mapping: 'The Venous Preservation Scan'

AIM

Formation of autogenous arteriovenous fistula (AVF) in patients with chronic kidney disease (CKD) is complicated by a high primary failure rate. We hypothesized that early (months to years before AVF creation) Venous Preservation Scan (VPS) followed by vasculature preservation is effective in protecting the patient's best 'for fistula' vasculature. This study was performed to evaluate the impact of VPS on AVF outcomes.

METHODS

The case records of 123 patients who underwent ultrasound mapping for AVF creation in a district hospital were reviewed. Ninety-seven were VPS and 26 were Routine Pre-Operative Planning Scan (RPOPS) performed immediately prior to surgery. Outcomes of 21 patients who went onto AVF creation in the VPS group were compared to 23 patients in the RPOPS group.

RESULTS

Success and complication rates for AVF placement in patients who underwent VPS versus RPOPS were 100% versus 91.3% (P = 0.27) and 0 versus 8.7% (P = 0.23). A greater proportion of AVF created following RPOPS required intervention before maturation (47.6% vs 19%, P = 0.05). The median primary patency of AVF created following VPS versus RPOPS was 492 (IQR 222, 1219) versus 169 (IQR 116, 414) days (P = 0.02). The cumulative patency did not differ between the two groups (median = 807 (IQR 499, 1308) versus 1059 (IQR 331, 1263) days, P = 0.26).

CONCLUSIONS

This small study suggests that VPS may favourably influence the survival of primary AVF and reduce the need for assisted interventions. However, confirmation with larger randomized controlled trial is warranted.

A Meta-analysis of Preoperative Duplex Ultrasound Vessel Diameters for Successful Radiocephalic Fistula Placement

Background

The Kidney Dialysis Outcomes Quality Initiative (K/DOQI) guidelines for vascular access recommend the use of radiocephalic wrist arteriovenous fistulas (RCAVFs) as the initial option for dialysis access. The survival rate of a successfully placed fistula is excellent. However, 10–24% of RCAVFs fail to reach functional status as the result of early thrombosis or maturation failure. Many authors have investigated the utility of preoperative vascular mapping by Duplex ultrasound to predict adequate vessel size for successful fistula placement. This meta-analysis is the first in which preoperative radial arterial (RAD) and cephalic venous diameters (CVD) required for favorable fistula outcomes are reviewed.

Methods

A literature search was performed by use of the MEDLINE electronic base for “arteriovenous, fistula, ultrasound, and hemodialysis.” The analysis yielded 166 studies, of which 20 studies included preoperative duplex data. Meta-analysis was performed by applying the statistical test of comparing two proportions, assuming equal variances.

Results

A total of 433 patients were duplexed for preoperative evaluation of the RAD and 386 for CVD. The total number of subjects ranged from 21 to 91, mean age 58.7 years. The subjects were 55.5% male, 39.0% with diabetes mellitus. Meta-analysis yielded 2.0 mm for RAD and 2.0 mm for CVD as designated cutoff vessel diameters. Our study showed the mean fistula success rate was significantly different between RAD >2.0 mm (59%) and RAD >2.0 mm (40%). The mean fistula success rate was also significantly different between CVD > 2.0 mm (71%) and >2.0 mm (29%). Successful fistula placement was defined as a functional fistula at least 4–6 weeks after creation.

Conclusion

On the basis of our study, the use of Duplex ultrasound is important in determining preoperative vessel diameter size, and subsequent functional success rate of fistula placement.

Post-operative arterio-venous fistula blood flow influences primary and secondary patency following access surgery

PURPOSE

Primary arteriovenous fistula arterio venous fistula (AVF) formation has proven to be the best and optimal vascular access for the majority of haemodialysis patients. At present there are limited data to suggest which haemodynamic parameters most correlate with the likelihood of early failure. The aim of this study is to identify the haemodynamic predictors of early failure, hence identify which fistulae may benefit from timely pre-emptive intervention.

MATERIAL AND METHODS

Retrospective analysis of data was performed of 201 patients undergoing native AVF creation over a one year period. Demographic details, co-morbidity, preoperative vessel calibre were collected. Flow was measured by duplex ultrasound post operatively.

RESULTS

Preoperative vein calibre (p = 0.01) and fistula flow (p < 0.001) positively affected primary patency. Age, gender, ethnicity, type of fistula, hypertension and preoperative arterial calibre did not influence outcome. Regression analysis showed that the strength of correlation between early postoperative fistula flow and patency decreased progressively with time. Six week flow predicts early, but not late, failure. ROC analysis identified 300 ml/min flow as the best predictor of patency. Fistulae with flow above 300 ml/min were more likely to remain patent over the next 12 months (p < 0.001, HR = 7.4).

CONCLUSION

Postoperative fistula flow of less than 300 ml/min identifies AVFs at high risk of early failure. These may be candidates for early intervention with balloon assisted maturation. The findings of this retrospective cohort study strongly support the need for a more robust prospectively designed trial identifying haemodynamic factors that can predict mid and long-term AVF patency.

Vascular Access Practice Patterns in Canada: A National Survey

Background:

One of the mandates of the Canadian Society of Nephrology’s (CSN) Vascular Access Working Group (VAWG) is to inform the nephrology community of the current status of vascular access (VA) practice within Canada. To better understand VA practice patterns across Canada, the CSN VAWG conducted a national survey.

Objectives:

(1) To inform on VA practice patterns, including fistula creation and maintenance, within Canada. (2) To determine the degree of consensus among Canadian clinicians regarding patient suitability for fistula creation and to assess barriers to and facilitators of fistula creation in Canada.

Design:

Development and implementation of a survey.

Setting:

Community and academic VA programs.

Participants:

Nephrologists, surgeons, and nurses who are involved in VA programs across Canada.

Measurements:

Practice patterns regarding access creation and maintenance, including indications and contraindications to fistula creation, as well as program-wide facilitators of and barriers to VA.

Methods:

A small group of CSN VAWG members determined the scope and created several VA questions which were then reviewed by 5 additional VAWG members (4 nephrologists and 1 VA nurse) to ensure that questions were clear and relevant. The survey was then tested by the remaining members of the VAWG and refinements were made. The final survey version was submitted electronically to relevant clinicians (nephrologists, surgeons, and nurses) involved or interested in VA across Canada. Questions centered around 4 major themes: (1) Practice patterns regarding access creation (preoperative assessment and maturation assessment), (2) Practice patterns regarding access maintenance (surveillance and salvage), (3) Indications and contraindications for arteriovenous (AV) access creation, and (4) Facilitators of and barriers to fistula creation and utilization.

Results:

Eighty-two percent (84 of 102) of invited participants completed the survey; the majority were nurses or VA coordinators (55%) with the remainder consisting of nephrologists (21%) and surgeons (20%). Variation in practice was noted in utility of preoperative Doppler ultrasound, interventions to assist nonmaturing fistulas, and procedures to salvage failing or thrombosed AV-access. Little consensus was seen regarding potential contraindications to AV-access creation (with the exception of limited life expectancy and poor vasculature on preoperative imaging, which had high agreement). Frequent barriers to fistula utilization were primary failure (77% of respondents) and long maturation times (73%). Respondents from centers with low fistula prevalence also cited long surgical wait times as an important barrier to fistula creation, whereas those from centers with high fistula prevalence cited access to multidisciplinary teams and interventional radiology as keys to successful fistula creation and utilization.

Conclusions:

There is significant variation in VA practice across Canada and little consensus among Canadian clinicians regarding contraindications to fistula creation. Further high-quality studies are needed with regard to appropriate fistula placement to help guide clinical practice.

Preoperative management of arteriovenous fistula (AVF) for hemodialysis

Native arteriovenous fistula (AVF) is the favorite access for hemodialysis (HD). The National Kidney Foundation's Kidney Disease Outcomes Quality Initiative (KDOQI) recommends its creation in most patients with renal failure. Unfortunately, intensive efforts to promote native AVF in patients with marginal vessels have increased the rate of primary fistula failure. A non-functioning fistula prompts the use of central venous catheter (CVC) that, unlike AVF, has been associated with an increased risk of morbidity and mortality among patients receiving HD. We believe that successful and timely AVF placement relies on the development of a multidisciplinary integrated preoperative program divided into five stages: (i) management of patients with advanced chronic kidney disease (CKD), (ii) management of preoperative risk factors for AVF failure, (iii) planning of native AVF, (iv) assessment of patient eligibility and (v) preoperative vascular mapping. Focusing specifically on native AVF, we review scientific evidence regarding preoperative management of this vascular access in order to favor construction of long-term functioning fistula minimizing development of severe complications.

Outcomes of arteriovenous fistula creation, effect of preoperative vein mapping and predictors of fistula success in incident haemodialysis patients: A single-centre experience

AIM

Vascular access in haemodialysis is critical for effective therapy. We aim to evaluate the outcomes of arteriovenous fistula (AVF) creation in incident haemodialysis patients, impact of preoperative vein mapping and predictors of successful AVF maturation in our centre.

METHODS

Data of End-stage Renal Disease (ESRD) patients initiated on haemodialysis from January 2010 to December 2012 in our centre were retrospectively obtained from electronic medical records and clinical notes. Demographic characteristics, medical comorbidities, perioperative details were collected, and patients were followed up until 1 January 2014.

RESULTS

A total of 708 patients (median age 64, IQR 55-72) were included with mean duration of follow up of 2.3 ± 1.2 years, with access of AVF and arteriovenous graft (AVG) in 694 (98%) and 14 (2%) patients respectively. Eight patients were lost to follow-up. Successful AVF maturation was achieved in 542 patients (78%), with 1-year cumulative patency rate of 74%. Multivariate analysis revealed male gender, upper arm AVF and good postoperative thrill and pulse as predictors of successful AVF maturation. Preoperative vein mapping was performed in 42.5% (295/694) of patients, with mean vein diameter of 2.44 ± 0.82 mm. Maturation rates with and without vein mapping were 72.2% and 82.4%, respectively, (P = 0.001). In patients with vein diameters of <2 mm and ≥2 mm, there was no statistically significant difference in maturation rates (71.3% vs. 72.6%; P = 0.887) and median maturation time (66 vs. 78 days; P = 0.73).

CONCLUSION

Arteriovenous fistula can be successfully created in most incident haemodialysis patients. Routine vein mapping is not necessary if veins are suitable on physical examination alone, and vein sizes of <2 mm on ultrasound is not associated with lower AVF maturation rate.

Pre-operative Duplex Ultrasonography in Arteriovenous Fistula Creation: Intra- and Inter-observer Agreement

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.

Imaging in Vascular Access

This review examines four imaging modalities; ultrasound (US), digital subtraction angiography (DSA), magnetic resonance imaging (MRI) and computed tomography (CT), that have common or potential applications in vascular access (VA). The four modalities are reviewed under their primary uses, techniques, advantages and disadvantages, and future directions that are specific to VA. Currently, US is the most commonly used modality in VA because it is cheaper (relative to other modalities), accessible, non-ionising, and does not require the use of contrast agents. DSA is predominantly only performed when an intervention is indicated. MRI is limited by its cost and the time required for image acquisition that mainly confines it to the realm of research where high resolution is required. CT’s short acquisition times and high resolution make it useful as a problem-solving tool in complex cases, although accessibility can be an issue. All four imaging modalities have advantages and disadvantages that limit their use in this particular patient cohort. Current imaging in VA comprises an integrated approach with each modality providing particular uses dependent on their capabilities. MRI and CT, which currently have limited use, may have increasingly important future roles in complex cases where detailed analysis is required.

Preoperative ultrasound still valuable for radio-cephalic arteriovenous fistula creation?

Radio-cephalic arteriovenous fistula is a prototype hemodialysis access with small incidences of infection and distal ischemia, it spares proximal veins for future access use and it helps in the maturation of veins that may be used for more proximal access creations. This access type is prone to higher early failure rates compared to more proximal fistulas and there are unsolved uncertainties regarding exact ultrasound parameters predictive of fistula outcome. Evolution of ultrasound use has yielded several functional parameters that can be measured in addition to anatomical lumen sizes, which remain core parameters on which the decision to construct fistula in radio-cephalic forearm position is based. We propose to use arterial hyperemic response and wall morphology to aid in this decision when radial artery diameter falls in the interval with predictive uncertainty of 1.6-1.9 mm and to use venous flow pattern, respiratory variation, radial artery status and possibly venous distensibility when cephalic vein augmented diameter lies in the borderline interval of 2-2.4 mm. Ultrasound preoperative mapping and planning should be followed by expert surgical technique and several technique modifications of the classical end-to-side approach are possible to enhance operation outcome and diminish the incidence of stenosis most often present at juxta-anastomotic location. In our experience radio-cephalic arteriovenous fistula remains the golden standard for hemodialysis access and preoperative ultrasound the single best imaging modality to plan the operation and predict its success.

Repeated mappings of arm veins by physical examination: role of nephrologists in the selection of suitable veins for AV fistula surgery

Multidisciplinary team work is important for a successful hemodialysis vascular access program. The authors present a clinical case to illustrate the potential dynamic factors that can affect vein sizes, independent from the operators' skills and experiences. Therefore, if the first examination fails to detect suitable veins, repeated examinations of arm veins by nephrologists during routine office visits may greatly assist the surgeons in the selection of suitable arm veins for arteriovenous fistula surgery.

Vascular imaging for hemodialysis vascular access planning

INTRODUCTION

Central venous catheters (CVC) increase risks associated with hemodialysis (HD), but may be necessary until an arteriovenous fistula (AVF) or graft (AVG) is achieved. The impact of vascular imaging on achievement of working AVF and AVG has not been firmly established.

METHODS

Retrospective cohort of patients initiating HD with CVC in 2010-2011, classified by exposure to venography or Doppler vein mapping, and followed through December 31, 2012. Standard and time-dependent Cox models were used to determine hazard ratios (HRs) of death, working AVF, and any AVF or AVG. Logistic regression was used to assess the association of preoperative imaging with successful AVF or AVG among 18,883 individuals who had surgery. Models were adjusted for clinical and demographic factors.

FINDINGS

Among 33,918 patients followed for a median of 404 days, 39.1% had imaging and 55.7% had surgery. Working AVF or AVG were achieved in 40.6%; 46.2% died. Compared to nonimaged patients, imaged patients were more likely to achieve working AVF (HR = 1.45 [95% confidence interval [CI] 1.36, 1.55], P < 0.001]), any AVF or AVG (HR = 1.63 [1.58, 1.69], P > 0.001), and less likely to die (HR = 0.88 [0.83-0.94], P < 0.001). Among patients who had surgery, the odds ratio for any successful AVF or AVG was 1.09 (1.02-1.16, P = 0.008).

DISCUSSION

Fewer than half of patients who initiated HD with a CVC had vascular imaging. Imaged patients were more likely to have vascular surgery and had increased achievement of working AV fistulas and grafts. Outcomes of surgery were similar in patients who did and did not have imaging.

The Combination of Sonography and Physical Examination Improves the Patency and Suitability of Hemodialysis Arteriovenous Fistula in Vascular Access

PURPOSE

We compared the patency and the suitability of arteriovenous fistula (AVF) created for vascular access by two approaches: (a) physical examination with preoperative vascular mapping and (b) physical examination alone.

METHODS

We compared the patency and the suitability of AVF created in patients for dialysis. There were two cohorts of patients of 79 patients each: (a) patients with AVF created based on the combination of physical examination and preoperative vascular mapping (PE+VM) and (b) patients with AVF created based on physical examination (PE) alone. Fistula patency is defined as clinical detection of thrill (or auscultation) of murmur over the fistula and coded as having thrills (patent) versus not having thrills (not patent). Suitability of fistula is defined as functioning AVF (AVF can be adequately used via 2-needle cannulation for dialysis) and coded as suitable versus not suitable.

RESULTS

AVF created after the preoperative vascular mapping (PE+VM) has 5.70 (at six weeks) and 3.76 (at three months) times higher chance for patency, and 3.08 times higher chance for suitable AVF for dialysis than AVF created after the physical examination (PE) alone.

CONCLUSION

Physical examination with preoperative ultrasound mapping (PE+VM) significantly improves the short term patency and the suitability of AVF for dialysis.

Impact of a preoperative evaluation on the outcomes of an arteriovenous fistula

PURPOSE

The aim of this study was to determine the possible predictors of primary arteriovenous fistula (AVF) failure and examine the impact of a preoperative evaluation on AVF outcomes.

METHODS

A total of 539 patients who underwent assessment for a suitable site for AVF creation by physical examination alone or additional duplex ultrasound were included in this study. Demographics, patient characteristics, and AVF outcomes were analyzed retrospectively.

RESULTS

AVF creation was proposed in 469 patients (87.0%) according to physical examination alone (351 patients) or additional duplex ultrasound (118 patients); a prosthetic arteriovenous graft was initially placed in the remaining 70 patients (13.0%). Although the primary failure rate was significantly higher in patients assessed by duplex ultrasound (P = 0.001), ultrasound information changed the clinical plan, increasing AVF use for dialysis, in 92 of the 188 patients (48.9%) with an insufficient physical examination. Female sex and diabetes mellitus were risk factors significantly associated with primary AVF failure. Because of different inclusion criteria and a lack of adjustment for baseline differences, Kaplan-Meier survival analysis showed better AVF outcomes in patients assessed by physical examination alone; an insufficient physical examination was the only risk factor significantly associated with AVF outcomes.

CONCLUSION

Routine use of duplex ultrasound is not necessary in chronic kidney disease patients with a satisfactory physical examination. Given that female gender and diabetes mellitus are significantly associated with primary AVF failure, duplex ultrasound could be of particular benefit in these subtypes of patients without a sufficient physical examination.

Arteriovenous fistula in dialysis patients: Factors implicated in early and late AVF maturation failure

Increasing numbers of patients are being diagnosed with end-stage renal disease (ESRD), and the demand for on haemodialysis (HD) is rising. Arteriovenous fistulae (AVFs) remain the best conduit for adequate HD, with fewer complications associated with long-term use compared to bypass grafts and central venous catheters. However, it is known that many newly formed fistulae do not mature to provide useful HD access. The paper provides a narrative overview of factors influencing the process of AVF maturation failure.

Surgical interventions for late complications of arteriovenous fistulas

Our aim was to determine the most effective surgical treatment for arteriovenous fistula (AVF) complications after all other methods of salvage have failed. We evaluated 110 patients for 139 complications that occurred after the initial AVF placement and for whom surgical intervention was the last hope for retaining fistula access. Vascular steal syndrome and venous hypertension were the most common complications seen in our patients. The anastomoses of 17 of the vascular steal syndrome cases were narrowed either by stitches or by a polytetrafluoroethylene graft. The second most performed revision surgery was excision of the aneurysm and repair with primary suturing, followed by excision of the aneurysm and interposition grafting. Successful surgical outcomes were achieved in 111 of 139 procedures after revision surgery without constructing a new AVF. AVF salvage surgery is of paramount importance in order to increase the patency rate, which prolongs survival and increases the patient's quality of life.

Preoperative vascular access evaluation for haemodialysis patients

BACKGROUND

Haemodialysis treatment requires reliable vascular access. Optimal access is provided via functional arteriovenous fistula (fistula), which compared with other forms of vascular access, provides superior long-term patency, requires few interventions, has low thrombosis and infection rates and cost. However, it has been estimated that between 20% and 60% of fistulas never mature sufficiently to enable haemodialysis treatment. Mapping blood vessels using imaging technologies before surgery may identify vessels that are most suitable for fistula creation.

OBJECTIVES

We compared the effect of conducting routine radiological imaging evaluation for vascular access creation preoperatively with standard care without routine preoperative vessel imaging on fistula creation and use.

SEARCH METHODS

We searched Cochrane Kidney and Transplant's Specialised Register to 14 April 2015 through contact with the Trials' Search Co-ordinator using search terms relevant to this review.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) that enrolled adult participants (aged ≥ 18 years) with chronic or end-stage kidney disease (ESKD) who needed fistulas (both before dialysis and after dialysis initiation) that compared fistula maturation rates relating to use of imaging technologies to map blood vessels before fistula surgery with standard care (no imaging).

DATA COLLECTION AND ANALYSIS

Two authors assessed study quality and extracted data. Dichotomous outcomes, including fistula creation, maturation and need for catheters at dialysis initiation, were expressed as risk ratios (RR) with 95% confidence intervals (CI). Continuous outcomes, such as numbers of interventions required to maintain patency, were expressed as mean differences (MD). We used the random-effects model to measure mean effects.

MAIN RESULTS

Four studies enrolling 450 participants met our inclusion criteria. Overall risk of bias was judged to be low in one study, unclear in two, and high in one.There was no significant differences in the number of fistulas that were successfully created (4 studies, 433 patients: RR 1.06, 95% CI 0.95 to 1.28; I² = 76%); the number of fistulas that matured at six months (3 studies, 356 participants: RR 1.11, 95% CI 0.98 to 1.25; I² = 0%); number of fistulas that were used successfully for dialysis (2 studies, 286 participants: RR 1.12, 95% CI 0.99 to 1.28; I² = 0%); the number of patients initiating dialysis with a catheter (1 study, 214 patients: RR 0.66, 95% CI 0.42 to 1.04); and in the rate of interventions required to maintain patency (1 study, 70 patients: MD 14.70 interventions/1000 patient-days, 95% CI -7.51 to 36.91) between the use of preoperative imaging technologies compared with standard care (no imaging).

AUTHORS' CONCLUSIONS

Based on four small studies, preoperative vessel imaging did not improve fistula outcomes compared with standard care. Adequately powered prospective studies are required to fully answer this question.

Intraoperative assessment of vascular access

PURPOSE

The intraoperative quality assessment of the arteriovenous fistula for hemodialysis is an essential process to limit early failure due to technical problems or inadequate vascular quality. This step is not clearly defined in the literature with no recommendations.

METHODS

We selected published articles related to the topic of intraoperative quality control of the vascular access for hemodialysis.

RESULTS

The intraoperative blood flow measurement greater than 120 ml/min in autologous fistula and less than 320 ml/min in arteriovenous graft was described as predictive factors for early failure.

CONCLUSIONS

The blood flow measurement should be performed after the confection of the anastomosis. When blood flow is limited, fistulography is an essential step to assess patency.

Pre-Operative Ultrasonography and Arteriovenous Fistulae Maturation

Background

Arteriovenous fistulae (AVF) are preferred for haemodialysis access, but maturation is unpredictable.

Results

Clinical examination alone is unreliable for AVF planning. Duplex ultrasonography may provide useful anatomical and physiological data to allow more accurate prediction of likely AVF success.

Conclusion

Selective use of duplex ultrasonography appears to enhance AVF success rates, but there are insufficient data to recommend routine duplex screening of AVF candidates. Agreed vessel criteria are needed.

Randomized clinical trial of selective versus routine preoperative duplex ultrasound imaging before arteriovenous fistula surgery

Background

Anatomical suitability for arteriovenous fistula (AVF) formation was formerly determined by clinical examination alone. There are potential benefits from imaging to assess anatomical suitability. Existing studies examined the role of routine preoperative ultrasonography versus clinical examination alone. The role of a selective duplex ultrasound imaging policy is unknown. This study aimed to compare a policy of selective versus routine ultrasound assessment before AVF formation.

Methods

All patients referred for fistula formation were assessed for inclusion. Suitable patients were randomized to either routine or selective preoperative ultrasound imaging; selective imaging was performed only when clinical criteria were not met. The primary outcome measures were site of AVF formation and 30-day primary failure rate, and secondary outcome measures included the rate of complications.

Results

A total of 106 patients were assessed, and 94 were randomized: 47 to selective and 47 to routine duplex ultrasonography. The groups were well matched for age, co-morbidities and medications. The primary failure rate (29 per cent overall) was not significantly different between the selective and routine imaging groups: 36 per cent (14 of 39) and 21 per cent (8 of 38) respectively (P = 0·144). There were no significant differences in the sites of AVF formation or complication rates.

Conclusion

Routine preoperative ultrasound vessel imaging did not significantly reduce early failure rates, influence the site of AVF formation or reduce complications. If clinical evaluation detects anatomy suitable for AVF formation, duplex imaging may not be needed. Registration number: NCT01004627 (http://www.clinicaltrials.gov).

Fistula eligibility: a work in progress

Effective hemodialysis requires a reliable vascular access. Clinical practice guidelines strongly recommend the fistula as the preferred option followed by arteriovenous (AV) grafts, with central venous catheters being least preferred. Recently, there has been a growing awareness of the limitations of the fistula, its high rate of primary failure and that a fistula may not be appropriate for all patients initiating or on hemodialysis. However, determinates for fistula eligibility have not been clearly defined. The creation and use of a fistula requires the complex integration of patient, biological, and surgical factors, none of which can be easily predicted or planned. There have been several successful initiatives over the last decade addressing patient suitability for AV access, but none have validated defined criteria for fistula eligibility. We discuss these initiatives by addressing: 1) process of care, 2) radiological and nonradiological tests and procedures, and 3) alternative surgical approaches. Careful clinical judgment, appropriate vascular access assessment and placement, and an individualized approach to the risks and benefits will optimize patient health outcomes while minimizing prolonged catheter dependence among hemodialysis patients.

Retrospective review of angiography before cannulation of newly created vascular accesses in hemodialysis patients

PURPOSE

To investigate vascular access status before first cannulation and the clinical implications of angiography performed before cannulation.

MATERIALS AND METHODS

A retrospective review of 300 consecutive patients who underwent angiography after vascular access surgery and before cannulation between August 2004 and April 2010 was performed. Angiography was performed 4-6 weeks after the surgery but before the first cannulation.

RESULTS

Angiography revealed 94 (31.3%) cases of severe stenosis (≥ 50% luminal narrowing) that required percutaneous transluminal angioplasty (PTA) or a second operation. No stenosis was observed in 122 (40.7%) cases, and mild stenosis (< 50% luminal narrowing) was observed in 84 (28%) cases. For the 94 cases with severe stenosis, PTA was performed in 66, and a second operation was performed in 16. In the other cases (n = 12), HD was maintained by a permanent catheter, or the patients were transferred to another institution. PTA was an immediate success in all patients who underwent the procedure except two. Of 84 patients with mild stenosis, 70 were followed for 1 year; vascular access dysfunction occurred in 15, and 11 of these underwent successful PTA. Of the 122 patients with normal angiographic findings, 102 were followed for 1 year, and vascular access dysfunction did not occur in any of these patients.

CONCLUSIONS

Early postoperative angiography before the first hemodialysis is helpful for the early detection and treatment of vascular access dysfunction.

Patient oriented management for the creation of arteriovenous fistula for hemodialysis

OBJECTIVE

Hemodialysis access is of paramount importance for end-stage renal failure (ESRF) patients. Creation and maintenance of arteriovenous fistula (AVF) by a dedicated team increases the success and duration of the hemodialysis. The aim of this study is to report a patient oriented standardized surgical technique performed by a single surgeon on the success of AVF creation.

MATERIAL AND METHODS

A single surgeon performed all AVF operations. The records of all patients who were operated for AVF creation without using synthetic grafts through a 3 year period (2009-2011) were included. The patients were examined and operated on by a previously defined standard protocol.

RESULTS

A total of 221 procedures were done for 209 patients. The mean age was 65±11,4 years. Immediate function rate was 95.9% (n=212). Follow-up was possible for 182 patients (82.3%). For an average follow-up time of 11,3 months, the death rate was 20.8% (n=38) and the rate of AVF patency was 73.7% (n=134).

CONCLUSION

Sustaining patency of AVF is difficult in these systemically deranged patients. A focused approach by a dedicated team will increase the success rate.

When should a patient receive an arteriovenous graft rather than a fistula?

There has been a dramatic increase in the placement and use of arteriovenous fistulas (AVF) in US patients with chronic kidney disease over the past few years, in accordance with strong recommendations by Fistula First Initiative and KDOQI guidelines. However, AVF nonmaturation remains a substantial obstacle to achieving functional AVFs in a subset of patients, despite the widespread use of preoperative vascular mapping to assist surgeons in planning access surgery, and the growing use of interventions to salvage nonmaturing AVFs. In the right patient, aggressive efforts result in a functioning AVF, which provides adequate dialysis with relatively few interventions required to maintain its long-term patency for dialysis. In the wrong patient, aggressive efforts to achieve a mature AVF may result in numerous failed surgical and percutaneous procedures and prolonged catheter dependence, with all its associated complications. Thus, strict recommendations to place an AVF in all dialysis patients might not benefit every patient, and may actually harm some patients. There are no randomized clinical trials to address which patients are more suitable for placement of an arteriovenous graft (AVG), rather than an AVF. However, there is a wealth of observational studies, which taken cumulatively, may assist clinicians in identifying those patients who should receive an AVG. In this article, we review the relevant published literature regarding this topic and provide suggestions for stratifying patients who should receive each type of vascular access.

The Clinical Utility of Vascular Mapping with Doppler Ultrasound Prior to Arteriovenous Fistula Construction for Hemodialysis Access

Purpose

To compare the outcomes of vascular access (VA) procedures performed using physical examination (PE) alone to PE and ultrasound vein mapping for assessment of patients needing hemodialysis access.

Methods

Comparative analysis of data obtained by retrospective review of records of 63 patients who underwent PE and vascular mapping (VM) using colored Doppler ultrasonography (CDUS) and 76 patients assessed by physical examination alone to schedule vascular access surgery. The parameters assessed to study the impact of these two different pre-operative assessment approaches included selection of surgical site, procedure, construction of arteriovenous fistulas (AVF) and grafts (AVG), negative surgical exploration rates and surgical outcomes (maturation and patency rates).

Results

The rate of successfully constructed AVF increased significantly from 75% to 97% (P=.001) with pre-operative ultrasonographic vascular mapping. In 22 patients (34.9%) the access planned with physical examination was modified based on CDUS examination. In 12 patients, the surgical site for AVF creation and type of surgical procedure were modified based on the CDUS results. Permanent access placement rates were significantly higher in patients assessed with CDUS (P=.001). All patients who underwent vascular mapping had successful VA construction while the PE group had a 18.4% negative surgical exploration rate. When fistulas were assessed at six months, the patency rate was 80.7% for the physical examination (PE) group and 93.4% for the vascular mapping (VM) group.

Conclusions

Pre-operative vascular mapping using CDUS significantly increases the success of AVF construction and patency.