Hemodialysis arteriovenous fistula maturity: US evaluation

Cathepsin G promotes arteriovenous fistula maturation by positively regulating the MMP2/MMP9 pathway

BACKGROUND

Arteriovenous fistula (AVF) is currently the preferred vascular access for hemodialysis patients. However, the low maturation rate of AVF severely affects its use in patients. A more comprehensive understanding and study of the mechanisms of AVF maturation is urgently needed.

METHODS AND RESULTS

In this study, we downloaded the publicly available datasets (GSE119296 and GSE220796) from the Gene Expression Omnibus (GEO) and merged them for subsequent analysis. We screened 84 differentially expressed genes (DEGs) and performed the functional enrichment analysis. Next, we integrated the results obtained from the degree algorithm provided by the Cytohubba plug-in, Molecular complex detection (MCODE) plug-in, weighted gene correlation network analysis (WGCNA), and Least absolute shrinkage and selection operator (LASSO) logistic regression. This integration allowed us to identify CTSG as a hub gene associated with AVF maturation. Through the literature search and Pearson's correlation analysis, the genes matrix metalloproteinase 2 (MMP2) and MMP9 were identified as potential downstream effectors of CTSG. We then collected three immature clinical AVF vein samples and three mature samples and validated the expression of CTSG using immunohistochemistry (IHC) and double-immunofluorescence staining. The IHC results demonstrated a significant decrease in CTSG expression levels in the immature AVF vein samples compared to the mature samples. The results of double-immunofluorescence staining revealed that CTSG was expressed in both the intima and media of AVF veins. Moreover, the expression of CTSG in vascular smooth muscle cells (VSMCs) was significantly higher in the mature samples compared to the immature samples. The results of Masson's trichrome and collagen I IHC staining demonstrated a higher extent of collagen deposition in the media of immature AVF veins compared to the mature. By constructing an in vitro CTSG overexpression model in VSMCs, we found that CTSG upregulated the expression of MMP2 and MMP9 while downregulating the expression of collagen I and collagen III. Furthermore, CTSG was found to inhibit VSMC migration.

CONCLUSIONS

CTSG may promote AVF maturation by stimulating the secretion of MMP2 and MMP9 from VSMCs and reducing the extent of medial fibrosis in AVF veins by inhibiting the secretion of collagen I and collagen III.

The knowledge, attitudes, and practices of arteriovenous access assessment among hemodialysis nurses: A multicenter cross-sectional survey

INTRODUCTION

Hemodialysis nurses' cannulation technique, monitoring, and management methods can affect patients' vascular access longevity. An arteriovenous access assessment comprises a medical history and vascular assessment through physical examination and surveillance. However, further exploration is needed to fully understand hemodialysis nurses' knowledge, attitudes, and practices (KAP) in this area.

METHODS

Between June and July 2023, we recruited hemodialysis nurses from 21 cities in Guangdong Province using a convenience sampling method. Four questionnaires-the General Data Questionnaire, the KAP Scale of Arteriovenous Access Assessment among Hemodialysis Nurses, the Utrecht Work Engagement Scale, and the NASA Task Load Index-were utilized for data collection through the Questionnaire Star platform.

FINDINGS

Of the 530 hemodialysis nurses participating in the study, 458 (86.4%) had a valid response. The participants demonstrated moderate knowledge and practice levels regarding arteriovenous access assessment and exhibited positive attitudes. We identified several factors related to arteriovenous access assessment that predict KAP in hemodialysis nurses. These factors included years of experience as a hemodialysis nurse, whether a nurse's knowledge of physical examination was sufficient to meet clinical needs, whether a nurse had received training in performing physical examination, whether a nurse's department regularly checked the quality of physical examination, and nurses' levels of work engagement and mental workload. All factors explained 32.4% of the variance in participants' KAP regarding arteriovenous access assessment.

DISCUSSION

Improving hemodialysis nurses' assessment of arteriovenous access is crucial to ensure optimal patient care. Dialysis center managers and educators should prioritize understanding hemodialysis nurses' KAP of arteriovenous access assessment and any factors influencing these areas.

Application of a supporting catheter in surgery for forearm arteriovenous fistula construction

INTRODUCTION

This study explored the feasibility of a supporting catheter combined with modified end-to-side anastomosis in the operation of radio-cephalic arteriovenous fistula (RC-AVF) and evaluated the clinical application value of this technique.

METHODS

Sixty patients underwent RC-AVF operations in our hospital from January 2022 to June 2022. All the patients were treated with modified end-to-side AVF anastomosis and divided into the control group or the test group depending on whether a supporting catheter was applied. The clinical data of 60 cases were analysed retrospectively. Intraoperative related indices, the first time the fistula was used, the success rate of first puncture, the blood flow of first dialysis, the maturity condition of fistula, the size of anastomosis, the diameter of radial artery and drainage vein, the blood flow of brachial artery 8 weeks after operation and the incidence of complications within 6 months after operation were compared between the two groups.

RESULTS

Compared with that in the control group, the time spent on the vascular anastomosis in the test group was significantly shortened (p<0.05). The blood flow of the first dialysis, the size of the anastomosis, the diameter of the drainage vein, the blood flow of the brachial artery 8 weeks after the operation and the incidence of complications within 6 months after operation were significantly different between the two groups (p<0.05).

CONCLUSION

In the RC-AVF operation, using a supporting catheter can not only increase operation efficiency by reducing surgical injury and difficulty of vascular anastomosis, but also improve postoperative prognosis. RC-AVF is worth promoting in clinical practice.

Doppler ultrasound surveillance of recently formed haemodialysis arteriovenous fistula: the SONAR observational cohort study

Background

Arteriovenous fistulas are considered the best option for haemodialysis provision, but as many as 30% fail to mature or suffer early failure.

Objective

To assess the feasibility of performing a randomised controlled trial that examines whether, by informing early and effective salvage intervention of fistulas that would otherwise fail, Doppler ultrasound surveillance of developing arteriovenous fistulas improves longer-term arteriovenous fistula patency.

Design

A prospective multicentre observational cohort study (the 'SONAR' study).

Setting

Seventeen haemodialysis centres in the UK.

Participants

Consenting adults with end-stage renal disease who were scheduled to have an arteriovenous fistula created.

Intervention

Participants underwent Doppler ultrasound surveillance of their arteriovenous fistulas at 2, 4, 6 and 10 weeks after creation, with clinical teams blinded to the ultrasound surveillance findings.

Main outcome measures

Fistula maturation at week 10 defined according to ultrasound surveillance parameters of representative venous diameter and blood flow (wrist arteriovenous fistulas: ≥ 4 mm and > 400 ml/minute; elbow arteriovenous fistulas: ≥ 5 mm and > 500 ml/minute). Mixed multivariable logistic regression modelling of the early ultrasound scan data was used to predict arteriovenous fistula non-maturation by 10 weeks and fistula failure at 6 months.

Results

A total of 333 arteriovenous fistulas were created during the study window (47.7% wrist, 52.3% elbow). By 2 weeks, 37 (11.1%) arteriovenous fistulas had failed (thrombosed), but by 10 weeks, 219 of 333 (65.8%) of created arteriovenous fistulas had reached maturity (60.4% wrist, 67.2% elbow). Persistently lower flow rates and venous diameters were observed in those fistulas that did not mature. Models for arteriovenous fistulas' non-maturation could be optimally constructed using the week 4 scan data, with fistula venous diameter and flow rate the most significant variables in explaining wrist fistula maturity failure (positive predictive value 60.6%, 95% confidence interval 43.9% to 77.3%), whereas resistance index and flow rate were most significant for elbow arteriovenous fistulas (positive predictive value 66.7%, 95% confidence interval 48.9% to 84.4%). In contrast to non-maturation, both models predicted fistula maturation much more reliably [negative predictive values of 95.4% (95% confidence interval 91.0% to 99.8%) and 95.6% (95% confidence interval 91.8% to 99.4%) for wrist and elbow, respectively]. Additional follow-up and modelling on a subset (n = 192) of the original SONAR cohort (the SONAR-12M study) revealed the rates of primary, assisted primary and secondary patency arteriovenous fistulas at 6 months were 76.5, 80.7 and 83.3, respectively. Fistula vein size, flow rate and resistance index could identify primary patency failure at 6 months, with similar predictive power as for 10-week arteriovenous fistula maturity failure, but with wide confidence intervals for wrist (positive predictive value 72.7%, 95% confidence interval 46.4% to 99.0%) and elbow (positive predictive value 57.1%, 95% confidence interval 20.5% to 93.8%). These models, moreover, performed poorly at identifying assisted primary and secondary patency failure, likely because a subset of those arteriovenous fistulas identified on ultrasound surveillance as at risk underwent subsequent successful salvage intervention without recourse to early ultrasound data.

Conclusions

Although early ultrasound can predict fistula maturation and longer-term patency very effectively, it was only moderately good at identifying those fistulas likely to remain immature or to fail within 6 months. Allied to the better- than-expected fistula patency rates achieved (that are further improved by successful salvage), we estimate that a randomised controlled trial comparing early ultrasound-guided intervention against standard care would require at least 1300 fistulas and would achieve only minimal patient benefit.

Trial Registration

This trial is registered as ISRCTN36033877 and ISRCTN17399438.

Funding

This award was funded by the National Institute for Health and Care Research (NIHR) Health Technology Assessment programme (NIHR award ref: NIHR135572) and is published in full in Health Technology Assessment; Vol. 28, No. 24. See the NIHR Funding and Awards website for further award information.

Distal Forearm Arteriovenous Fistula Maturation in Diabetic Hemodialysis Patients

PURPOSE

Atherosclerotic disease of the forearm arteries can impede the maturation of distal fistulas in diabetic patients. The goal of this study was to look at the maturity of diabetic hemodialysis patients' distal forearm (radiocephalic snuffbox or distal forearm) arteriovenous fistulas.

MATERIALS AND METHODS

Patients with chronic renal failure who were candidates for distal forearm radiocephalic arteriovenous fistula implantation were evaluated in this cross-sectional study. Patients' demographic details, underlying disorders, laboratory measurements, vital signs, and information on their surgery were all noted. Patients were checked for fistula development 1 week, 1 month, 2 months, and then monthly until 6 months after surgery. Arteriovenous fistula maturation characterized by optimal blood flow, vessel dilation, and structural adaptations.

RESULTS

Among 343 patients (56% male, 44% female, mean age: 57.32 ± 12.48 years), hypertension prevailed (81.9%), followed by hyperlipidemia (42.3%) and coronary artery disease history (25.9%). AVFs achieved 58.3% maturation in 64.98 ± 11.05 days; higher BP during creation correlated with successful maturation (17.02 ± 1.46 mmHg vs 13.90 ± 1.93 mmHg, P < .05). No significant statistical difference found in distal forearm arteriovenous fistula maturation between males (57.8%) and females (58.9%) (P > .005). However, 41.7% of AVFs failed in 18.83 ± 17.89 days. Failed AVFs exhibited lower BP during operation and failure (11.75 ± 1.86 mmHg). Kaplan-Meier analysis depicted maturation probabilities over 90 days post-surgery.

CONCLUSION

Diabetes and patient sex did not affect the maturation time of distal forearm AVFs in hemodialysis patients. Increased blood pressure during and after surgery correlated with shorter maturation time.

Accuracy of physical examination versus Doppler ultrasonography for determining maturity in postoperative arteriovenous fistula formation

BACKGROUND

Differentiating between arteriovenous fistula (AVF) maturation and failure can help determine which AVF will undergo successful canulation and which ones will require immediate rescue.

METHODS

A prospective observational study was conducted at Vajira Hospital in Bangkok, Thailand, between October 2020-November 2022. A single vascular surgeon performed a physical examination on patients with chronic kidney disease undergoing AVF placement, and a radiologist conducted Doppler ultrasonography during the second and sixth postoperative weeks. Dialysis nurses determined AVF maturity by performing cannulation. The study compared the accuracy of physical examination and Doppler ultrasonography. A model was developed to predict the success of AVF use.

RESULTS

Out Of the 125 recruited patients, 81% demonstrate unassisted maturation of their AVF. The male sex and brachiocephalic type are associated with AVF maturation. The physical examination findings of palpable thrill and the absence of a strong pulse at the 6th week show an area under the receiver operating curve (AUC) value of 0.79. Similarly, arterial end-diastolic velocity on ultrasonography at the 6th week also demonstrates a comparable predictive value with an AUC of 0.82 (p = 0.697). Meanwhile, the model that combined end-diastolic velocity and venous volume flow yields the best results for predicting AVF maturation, with an AUC of 0.92. These models provide more accurate predictions compared to physical examination alone (AUC: 0.92 vs. 0.79; p < 0.01).

CONCLUSION

Although a prudent physician predicts AVF maturation through a thorough physical examination, Doppler ultrasonography is preferred in anticipating the success of postoperative AVF placement.

Computer-assisted image analysis of preexisting histological patterns of the cephalic vein to predict wrist arteriovenous fistula non-maturation

BACKGROUND

We used computer-assisted image analysis to determine whether preexisting histological features of the cephalic vein influence the risk of non-maturation of wrist fistulas.

METHODS

This study focused on patients aged 20-80 years who underwent their first wrist fistula creation. A total of 206 patients participated, and vein samples for Masson's trichrome staining were collected from 134 patients. From these, 94 patients provided a complete girth of the venous specimen for automatic image analysis. Maturation was assessed using ultrasound within 90 days after surgery.

RESULTS

The collagen to muscle ratio in the target vein, measured by computer-assisted imaging, was a strong predictor of non-maturation in wrist fistulas. Receiver operating characteristic analysis revealed an area under the curve of 0.864 (95% confidence interval of 0.782-0.946, p < 0.001). The optimal cut-off value for the ratio was 1.138, as determined by the Youden index maximum method, with a sensitivity of 89.0% and specificity of 71.4%. For easy application, we used a cutoff value of 1.0; the non-maturation rates for patients with ratios >1 and ≤ 1 were 51.7% (15 out of 29 patients) and 9.2% (6 out of 65 patients), respectively. Chi-square testing revealed significantly different non-maturation rates between the two groups (X2 (1, N = 94) = 20.9, p < 0.01).

CONCLUSION

Computer-assisted image interpretation can help to quantify the preexisting histological patterns of the cephalic vein, while the collagen-to-muscle ratio can predict non-maturation of wrist fistula development at an early stage.

Fully no-touch technique without inflating the cephalic vein increase the patency rate of arteriovenous fistulas

INTRODUCTION

One of the most important problems for patients undergoing hemodialysis due to chronic renal failure is the need for a long-lasting vascular access. The patency of vascular access is affected by many factors. Factors related to surgery are also among these factors. No-touch techniques theoretically and practically prevent endothelial damage due to minimal contact on vascular structures. It is a well-known fact that surgeries performed with these methods also increase long-term survival.

METHODS

Patients who underwent distal radiocephalic arteriovenous fistula (AVF) surgery for the first time between 2017 and 2021 were included in our study. The groups, whose cephalic veins were inflated conventionally and not inflated, were compared in a prospective randomized manner.

RESULTS

There was a significant difference between both groups in terms of failure and patency rates, which is one of the study endpoints (p = 0.012). The fact that the patency period is long, and the failure rate is low stands out as the superiority of the fully no-touch technique in AVF surgery. On the other hand, no significant difference was observed in terms of failure to maturation and fistula maturation time.

CONCLUSIONS

Fully no-touch technique in AVF surgery should be considered primarily in suitable patients due to its long patency time and low failure rate.

The rodent models of arteriovenous fistula

Arteriovenous fistulas (AVFs) have long been used as dialysis access in patients with end-stage renal disease; however, their maturation and long-term patency still fall short of clinical needs. Rodent models are irreplaceable to facilitate the study of mechanisms and provide reliable insights into clinical problems. The ideal rodent AVF model recapitulates the major features and pathology of human disease as closely as possible, and pre-induction of the uremic milieu is an important addition to AVF failure studies. Herein, we review different surgical methods used so far to create AVF in rodents, including surgical suturing, needle puncture, and the cuff technique. We also summarize commonly used evaluations after AVF placement. The aim was to provide recent advances and ideas for better selection and induction of rodent AVF models. At the same time, further improvements in the models and a deeper understanding of AVF failure mechanisms are expected.

Hemodialysis Access: US for Preprocedural Mapping and Evaluation of Maturity and Access Dysfunction

Patients with kidney failure require kidney replacement therapy. While renal transplantation remains the treatment of choice for kidney failure, renal replacement therapy with hemodialysis may be required owing to the limited availability and length of time patients may wait for allografts or for patients ineligible for transplant owing to advanced age or comorbidities. The ideal hemodialysis access should provide complication-free dialysis by creating a direct connection between an artery and vein with adequate blood flow that can be reliably and easily accessed percutaneously several times a week. Surgical arteriovenous fistulas and grafts are commonly created for hemodialysis access, with newer techniques that involve the use of minimally invasive endovascular approaches. The emphasis on proactive planning for the placement, protection, and preservation of the next vascular access before the current one fails has increased the use of US for preoperative mapping and monitoring of complications for potential interventions. Preoperative US of the extremity vasculature helps assess anatomic suitability before vascular access creation, increasing the rates of successful maturation. A US mapping protocol ensures reliable measurements and clear communication of anatomic variants that may alter surgical planning. Postoperative imaging helps assess fistula maturation before cannulation for dialysis and evaluates for early and late complications associated with arteriovenous access. Clinical and US findings can suggest developing stenosis that may progress to thrombosis and loss of access function, which can be treated with percutaneous vascular interventions to preserve access patency. Vascular access steal, aneurysms and pseudoaneurysms, and fluid collections are other complications amenable to US evaluation. ©RSNA, 2023 Supplemental material is available for this article. Test Your Knowledge questions for this article are available through the Online Learning Center.

Predicting recurrent interventions after radiocephalic arteriovenous fistula creation with machine learning and the PREDICT-AVF web app

OBJECTIVE

Kidney Disease Outcomes Quality Initiative (KDOQI) guidelines discourage ongoing access salvage attempts after two interventions prior to successful use or more than three interventions per year overall. The goal was to develop a tool for prediction of radiocephalic arteriovenous fistula (AVF) intervention requirements to help guide shared decision-making about access appropriateness.

METHODS

Prospective cohort study of 914 adult patients in the United States and Canada undergoing radiocephalic AVF creation at one of the 39 centers participating in the PATENCY-1 or -2 trials. Clinical data, including demographics, comorbidities, access history, anatomic features, and post-operative ultrasound measurements at 4-6 and 12 weeks were used to predict recurrent interventions required at 1 year postoperatively. Cox proportional hazards, random survival forest, pooled logistic, and elastic net recurrent event survival prediction models were built using a combination of baseline characteristics and post-operative ultrasound measurements. A web application was created, which generates patient-specific predictions contextualized with the KDOQI guidelines.

RESULTS

Patients underwent an estimated 1.04 (95% CI 0.94-1.13) interventions in the first year. Mean (SD) age was 57 (13) years; 22% were female. Radiocephalic AVFs were created at the snuffbox (2%), wrist (74%), or proximal forearm (24%). Using baseline characteristics, the random survival forest model performed best, with an area under the receiver operating characteristic curve (AUROC) of 0.75 (95% CI 0.67-0.82) at 1 year. The addition of ultrasound information to baseline characteristics did not substantially improve performance; however, Cox models using either 4-6- or 12-week post-operative ultrasound information alone had the best discrimination performance, with AUROCs of 0.77 (0.70-0.85) and 0.76 (0.70-0.83) at 1 year. The interactive web application is deployed at https://predict-avf.com.

CONCLUSIONS

The PREDICT-AVF web application can guide patient counseling and guideline-concordant shared decision-making as part of a patient-centered end-stage kidney disease life plan.

Arterial revascularization in patients with hand pain dialyzing with upper arm Arteriovenous (AV) fistulas: A single center experience

BACKGROUND

Distal hand ischemia syndrome (DHIS) is a well reported adverse outcome in patients with upper arm AV access. 25%-40% of these patients have been reported to be due to primary arterial disease complicated with significant arterial calcification. The effectiveness of revascularization of the distal arterial circulation on symptom resolution has not been reported yet.

METHODS

Retrospective single center analysis of patients evaluated for hand/forearm pain in patients with upper arm AV access who had arterial revascularization between 01/2016 and 12/2020 were included for the analysis. Fifty-one patients met inclusion criteria. Stenotic lesions greater than 70% in the subclavian, axillary, brachial, radial, or ulnar artery were treated with balloon angioplasty. Institutional approval was obtained to review charts.

OUTCOMES

Successful revascularization, improvement in pain in 48 h, 1 month, and 3 months.

RESULTS

Seventy six percent of patients had an upper arm Arteriovenous Fistula (AVF) and 24% patients had an upper arm Arteriovenous Graft (AVG). Mean access flow was 1210 (556) ml/min. 55% of patients had radial or ulnar arterial stenosis, 45% had brachial/axillary or subclavian artery stenosis. 45% patients had lesions in both radial and ulnar arteries, 88% of patients were successfully revascularized. 76% (18) of patients had improvement in symptoms within 48 h and 68% remained symptom free in 3 months. Mean DHIS stage was 3.1 before intervention and improved to 1.1 post intervention (p < 0.001). Patient satisfaction with their AV access improved from 34% to 72% (p < 0.01). Multiple regression analysis did not reveal statistically significant correlations between time on dialysis vintage and other chronic medical conditions on post procedure symptom improvement.

CONCLUSIONS

DHIS with occlusive arterial disease can be successfully revascularized to improve symptoms. Complete evaluation of the inflow arterial segment and optimal endovascular revascularization could decrease the need for access revision procedures or access abandonment.

Outcome after early thrombotic occlusion of arteriovenous fistulas

OBJECTIVE

Arteriovenous fistulas (AVFs) are considered the first choice for venous access in end-stage renal disease patients, however, they are also known to have a high primary failure rate (early thrombosis and maturation failure). Of these, the outcome of thrombosed immature AVFs is not well known. This study aimed to investigate the outcome of AVFs with early thrombosis.

METHODS

Patients who underwent AVF creation from January 2009 to December 2019 at Seoul National University Hospital or Seoul Metropolitan Government - Seoul National University Boramae Medical Center were retrospectively reviewed. Patients who received salvage operations due to early thrombosis within 30 days after access creation were analyzed.

RESULTS

During the study period, a total of 45 patients (radiocephalic 26; brachiocephalic 19) developed early thrombosis and underwent salvage operations. The median age of patients was 61.0 (54.5-69.5) years, and 51.1% were male. The first salvage operation was performed on the median 1.0 (0.0-4.5) day after AVF creation. The most common cause for early thrombosis was venous stenosis (64.4%) and followed by poor arterial inflow (28.9%), especially in radiocephalic AVFs. About 20 AVFs were salvaged to maturation (46.5%). Post-salvage primary patency and secondary patency at 1 year was 72.6% and 100%. In a multivariate logistic regression, significant risk factors for maturation failures were minimum venous outflow diameter ⩽2.5 mm (OR, 4.433; 95% CI, 1.039-18.921; p = 0.044) and lower in patients with hypertension (OR, 0.064; 95% CI, 0.006-0.637; p = 0.019).

CONCLUSIONS

Thrombosed immature AVFs are associated with a high failure rate after salvage operation. However, if the salvage operation is successfully performed, it is associated with an acceptable 1-year outcome.

Automated 3D ultrasound enables novice users to measure arteriovenous fistula maturation parameters with comparable accuracy to conventional duplex by trained sonographers: Results of a benchtop study

BACKGROUND

Arteriovenous fistulae (AVF) are considered the preferred hemodialysis access but up to 50% of all AVF created in the United States never mature. Doppler ultrasound (DUS) is useful for predicting fistula maturity and impending fistula failure. DUS is resource-intensive and is associated with poor compliance rates in dialysis patients, ranging from 12% to 33%.

METHODS

EchoSure is an FDA-cleared 3D Doppler ultrasound device that automatically delivers quantitative blood flow and anatomic vascular information. The technology can be used at the bedside by personnel without formal sonographic training, nullifying limitations of traditional Duplex ultrasound imaging. This study compared the EchoSure system in the hands of inexpert personnel to a traditional expert-operated DUS for rapid assessment of a benchtop model vascular system with flow, diameter, and depth expected in a human AVF.

RESULTS

Both Duplex and EchoSure performed within the expected tolerance of ultrasound readings (35%) for volume flow, with the average error (AE) between the observed measurement and the ground truth being 8% for Duplex and 8% for EchoSure. However, the average coefficient of variation (CV) for Duplex pooled over all flow rate measurements was 17% versus 4% for EchoSure. Regarding diameter, Duplex measurements had AE of 15% with an average CV of 6% across all measurements versus EchoSure AE of 4% and average CV of 2%. Duplex and EchoSure measurements over all depths had the same AE of 2%. The two modalities were not statistically different for depth measurement (p = 0.05) but EchoSure measured closer to the ground truth for flow rate and vessel diameter (flow: p = 0.028, ρ = -0.07; diameter: p < 0.001, ρ = 0.69). The inexpert personnel using EchoSure acquired data 62% faster than the expert sonographers using the Duplex ultrasound (141 min for Duplex vs 87 min for EchoSure).

CONCLUSIONS

EchoSure may offer an accurate and convenient alternative for imaging fistulas in the clinic.

The outcomes of a novel two-stage proximal brachial artery to proximal basilic/brachial vein arteriovenous graft extension for dialysis access

BACKGROUND

We describe a technique to mature a basilic/brachial vein in the mid-arm in preparation for a second stage loop proximal brachial artery to basilic/brachial vein arteriovenous graft (BBAVG). This can occur after a failed basilic/brachial vein transposition or a lack of adequate veins in the distal arm. This allows a mature vein to be used in an end-to-end configuration as an outflow to a BBAVG while preserving proximal vessels for the future.

METHODS

This single-center retrospective study was performed from 2015 to 2021, including 104 AVG patients divided into three groups: (1) Patients who failed a basilic vein transposition and had an enlarged vein suitable for an AVG outflow; (2) Patients who had a small caliber basilic/brachial vein after the transposition, requiring a mid-arm brachial artery to brachial/basilic arteriovenous fistula (AVF) creation with a subsequent AVG extension; (3) and lastly, patients who had no distal arm veins available and required a primary brachial artery to basilic/brachial AVF with AVG extension. A survival analysis was performed looking at time to loss of primary and secondary patency, calculated with Kaplan-Meier estimates and Cox regression models adjusted for covariates.

RESULTS

The median follow-up time was 11 months (IQ = 11-30 months). The survival analysis showed 28% lost primary patency at a median time of 9 months, and 14% lost secondary patency at a median time of 61 months. Overall secondary patency of the vascular access measured at 12 months was 85.6%. Loss of primary (p = 0.008) and secondary patency (p = 0.017), as well as patency during the first 12 months (p = 0.036), were all significantly associated with increased age when adjusting for covariates.

CONCLUSIONS

Our results suggest that the graft extension technique using a mature vein from a previous fistula can result in reliable and durable access. This is important for patients with limited access for hemodialysis, as the axillary vein is preserved for future use if needed.

Guidelines on vascular access for hemodialysis from the Brazilian Society of Angiology and Vascular Surgery

Chronic kidney disease is a worldwide public health problem, and end-stage renal disease requires dialysis. Most patients requiring renal replacement therapy have to undergo hemodialysis. Therefore, vascular access is extremely important for the dialysis population, directly affecting the quality of life and the morbidity and mortality of this patient population. Since making, managing and salvaging of vascular accesses falls within the purview of the vascular surgeon, developing guideline to help specialists better manage vascular accesses for hemodialysis if of great importance. Thus, the objective of this guideline is to present a set of recommendations to guide decisions involved in the referral, evaluation, choice, surveillance and management of complications of vascular accesses for hemodialysis.

Predialysis Vascular Access Placement and Catheter Use at Hemodialysis Initiation

BACKGROUND

Current guidelines encourage placement of an arteriovenous (AV) fistula in patients with advanced CKD to avoid initiation of hemodialysis with a central venous catheter. However, the relative merits of predialysis placement of an AV fistula or graft have been poorly studied.

METHODS

This study included 380 patients (mean age 59±14 years, 73% Black patients, 51% male) from a large academic medical center who underwent predialysis placement of an AV fistula (286) or AV graft (94). The study quantified three end points: time from access placement to initiation of dialysis, likelihood of starting hemodialysis without a catheter, and number of vascular access procedures before dialysis initiation.

RESULTS

The eGFR at access surgery was <10, 10-14, and ≥15 ml/min per 1.73 m 2 in 87 (23%), 179 (47%), and 114 (30%) patients, respectively. The median time from access surgery to hemodialysis initiation was 69, 156, and 429 days in patients with an eGFR of <10, 10-14, and ≥15 ml/min per 1.73 m 2 , respectively ( P < 0.001). Hemodialysis was initiated within 2 years of access surgery in 298 (78%) of the patients. Catheter-free hemodialysis initiation was higher in patients with an AV graft versus an AV fistula when the eGFR was <10 ml/min per 1.73 m 2 (88% versus 43%; odds ratio [OR], 9.10 [95% confidence interval, 2.74 to 26.4]) and when the eGFR was 10-14 ml/min per 1.73 m 2 (88% versus 54%; OR, 6.05 [2.35 to 15.0]) but similar when the eGFR was ≥15 ml/min per 1.73 m 2 (90% versus 75%; OR, 3.00 [0.48 to 34.9]). Patients undergoing an AV fistula were more likely to undergo an angioplasty (11% versus 0%, P < 0.001), surgical access revision (26% versus 8%, P < 0.001), a second access placement (16% versus 6%, P = 0.02), and a catheter insertion (32% versus 11%, P < 0.001).

CONCLUSIONS

Among patients with CKD undergoing vascular access surgery when their eGFR was <15 ml/min per 1.73 m 2 , catheter use at dialysis initiation was much less likely when an AV graft, rather than an AV fistula, was placed.

Effects of a More Selective Arteriovenous Fistula Strategy on Vascular Access Outcomes

SIGNIFICANCE STATEMENT

The optimal choice of vascular access for patients undergoing hemodialysis-arteriovenous fistula (AVF) or arteriovenous graft (AVG)-remains controversial. In a pragmatic observational study of 692 patients, the authors found that among patients who initiated hemodialysis with a central vein catheter (CVC), a strategy that maximized AVF placement resulted in a higher frequency of access procedures and greater access management costs for patients who initially received an AVF than an AVG. A more selective policy that avoided AVF placement if an AVF was predicted to be at high risk of failure resulted in a lower frequency of access procedures and access costs in patients receiving an AVF versus an AVG. These findings suggest that clinicians should be more selective in placing AVFs because this approach improves vascular access outcomes.

BACKGROUND

The optimal choice of initial vascular access-arteriovenous fistula (AVF) or graft (AVG)-remains controversial, particularly in patients initiating hemodialysis with a central venous catheter (CVC).

METHODS

In a pragmatic observational study of patients who initiated hemodialysis with a CVC and subsequently received an AVF or AVG, we compared a less selective vascular access strategy of maximizing AVF creation (period 1; 408 patients in 2004 through 2012) with a more selective policy of avoiding AVF creation if failure was likely (period 2; 284 patients in 2013 through 2019). Prespecified end points included frequency of vascular access procedures, access management costs, and duration of catheter dependence. We also compared access outcomes in all patients with an initial AVF or AVG in the two periods.

RESULTS

An initial AVG placement was significantly more common in period 2 (41%) versus period 1 (28%). Frequency of all access procedures per 100 patient-years was significantly higher in patients with an initial AVF than an AVG in period 1 and lower in period 2. Median annual access management costs were significantly higher among patients with AVF ($10,642) versus patients with AVG ($6810) in period 1 but significantly lower in period 2 ($5481 versus $8253, respectively). Years of catheter dependence per 100 patient-years was three-fold higher in patients with AVF versus patients with AVG in period 1 (23.3 versus 8.1, respectively), but only 30% higher in period 2 (20.8 versus 16.0, respectively). When all patients were aggregated, the median annual access management cost was significantly lower in period 2 ($6757) than in period 1 ($9781).

CONCLUSIONS

A more selective approach to AVF placement reduces frequency of vascular access procedures and cost of access management.

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.

Imaging Patients with Kidney Failure

The approach to imaging a patient with kidney failure continues to evolve. Overstatement of the risk of iodinated contrast material-induced (ie, contrast-induced) acute kidney injury and new guidelines for administration of gadolinium-based contrast media affect screening and the choice of contrast material. Treatment of kidney failure requires dialysis or a kidney transplant. Pretransplant imaging includes assessment for the feasibility of performing a transplant and evaluation for underlying malignancy and peripheral vascular disease. Patients with kidney failure are at high risk for renal cell carcinoma. Subtypes that occur exclusively or more commonly in patients with kidney failure, such as acquired cystic kidney disease, renal cell carcinoma, and clear cell papillary renal cell carcinoma, have specific clinical-pathologic characteristics, with indolent behavior. Performing US for dialysis planning increases the success of placement of an arteriovenous fistula, while postoperative US evaluation is essential in assessment of access dysfunction. Systemic manifestations in patients with kidney failure are multifactorial and may relate to the underlying cause of renal failure or may be secondary to treatment effects. Disturbances in mineral and bone metabolism and soft-tissue and vascular calcifications are seen in patients with chronic kidney disease and mineral bone disorder. Neurologic and cardiothoracic complications are also common. The authors provide a comprehensive overview of imaging considerations for patients with kidney failure, including the appropriate use of CT, MRI, and US with their respective contrast agents; the use of imaging in transplant workup and dialysis assessment; and the common renal and extrarenal manifestations of kidney failure. ©RSNA, 2023 Quiz questions for this article are available in the supplemental material.

Arteriovenous fistula creation by nephrologist and its outcomes: a prospective cohort study from Vietnam

BACKGROUND

Arteriovenous fistula (AVF) is the gold standard vascular access for effective hemodialysis. There is a growing interest in AVF creations performed by nephrologists to help reduce vascular surgeons' workload and enhance the timely treatment of patients with end-stage renal disease (ESRD). However, little is known about the feasibility and effectiveness of this approach in the low-resource settings. We examined the AVF surgical success and failure rates and associated predictors as well as early complications of AVF creations by a trained nephrologist with supports from vascular surgeons in Vietnam.

METHODS

A prospective cohort study was conducted on all adult ESRD patients at the Hemodialysis Department of Thong Nhat Hospital between April 2018 and October 2020. Information on demographic characteristics, comorbidities, and AVF creations was collected using a standardized questionnaire. All patients were followed up until 18 weeks post-surgery.

RESULTS

Among 100 patients with a mean age of 61.22 ± 17.11 years old, male accounted for 54%. Common causes of ESRD included hypertension (57%) and diabetes (32%). Just more than half (52%) of them reported having an AVF creation prior to ESRD. The successful first-time AVF creation rate was 98% (13/99, 95%CI: 8.74-21.18%). The primary and secondary AVF failure rates were 13.13% (13/99, 95%CI: 8.74-21.18%) and 16.87% (14/83, 95%CI: 10.32-26.25%), respectively. Early complications included bleeding (1%) and early thrombosis of the anastomosis (2%). There was a statistically significant association between age and primary AVF failure (P = 0.005) and between operation time and secondary AVF failure (P = 0.038).

CONCLUSIONS

AVF creations performed by well-trained and skilled interventional nephrologists with supports from vascular surgeons can result in favorable short- and long-term outcomes. It is important to follow up older patients and those with a long operation time to detect AVF failures. A standardized AVF creation training program and practice for nephrologists is needed to increase successful rates.

Editor's Choice - Interventions to Achieve Functionality in Newly Created Arteriovenous Fistulas in the Shunt Simulation Study Cohort

OBJECTIVE

Although observational cohort studies report that interventions to achieve functionality are clinically successful in 85% of patients, the proportion of newly created autologous arteriovenous fistulas that result in functional vascular access typically is only 70 - 80%. To address this discrepancy, the selection and outcomes of interventions to achieve functionality in a multicentre prospective cohort study were analysed.

METHODS

The Shunt Simulation Study enrolled 222 patients who needed a first arteriovenous fistula in nine dialysis units in The Netherlands from 2015 to 2018 and followed these patients until one year after access creation. In this observational study, the technical and clinical success rates of interventions to achieve functionality based on lesion and intervention characteristics were analysed and the clinical outcomes of arteriovenous fistulas with assisted and unassisted functionality were compared.

RESULTS

For patients who were on dialysis treatment at the end of the study, unassisted fistula functionality was 54% and overall fistula functionality was 78%. Thirty-four per cent of arteriovenous fistulas required an intervention to achieve functionality, 68% of which eventually became functional. Seventy-five per cent of these interventions were percutaneous balloon angioplasties of vascular access stenoses. Patients with clinically successful interventions to achieve functionality had larger pre-operative vein diameters (2.8 ± 1.0 mm vs. 2.3 ± 0.6 mm, p = .036) and less often presented with thrombosed fistulas than patients with unsuccessful interventions (7% vs. 43%, p = .006). Arteriovenous fistulas with assisted functionality had similar secondary patency as fistulas with unassisted functionality (100% and 98% at six months, p = .44), although they required more interventions to maintain function (2.6 vs. 1.7 per year; rate ratio 1.52, 95% CI 1.04 - 2.18, p = .032).

CONCLUSION

Interventions to achieve functionality were needed in about a third of newly created arteriovenous fistulas. Most thrombosed fistulas were abandoned, and when selected for thrombectomy rarely reached clinical success. On the other hand, interventions to achieve functionality of patent fistulas had high clinical success rates and therefore can be done repeatedly until the fistula has become functional.

A systematic review aggregated data and individual participant data meta-analysis of percutaneous endovascular arteriovenous fistula

OBJECTIVE

To assess the short-term and mid-term safety and efficacy of percutaneous endovascular arteriovenous fistula (pAVF) creation.

METHODS

A systematic search was implemented corresponding to the PRISMA 2020 and the PRISMA for individual participant data (IPD) systematic reviews 2015. Aggregated data from the included studies were obtained and meta-analyzed regarding both the overall pAVF efficacy and the comparison of pAVF with surgical AVF (sAVF). We performed a two-stage IPD meta-analysis for studies comparing pAVF and sAVF regarding primary and secondary patency. Primary end points included primary patency, secondary patency, and functional cannulation.

RESULTS

Eighteen studies with 1863 patients were included. The overall pAVF, primary patency, secondary patency, functional cannulation and abandonment rates were 54.01% (95% confidence interval [CI], 40.69-66.79), 87.27% (95% CI, 81.53-91.42), 79.94% (95% CI, 65.94-89.13), and 15.58% (95% CI, 7.77-28.79), respectively. The overall pAVF, technical success, maturation, reintervention per person-years and mean time to maturation rates were 97.08% (95% CI, 95.66-98.04), 82.13% (95% CI, 71.64-89.32), 0.80 (95% CI, 0.34-1.47), and 58 days (95% CI, 36.64-92.82), respectively. Secondary patency and pAVF abandonment rates where the only end points were WavelinQ and Ellipsys displayed statistically significant differences of 81.36% (95% CI, 76.15-85.65) versus 92.12% (95% CI, 87.94-94.93) and 32.54% (95% CI, 22.23-44.87) versus 11.13% (95% CI, 4.82-23.65). An IPD meta-analysis of hazard ratios for primary and secondary patency between pAVF and sAVF were 1.27 (95% CI, 0.61-2.67) and 1.25 (95% CI, 0.87-1.80), favoring sAVF. Statistically significant difference between pAVF and sAVF were solely depicted for steal syndrome relative risk of 5.91 (95% CI, 1.12-31.12) and wound infections relative risk of 4.19 (95% CI, 1.04-16.88). Plotting of pAVF smoothed hazard estimate displayed an upsurge in the probability of primary patency failure at 1 month after the intervention.

CONCLUSIONS

Although we failed to identify statistically significant differences between pAVF and sAVF regarding any of the primary end points, pAVF displayed a decreased risk for steal syndrome and wound infection. Although both the Ellipsys and WavelinQ devices displayed satisfactory secondary patency rates, Ellipsys demonstrated a statistically significant improved rate compared with WavelinQ. Additionally, and despite the borderline statistically insignificant inferior reintervention rate displayed by WavelinQ, one in three WavelinQ pAVFs resulted in abandonment. The introduction of pAVF as a treatment modality calls for standardized definition adjustment and improvement.

Effectiveness of ultrasound-guided cannulation of AVF on infiltration rates: A single center quality improvement study

Though ultrasonography is increasingly used throughout the spectrum of hemodialysis access, its role in outpatient dialysis units in the United States has been limited so far. This may, in part, be due to limited ultrasound exposure, knowledge and training of dialysis staff. We implemented a quality improvement initiative in our dialysis units to expand the use of ultrasound by our frontline dialysis staff to prospectively evaluate newly placed AVF and guide cannulation. This manuscript describes our experience and the impact of our protocol on infiltration rates in our outpatient HD units.

A Randomized Trial of Postoperative Handgrip Exercises for Fistula Maturation in Patients With Newly Created Wrist Radiocephalic Arteriovenous Fistulas

Introduction

We aimed to substantiate the benefit of postoperative handgrip exercises (HGEs) in enhancing the maturation of an arteriovenous wrist fistula.

Methods

We randomly assigned 119 patients aged 20 to 80 years who had wrist arteriovenous fistulas (AVFs) to undergo either a basic HGE program (group A), an advanced program (group B), or an advanced-plus upper arm banding program (group C). Outcomes were assessed by ultrasonographic evaluation of the diameter and flow at each follow-up. The attending nephrologist decided the clinical use of the fistula.

Results

We identified no significant differences among the HGE groups in the mean diameter and blood flow 14, 30, 60, and 90 days after the creation of the wrist AVF (P = 0.55, 0.88, 0.21, and 0.19 for the diameter; 0.94, 0.81, 0.49, and 0.56 for the flow, respectively). The intent-to-treat analysis also found no difference in the clinical use of fistulas for hemodialysis (HD) (P = 0.997).

Conclusion

In patients with a newly created wrist AVF, advancing frequency, with or without adding intensity using an upper arm tourniquet, of postoperative HGEs did not enhance the growth of the fistula or increase the rate of clinical use over 3 months. (ClinicalTrials.gov ID: NCT03077815).

Bundle of Care Promotes Arteriovenous Fistula Maturity in Patients with End-Stage Kidney Disease

BACKGROUND

Arteriovenous fistula (AVF), as the hemodialysis access, has the advantages of safety, sufficient blood flow, and long use time. To establish an ideal AVF, patients require good vascular condition. However, many teams often neglect preoperative preparation and exercises and have no concept of specialized nursing or bundle of care, directly leading to stenosis of the outflow tract and seriously affected surgical efficacy. This study aimed to evaluate the influence of bundle of care on AVF.

METHODS

A total of 260 patients with end-stage kidney disease were included from January 2019 to December 2020 at Qilu Hospital, Shandong University. Patients were divided into 2 groups, and were treated with ordinary nursing care (the control group) or bundle of care (the observation group). Maturity of AVF fistula and postoperative complications were compared between 2 groups.

RESULTS

The observation group was associated with larger internal diameter of the cephalic vein (6.524 ± 0.347 vs. 6.346 ± 0.32 4 mm) and faster blood flow at the anastomosis of AVF (568.2 ± 26.8 vs. 565.7 ± 27.5 mL/min) than the control group at 2 weeks after surgery (both P < 0.05). The observation group had a higher maturity rate than the control group (93.1% vs. 81.5%, P < 0.05) at 8 weeks after surgery. There were lower incidences of fistula stenosis (4.6% vs. 10.8%) and fistula thrombosis (2.3% vs. 7.7%) in the observation group than in the control group (both P < 0.05). The secondary patency was higher in the observation group than in the control group (97.7% vs. 92.3%, P < 0.05).

CONCLUSIONS

The use of bundle of care promotes AVF maturity and reduces postoperative complications in patients with end-stage kidney disease.

How to choose the appropriate cannulation technique for vascular access in hemodialysis patients

The cannulation technique is important for the survival of the arteriovenous access. Choosing the appropriate technique is a complex decision. Such choice must be customized to patients, considering their characteristics, the type of arteriovenous access and the experience of the hemodialysis team. We describe seven items that can help nurses to identify the appropriate cannulation technique: type of arteriovenous access; drainage vein; hygienic self-care profile; experience of the nursing staff in the cannulation technique and nurse-to-patient ratio; hemodialysis treatment method; patient's condition; and patient's decision. Such items can help nurses in decision-making on the "ideal" cannulation technique for each patient.

An eighth note

Venous stenosis is the most common cause of arteriovenous fistula (AVF) failure in hemodialysis patients. For patients with AVF stenosis, the pressure over the antecedent part of the AVF stenotic lesion will increase if arterial inflow is sufficient. We report a chronic hemodialysis patient who received an angiographic examination for the juxta-anastomosis stenosis of his AVF. A unique feature of a collateral venous branch antecedent to the stenotic lesion was noted, resembling a musical sign as the "eighth note." After percutaneous transluminal angioplasty, the eighth note attenuated markedly at once. Of note, the eighth note sign is not seen frequently, and thus we postulate that the formation of an eighth note sign on the radiocephalic fistula should fulfill the following requirements, including a sufficient arterial inflow, an adjacent collateral branch close enough to the arteriovenous anastomosis, a severe juxta-anastomotic stenotic lesion, and an intact ulnar venous drainage system.

Lumen diameter is associated with the patency after percutaneous angioplasty of arteriovenous fistulas

AIM

To assess the value of lumen diameter after percutaneous angioplasty (PTA) to predict functional dialysis use (FDU) of arteriovenous fistulas (AVF).

METHODS

We performed a retrospective study of all patients who underwent first PTA because of AVF stenosis between March 2019 and March 2021. The outcome was FDU of AVF at 6 months follow up. Independent factors of FDU were identified using multivariate regression analyses. Receiver operating characteristic (ROC) curve was performed to investigate the predictive ability of lumen diameter for FDU.

RESULTS

A total 68 patients were included into this study and the AVF of 53 cases (77.9%) were good for FDU after 6 months. The AVF age was younger in failure group than that in success group (16.1 ± 9.1 months vs 28.3 ± 20.0 months, p = 0.026). Compared with failure group, the post-PTA minimum luminal diameter (MLD) was bigger in success group (4.5 [4.0-4.5 mm] vs 5.5 mm [4.5-5.5 mm], p < 0.001). Meanwhile, the gain of lumen diameter in success group was also bigger than that in failure group (2.5 mm [2.0-3.0 mm] in failure group vs 3.0 mm [2.75-3.5 mm] in success group, p = 0.012). The residual stenosis was higher in failure group than that in success group (30% [10%-40%] vs 10% [0%-20%], p = 0.003). Logistic regression showed that AVF age and post-PTA MLD were independent predictors of FDU. ROC analysis showed that the gain of lumen diameter, post-PTA MLD and improvement of stenosis were comparable to predict FDU. For post-PTA MLD, the area under ROC curve was 0.804 (95% CI, 0.681-0.927, p < 0.001). The best cutoff is 4.75 mm, with the sensitivity and specificity was 71.7% and 80.0%, respectively.

CONCLUSIONS

AVF age and post-PTA MLD were independently predictors for FDU of AVF after PTA. To get the best performance, a minimum vein diameter of 4.75 mm should be obtained after angioplasty.

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.

Nurses' Use of Ultrasound Location for Puncturing Arteriovenous Fistulas in Hemodialysis

Puncturing an arteriovenous fistula (AVF) in chronic hemodialysis (HD) patients is a source of difficulty even for experienced dialysis nurses. The objective of this study was to compare the failure rate of AVF puncture by the usual technique (visual or by palpation) and after ultrasound location. This nonrandomized prospective single-center study was carried out at the Safi HD Hospital Center for 16 weeks in two successive phases, with the time between each phase dedicated to training nurses in locating punctures by ultrasound. We first evaluated 30 HD patients (300 HD sessions, i.e., 600 punctures) without ultrasound location, then the same patients (300 sessions, i.e., 600 punctures) using ultrasound location for all punctures. Ultrasound location carried out by a single nurse did not show a significant reduction in the rate of failure to puncture the AVF compared with the standard method (2.6% vs. 4%, P = 0.07). However, the rate of complications at the puncture site, recourse to medical advice, or mobilization of a second nurse were significantly reduced (P < 0.05). This single-center study showed no advantage of this approach for the effective cannulation of AVF in HD patients known to be not difficult to cannulate.

Predicting radiocephalic arteriovenous fistula success with machine learning

After creation of a new arteriovenous fistula (AVF), assessment of readiness for use is an important clinical task. Accurate prediction of successful use is challenging, and augmentation of the physical exam with ultrasound has become routine. Herein, we propose a point-of-care tool based on machine learning to enhance prediction of successful unassisted radiocephalic arteriovenous fistula (AVF) use. Our analysis includes pooled patient-level data from 704 patients undergoing new radiocephalic AVF creation, eligible for hemodialysis, and enrolled in the 2014-2019 international multicenter PATENCY-1 or PATENCY-2 randomized controlled trials. The primary outcome being predicted is successful unassisted AVF use within 1-year, defined as 2-needle cannulation for hemodialysis for ≥90 days without preceding intervention. Logistic, penalized logistic (lasso and elastic net), decision tree, random forest, and boosted tree classification models were built with a training, tuning, and testing paradigm using a combination of baseline clinical characteristics and 4-6 week ultrasound parameters. Performance assessment includes receiver operating characteristic curves, precision-recall curves, calibration plots, and decision curves. All modeling approaches except the decision tree have similar discrimination performance and comparable net-benefit (area under the ROC curve 0.78-0.81, accuracy 69.1-73.6%). Model performance is superior to Kidney Disease Outcome Quality Initiative and University of Alabama at Birmingham ultrasound threshold criteria. The lasso model is presented as the final model due to its parsimony, retaining only 3 covariates: larger outflow vein diameter, higher flow volume, and absence of >50% luminal stenosis. A point-of-care online calculator is deployed to facilitate AVF assessment in the clinic.

Adapting a Dialysis Service for Delivery of Percutaneous Arteriovenous Fistulas

The percutaneous arteriovenous fistula (pAVF) is an exciting and novel addition to the vascular access options available to patients with end-stage kidney disease who require dialysis. Early clinical results have been promising, with high rates of maturation and low rates of reintervention. To successfully adapt an existing hemodialysis service to include the provision of pAVF formation, it is essential to identify and align the interests of key clinical and nonclinical stakeholders. Only through strong collaboration can the service be supported. The authors provide a comprehensive overview of the planning fundamentals required, including the referral pathway, screening and clinical assessment, and practical procedural elements and considerations, as well as follow-up requirements such as cannulation, fistula surveillance, and maintenance. Key staffing requirements are highlighted, including those pertaining to vascular US screening and dialysis nurse training. A broad and structured planning approach ensures that the entire network of key stakeholder interests is included and provides a strong foundation for a compelling business plan to attract the necessary funding and managerial support for the service. The authors present a systematic framework of the essential considerations necessary to facilitate the planning, funding, and ultimately delivery of a successful pAVF service. Online supplemental material is available for this article. ^©RSNA, 2022.

Oxidative stress: An essential factor in the process of arteriovenous fistula failure

For more than half a century, arteriovenous fistula (AVFs) has been recognized as a lifeline for patients requiring hemodialysis (HD). With its higher long-term patency rate and lower probability of complications, AVF is strongly recommended by guidelines in different areas as the first choice for vascular access for HD patients, and its proportion of application is gradually increasing. Despite technological improvements and advances in the standards of postoperative care, many deficiencies are still encountered in the use of AVF related to its high incidence of failure due to unsuccessful maturation to adequately support HD and the development of neointimal hyperplasia (NIH), which narrows the AVF lumen. AVF failure is linked to the activation and migration of vascular cells and the remodeling of the extracellular matrix, where complex interactions between cytokines, adhesion molecules, and inflammatory mediators lead to poor adaptive remodeling. Oxidative stress also plays a vital role in AVF failure, and a growing amount of data suggest a link between AVF failure and oxidative stress. In this review, we summarize the present understanding of the pathophysiology of AVF failure. Furthermore, we focus on the relation between oxidative stress and AVF dysfunction. Finally, we discuss potential therapies for addressing AVF failure based on targeting oxidative stress.

Percutaneous Hemodialysis Fistula Creation

Two devices have been recently introduced to European Union and North American clinical practice that allow for percutaneous creation of autogenous hemodialysis fistulas (pAVF). Although there are similarities between the devices, there are many differences. Adoption of either or both technologies by an interventionalist may be determined by the individual's comfort with the device. Importantly, current and future outcomes will shape acceptance and use of these devices. This review focuses on the similarities and differences of each device, the procedures, published outcomes to date and their interpretation and other clinical considerations towards initiation of a successful pAVF program.

Real-Time Internet of Medical Things System for Detecting Blood Leakage during Hemodialysis Using a Novel Multiple Concentric Ring Sensor

Venous needle dislodgement (VND) is a major healthcare safety concern in patients undergoing hemodialysis. Although VND is uncommon, it can be life-threatening. The main objective of this study was to implement a real-time multi-bed monitoring system for VND by combining a novel leakage-detection device and IoMT (Internet of Medical Things) technology. The core of the system, the Acusense IoMT platform, consisted of a novel leakage-detection patch comprised of multiple concentric rings to detect blood leakage and quantify the leaked volume. The performance of the leakage-detection system was evaluated on a prosthetic arm and clinical study. Patients with a high risk of blood leakage were recruited as candidates. The system was set up in a hospital, and the subjects were monitored for 2 months. During the pre-clinical simulation experiment, the system could detect blood leakage volumes from 0.3 to 0.9 mL. During the test of the IoMT system, the overall success rate of tests was 100%, with no lost data packets. A total of 701 dialysis sessions were analyzed, and the accuracy and sensitivity were 99.7% and 90.9%, respectively. Evaluation questionnaires showed that the use of the system after training changed attitudes and reduced worry of the nursing staff. Our results show the feasibility of using a novel detector combined with an IoMT system to automatically monitor multi-bed blood leakage. The innovative concentric-circle design could more precisely control the warning blood-leakage threshold in any direction to achieve clinical cost-effectiveness. The system reduced the load on medical staff and improved patient safety. In the future, it could also be applied to home hemodialysis for telemedicine during the era of COVID-19.

New hemodynamic variables as predictors of arteriovenous fistula maturation

INTRODUCTION

Failure to mature of native arteriovenous fistula (AVF) assessed by image is not well documented.

METHODS

The aim of this study is to evaluate AVF maturation by Doppler ultrasound within 6 weeks after surgery and check for new hemodynamic variables as prognostic factors.

RESULTS

A total of 155 native AVFs were created in 3 years. Median age of patients was 71 years (60;79), with male gender predominance of 59.4% (n = 92). Diabetes was present in 60.6% (n = 94). AVF was created in distal forearm in 49.7% (n = 77). Un-assisted and overall maturation was of 67.1% (n = 104) and 83.9% (n = 130), respectively. Failure to mature occurred in 21.3% (n = 33) and primary failure in 9.7% (n = 15). In univariate analysis, preoperative variables such as diameter of artery (3.5 vs. 2.2 mm; p < 0.001) and pulsatility index (7.9 vs. 6.6; p = 0.055) were associated with failure to mature of AVF. Postoperative variables as Qa (994 vs. 401 mL/min; p < 0.001), resistance index (0.52 vs. 0.63; p < 0.001), pulsatility index (0.74 vs. 1.21; p < 0.001), and acceleration time (0.17 vs. 0.12; p < 0.001) also predicted an unfunctional AVF. Spearman correlation coefficient (r) was good for resistance index (-0.628) and pulsatility index (-0.707) in comparison with blood flow (Qa). In multivariate analysis, postoperative pulsatility index was an independent predictor of AVF dysfunction (OR: 16.5; p < 0.001).

CONCLUSIONS

Failure to mature was of 21.3%. Pulsatility index could be an important tool as new hemodynamic variable to predict failure to mature of native AVF.

Clinical Aspects of Dialysis Interventions: Physical and Sonographic Findings

Physical examination (PE) of arteriovenous access remains of high clinical value and continues to be recommended by leading societies and guidelines. PE is easy to learn and perform. Once learned, examiners can provide a comprehensive arteriovenous (AV) access examination in 20 to 30 seconds. Therefore, we continue to advocate that AV access PE should be part of the training for all dialysis care providers. Similarly, ultrasound can provide important AV access evaluation and provide key information. It is relatively cheap and can be readily available at the bed side. Additionally, it is well accepted by patients, as it is not expected to be associated with pain or discomfort during the examination. We present in this review the key components of PE, signs and symptoms of AV access dysfunction, and the role of ultrasound in AV access evaluation as a complementary tool to PE.

Ultrasound Measurement of Vascular Distensibility Based on Edge Detection and Speckle Tracking Using Ultrasound DICOM Data

This study presents an edge detection and speckle tracking (EDST) based algorithm to calculate distensibility as percentage of change of vessel diameter during cardiac cycles. Canny edge detector, Vandermonde matrix representation, Kanade Lucas Tomasi algorithm with pyramidal segmentation, and penalized least squares technique identifies the vessel lumen edge, track the vessel diameter, detrend the signal and find peaks and valleys when the vessel is fully distended or contracted. An upper extremity artery from 10 patients underwent an ultrasound examination as part of preoperative evaluation before arteriovenous fistula surgery. Three studies were performed to evaluate EDST with automatic peak and valley selection versus manual speckle selection of expert users using manual peak and valley selection. Results demonstrate the effectiveness of the proposed methodology, to obtain comparable results as those obtained by expert-users, and considerably reducing the variability associated with external factors such as excessive motion, fluctuations in stroke volume, beat-to-beat blood pressure changes, breathing cycles, and arm-transducer pressure.

Nitric oxide releasing nanomatrix gel treatment inhibits venous intimal hyperplasia and improves vascular remodeling in a rodent arteriovenous fistula

Vascular access is the lifeline for hemodialysis patients and the single most important component of the hemodialysis procedure. Arteriovenous fistula (AVF) is the preferred vascular access for hemodialysis patients, but nearly 60% of AVFs created fail to successfully mature due to early intimal hyperplasia development and poor outward remodeling. There are currently no therapies available to prevent AVF maturation failure. First, we showed the important regulatory role of nitric oxide (NO) on AVF development by demonstrating that intimal hyperplasia development was reduced in an overexpressed endothelial nitric oxide synthase (NOS3) mouse AVF model. This supported the rationale for the potential application of NO to the AVF. Thus, we developed a self-assembled NO releasing nanomatrix gel and applied it perivascularly at the arteriovenous anastomosis immediately following rat AVF creation to investigate its therapeutic effect on AVF development. We demonstrated that the NO releasing nanomatrix gel inhibited intimal hyperplasia formation (more than 70% reduction), as well as improved vascular outward remodeling (increased vein diameter) and hemodynamic adaptation (lower wall shear stress approaching the preoperative level and less vorticity). Therefore, direct application of the NO releasing nanomatrix gel to the AVF anastomosis immediately following AVF creation may enhance AVF development, thereby providing long-term and durable vascular access for hemodialysis.

Rationale and Trial Design of MesEnchymal Stem Cell Trial in Preventing Venous Stenosis of Hemodialysis Vascular Access Arteriovenous Fistula (MEST AVF Trial)

Background

Hemodialysis arteriovenous fistulas (AVFs) are the preferred vascular access for patients on hemodialysis. In the Hemodialysis Fistula Maturation Study, 44% of the patients achieved unassisted maturation of their fistula without needing an intervention. Venous neointimal hyperplasia (VNH) and subsequent venous stenosis are responsible for lack of maturation. There are no therapies that can prevent VNH/VS formation. The goal of this paper is to present the background, rationale, and trial design of an innovative phase 1/2 clinical study that is investigating the safety of autologous adipose-derived mesenchymal stem cells delivered locally to the adventitia of newly created upper extremity radiocephalic (RCF) or brachiocephalic fistula (BCF).

Methods

The rationale and preclinical studies used to obtain a physician-sponsored investigational new drug trial are discussed. The trial design and end points are discussed.

Results

This is an ongoing trial that will complete this year.

Conclusion

This is a phase 1/2 single-center, randomized trial that will investigate the safety and efficacy of autologous AMSCs in promoting maturation in new upper-extremity AVFs.Clinical Trial registration number: NCT02808208.

Anaesthesia Choice for Creation of Arteriovenous Fistula (ACCess) study protocol : a randomised controlled trial comparing primary unassisted patency at 1 year of primary arteriovenous fistulae created under regional compared to local anaesthesia

INTRODUCTION

Arteriovenous fistulae (AVF) are the 'gold standard' vascular access for haemodialysis. Universal usage is limited, however, by a high early failure rate. Several small, single-centre studies have demonstrated better early patency rates for AVF created under regional anaesthesia (RA) compared with local anaesthesia (LA). The mechanistic hypothesis is that the sympathetic blockade associated with RA causes vasodilatation and increased blood flow through the new AVF. Despite this, considerable variation in practice exists in the UK. A high-quality, adequately powered, multicentre randomised controlled trial (RCT) is required to definitively inform practice.

METHODS AND ANALYSIS

The Anaesthesia Choice for Creation of Arteriovenous Fistula (ACCess) study is a multicentre, observer-blinded RCT comparing primary radiocephalic/brachiocephalic AVF created under regional versus LA. The primary outcome is primary unassisted AVF patency at 1 year. Access-specific (eg, stenosis/thrombosis), patient-specific (including health-related quality of life) and safety secondary outcomes will be evaluated. Health economic analysis will also be undertaken.

ETHICS AND DISSEMINATION

The ACCess study has been approved by the West of Scotland Research and ethics committee number 3 (20/WS/0178). Results will be published in open-access peer-reviewed journals within 12 months of completion of the trial. We will also present our findings at key national and international renal and anaesthetic meetings, and support dissemination of trial outcomes via renal patient groups.

TRIAL REGISTRATION NUMBER

ISRCTN14153938.

SPONSOR

NHS Greater Glasgow and Clyde GN19RE456, Protocol V.1.3 (8 May 2021), REC/IRAS ID: 290482.

Evaluation of Factors Affecting Wrist Radio-Cephalic Arteriovenous Fistula Maturation: A Single Institutional Observational Study

Background: Chronic renal failure is the most common indication for which arterio-venous (AV) fistula creation surgery is being performed. Various studies have found that native arteriovenous fistulas are the best in long-term patency with lower complications. We conducted this study to find out the role of preprocedural duplex ultrasound (DUS) in predicting outcomes of radio-cephalic fistula in the wrist in the North-Karnataka population. Methods: This prospective study was conducted from May 2019 to July 2020 on 50 patients who were hemodialysis-dependent and underwent AV fistula creation with age from 20 to 70 years. All the patients underwent preoperative DUS and were followed up post-operatively after one, two, and six weeks. Hemodialysis was initiated through the constructed fistula once it was mature, and the maximum blood flow through the fistula was measured. SPSS version 20.0 was used for statistical analysis. Results: Among 50 subjects, the overall cumulative success of AVF maturation was 86% (43), and failure to mature rate was 14% (7). Logistic regression of maturation outcome in the wrist autologous arteriovenous fistula for individual factors showed statistically significant results (P < 0.05) for the diameter of the radial artery > 1.6 mm and the distensibility of the cephalic vein > 0.4 mm. Conclusions: Vein distensibility and radial artery diameter are key factors in predicting successful AVF maturation. The use of intraoperative papaverine instillation directly on vessels can improve arteriovenous fistula outcomes.

Maturation and survival of arteriovenous fistula: The challenge starts from the preoperative assessment stage

BACKGROUND

It is necessary to assess the association between the preoperative indicators and the maturation and survival of arteriovenous fistula (AVF).

METHODS

We retrospectively identified 236 patients with a new AVF created between 2016 and 2018 in our Dialysis Center.

RESULTS

Multivariate Logistic regression showed that preoperative arterial diameter (odds ratio [OR] = 1.452, 95% confidence interval [CI] [1.233, 1.710], p < 0.001), preoperative venous diameter (OR = 1.296, 95% CI [1.166, 1.477], p < 0.001), left ventricular ejection fraction (LVEF) (OR = 1.187, 95% CI [1.103, 1.277], p < 0.001), and diabetes mellitus (OR = 0.245, 95% CI [0.107, 0.560], p = 0.01) were independent influential factors for AVF maturation. Two years after the AVF surgery follow-up, multivariate Cox proportional-hazards model showed that the preoperative arterial diameter (OR = 0.510, 95% CI [0.320, 0.813], p = 0.005), preoperative venous diameter (OR = 0.940, 95% CI [0.897, 0.985], p = 0.010) and diabetes mellitus (OR = 1.785, 95% CI [1.117, 2.855], p = 0.016) was prognostic factors of AVF survival. The Kaplan-Meier method showed that the primary survival of AVF in patients with different preoperative arterial diameter was statistically significant (log-rank χ²  = 15.415, p < 0.001), while the secondary survival was not statistically significant (log-rank χ²  = 0.131, p = 0.717).

CONCLUSION

In our cohort, the preoperative arterial and venous diameter and diabetes mellitus were independent influential factors for AVF maturation and prognostic factors of AVF survival. However, the preoperative LVEF only associated with the maturation of AVF. Meanwhile, smaller arterial diameter (≤2.15 mm) was associated with AVF maturation failure, but did not impact secondary survival of AVF.

Basics for performing a high-quality color Doppler sonography of the vascular access

In the last years, the systematic use of ultrasound mapping of the upper limb vascular network before the arteriovenous fistula (AVF) implantation, access maturation, and clinical management of late complications is widespread and expanding. Therefore, a good knowledge of theoretical outlines, instrumentation, and operative settings is undoubtedly required for a thorough examination. In this review, the essential Doppler parameters, B-Mode setting, and Doppler applications are considered. Basic concepts on the Doppler shift equation, angle correction, settings on pulse repetition frequency, operative Doppler frequency, gain are reported to ensure adequate and correct sampling of blood flow velocity. A brief analysis of the Doppler inherent artefacts (as random noise, blooming, aliasing, and motion artefacts) and the adjustment setting to minimize or eliminate the confounding artefacts are also considered. Doppler aliasing occurs when the pulse repetition frequency is set too low. This artefact is particularly frequent in vascular access sampling due to the high velocities range registered in the fistula's different segments. Aliasing should be recognized because its correction is crucial to analyse the Doppler signals correctly. Recent advances in instrumentation are also considered about a potential purchase of a portable ultrasound machine or a top-of-line, high-end, or mid-range ultrasound system. Last, the pulse wave Doppler setting for vascular access B-Mode and Doppler assessment is summarized.

Percutaneous Arteriovenous Fistula Creation with the 4 French WavelinQ™ EndoAVF System

BACKGROUND

Percutaneous devices for creation of native arteriovenous fistulae offer an alternative to traditional open surgical techniques. The 4 Fr WavelinQ EndoAVF System was developed as a lower profile alternative to facilitate access through smaller vessels and minimize access site complications; The current report is the original first experience of this device, assessing outcome in 120 patients followed for 6 months.

METHODS

The use of the 4 Fr WavelinQ system in three studies, EASE (32 patients), EASE-2 (24 patients), and the EU post-market clinical follow-up study (64 patients) was aggregated and analyzed. Patients were followed with duplex ultrasound at discharge and follow-up visits at 1, 3, and 6 months. Primary, assisted primary, and secondary patency rates were evaluated as Kaplan-Meier (KM) estimates and standard errors. Time to maturity and time to successful cannulation were defined as the mean ± SD days from the procedure in patients enrolled on dialysis.

RESULTS

Procedural success was achieved in 116 patients (96.7%). Primary, assisted-primary, and secondary 6-month patency rates were 71.9%±4.5%, 80.7%±4.1%, and 87.8%±3.3%, respectively. Time to maturity averaged 41±17 days. Time to successful cannulation averaged 68±51 days. Device-related serious adverse events were reported in 3/120 patients (2.5%) and procedure-related serious adverse events occurred in 7/120 patients (5.8%). Arterial or venous access complications were not reported in any of the patients. Access circuit reinterventions were performed in 23 patients (19.2%), split between those performed for EndoAVF maturation (13/120, 10.8%) and maintenance (11/120. 9.2%).

CONCLUSIONS

Percutaneous creation of native dialysis fistulae with the 4 Fr WavelinQ EndoAVF System is safe and effective, with favorable durability and a low rate of serious complications and reinterventions through 6-month follow-up. Utilization of the 4F device allows for percutaneous fistula creation between the radial artery and radial vein or the ulnar artery and ulnar vein. These findings suggest that the 4 Fr device is a useful percutaneous alternative to open surgical AVF or endovascular AVF with larger-bore devices.