Outcomes of arteriovenous fistula creation after the Fistula First Initiative

Personalized decision-making for vascular access creation in hemodialysis

Selecting the appropriate kidney replacement therapy (KRT) is crucial in order to secure optimal care for chronic kidney disease (CKD) patients with end-stage renal disease (ESRD). Next to renal transplantation, the choice of dialysis modality directly affects patient well-being, treatment effectiveness, and long-term outcomes. Therefore, clinical decision-making must take into account a range of factors to tailor decisions to each patient's unique needs. Previously, when the dialysis population was less diverse and resources more limited, straight-forward algorithms could be effectively implemented both for selection of KRT as well as for hemodialysis (HD) vascular access (VA). Recently, the growing ESRD population with more elderly being considered for dialysis care together with improved treatment opportunities have resulted in more challenging decision-making where on-size-fits-all strategies are being replaced by more tailored and personalized strategies aimed to ensure "the right dialysis access - to the right patient - at the right time - for the right reason." In this review, recent trends enforcing a more personalized approach in the selection of VA for HD are summarized and discussed, where these concerns have become especially relevant.

Outcomes Following Arteriovenous Fistula Creation in Medicare Beneficiaries With End-Stage Kidney Disease

The objective of this study was to measure the contemporary patency rates and frequency of interventions required for arteriovenous fistula (AVF) care in a representative US population of patients with end-stage kidney disease, including by age, race, and gender. All Medicare beneficiaries aged >20 years who underwent AVF graft creation for end-stage kidney disease between 2017 and 2019 were included for analysis. The primary end points included primary patency, primary assisted patency, postintervention patency, and fistula functionality up to 1 year after AVF placement. The secondary end point included admission for an associated adverse event after AVF creation. Multivariate analysis of patency rates was also assessed. Of 43,457 patients included in the analysis, the cumulative primary patency at 90 days was 68.4% and at 1 year, 31.5%. At 1 year, the primary assisted patency rate, postintervention patency, and fistula use were 70.4%, 30.2%, and 59.1%, respectively. There was no difference in primary patency rates when comparing age groups (age 40 to 59 years: hazard ratio [HR] 1.01, 95% confidence interval [CI] 0.95 to 1.06, p = 0.84 or age ≥60 years: HR 0.99, 95% CI 0.93 to 1.04, p = 0.61) with the reference of age group 20 to 39 years. Women were at greater risk of experiencing primary patency failure than were men (HR 1.16, 95% CI 1.14 to 1.20, p <0.001), and Black patients were at greater risk of experiencing primary patency failure than were White patients (HR 1.34, 95% CI 1.31 to 1.38, p <0.001). The cumulative incidence of admissions for adverse events was 32.6% at 1 year. In conclusion, our findings suggest that the real-world AVF patency rates remain low, with disproportionately low rates in women and Black patients.

Elevated Shear Stress Modulates Heterogenous Cellular Subpopulations to Induce Vascular Remodeling

Rationale: Elevated shear stress (ESS) induces vascular remodeling in veins exposed to arterial blood flow, which can lead to arteriovenous (AV) fistula failure. The molecular mechanisms driving remodeling have not been comprehensively examined with a single-cell resolution before. Objective: Using an in vivo animal mode, single-cell RNA sequencing, and histopathology, we precisely manipulate blood flow to comprehensively characterize all cell subpopulations important during vascular remodeling. Methods: AV loops were created in saphenous vessels of rats using a contralateral saphenous vein interposition graft to promote ESS. Saphenous veins with no elevated shear stress (NSS) were anastomosed as controls. Findings: ESS promoted transcriptional homogeneity, and NSS promoted considerable heterogeneity. Specifically, ESS endothelial cells (ECs) showed a more homogeneous transcriptional response promoting angiogenesis and upregulating endothelial-to-mesenchymal transition inhibiting genes (Klf2). NSS ECs upregulated antiproliferation genes such as Cav1, Cst3, and Btg1. In macrophages, ESS promoted a large homogeneous subpopulation, creating a mechanically activated, proinflammatory and thus proangiogenic myeloid phenotype, whereas NSS myeloid cells expressed the anti-inflammatory and antiangiogenetic marker Mrc1. Conclusion: ESS activates unified gene expression profiles to induce adaption of the vessel wall to hemodynamic alterations. Targeted depletion of the identified cellular subpopulations may lead to novel therapies to prevent excessive venous remodeling, intimal hyperplasia, and AV fistula failure.

Retrospective evaluation of three types of expanded polytetrafluoroethylene grafts for upper limb vascular access

Currently, three expanded polytetrafluoroethylene (ePTFE) prosthetic graft types are most commonly used for patients with end-stage kidney disease (ESKD) who require long-term vascular access for hemodialysis. However, studies comparing the three ePTFE grafts are limited. This study compared the clinical efficacy and postoperative complications of three ePTFE prosthetic graft types used for upper limb arteriovenous graft (AVG) surgery among patients with ESKD. Patients with ESKD requiring upper limb AVG surgery admitted to our center between January 2016 and September 2019 were enrolled. Overall, 282 patients who completed the 2-year follow-up were included and classified into the following three groups according to the ePTFE graft type: the GPVG group with the PROPATEN® graft, the GAVG group with the straight-type GORE® ACUSEAL, and the BVVG group with the VENAFLO® II. The patency rate and incidence of access-related complications were analyzed and compared between groups. The patients were followed up postoperatively, and data were collected at 6, 12, 18, and 24 months postoperatively. Respective to these follow-up time points, in the GPVG group, the primary patency rates were 74.29%, 65.71%, 51.43%, and 42.86%; the assisted primary patency rates were 85.71%, 74.29%, 60.00%, and 48.57%; and the secondary patency rates were 85.71%, 80.00%, 71.43%, and 60.00%. In the GAVG group, the primary patency rates were 73.03%, 53.93%, 59.42%, and 38.20%; the assisted primary patency rates were 83.15%, 68.54%, 59.55%, and 53.93%; and the secondary patency rates were 85.39%, 77.53%, 68.54%, and 62.92%, respectively. In the BVVG group, the primary patency rates were 67.24%, 53.45%, 41.38%, and 29.31%; the assisted primary patency rates were 84.48%, 67.24%, 55.17%, and 44.83%; and the secondary patency rates were 86.21%, 81.03%, 68.97%, and 60.34%, respectively. The differences in patency rates across the three grafts were not statistically significant. Overall, 18, 4, and 12 patients in the GPVG, GAVG, and BVVG groups, respectively, experienced seroma. Among the three grafts, GORE® ACUSEAL had the shortest anastomosis hemostatic time. The first cannulation times for the three grafts were GPVG at 16 (±8.2), GAVG at 4 (±4.9), and BVVG at 18 (±12.7) days. No significant difference was found in the postoperative swelling rate between the GPVG group and the other two groups. Furthermore, no statistically significant differences were found across the three graft types regarding postoperative vascular access stenosis and thrombosis, ischemic steal syndrome, pseudoaneurysm, or infection. In conclusion, no statistically significant differences in the postoperative primary, assisted primary, or secondary graft patency rates were observed among the three groups. A shorter anastomosis hemostatic time, first cannulation time, and seroma occurrence were observed with the ACUSEAL® graft than with its counterparts. The incidence of upper extremity swelling postoperatively was greater with the PROPATEN® graft than with the other grafts. No statistically significant differences were observed among the three grafts regarding the remaining complications.

Comparison of clinical examination, doppler and fistulogram for arterio-venous fistula surveillance in detecting secondary failure

BACKGROUND

Arteriovenous Fistula (AVF) surveillance is required to detect early dysfunction (thrombosis, stenosis) and its timely correction prolongs access-patency. Clinical examination (CE) and doppler have been used as screening/surveillance of AVF, for early detection of AVF dysfunction. Since there was inadequate evidence for KDOQI to make recommendations on AVF surveillance and on secondary failure rate. We compared CE, doppler and fistulogram as surveillance modalities in detecting a secondary failure in matured AVF.

METHODOLOGY

This prospective-observational, single-center study, was done between December 2019-April 2021. CKD stage 5 patients on dialysis/Not-on-dialysis with matured AVF were included at third month. CE, doppler (blood flow, vein diameter, depth), and fistulogram were done at third and sixth month. Secondary failure was assessed at sixth month classifying AVF to patent/functional and failed group. Diagnostic tests were performed by comparing three methods considering fistulogram as gold-standard. Residual urine output is also monitored to look for any contrast induced residual renal function loss.

RESULTS

Of total 407 created AVF, 98 (24%) had primary failure. Twenty-five (6%) had surgical complications including unsuccessful AVF and aneurysm/rupture, 156 lost follow-up at third month, 104 consented patients were enrolled, 16 lost to follow-up subsequently, and 88 patients' data were analyzed at the end. At the sixth month, 76(86.4%) had patent AVF, 8 (9.1%) had secondary failure (Thrombosis-4, Central Venous Stenosis-4), and 4 (4.1%) patients expired. Considering fistulogram as a diagnostic standard, CE showed 87.5% sensitivity, and 93.4% specificity (cohen's kappa value of 0.66). Doppler had sensitivity and specificity of 87% and 96% respectively (cohen's kappa value of 0.75), Combination of clinical examination with doppler showed sensitivity and specificity of 100% and 89% respectively.

CONCLUSION

Although the secondary AVF failure rate is less than the primary, CE is an important and valuable tool in the diagnosis and surveillance of AVF in detecting its dysfunction. Moreover, CE with doppler can be used as a surveillance protocol that can detect early AVF dysfunction at par with Fistulogram.

Artificial neural networks analysis predicts long-term fistula function in hemodialysis patients following percutaneous transluminal angioplasty

Kidney failure is particularly common in the United States, where it affects over 700,000 individuals. It is typically treated through repeated sessions of hemodialysis to filter and clean the blood. Hemodialysis requires vascular access, in about 70% of cases through an arteriovenous fistula (AVF) surgically created by connecting an artery and vein. AVF take 6 weeks or more to mature. Mature fistulae often require intervention, most often percutaneous transluminal angioplasty (PTA), also known as fistulaplasty, to maintain the patency of the fistula. PTA is also the first-line intervention to restore blood flow and prolong the use of an AVF, and many patients undergo the procedure multiple times. Although PTA is important for AVF maturation and maintenance, research into predictive models of AVF function following PTA has been limited. Therefore, in this paper we hypothesize that based on patient-specific information collected during PTA, a predictive model can be created to help improve treatment planning. We test a set of rich, multimodal data from 28 patients that includes medical history, AVF blood flow, and interventional angiographic imaging (specifically excluding any post-PTA measurements) and build deep hybrid neural networks. A hybrid model combining a 3D convolutional neural network with a multi-layer perceptron to classify AVF was established. We found using this model that we were able to identify the association between different factors and evaluate whether the PTA procedure can maintain primary patency for more than 3 months. The testing accuracy achieved was 0.75 with a weighted F1-score of 0.75, and AUROC of 0.75. These results indicate that evaluating multimodal clinical data using artificial neural networks can predict the outcome of PTA. These initial findings suggest that the hybrid model combining clinical data, imaging and hemodynamic analysis can be useful to treatment planning for hemodialysis. Further study based on a large cohort is needed to refine the accuracy and model efficiency.

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.

Periadventitial biomaterials to improve arteriovenous fistula and graft outcomes

Periadventitial biomaterials have been employed for nearly three decades to promote adaptive venous remodeling following hemodialysis vascular access creation in preclinical models and clinical trials. These systems are predicated on the combination of scaffolds, hydrogels, and/or particles with therapeutics (small molecules, proteins, genes, and cells) to prevent venous stenosis and subsequent maturation failure. Periadventitial biomaterial therapies have evolved from simple drug delivery vehicles for traditional drugs to more thoughtful designs tailored to the pathophysiology of access failure. The emergence of tissue engineering strategies and gene therapies are another exciting new direction. Despite favorable results in experimental and preclinical studies, no periadventitial therapy has been clinically approved to improve vascular access outcomes. After conducting an exhaustive review of the literature, we identify the seminal studies and clinical trials that utilize periadventitial biomaterials and discuss the key features of each biomaterial format and their respective shortcomings as they pertain to access maturation. This review provides a foundation from which clinicians, surgeons, biologists, and engineers can refer to and will hopefully inspire thoughtful, translatable treatments to finally address access failure.

Hemodynamics and Wall Mechanics of Vascular Graft Failure

Blood vessels are subjected to complex biomechanical loads, primarily from pressure-driven blood flow. Abnormal loading associated with vascular grafts, arising from altered hemodynamics or wall mechanics, can cause acute and progressive vascular failure and end-organ dysfunction. Perturbations to mechanobiological stimuli experienced by vascular cells contribute to remodeling of the vascular wall via activation of mechanosensitive signaling pathways and subsequent changes in gene expression and associated turnover of cells and extracellular matrix. In this review, we outline experimental and computational tools used to quantify metrics of biomechanical loading in vascular grafts and highlight those that show potential in predicting graft failure for diverse disease contexts. We include metrics derived from both fluid and solid mechanics that drive feedback loops between mechanobiological processes and changes in the biomechanical state that govern the natural history of vascular grafts. As illustrative examples, we consider application-specific coronary artery bypass grafts, peripheral vascular grafts, and tissue-engineered vascular grafts for congenital heart surgery as each of these involves unique circulatory environments, loading magnitudes, and graft materials.

Frailty screening for determination of hemodialysis access placement

OBJECTIVE

Choosing the right hemodialysis vascular access for frail patients remains difficult because the patient's preferences and the likelihood of access function and survival must be considered. We hypothesize that patients identified before arteriovenous (AV) access as frail by the PRISMA-7 score may have worse outcomes, indicating that fistula creation may not be the most clinically beneficial option and it would be in the best interest of the patient to receive either AV graft (AVG) placement or dialysis through a percutaneous catheter. Our pilot study aims to determine whether an association exists between patient frailty as defined by PRISMA-7 and newly created AV fistula (AVF) and AVG access outcomes.

METHODS

This was a single institutional prospective cohort study of patients undergoing new AVF or AVG intervention from April 2021 to May 2023. Patients were assessed using the PRISMA-7 frailty questionnaire before their AV access surgery. Patients were grouped by frailty score and score groups were examined for trends. Univariable analysis was performed for baseline differences between frail and nonfrail patients. Failure to achieve maturation, postoperative infection, and 180-day mortality difference was also investigated for frail vs nonfrail patients. Univariable analysis was performed for nonmaturation using standard comorbidities, arterial and venous diameters, and frailty. Multivariable binary logistic regression was performed for the outcome of nonmaturation using frailty as one of the variables in conjunction with the univariable risks associated with nonmaturation.

RESULTS

A total of 40 patients undergoing new AV access placement were investigated, among whom 53% were designated as frail (PRISMA-7 score ≥3). When comparing the frail and nonfrail new AV access groups, the access (AVF and AVG combined) failed in 48% (10/21) of the frail patients, but only failed in 5% (1/19) of the nonfrail patients 1 (P = .012). When distinguishing between AV access types, AVF creations followed the overall trend with 60% of AVF access (9/15) sites in frail patients failing to mature when compared with nonfrail patients, who all had fistulas that matured to use (P = .049). Surgical site infection was absent in all frail patients and present in 5% of nonfrail patients (1/19). Both 30-day and 60-day readmission rates were higher in the frail group compared with the nonfrail group. There was 180-day mortality present in 5 of frail patients % (1/21) and absent in nonfrail patients. Multivariable analysis revealed that both frailty (adjusted odd ratio, 10.19; 95% confidence interval, 1.20-82.25); P = .033) and younger age (adjusted odd ratio, 0.953; 95% confidence interval, 0.923-0.983; P = .002) both had a significant association with nonmaturation. Power analysis revealed a power statistic of 0.898 indicating a probability of type 2 error of 10.02% with a P value of .002. Hosmer-Lemeshow goodness of fit for the logistic regression had 75% overall accuracy for the model.

CONCLUSIONS

Patient frailty is significantly associated with an increased incidence of AV access failure to mature.

Early Ultrasound Surveillance of Newly-Created Hemodialysis Arteriovenous Fistula

Introduction

We assess if ultrasound surveillance of newly-created arteriovenous fistulas (AVFs) can predict nonmaturation sufficiently reliably to justify randomized controlled trial (RCT) evaluation of ultrasound-directed salvage intervention.

Methods

Consenting adults underwent blinded fortnightly ultrasound scanning of their AVF after creation, with scan characteristics that predicted AVF nonmaturation identified by logistic regression modeling.

Results

Of 333 AVFs created, 65.8% matured by 10 weeks. Serial scanning revealed that maturation occurred rapidly, whereas consistently lower fistula flow rates and venous diameters were observed in those that did not mature. Wrist and elbow AVF nonmaturation could be optimally modeled from week 4 ultrasound parameters alone, but with only moderate positive predictive values (PPVs) (wrist, 60.6% [95% confidence interval, CI: 43.9-77.3]; elbow, 66.7% [48.9-84.4]). Moreover, 40 (70.2%) of the 57 AVFs that thrombosed by week 10 had already failed by the week 4 scan, thus limiting the potential of salvage procedures initiated by that scan's findings to alter overall maturation rates. Modeling of the early ultrasound characteristics could also predict primary patency failure at 6 months; however, that model performed poorly at predicting assisted primary failure (those AVFs that failed despite a salvage attempt), partly because patency of at-risk AVFs was maintained by successful salvage performed without recourse to the early scan data.

Conclusion

Early ultrasound surveillance may predict fistula maturation, but is likely, at best, to result in only very modest improvements in fistula patency. Power calculations suggest that an impractically large number of participants (>1700) would be required for formal RCT evaluation.

Knowledge of arteriovenous fistula care in patients with end-stage kidney disease in south Asian countries: A systematic review and meta-analysis

OBJECTIVES

To find the prevalence of knowledge of arteriovenous fistula (AVF) self-care, its characteristics, and associated factors among hemodialysis patients and summarize the findings of various domains of AVF self-care in south Asian countries.

METHODS

The systematic literature search was performed on online databases and additional sources to retrieve published articles on AVF self-care. We estimated the pooled prevalence using a random effects model in meta-analysis. Additionally, thematic knowledge regarding various aspects of AVF self-care was narratively summarized.

RESULTS

Among the articles retrieved seven studies met our inclusion and exclusion criteria. The prevalence of AVF self-care in individual studies ranged from 59% to 99%, with an overall random pooled prevalence of 81% (95% CI, 68% to 94%). Major factors associated with self-care of AVF knowledge included patients' educational status, age, vintage of hemodialysis, and healthcare personnel's advice.

DISCUSSION

Knowledge scarcity regarding potential measures of AVF self-care obligates the need for continuous education in hemodialysis patients. A multidisciplinary approach is vital to enhance self-care from pre- to post-creation of AVF in hemodialysis patients as well as their caregivers in order to prolong the patency rates and decrease the subsequent morbidity and mortality due to failure of AVF.

Role of platelet factor 4 in arteriovenous fistula maturation failure: What do we know so far?

The rate of arteriovenous fistula (AVF) maturation failure remains unacceptably high despite continuous efforts on technique improvement and careful pre-surgery planning. In fact, half of all newly created AVFs are unable to be used for hemodialysis (HD) without a salvage procedure. While vascular stenosis in the venous limb of the access is the culprit, the underlying factors leading to vascular narrowing and AVF maturation failure are yet to be determined. We have recently demonstrated that AVF non-maturation is associated with post-operative medial fibrosis and fibrotic stenosis, and post-operative intimal hyperplasia (IH) exacerbates the situation. Multiple pathological processes and signaling pathways are underlying the stenotic remodeling of the AVF. Our group has recently indicated that a pro-inflammatory cytokine platelet factor 4 (PF4/CXCL4) is upregulated in veins that fail to mature after AVF creation. Platelet factor 4 is a fibrosis marker and can be detected in vascular stenosis tissue, suggesting that it may contribute to AVF maturation failure through stimulation of fibrosis and development of fibrotic stenosis. Here, we present an overview of the how PF4-mediated fibrosis determines AVF maturation failure.

Factors Affecting the Early Maturation of Arteriovenous Fistulae Created at a Tertiary Centre in Oman

Objectives

This study aimed to determine the risk factors associated with the failure of arteriovenous fistulae (AVF) maturation.

Methods

This retrospective cohort study was conducted from January 2014 to December 2018 in Sultan Qaboos University Hospital, Muscat, Oman. Patients were followed-up 3 months after surgery, and their electronic medical records were accessed for demographic and clinical data. Univariate analysis was used to determine the risk factors associated with early AVF maturation and multivariant analysis was used to determine the predictive factors for AVF failure.

Results

A total of 269 patients were included. Female gender was a significant factor affecting AVF maturity (P = 0.049), while age (P = 0.626), diabetes (P = 0.954), hypertension (P = 0.378), dyslipidaemia (P = 0.907), coronary artery disease (P = 0.576), cerebrovascular accident (P = 0.864), congestive heart failure (P = 0.685), previous central venous catheterisation (P = 0.05), fistula type (P = 0.863) and fistula site (P = 0.861) did not affect AVF maturation. Binary logistic regression showed that all the risk factors were insignificant. Failure of early AVF maturation affected 11.5% in the cohort.

Conclusion

This study found that the proportion of early AVF maturation at our hospital is at par with that in the international literature. Failure of AVF maturation was significantly associated with the female gender. These findings can help nephrologists and vascular surgeons prognosticate AVF maturation rates. However, a larger study is needed for definitive conclusions.

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.

High pulse pressure predicts primary arteriovenous fistula failure within 1 year

BACKGROUND

The arteriovenous fistula is the preferred access route for hemodialysis, although its high primary failure rate remains a clinical challenge. Multiple studies have attempted to determine the risk factors for primary arteriovenous fistula failure; however, none have identified pulse pressure as a potential predictive marker. High pulse pressure is a surrogate poor arterial compliance endpoint and leads to inferior cardiovascular outcomes. Our aim was to determine whether elevated pulse pressure indicates poor arteriovenous fistula maturation.

METHODS

We retrospectively reviewed 274 patients who underwent an arteriovenous fistula index operation between September 1, 2018 and May 31, 2019. Demographic, clinical data, and operative parameters were collected and analyzed. The maximum follow-up period was 365 days. Arteriovenous fistula failure was defined as the inability to achieve functional use during the follow-up period. We identified risk factors for arteriovenous fistula failure by performing a multivariate logistic regression analysis using backward elimination procedures.

RESULTS

A total of 274 patients were included in the study. The patients' average age was 61.3 ± 14.0 years, approximately half of the patients (n = 161, 58.8%) were male, and the majority had hypertension. At the end of the follow-up period, 68 (24.8%) had arteriovenous fistula failure. The proportion of patients with pulse pressure values of >60 mmHg was significantly higher in the failure group than in the maturation group (66.0% vs 80.9%; p = 0.021). A PP value of >60 mmHg (odds ratio = 2.25; 95% confidence interval = 1.14-4.42; p = 0.019) and coronary artery disease or myocardial infarction (odds ratio = 1.97; 95% confidence interval = 1.01-3.84; p = 0.045) were found to be independent risk factors for primary arteriovenous fistula failure.

CONCLUSIONS

High pulse pressure is an independent risk factor for primary arteriovenous fistula failure.

Early Follow-Up after Arteriovenous Fistula Creation is Associated with Improved Access-Related Outcomes

BACKGROUND

Up to 60% of arteriovenous fistulas (AVF) require intervention to assist maturation, which prolongs the time until it can be used for hemodialysis (HD). Current guidelines recommend early postoperative AVF examination to detect and address immaturity to decrease time to maturation. This study evaluates how the timing of postoperative follow-up to assess AVF maturity affects patients' outcomes.

METHODS

All patients who underwent AVF creation between 2017 and 2021 in an academic medical center were retrospectively reviewed, excluding patients lost to follow-up or not on HD. Outcomes were compared between patients that had delayed follow-up to assess AVF maturity, >8 weeks post surgery, versus early follow-up, <8 weeks post-surgery. AVF evaluation for maturity consisted of physical examination and duplex ultrasound. Primary endpoints were time to first cannulation (interval from AVF creation to first successful cannulation) and time to catheter-free dialysis (interval from AVF creation to central venous catheter removal).

RESULTS

A total of 400 patients were identified: 111 in the delayed follow-up group and 289 in the early follow-up group. The median time to follow-up was 78 days (interquartile range [IQR], 66-125) in the delayed follow-up group versus 39 days (IQR, 36-47) in the early follow-up group, (P < 0.0001). The maturation rate was 87% in the delayed follow-up group versus 81% in the early follow-up group, (P = 0.1) and both groups had similar rates of interventions to assist maturation (66% vs. 57%, P = 0.2). The early follow-up group had a significantly shorter median time to first cannulation (50 vs. 88 days; P < 0.0001) and shorter time to catheter-free HD (75 vs. 118 days; P <0.0001). At 4 months after AVF creation, the incidence of first cannulation was 74% in the early follow-up group versus 63% in the delayed follow-up group (P = 0.001). Similarly, the incidence of catheter-free dialysis was 65% in the early follow-up group versus 50% in the delayed follow-up group at 4 months postoperatively, (P = 0.036).

CONCLUSIONS

Early postoperative follow-up for evaluation of fistula maturation is associated with reduced time to first successful cannulation of AVF for HD and reduced time to catheter-free dialysis.

Early clinical experience and comparison between percutaneous and surgical arteriovenous fistula

BACKGROUND

Percutaneous arteriovenous fistula (pAVF) has been recently developed as an alternative to surgical AVF (sAVF). We report our experience with pAVF in comparison with a contemporaneous sAVF group.

METHODS

Charts of all 51 patients with pAVF performed at our institution were analyzed retrospectively, in addition to 51 randomly selected contemporaneous patients with sAVF (2018-2022) with available follow-up. Outcomes of interest were (i) procedural success rate, (ii) number of maturation procedures required, (iii) fistula maturation rates, and (iv) rates of tunneled dialysis catheter (TDC) removal. For patients on hemodialysis (HD), sAVF and pAVF were considered mature when the AVF was used for HD. For patients not on HD, pAVF were considered mature if flow rates of ≥500 mL/min were documented in superficial venous outflow; for sAVF, documentation of maturity based on clinical criteria was required.

RESULTS

Compared patients with sAVF, patients with pAVF were more likely to be male (78% vs 57%; P = .033) and less likely to have congestive heart failure (10% vs 43%; P < .001) and coronary artery disease (18% vs 43%; P = .009). Procedural success was achieved in 50 patients with pAVF (98%). Fistula angioplasties (60% vs 29%; P = .002) and ligation (24% vs 2%; P = .001) or embolization (22% vs 2%; P = .002) of competing outflow veins were more frequently performed on patients with pAVF. The surgical cohort had more planned transpositions (39% vs 6%; P < .001). When all maturation interventions were combined, pAVF required more maturation procedures, but this was not statistically significant (76% vs 53%; P = .692). When planned second-stage transpositions were excluded, pAVF had a statistically significant higher rate of maturation procedures (74% vs 24%; P < .001). Overall, 36 pAVF (72%) and 29 sAVF (57%) developed mature fistulas. This difference, however, was not statistically significant (P = .112). At the time of AVF creation, 26 patients with pAVF and 40 patients with sAVF were on HD, all through use of a TDC. Catheter removal was recorded in 15 patients with pAVF (58%) and 18 patients with sAVF (45%) (P = .314). The mean time until TDC removal in pAVF group was 146 ± 74 days, compared with 175 ± 99 in the sAVF group (P = .341).

CONCLUSIONS

Compared with sAVF, rates of maturation after pAVF seem to be similar, but this result may be related to the higher intensity of maturation procedures and patient selection. An analysis of appropriately matched patients will assist in elucidating the possible role of pAVF vis-a-vis sAVF.

Anesthetic choice for arteriovenous access creation: A National Anesthesia Clinical Outcomes Registry analysis

BACKGROUND

We sought to evaluate differences in primary anesthetic type used in arteriovenous access creation with the hypothesis that administration of regional anesthesia and monitored anesthesia care (MAC) with local anesthesia as the primary anesthetic has increased over time.

METHODS

National Anesthesia Clinical Outcomes Registry data were retrospectively evaluated. Covariates were selected a priori within multivariate models to determine predictors of anesthetic type in adults who underwent elective arteriovenous access creation between 2010 and 2018.

RESULTS

A total of 144,392 patients met criteria; 90,741 (62.8%) received general anesthesia. The use of regional anesthesia and MAC decreased over time (8.0%-6.8%, 36.8%-27.8%, respectively; both p < 0.0001). Patients who underwent regional anesthesia were more likely to have ASA physical status >III and to reside in rural areas (52.3% and 12.9%, respectively; both p < 0.0001). Patients who underwent MAC were more likely to be older, male, receive care outside the South, and reside in urban areas (median age 65, 56.8%, 68.1%, and 70.8%, respectively; all p < 0.0001). Multivariate analysis revealed that being male, having an ASA physical status >III, and each 5-year increase in age resulted in increased odds of receiving alternatives to general anesthesia (regional anesthesia adjusted odds ratios (AORs) 1.06, 1.12, and 1.26, MAC AORs 1.09, 1.2, and 1.1, respectively; all p < 0.0001). Treatment in the Midwest, South, or West was associated with decreased odds of receiving alternatives to general anesthesia compared to the Northeast (regional anesthesia AORs 0.28, 0.38, and 0.03, all p < 0.0001; MAC 0.76, 0.13, and 0.43, respectively; all p < 0.05).

CONCLUSIONS

Use of regional anesthesia and MAC with local anesthesia for arteriovenous access creation has decreased over time with general anesthesia remaining the primary anesthetic type. Anesthetic choice, however, varies with patient characteristics and geography.

Early identification of bloodstream infection in hemodialysis patients by machine learning

Background

Bloodstream infection (BSI) is a prevalent cause of admission in hemodialysis (HD) patients and is associated with increased morbidity and mortality. This study aimed to establish a diagnostic, predictive model for the early identification of BSI in HD patients.

Methods

HD patients who underwent blood culture testing between August 2018 and March 2022 were enrolled in this study. Machine learning algorithms, including stepwise logistic regression (SLR), Lasso logistic regression (LLR), support vector machine (SVM), decision tree, random forest (RF), and gradient boosting machine (XGboost), were used to predict the risk of developing BSI from the patient's clinical data. The accuracy (ACC) and area under the subject working curve (AUC) were used to evaluate the performance of such models. The Shapley Additive Explanation (SHAP) values were used to explain each feature's predictive value on the models' output. Finally, a simplified nomogram for predicting BSI was devised.

Results

A total of 391 HD patients were enrolled in this study, of whom 74 (18.9%) were diagnosed with BSI. The XGboost model achieved the highest AUC (0.914, 95% confidence interval [CI]: 0.861-0.964) and ACC (86.3%) for BSI prediction. The four most significant co-variables in both the significance matrix plot of the XGboost model variables and the SHAP summary plot were body temperature, dialysis access via a non-arteriovenous fistula (non-AVF), the procalcitonin levels (PCT), and neutrophil-lymphocyte ratio (NLR).

Conclusions

This study created an effective machine-learning model for predicting BSI in HD patients. The model could be used to detect BSI at an early stage and hence guide antibiotic treatment in HD patients.

Patency Rates and Outcomes of Renal Access Arteriovenous Fistulas for Hemodialysis in Patients with Chronic Kidney Disease

Hemodialysis remains the most popular modality of renal replacement therapy for end-stage renal disease patients with chronic kidney disease. Various factors such as a radial artery, cephalic vein diameter, age, hypertension, and diabetes mellitus can affect the fistula maturation. This study was carried out to know the patency rates and factors affecting fistula maturation in the Indian population. This is a prospective observational study which aimed to study the patency rate of arteriovenous (AV) fistulas. On the day of surgery, patients were shifted inside the operation theater. Under all aseptic precautions, an AV fistula was formed using the radial artery and cephalic vein. All patients were followed up for 6 months. The data were analyzed using IBM SPSS version 22. To see the change over a period of time, McNemar test for categorical data and repeated measure for continuous data followed by post hoc comparison by Bonferroni method were used. The mean age of the patients was 46.98 ± 13.33 years. The mean diameter of the cephalic vein, ulnar artery, and radial artery at the wrist was 1.733 ± 0.528, 1.700 ± 0.364, and 1.908 ± 0.420, respectively, whereas the mean diameter of the cephalic vein, ulnar artery, and radial artery at the forearm was 1.952 ± 0.488, 1.910 ± 0.421, and 2.058 ± 0.458, respectively. Immediate thrill after the surgery was present in 36/52 (69.2%) of the patients. The radial artery diameter at the wrist was significantly less in the patients with primary failure in whom immediate thrill was not present (P = 0.016). At 1-month follow-up, 30/49 (61.2%) and, at 6 months, 29/48 (60.4%) fistulas were functional. Radiocephalic AV fistulas have a reasonable success rate and minimal morbidity, and radial artery diameter is a good predictor of the outcome.

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.

A 2-year Comparative Analysis of Outcomes and Endovascular Interventions in Radio-Cephalic vs. Brachio-Cephalic Fistulae

BACKGROUND

Arterio-venous fistulae are often compromised by complications, notably thrombosis. We assess the 2 year follow-up data of a cohort of patients from a single vascular centre in the UK who underwent BCF or RCF creation with the objective of assessing the outcome differences and intervention rates between fistula types.

MATERIALS AND METHODS

We retrospectively assessed a cohort of 195 patients who underwent creation of arterio-venous fistula (100 BCF, 95 RCF) between January 2016 and December 2018, following them up for 2 years assessing the outcomes and interventions on their AVFs. The outcomes assessed were primary and cumulative patency at 6 weeks, 6, 12 and 24 months. Multinomial logistic regression to account for confounding variables age, gender, procedure, side, anticoagulant, vessel size and co-morbidities was performed. A Kaplan-Meier analysis of time to endovascular intervention was also performed comparing RCF and BCF.

RESULTS

Cumulative patency rates for BCF vs RCF were 91% vs. 89% at 6 weeks (X² (3, N = 194) = 4.70, P = .19), 83% vs. 76% at 6 months (X² (3, N = 188) = 7.72, P = .05), 78% vs. 69% at 12 months (X² (4, N = 175) = 5.37, P = .25) and 68% vs. 65% at 24 months (X² (4, N = 161) = 5.24, P = .24). Endovascular intervention rate becomes divergent at 5 months, with the steepest difference between 6 and 12 months. Comparative endovascular intervention rates between BCF and RCF were 20% vs. 31% at 6 months, 41% vs. 40% at 12 months and 40% vs. 49% at 24 months.

CONCLUSION

RCF seem to have significantly lower patency at 6 months and have higher endovascular intervention rates compared to BCF. A focussed surveillance protocol could prove effective in improving outcomes for RCF.

Reassessing the utility of access recirculation and Kt/V for the prediction of arteriovenous fistula failure using online clearance monitoring: the SHUNT STUDY

BACKGROUND

The arteriovenous fistula (AVF) is prone to thrombosis which can be avoided by use of monitoring and surveillance programmes. Although surveillance imaging techniques have been shown to be more sensitive and specific than clinical monitoring during dialysis, monitoring may have significant advantages in terms of cost and time saving. In this study we evaluate the yield of two monitoring techniques [blood temperature monitoring (BTM) access recirculation (AR) and Kt/V via online-clearance-monitoring (OCM)].

METHODS

In this single-centre prospective observational study, 101 patients were followed-up for one year. The primary outcome measure was a composite of AVF failure. OCM-Kt/V and BTM-AR were recorded at every dialysis session.

RESULTS

Of all baseline characteristics only a prior history of percutaneous transluminal angioplasty (PTA) to the AVF conferred a significant change in AVF survival (failure events/100 pt years with prior PTA vs. without = 64.0 vs. 17.3, log-rank p = 0.0014; unadjusted hazard ratio (HR) 3.74 (95% CI 1.56-8.94) p = 0.003). Participants with baseline AR < 10% vs. > 15% had poorer AVF survival (p = 0.0002) and HR for baseline AR 10-15% group vs. AR > 15% group = 4.5 (95% CI 1.55-13.05). There was no combination of change in (Δ) AR, ΔKt/V or its presence over any number of dialysis sessions that provided an acceptable combination of sensitivity and specificity or discrimination for AVF failure.

CONCLUSIONS

BTM-AR and OCM-Kt/V are specific but insufficiently sensitive tools for the prediction of AVF failure. BTM-AR and OCM-Kt/V use at every dialysis session appears to add little to the traditional, infrequent use of these evaluations.

Achieving high maturation and cannulation rates of radial-cephalic arteriovenous fistulas with VasQ™ device

BACKGROUND

Hemodialysis is the predominant treatment modality for chronic kidney disease, with arteriovenous fistula (AVF) being considered to be the preferred type of long-term vascular access. Implantation of the external anastomotic VasQ™ support device during AVF creation has been suggested to improve the functional outcomes of AVFs. In the current study, we report the clinical outcomes when using the device with radial-cephalic AVF (RCAVF) creation in a large cohort over 3 years.

METHODS

One hundred fifty RCAVFs were created between June 2018 and August 2021 with implantation of VasQ™. Time to maturation, cannulation characteristics, and assisted (AP) and secondary patency (SP) rates were analyzed.

RESULTS

In this predominantly male (68%), median 64 years old cohort, 150 VasQ™ devices were implanted. Physiological maturation was achieved in 142/150 (95%) and was unassisted in 133/150 (89%). Of those, 129 matured within 1 month and four additional AVFs within 165 days. Eight AVFs achieved maturation following percutaneous transluminal angioplasty, and one required surgical patch angioplasty. The median time from creation to first successful cannulation in dialysis patients was 41 days. AP at 6, 12, 18, 24, and 30 months was 89%, 81%, 78%, 73%, and 73%, and SP was 94%, 87%, 86%, 84%, and 84%, respectively.

CONCLUSIONS

Consistent use of the VasQ™ device in RCAVF creation demonstrates excellent AVF maturation and patency rates with very low frequency of assisted maturation and interventions for maintenance. The VasQ™ device appears a suitable aid in increasing the creation of functional RCAVFs.

Strategies to counteract adverse remodeling of vascular graft: A 3D view of current graft innovations

Vascular grafts are widely used for vascular surgeries, to bypass a diseased artery or function as a vascular access for hemodialysis. Bioengineered or tissue-engineered vascular grafts have long been envisioned to take the place of bioinert synthetic grafts and even vein grafts under certain clinical circumstances. However, host responses to a graft device induce adverse remodeling, to varied degrees depending on the graft property and host's developmental and health conditions. This in turn leads to invention or failure. Herein, we have mapped out the relationship between the design constraints and outcomes for vascular grafts, by analyzing impairment factors involved in the adverse graft remodeling. Strategies to tackle these impairment factors and counteract adverse healing are then summarized by outlining the research landscape of graft innovations in three dimensions-cell technology, scaffold technology and graft translation. Such a comprehensive view of cell and scaffold technological innovations in the translational context may benefit the future advancements in vascular grafts. From this perspective, we conclude the review with recommendations for future design endeavors.

Sex Differences in Arteriovenous Fistula Failure: Insights from Bioinformatics Analysis

(1) Background: Arteriovenous fistulas (AVFs) are the preferred access for hemodialysis. Unfortunately, about 60% of patients, especially female patients, fail to receive normal dialysis within one year after surgery because of AVF failure. However, the underlying mechanisms caused by sex differences in AVF failure remain unclear. (2) Methods: We performed analysis of DEGs and functional analysis with the dataset GSE119296 to reveal the biology underlying AVF failure. Immune responses were calculated using CIBERSORT. A protein-protein interaction network and hub gene were constructed using STRING and stepwise identification of potential drugs was performed online. (3) Results: Functional analysis showed that extracellular matrix reprogramming and PI3K-AKT pathway enrichment were significant in both male and female patients. COL1A1 was the hub gene in male patients, whereas CDK1 was the hub gene in female patients. Immune responses including γδ-T cells and mast cells are activated in female patients while no significant differences were noted in the male group. (4) Conclusions: In this study, we used a series of mature and recognized bioinformatic strategies to determine the following items: (1) Reveal the pathogenesis of AVF failure through HUB genes and signaling pathways between the different sexes. (2) Determine the relationship between sex differences in AVF failure and immune abnormalities. (3) Search for relevant sex-specific drugs targeting AVF failure.

Health insurance provider and endovascular treatment availability are associated with different hemodialysis vascular access profiles: A Brazilian national survey

In Brazil, most hemodialysis (HD) patients are treated by the country's public health system. However, accessibility to healthcare is different for public and private patients. This study aimed to identify the profile of vascular access in a Brazilian HD sample. Additionally, it aimed to examine the influence of public and private health insurance, accessibility to endovascular treatments, and timely arteriovenous access creation on the prevalence of tunneled catheters (TCs), non-tunneled catheters (NTCs), and arteriovenous (AV) access. We conducted a cross-sectional electronic survey across 834 centers. Centers were inquired about the number of patients with public and private health insurance, the profiles of vascular access, time for AV access creation, accessibility to TC insertion and endovascular treatments, and the availability of peritoneal dialysis and kidney transplantation. Logistic regression and multilevel logistic regression were performed to evaluate possible interactions between the independent variables. A total of 7,973 patients across 47 HD centers were included in the survey. Public health patients accounted for 77% of the study sample. The overall vascular access profiles of the public and private insurance groups were significantly different (p < 0.001). For patients with public health insurance, the prevalence of any catheter was 25%, while that for private patients was 31.8% (p < 0.001). The prevalence of TCs was more common in private patients (15.3% vs. 23.1%, p < 0.001). AV accesses were more common in public health patients (75% vs. 68.2%, p < 0.001), as were fistulas (72.4% vs. 63.1%, p < 0.001). AV grafts were more prevalent among patients with private insurance (2.6 vs. 5.1%, p < 0.001). The availability of endovascular treatments increased the chance of having a TC by 2.3-fold (OR = 2.33, 95% CI = 1.30-4.18); however, it did not reduce the chance of having any catheter. A high chance of having a catheter was found when the time to AV access creation exceeded 60 days. The differences between public and private patients may be explained by underpayments and the decreased accessibility to care infrastructure in the public system, especially for endovascular treatments. In this sample, public health patients had a decreased risk of having a TC over an NTC. Differences in care accessibility and insurance type might influence the type of vascular access.

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.

Contemporary Strategies to Promote Dialysis Access Fistula Maturation

Background: The inability of a newly created arteriovenous fistula to support hemodialysis due to non-maturation results in increased complications secondary to catheter dependence. Methods: In view of the highly variable approaches by providers with heterogenous backgrounds (general surgery, vascular surgery, interventional radiology and interventional nephrology, urology, transplant surgery, etc.) we sought to describe a collection of algorithms that have functioned well in our hands to manage this challenging clinical problem and guide trainees and practicing clinicians alike.Results: Physical examination along with selective duplex ultrasound and fistulogram can identify most pathologies underlying non-maturation.Conclusion: Both endovascular and open techniques can be employed to optimize maturation rates in this complex population.

Inhibition of β-catenin signaling attenuates arteriovenous fistula thickening in mice by suppressing myofibroblasts

Background

Arteriovenous fistula (AVF) is the most important vascular access for hemodialysis; however, preventive treatment to maintain the patency of AVFs has not been developed. In endothelium, β-catenin functions in both the intercellular adherens complex and signaling pathways that induce the transition of endothelial cells to myofibroblasts in response to mechanical stimuli. We hypothesize that mechanical disturbances in the AVF activate β-catenin signaling leading to the transition of endothelial cells to myofibroblasts, which cause AVF thickening. The present study aimed to test this hypothesis.

Methods

Chronic kidney disease in mice was induced by a 0.2% adenine diet. AVFs were created by aortocaval puncture. Human umbilical vein endothelial cells (HUVECs) were used in the cell experiments. A pressure-culture system was used to simulate mechanical disturbances of the AVF.

Results

Co-expression of CD31 and smooth muscle alpha-actin (αSMA), loss of cell–cell adhesions, and the expression of the myofibroblast marker, integrin subunit β6 (ITGB6), indicated transition to myofibroblasts in mouse AVF. Nuclear translocation of β-catenin, decreased axin2, and increased c-myc expression were also observed in the AVF, indicating activated β-catenin signaling. To confirm that β-catenin signaling contributes to AVF lesions, β-catenin signaling was inhibited with pyrvinium pamoate; β-catenin inhibition significantly attenuated AVF thickening and decreased myofibroblasts. In HUVECs, barometric pressure-induced nuclear localization of β-catenin and increased expression of the myofibroblast markers, αSMA and ITGB6. These changes were attenuated via pretreatment with β-catenin inhibition.

Conclusions

The results of this study indicate that mechanical disturbance in AVF activates β-catenin signaling to induce the transition of endothelial cells to myofibroblasts. This signaling cascade can be targeted to maintain AVF patency.

Supplementary Information

The online version contains supplementary material available at 10.1186/s10020-022-00436-1.

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.

Vessel diameter and close surveillance helps predict early patency in native arteriovenous fistulas

INTRODUCTION

Arteriovenous fistulas are the preferred method of vascular access for haemodialysis. Data suggests patency rates can be low and may be related to vessel diameters prior to creation. We use specific size criteria for fistula selection. We aimed to establish patency rates in relation to vessel size and whether other factors affect fistula patency.

METHODS

Consecutive patients undergoing radiocephalic (RCF) or brachiocephalic (BCF) creation between 2016 and 2018 were analysed. Preoperative arterial and venous diameters were collected. Six-week and six-month primary and secondary patency rates were analysed to establish any impact of vessel size on patency and re-intervention rates between groups. A univariate analysis was performed.

RESULTS

Ninety four RCFs and 101 BCFs were created. Median artery and vein size for RCF were 2.7 and 3.0 mm respectively. For BCF, they were 4.6 and 4.3 mm respectively. At 6-weeks, overall satisfactory patency for RCF and BCF combined was 91.8%. 89.7% demonstrated primary patency; 2.1% secondary patency. At 6-months, overall patency was 78.7%; 58.5% demonstrated primary patency, 20.2% secondary patency. A univariate analysis, for both groups, revealed vein size was a significant predictor of overall satisfactory patency at 6-weeks, with larger veins more likely to remain patent (p = 0.025 RCF, p = 0.007 BCF). However, artery size was not predictive (p = 0.1 RCF, p = 0.5 BCF). At 6-months, neither artery nor vein diameter were predictive in either group. When comparing size of vessel based on fistula type, vessels used to create RCFs were smaller than those for BCFs (p < 0.001). RCFs were more likely to receive endovascular intervention or occlude when compared to BCFs (p = 0.014).

DISCUSSION

Excellent patency and maturation rates can be achieved using fairly strict vessel size criteria. Vein size might be the more important predictor of early success. RCFs can be challenging due to smaller vessels, but maturation rates can be optimised by close surveillance and aggressive re-intervention.

Ultrasound evaluation of access complications: Thrombosis, aneurysms, pseudoaneurysms and infections

Arteriovenous fistula (AVF) complications are classified based on fistula outcomes. This review aims to update colour Doppler (CD) and pulse wave Doppler (PWD) roles in managing early and late complications of the native and prosthetic AVF. Vascular access (VA) failure occurs because inflow or outflow stenosis activates Wirchow's triad inducing thrombosis. Therefore, the diagnosis of the tributary artery and outgoing vein stenosis will be the first topic considered. Post-implantation complications occur from the inability to achieve AVF maturation and dialysis suitability due to inflow/outflow stenosis. Late stenosis is usually a sequence of early defects repaired to maintain patency. Less frequently, in the mature AVF or graft, complications are acquired 'de novo'. They derive either from incorrect management of vascular access (haematoma, pseudoaneurysm, prosthesis infection) or wall pathologies (aneurysm, myxoid valve degeneration, kinking, coiling, abnormal dilation from defects of elastic structures). High-resolution transducers (10-20 MHz) allow the characterization of the wall damage, haemodynamic dysfunctions, early and late complications even if phlebography remains the gold standard for the diagnosis for its sensitivity and specificity.

The development of the Western Australian Haemodialysis Vascular Access Complexity instrument

Background

The Western Australian Haemodialysis Vascular Access Classification instrument was developed to classify the cannulation complexity of the arteriovenous fistula or arteriovenous graft as simple, challenging, or complex. Although the instrument was developed by experts in haemodialysis nursing, the instrument had not undergone formal validity or reliability testing.

Objectives

Evaluate the Western Australian Haemodialysis Vascular Access Classification instrument for content validity, interrater and test–retest reliability.

Design

Prospective cohort study.

Participants

Content validity was assessed by haemodialysis nursing experts (n = 8). The reliability testing occurred in one in‐centre and one satellite haemodialysis unit in Western Australia from September to November 2019. Reliability testing was performed by 38 haemodialysis nurses in 67 patients receiving haemodialysis and 247 episodes of cannulation.

Measurements

Interrater and test–retest reliability assessment was conducted using κ, adjusted κ, Bland–Altman plots, intraclass correlation coefficient and Pearson's correlation coefficient.

Results

The final version of the instrument (n = 20 items) had individual item‐level content validity indices ranging from 0.625 to 1.00 with a scale‐level content validity index of 0.89. For both interrater (n = 172 pairs) and test–retest (n = 101 pairs), most individual variables had excellent adjusted κ (n = 33 variables), some fair to good agreement (n = 6 variables) and one variable with poor agreement. The classification of simple, challenging and complex demonstrated adjusted κ of fair to good, to excellent agreement for interrater reliability with lower levels of agreement for test–retest reliability.

Conclusions

This instrument may be used to match a competency‐assessed nurse to perform the cannulation thereby minimising the risk of missed cannulation and trauma.

A prospective randomized feasibility trial comparing angiography and angiography with intravascular ultrasound for treatment of hemodialysis access failures

OBJECTIVE

Hemodialysis accesses suffer from limited primary patency requiring frequent interventions, revisions, or even abandonment. Prolongation of access life and usability with minimization of these adverse events is paramount. Endovascular methods are established first-line interventions for failing arteriovenous access and treatment of venous outflow stenoses. The Primary goal of this feasibility study was to evaluate intravascular ultrasound (IVUS) during interventional treatments on outcomes in those undergoing angiography for failing hemodialysis access. Secondary goals were to determine differences between IVUS and angiography on vessel and lesion characteristics and impact on treatment.

METHODS

In this prospective, randomized controlled trial, patients scheduled for angiography to evaluate and treat a failing hemodialysis access were randomized to use of angiography (DSA) alone or angiography plus IVUS (DSA + IVUS). Patients were treated by a standardized protocol and seen in follow-up at 2 weeks, and every 3 months for 2 years or until a study endpoint was reached. Measurement of vessel diameters, % stenosis, lesion length, and study endpoints (AV access thrombosis, re-intervention, or surgical revision) were recorded.

RESULTS

A total of 55 subjects were enrolled, 27 in the DSA cohort and 28 in the DSA + IVUS cohort. There were 41 treated lesions in each group. Freedom from the composite endpoint of AV access thrombosis or re-intervention was 46.3% in the DSA cohort and 61.0% in the DSA + IVUS cohort (p = 0.27). Diameter measurements matched between the two imaging modalities only 9 times out of 41 total comparison measures. In pre-treatment lesions with >80% stenosis, IVUS had a greater tendency than DSA to underestimate the severity of stenosis, whereas in pre-treatment lesions with 50-80% stenosis, DSA was more likely than IVUS to underestimate the severity of stenosis. Post-treatment % stenosis had mean difference of -7.5% between DSA versus DSA + IVUS cohorts. In five lesions with <30% stenosis measured by angiogram, IVUS led to treatment escalation.

CONCLUSION

In the interventional treatment of failing angioaccess, IVUS and angiography differ in the vast majority of cases in measurement of vessel diameter. A significant number of patients were found to have suboptimal therapeutic response by IVUS only, which led to an escalation in treatment, and in over one-third of cases, the IVUS results led to a change in treatment plan. The improved patency rates in the IVUS group was not statistically significant in this small population but should be further investigated in a larger trial.

Comparison of one-year patency rates of end-to-side and side-to-side anastomosis technique in proximal forearm region radial-cephalic fistulas

OBJECTIVES

In this study, the effects of anastomosis techniques on the results of patients with autogenous radial-cephalic proximal forearm fistula were investigated.

METHODS

Patients who underwent radial-cephalic proximal forearm fistula surgery (arteriovenous fistula) between April 2015 and August 2017 at the Department of Cardiovascular Surgery of Ordu University were compared retrospectively in terms of the results of anastomosis techniques. The study included 131 patients who had arteriovenous fistulas created by side-to-side and end-to-side anastomosis technique.

RESULTS

There was no significant difference in demographic data, comorbidities, radial artery, and cephalic vein diameters in patients undergoing radial-cephalic proximal forearm fistula surgery. However, it was observed that fistula maturation was earlier in the group with end-to-side anastomosis technique, and the one-year patency rates were higher in the group with side-to-side anastomosis technique.

CONCLUSION

In Arteriovenous fistulas created in the proximal forearm region, the one-year patency rate of the side-to-side anastomosis technique was higher, while the maturation of the end-to-side technique observed earlier.

Is the Fistula First Approach still valid?

The Fistula First Breakthrough Initiative, founded in 2003, was responsible for changing the access profile in the United States, increasing the prevalence of arteriovenous fistulas (AVFs) by 50% and reducing that of arteriovenous grafts (AVGs). However, the concept that AVFs are always the best access for all patients has been challenged. Discussion points are: (1) the questionable survival benefit of AVFs over AVGs, if one takes into account the high rates of primary AVF failure; (2) the potential benefits of using AVGs for greater primary success; and (3) the questionable benefit of AVFs over AVGs in patients with shorter survival, such as the elderly. The high rate of primary failure and maturation procedures leads to prolonged use of catheters, and it is one of the weaknesses of the fistula first strategy. AVGs proved to be better than AVFs as a second access after the failure of a first AVF, and in patients with non-ideal vessels, with greater primary success and reduced catheter times. AVGs appear to have a similar survival to AVFs in patients older than 80 years, with less primary failures and interventions to promote maturation. The most recent KDOQUI guidelines suggest an individualized approach in access planning, taking into account life expectancy, comorbidities and individual vascular characteristics, with the aim of chosing adequate access for the right patient, at the right time, for the right reasons.

Multicentre Study on the Efficacy of Brachial Artery Transposition Among Haemodialysis Patients

OBJECTIVE

Brachial artery transposition (BAT) is not a well known method for obtaining vascular access (VA) for maintenance haemodialysis. This study evaluated the outcomes of BAT.

METHODS

This multicentre retrospective cohort study included 233 consecutive patients who underwent BAT between January 2012 and December 2013. The indications were inadequate vessels for obtaining VA, severe heart failure, hand ischaemia, central vein stenosis/occlusion, or a history of catheter/graft infection. The transposed brachial artery was used only for arterial inflow and other routes were used for outflow.

RESULTS

BAT was successful in 227 patients, and adequate blood flow was achieved during dialysis sessions. The first successful cannulation was after a median of 18 days. BAT was performed using superficial veins as the return route in 127 patients and arteriovenous fistula (AVF) creation in 63 patients to prevent maturation failure. In 41 patients with central venous catheterisation, the transposed brachial artery was used for arterial inflow. The complications of BAT were impaired wound healing in 14 patients, including skin necrosis in two; large aneurysms in six, including a mycotic pseudo-aneurysm in one; arterial thrombosis in five; hand ischaemia in five; lymphorrhoea in four; and haematoma/bleeding in three. The transposed brachial artery was abandoned in four, three, three, and one case of arterial thrombosis/stenosis, haematoma/bleeding, skin necrosis, and large aneurysm, respectively. Access to the return routes failed in 48 cases because of vein damage caused by cannulation in 22, AVF thrombosis/stenosis in 14, catheter infection in six, and catheter occlusion in six. At two years, the primary patency rates of the transposed brachial artery and access circuit were 88% and 54%, respectively.

CONCLUSION

BAT is a safe and effective technique. The patency was high for the transposed brachial artery but adequate for the access circuit. BAT can be considered for patients with an unobtainable standard arteriovenous access.

Sterile inflammation in the pathogenesis of maturation failure of arteriovenous fistula

Chronic kidney disease is a widespread terminal illness that afflicts millions of people across the world. Hemodialysis is the predominant therapeutic management strategy for kidney failure and involves the external filtration of metabolic waste within the circulation. This process requires an arteriovenous fistula (AVF) for vascular access. However, AVF maturation failures are significant obstacles in establishing long-term vascular access for hemodialysis. Appropriate stimulation, activation, and proliferation of smooth muscle cells, proper endothelial cell orientation, adequate structural changes in the ECM, and the release of anti-inflammatory markers are associated with maturation. AVFs often fail to mature due to inadequate tissue repair and remodeling, leading to neointimal hyperplasia lesions. The transdifferentiation of myofibroblasts and sterile inflammation are possibly involved in AVF maturation failures; however, limited data is available in this regard. The present article critically reviews the interplay of various damage-associated molecular patterns (DAMPs) and the downstream sterile inflammatory signaling with a focus on the NLRP3 inflammasome. Improved knowledge concerning AVF maturation pathways can be unveiled by investigating the novel DAMPs and the mediators of sterile inflammation in vascular remodeling that would open improved therapeutic opportunities in the management of AVF maturation failures and its associated complications.

PATENCY-2 trial of vonapanitase to promote radiocephalic fistula use for hemodialysis and secondary patency

OBJECTIVE

Arteriovenous fistulas created for hemodialysis often fail to become usable and are frequently abandoned. This prospective trial evaluated the efficacy of vonapanitase, a recombinant human elastase, in increasing radiocephalic fistula use for hemodialysis and secondary patency.

METHODS

PATENCY-2 was a randomized, double-blind, placebo-controlled trial in patients on or approaching the need for hemodialysis undergoing radiocephalic arteriovenous fistula creation. Of 696 screened, 613 were randomized, and 603 were treated (vonapanitase n = 405, placebo n = 208). The study drug solution was applied topically to the artery and vein for 10 min immediately after fistula creation. The primary endpoints were fistula use for hemodialysis and secondary patency (fistula survival without abandonment). Other efficacy endpoints included unassisted fistula use for hemodialysis, primary unassisted patency, fistula maturation and unassisted maturation by ultrasound criteria, and fistula procedure rates.

RESULTS

The proportions of patients with fistula use for hemodialysis was similar between groups, 70% vonapanitase and 65% placebo, (p = 0.33). The Kaplan-Meier estimates of 12-month secondary patency were 78% (95% confidence interval [CI], 73-82) for vonapanitase and 76% (95% CI, 70-82) for placebo (p = 0.93). The proportions with unassisted fistula use for hemodialysis were 46% vonapanitase and 37% placebo (p = 0.054). The Kaplan-Meier estimates of 12-month primary unassisted patency were 50% (95% CI, 44-55) for vonapanitase and 43% (95% CI, 35-50) for placebo (p = 0.18). There were no differences in the proportion of patients with fistula maturation or in fistula procedure rates. Adverse events were similar between groups. Vonapanitase was not immunogenic.

CONCLUSIONS

Vonapanitase treatment did not achieve clinical or statistical significance to meaningfully improve radiocephalic fistula surgical outcomes. Outcome in the placebo group were better than in historical controls. Vonapanitase was well-tolerated and safe.

TRIAL REGISTRATION

clinicaltrials.gov: NCT02414841 (https://clinicaltrials.gov/ct2/show/NCT02414841).

Single Asian Center Experience Using the Flixene™ Early Cannulation Graft for Hemodialysis Access Creation

BACKGROUND

The aim of this study was to review the efficacy of the Flixene™ (Atrium™, Hudson, NH, USA) hemodialysis arterio-venous graft (AVG) in a multiethnic Asian cohort of patients with end-stage renal failure (ESRF). Primary outcome was graft primary patency rate and secondary end points included graft usability, time to cannulation, reinterventions required for access salvage, complications, and patient mortality.

METHODS

Single-center, single-arm, multi-investigator nonrandomized retrospective study. Patients with ESRF who underwent Flixene™ graft implantation over a two-year period (January 2017 - December 2018) were included to allow at least one-year follow-up. Demographics, procedural and follow-up data were collected from the hospital electronic medical records.

RESULTS

About 48 patients (49 AVG) were included. There were 24 (50%) men; mean age 63.7 (IQR 58.2-71.3) years. Technical success rate was 45/49 (91.8%); 4/49 (8.2%) AVG created did not reach cannulation. 11/49 (22.4%) and 28/49 (57.1%) achieved cannulation within 1 and 2 weeks, respectively. 6- and 12- month primary patencies were 33.5% and 19.6%, respectively. Primary-assisted patency rates were 46.6% and 29.6% at the same time intervals. Secondary patency rate was 77.6% and 63.9% at 6 and 12 months, respectively. There were 6 (12.2%) graft infections requiring explant and one-year mortality was 14%.

CONCLUSIONS

Our experience with the Flixene™ early cannulation graft is comparable with other AVGs in terms of patency and infection rates. However, early cannulation rates are lower than in other case series.

PDGFRA in vascular adventitial MSCs promotes neointima formation in arteriovenous fistula in chronic kidney disease

Chronic kidney disease (CKD) induces the failure of arteriovenous fistulas (AVFs) and promotes the differentiation of vascular adventitial GLI1-positive mesenchymal stem cells (GMCs). However, the roles of GMCs in forming neointima in AVFs remain unknown. GMCs isolated from CKD mice showed increased potential capacity of differentiation into myofibroblast-like cells. Increased activation of expression of PDGFRA and hedgehog (HH) signaling were detected in adventitial cells of AVFs from patients with end-stage kidney disease and CKD mice. PDGFRA was translocated and accumulated in early endosome when sonic hedgehog was overexpressed. In endosome, PDGFRA-mediated activation of TGFB1/SMAD signaling promoted the differentiation of GMCs into myofibroblasts, extracellular matrix deposition, and vascular fibrosis. These responses resulted in neointima formation and AVF failure. KO of Pdgfra or inhibition of HH signaling in GMCs suppressed the differentiation of GMCs into myofibroblasts. In vivo, specific KO of Pdgfra inhibited GMC activation and vascular fibrosis, resulting in suppression of neointima formation and improvement of AVF patency despite CKD. Our findings could yield strategies for maintaining AVF functions.

Quality indicators of vascular access procedures for hemodialysis

Improved quality of surgical procedures can minimize complications, the morbidity and mortality of patients, and in addition decrease costs. Quality indicators in angioaccess surgery are, however, not clearly defined. The aim of this review article is therefore to find the most important factors affecting quality in vascular access procedures. Even though autogenous arteriovenous fistula has been recognized as the best vascular access for hemodialysis, the high percentage of unsuccessful attempts associated with it raises the question about quality assessment in angioaccess procedures. Unfortunately, quality indicators in vascular access surgery are difficult to define and measure. Among those that can be obtained are: the time between the presentation of patients to a vascular access surgeon and the construction of a fistula, the percentage of autogenous fistulas, the percentage of functional fistulas in prevalent and incident hemodialysis patients, the percentage of creation of a functional fistula in the first attempt, and durability of an access. Organizational improvement and educational programs are also necessary at institutions with inferior quality indicators of vascular access care, as even small increase in quality may mean the survival of an individual patient. Quality indicators in angioaccess surgery can also serve as a helpful tool in choosing the best vascular access surgeon or vascular access center. The choice can consequently reflect on increased survival and quality of life in patients needing hemodialysis.

The Role of Far Infrared Therapy in the Unassisted Maturation of Arterio-venous Fistula in Patients with Chronic Kidney Disease

Introduction:

The goal of arterio-venous fistula (AVF) creation is to achieve a well-functioning access that can be cannulated repetitively and can provide adequate flow for the dialysis. The objective of this study was to assess the role of far infrared (FIR) therapy in the unassisted maturation of newly created AVF in patients with chronic kidney disease (CKD).

Materials and Methods:

In this prospective open labeled randomised control trial, 107 patients were randomized. Participants in the control arm received oral clopidogrel 75 mg once daily for 30 days along with isometric hand exercise, whereas those in the test arm received FIR therapy twice weekly, 40 min session each, for 4 weeks. A biopsy from venous end was taken during fistula surgery. Doppler study of AVF was done at the end of the 4^th and 12^th week to assess AVF. Vascular access guidelines proposed by National Kidney Foundation –Kidney Disease Outcomes Quality Initiative (NKF- KDOQI) in 2006 were adapted to define the maturation of AVF.

Results:

Out of 107 patients, 51 were randomized to the test arm and 56 to the control arm. During follow-up, the blood flow rate through AVF (Qa) and the diameter of the cephalic vein draining (CVd) the AVF were measured. At the end of 3 months, Qa in Radio-Cephalic Fistula (RCF) was high in the test arm (p–0.003). The AVF failures were 5 (10.2%) and 14 (28%) in the test and control arms, respectively (p: 0.025). However, when adjusted for AVF failure within 6 h of surgery (may be related to surgical technique) this difference in AVF patency was statistically insignificant (p: 0.121). The mean Qa was high in patients with an arterial intimal medial thickness (AIMT) <0.5 mm. The IMT of the anastomosed artery had statistically significant correlation with the primary failure rate of AVF (P < 0.001).

Conclusion:

In patients with CKD, FIR therapy was effective in increasing the AVF blood flow rate at the end of 3 months, though the difference in primary failure rate was statistically insignificant.