Hemodialysis Vascular Access Research Articles

Snuff-Box Versus Wrist Radiocephalic Arteriovenous Fistulas for Hemodialysis: Maturation Tend and its Affecting Factors

Thanks to its well proved long-term patency rates, native radiocephalic arteriovenous fistula remains the most commonly used vascular access type. Many articles had approached the criteria leading to a mature fistula. The aims of this work are to evaluate variables that may affect the maturation of distal fistulas and to determine if wrist fistulas have less risk of maturation failure than the snuff-box fistulas. We recorded all distal radiocephalic fistulas that had been created from January 2018 to February 2021. Epidemiological and clinical profile of patients, characteristics of performed fistulas and per and post-operative data were recorded and analyzed. From January 2018 to February 2021, 165 upper limb vascular accesses for hemodialysis had been created including 47 (28.5%) distal radiocephalic fistulas. Among the latter, 39 (83%) fistulas were performed at the wrist and 8 (17%) at snuff-box area. There were 34 men (72.3%). Mean age was 67years (37-87). Both types of fistulas had approximately an identic frequency of primary maturation failure (50% for radiocephalic versus 47.2% for snuff-box fistulas). Secondary maturation had been achieved in 9 fistulas. Patients with medical history of dyslipidemia, peripheral arterial disease (PAD), central catheter placement, and bad quality of vessels tend to develop an immature fistula. No significant differences in maturation tend between snuff-box and wrist fistulas had been demonstrated. Thus, it seems reasonable to privilege the creation of the most distal fistulas allowing preservation of wrist fistulas as a second option in case of snuff-box fistulas maturation failure. However, selection of the most suitable cases for snuff-box fistulas creation, based on clinical and duplex ultrasound data, remains primordial.

Forearm Arteriovenous Fistula Maturation Delay due to Juxta-Anastomotic Stenosis: Role of Percutaneous Angioplasty

Introduction: Arteriovenous fistula is the optimal vascular access for hemodialysis as it has the best long-term patency rate and the lowest complication rate. Although we are still lacking consensus, surgery has been advocated as the best treatment option for maturation delay. We proposed to evaluate the results of endovascular approach of arteriovenous fistula’s maturation delay in our hospital. Methods: We conducted a retrospective study, selecting patients referred to our diagnostic and therapeutic angiography unit due to arteriovenous fistula delayed maturation, between April 2017 and June 2020. Results: Thirty-four patients were referred to our center due to maturation delay, of which six (17.7%) were excluded as the diagnosis was not confirmed and six (17.7%) because the lesions were not suitable for percutaneous angioplasty. The other 22 patients (64.7%) were subjected to percutaneous endovascular treatment. Mean age was 67.3 ± 13.8 years. Eighteen patients (81.8%) had maturation delay due to peri-anastomotic stenosis; 12 (66.7%) were forearm fistulas (all radio-cephalic). Mean follow-up time was 21.2 ± 11.2 months. Eleven (91.7%) fistulas were salvaged, although four (33.3%) needed reintervention. Primary and assisted primary patencies at 6 and 12 months were 66.7% vs 91.7% and 58.3% vs 91.7%, respectively. Conclusion: Our results point out that endovascular treatment is a good treatment option for maturation delay of forearm arteriovenous fistulas due to juxta-anastomotic stenosis. Even though surgical treatment appears to have better primary patency, a step-by-step approach seems to be a valid strategy, as our assisted primary patency shows.

Vascular Factors Affecting Outcomes of Snuffbox AV Fistula with Side-to-Side Anastomosis: A Single Institutional Observational Study

Background: Angioaccess is considered the "Tendon of Achilles" for hemodialysis. Arteriovenous fistula (AVF) is the commonly entailed vascular access for hemodialysis. Objectives: The present study evaluates the outcomes of anatomical snuffbox AVF by preoperative and postoperative color Doppler scans. It also determines the anatomical snuffbox AVF maturation rate concerning preoperative radial artery diameter (RAD), cephalic vein diameter (CVD), cephalic vein distensibility, and peak systolic velocity (PSV). Methods: This study was conducted from April 2020 to January 2021 on end-stage renal diseases (ESRD) patients undergoing an operation for anatomical snuffbox AVF creation at our center after taking permission from the institutional ethics committee and written informed consent from patients. Results: Thirty-five ESRD patients underwent snuffbox arteriovenous fistula (SBAVF) creation, including 68% males and 32% females. Diabetes mellitus was noted in 40% and hypertension in 80%. Successful AVF maturation was noted in 92% (69.57% of males and 30.43% of females). The mean RAD assessed on color Doppler ultrasonography (CDUS) preoperatively was 1.79 mm, while the peak velocity of the radial artery at the snuffbox was 23.80 cm/s. Conclusions: We recommend applying the side-to-side configuration as its anastomosis angle is less owing to the lesser kink on the anastomotic site. A longer segment of anastomosis is achieved, and better fluid dynamics and WSS profiles are seen in this configuration with good outcomes.

Using root cause analysis as a tool to reduce central venous catheters in haemodialysis patients.

Haemodialysis remains the most common modality of renal replacement therapy. National and international guidelines continue to promote arteriovenous fistulas or grafts as the preferred vascular access for haemodialysis, given the increased risks associated with use of central venous catheters (CVCs). Our renal centre pursues a 'fistula first' culture and uses root cause analysis and a patient safety incident based approach to meet the recommended standards of minimal CVC use in dialysis patients. We undertook a retrospective observational review looking at patterns of CVC use amongst our patients to identify themes and changes over time. Using data collected over a 5 year period, we examined 100 patient safety incidents involving CVC use in planned haemodialysis patients. We used a contributory factors framework to identify systemic contributors to each incident. During the study period our centre achieved the national standard of at least 60% of incident dialysis patients commencing planned haemodialysis via arteriovenous access. About 26% of cases of CVC use in incident dialysis patients were deemed potentially avoidable. The most common contributory factor identified in these cases was poor communication. Using a root cause analysis based methodology to examine CVC use in haemodialysis is a novel approach to quality improvement in this area. Our methodology can be used as a framework by other centres to optimise the provision of safe, effective, and timely vascular access for dialysis, with multiple benefits for both renal services and individual patients.

Vascular accesses for hemodialysis in Ceará-Brazil

Backgroung: the ideal access for hemodialysis is represented by arteriovenous fistulas both as initial access and in use and are determinants of health care parameters for chronic renal patients. Objective: to evaluate vascular access for hemodialysis. Methods: this is a cross-sectional study, with a sample of 2513 individuals on hemodialysis in Ceará. Data were collected on age, sex, time of treatment, underlying disease, initial access and access in use. The data were divided into two groups, the interior of the state and the Metropolitan Region of Fortaleza, in the State of Ceará, and compared using the Student’s Test (p<0.05). Results: the most common age group was between 19 and 64 years (73%). Men prevailed in both regions, 713 (63%) in the countryside and 792 (57%) in the metropolitan area. The most common cause of Chronic Kidney Disease was Hypertension 306 (27%), followed by Disease of undetermined cause 295 (26%) in the countryside; in the metropolitan region, Diabetes Mellitus 356 (26%) was the main cause, followed by Hypertension and Disease of undetermined cause, each with 344 (25%), p=0.001. In the countryside, 9% started treatment for fistula while in the metropolitan area 12%, p=0.011. 79% of patients in the countryside used fistulas and 81% in the metropolitan area, p=0.156. Conclusion: arteriovenous fistulas are more frequent as initial accesses in the metropolitan region than in the interior, but there is an equivalence of fistulas in use in both regions. Catheter is the main initial access route. The evaluation of vascular accesses in Ceará showed that hemodialysis services are able to maintain good parameters of care for patients with chronic kidney disease.

Direct arterial puncture for hemodialysis, a neglected but simple and valuable vascular access

IntroductionThe purpose of this study is to present the prevalence and effects of direct arterial puncture (DAP) for hemodialysis patients, and to introduce optimal option for the vascular access (VA) in certain hemodialysis patients with poor condition of vascular or cardiac function in a compelling situation.MethodsThis was a cross-sectional study. Demographic characteristics and laboratory data were extracted from the health care system. Relevant DAP information was collected by a questionnaire. Case-control matching was performed to compare the hemodialysis adequacy between DAP and other VAs.ResultsA total of 526 patients were selected for analysis by convenience sampling, of which 38 patients relied on DAP for hemodialysis. The main reasons using DAP for hemodialysis included the cost of arteriovenous access creation or maintenance in 19(50%) patients and the poor condition of vascular or cardiac function in 14 (39.5%) patients. Some complications of DAP occurred, such as aneurysm or pseudoaneurysm in 16(42.1%) patients, infiltration in 12 (31.6%) patients. Differences in hemodialysis adequacy were not statistically significant between DAP and other types of VA.ConclusionIn conclusion, DAP can meet the need of prescription hemodialysis, yet it has several limitations. Although the patients in our study were long-term dependent on DAP for hemodialysis with various reasons, we do not recommend DAP as a long-term vascular access if better options are available. However, DAP should not be overlooked to be a supplemental VA for hemodialysis with adequate blood flow and availability for individuals with poor condition of vascular or cardiac function in a compelling situation.

Functional analysis of arteriovenous fistulae in non-contrast magnetic resonance images

Background and ObjectiveArteriovenous fistulae (AVF) are the preferred mode of hemodialysis vascular access and their successful maturation is critical to reduce patient morbidity, mortality, cost, and improve quality of life. Peri-anastomotic venous segment stenosis is the primary cause of AVF maturation failure. The objective is to develop a software protocol for the functional analysis of arteriovenous fistula. MethodWe have developed a standard protocol for the anatomical analysis of the AVF to better understand the mechanisms involved in AVF stenosis and to identify future imaging biomarkers for AVF success or failure using non-contrast magnetic resonance imaging (MRI). The 3D model of the AVF is created using a polar dynamic programming technique. Analysis has been performed on six Yorkshire cross domestic swine, but techniques can be applied into clinical settings. ResultsDifferences in AVF angles and vein curvature are associated with significant variability of venous cross-sectional area. This suggests that the pattern of stenosis is likely to be dependent upon hemodynamic profiles which are largely determined by AVF anatomical features and could play an important role in AVF maturation. ConclusionsThis protocol enables us to visualize and study the hemodynamic profiles indirectly allowing early stratification of patients into high and low risk groups for AVF maturation failure. High risk patients could then be targeted with an enhanced process of care or future maturation enhancing therapies resulting in a much-needed precision-medicine approach to dialysis vascular access.

Contact Laxative Use and the Risk of Arteriovenous Fistula Maturation Failure in Patients Undergoing Hemodialysis: A Multi-Center Cohort Study.

Laxatives are commonly prescribed for constipation management; however, they are recognized as an independent factor associated with cardiovascular diseases. Arteriovenous fistula (AVF) is the closest to the ideal model of hemodialysis (HD) vascular access and part of the cardiovascular system. Our study aims to explore the association of contact laxative use with AVF maturation outcomes in patients undergoing HD. We conducted a multi-center cohort study of 480 contact laxative users and 472 non-users who had undergone initial AVF creation. All patients were followed until the outcomes of AVF maturation were confirmed. Multivariable logistic regression models were performed to evaluate the risk of AVF maturation failure imposed by laxatives. Here, we found that patients who used contact laxatives were significantly associated with an increased risk of AVF maturation failure compared to non-users (adjusted odds ratio, 1.64; p = 0.003). Notably, the risk of AVF maturation failure increased when increasing their average daily doses and cumulative treatment days. In conclusion, our study found a significant dose- and duration-dependent relationship between contact laxative use and an increased risk of AVF maturation failure. Thus, laxatives should be prescribed with caution in this population. Further studies are needed to validate these observations and investigate the potential mechanisms.

Abstract No. 523 National trends in complications of vascular access for hemodialysis and analysis of racial disparities among patients with end-stage renal disease

Abstract No. 523 National trends in complications of vascular access for hemodialysis and analysis of racial disparities among patients with end-stage renal disease

A longitudinal study of the arterio-venous fistula maturation of a single patient over 15 weeks

Arterio-venous fistula creation is the preferred vascular access for haemodialysis, but has a large failure rate in the maturation period. Previous research, considering the remodelling mechanisms for failure-to-mature patients, has been limited by obtaining the patient-specific boundary conditions at only a few points in the patient history. Here, a non-invasive imaging system was used to reconstruct the three-dimensional vasculature, and computational fluid dynamics was used to analyse the haemodynamics for one patient over 15 weeks. The analysis suggested evidence of a control mechanism, which adjusts the lumen diameter to keep the wall shear stress near constant in the proximal regions of the vein and artery. Additionally, the vein and artery were shown to remodel at different growth rates, and the blood flow rate also saw the largest increase within the first week. Wall shear stress at time of creation may be a useful indicator for successful AVF maturation.

The vulnerability of maintenance dialysis patients with COVID-19: mortality and risk factors from a developing country

Patients on maintenance dialysis therapy are especially vulnerable to COVID-19 and its complications. This study aimed to assess the incidence, epidemiological characteristics, and mortality rate of COVID-19 among maintenance dialysis patients. This retrospective observational chart review study included 548 patients from all dialysis units in the West Bank of Palestine who acquired COVID-19 between 5 March 2020, and 11 August 2021. We collected data on patients' demographics, clinical features, and outcomes. A multivariable logistic regression model was used to assess independent risk factors for COVID-19-related mortality. The incidence of COVID-19 among maintenance dialysis patients was 35.3%, as 548 out of 1554 patients have tested positive during the study period. Patients on haemodialysis were three times riskier to get infected than those on peritoneal dialysis (37% vs 11.3%). Half (50.2%) of infected patients required hospitalisation, and 24.5% were admitted to an intensive care unit, while the mortality rate stood at 26.8%. Old age, male sex, central venous catheter use, comorbid diabetes, smoking, and having an RH negative blood group type were determined to be significantly associated with increased risk of mortality. In conclusion, the incidence of COVID-19 among Palestinian maintenance dialysis patients was notably high, especially among haemodialysis patients. High rates of hospitalisation, ICU admission, intubation and death were observed, and predictive factors for COVID-19-related mortality were identified. Therefore, the implementation of strict infection control measures and promotion of home dialysis are warranted to reduce the infection rate. KEY MESSAGES The incidence of COVID-19 among Palestinian maintenance dialysis patients was notably high; more than one-third of the total dialysis population acquired COVID-19, with haemodialysis patients being three times more likely to get infected compared to their peritoneal dialysis counterparts. The mortality rate among maintenance dialysis patients was 26.8%, more than 25 times higher than that of the general population. The risk of mortality was significantly increased with age, male sex, smoking, diabetes, and having central venous catheter as vascular access for haemodialysis. Strict infection control measures, as well as the promotion of home dialysis, are necessary to reduce the risk of infection.

A Comparison Between the Efficacy and Safety of Endovascular Arteriovenous Fistula Creation and Surgical Fistula Creation: A Systematic Review and Meta-Analysis.

An endovascular arteriovenous fistula is a recent technological advancement in hemodialysis vascular access. This systematic review and meta-analysis aimed to investigate the efficacy and safety of endovascular arteriovenous fistula (eAVF) creation compared with surgical arteriovenous fistula (sAVF) creation among patients with chronic kidney disease.We searched Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE, Clinical Trials.gov, and the WHO International Clinical Trials Registry Platform until May 2021 to perform meta-analyses using random-effects models. Pre-specified primary outcomes were fistula maturation, procedure-related complications, and patient satisfaction. Secondary outcomes were procedural technical success, procedure time, all adverse events, and medical expenditure. The risk of bias in non-randomized studies of the interventions assessment tool, and the Grading of Recommendation, Assessment, Development, and Evaluation (GRADE) approach were used to assess the quality of individual studies and the body of evidence, respectively.In seven studies including 860 patients, endovascular arteriovenous fistula creation had little to no effect on fistula maturation (odds ratio, 0.58; 95% confidence intervals, 0.05 to 6.91). Meta-analysis could not be performed for procedure-related complications and patient satisfaction due to insufficient data. For secondary outcomes, endovascular arteriovenous fistula resulted in a slight to no difference in procedural technical success (odds ratio, 0.69: 95% confidence intervals, 0.04 to 11.98) and all adverse events (odds ratio, 6.31; 95% confidence intervals, 0.64 to 62.22). Endovascular fistula creation incurred less medical expenditure than sAVF (mean difference, USD 12760; 95% confidence intervals, -19710 to -5820). Meta-analysis for procedure time was not performed because one of the studies had a critical risk of bias. All of these outcomes were of low certainty of evidence or very low certainty of evidence.There was limited evidence for supporting endovascular arteriovenous fistula creation over conventional surgical arteriovenous fistula creation for patients with chronic kidney disease. Multicenter randomized controlled trials are needed to confirm the efficacy and safety of eAVFs in selected populations.

Hemodialysis vascular access in elderly patients: A comprehensive review.

The number of elderly patients initiating hemodialysis (HD) increased considerably over the past decade. Arteriovenous fistulas (AVFs) are the preferred vascular access (VA) type in most HD patients. Choice of VA for older hemodialysis patients presents a challenge. The higher incidence of comorbidities, longer AVF maturation times, risk of primary failure, risk of patency loss, and shorter life expectancy are important factors to consider. In this review we provide a comprehensive analysis on maturation rates, primary failure, patency, and mortality regarding vascular access in patients older than 75 years of age.

Patient-specific computational haemodynamics associated with the surgical creation of an arteriovenous fistula

Despite arteriovenous fistulae (AVF) being the preferred vascular access for haemodialysis, high primary failure rates (30-70%) and low one-year patency rates (40-70%) hamper their use. Furthermore, AVF creation has been associated with haemodynamic changes causing maladaptive cardiac remodelling leading to cardiovascular (CV) complications. In this study, we present a new workflow for characterising the haemodynamic profile prior to and following surgical creation of a successful left radiocephalic AVF in a 20-year-old end-stage kidney disease patient. The reconstructed vasculature was generated using multiple ferumoxytol-enhanced magnetic resonance angiography (FeMRA) datasets. Computational fluid dynamics (CFD) simulations utilising a scale-resolving turbulence model were completed to investigate the changes in the proximal haemodynamics following AVF creation, in addition to the post-AVF juxta-anastomosis flow patterns, which is impractical to obtain in-vivo. Following AVF creation, a significant 2-3-fold increase in blood flow rate was induced downstream of the left subclavian artery. This was validated through comparison with post-AVF patient-specific phase-contrast data. Proximal to the anastomosis, the increased flow rate yielded an increase in time-averaged wall shear stress (WSS), which is a key marker of adaptive vascular remodelling. In the juxta-anastomosis region, the success of the AVF was discussed with respect to the National Kidney Foundation's vascular access guidelines, where the patient-specific AVF met the flow rate and geometry criterion. The AVF venous diameter exceeded 6mm and the venous flow rate surpassed 600mL/min. This workflow may potentially be significant clinically when applied to multi-patient cohorts, with population-wide patient-specific conclusions being ascertained for the haemodynamic assessment of AVFs and improved surgical planning.

Endothelial Cell TGF-β (Transforming Growth Factor-Beta) Signaling Regulates Venous Adaptive Remodeling to Improve Arteriovenous Fistula Patency.

Arteriovenous fistulae (AVF) are the gold standard for vascular access for hemodialysis. Although the vein must thicken and dilate for successful hemodialysis, excessive wall thickness leads to stenosis causing AVF failure. Since TGF-β (transforming growth factor-beta) regulates ECM (extracellular matrix) deposition and smooth muscle cell (SMC) proliferation-critical components of wall thickness-we hypothesized that disruption of TGF-β signaling prevents excessive wall thickening during venous remodeling. A mouse aortocaval fistula model was used. SB431542-an inhibitor of TGF-β receptor I-was encapsulated in nanoparticles and applied to the AVF adventitia in C57BL/6J mice. Alternatively, AVFs were created in mice with conditional disruption of TGF-β receptors in either SMCs or endothelial cells. Doppler ultrasound was performed serially to confirm patency and to measure vessel diameters. AVFs were harvested at predetermined time points for histological and immunofluorescence analyses. Inhibition of TGF-β signaling with SB431542-containing nanoparticles significantly reduced p-Smad2-positive cells in the AVF wall during the early maturation phase (days 7-21) and was associated with decreased AVF wall thickness that showed both decreased collagen density and decreased SMC proliferation. SMC-specific TGF-β signaling disruption decreased collagen density but not SMC proliferation or wall thickness. Endothelial cell-specific TGF-β signaling disruption decreased both collagen density and SMC proliferation in the AVF wall and was associated with reduced wall thickness, increased outward remodeling, and improved AVF patency. Endothelial cell-targeted TGF-β inhibition may be a translational strategy to improve AVF patency.

FC 100: Echocardiography: A Promising Screening and Monitoring Tool for Central Venous Stenosis in Hemodialysis Patients

Abstract BACKGROUND AND AIMS Central venous stenosis (CVS) is a common but underestimated complication of vascular access in hemodialysis (HD) patients. The objective of this study was to compare the diagnostic efficacy of echocardiography and computed tomography angiography (CTA) for CVS in HD patients with access dysfunction. METHOD This was a retrospective study. HD patients with access dysfunction admitted to our institute between 1 April 2021 and 31 October 2021 were enrolled. Echocardiography, CTA and digital subtraction angiography (DSA) were performed to assess CVS. Receiver operator characteristic analysis was performed to compare the diagnostic efficacy of echocardiographic parameters and CTA for CVS, with DSA results as the reference standard. RESULTS A total of 167 HD patients (70 males, age 63 ± 13 years) were enrolled, among whom 99 (59%) were diagnosed with CVS based on DSA and only 9 presented with significant clinical symptoms of CVS. Among all of the echocardiographic parameters, superior vena cava (SVC) diameter showed the highest efficacy for CVS diagnosis (cut-off value ≤12 mm, specificity 70%, sensitivity 77%), which was equivalent to CTA (AUC 0.79 versus 0.81; P = 0.646) (Figure 1A). Some of the other echocardiographic parameters, including maximal and minimal right atrial volume (RAV), also showed moderated diagnostic efficacy for CVS. The specificity and sensitivity increased when echocardiography and CTA were used to diagnose brachiocephalic vein and SVC stenosis instead of total CVS (Figure 1B). Patients with CVS had a smaller SVC diameter (9.8 ± 3.5 mm versus 13.7 ± 3.3 mm; P < 0.001) and a reduced right RAV [RAV max median 20 (interquartile range 15–27) mL versus 31(24–39) mL; P < 0.001; RAV min 8 (5–10) mL versus 14 (10–17) mL; P < 0.001] compared with non-CVS patients. Spearman's rank correlation showed a significant negative correlation between RAV and hemodialysis vintage. CONCLUSION With equivalent diagnostic power for CVS to CTA, echocardiography has the potential to be used as a screening and monitoring tool for CVS in HD patients with access dysfunction.

MO792: Validation and Applicability of an Innovative Monitoring System for Vascular Access in Haemodialysis—A Multicentre Study

Abstract BACKGROUND AND AIMS Routine systems for monitoring vascular access (VA) performance are lacking. We recently showed that with a VA triage system it is possible to improve the average value of a number of HD efficiency parameters and that the triage score was associated with clinical outcomes [1]. The triage categorization is generated monthly by a scoring system which is based on a number of parameters (blood flows, VA pressure values, end HD circuit clots and a dedicated score of the external VA examination) recorded at each session by the staff and by the KT/V value recorded once every month. According to threshold values, each VA is classified as Green (G), Yellow (Y) or Red (R), thus attracting the attention of the staff. In our open-label single centre study, with 3 years of follow-up, the average VA scores improved significantly and G VA associated with lower mortality, compared to the Y and R VA. To validate our triage system with a multicentre, blinded approach in a large number of patients. The primary outcome was to evaluate if the triage identifies VA with an increased rate of complications; the secondary outcome was to verify the association of G VA score with better clinical outcomes. METHOD In this interventional prospective multicentre study, each centre used the electronic spreadsheet without knowledge of the generated score and triage. After 6 months of system implementation, 2 years of follow-up (1 January 2020–1 December 2021) were planned to record VA-related events. Two external reviewers evaluated the records. A minimum of 3 months VA follow-up was necessary for patients’ enrolment. RESULTS From 18 HD centres we enrolled 757 patients, aged 64.5 ± 15.5 years; x/y M/F; 27% diabetics; HD since 24.4 ± 32.4 months; 369 (48.7%) with arteriovenous fistula (AVF) and 388 (51.3%) with permanent central venous catheter (CVC). During 11.4 ± 5.6 months of follow-up (range 3–23), 108 537 HD sessions were recorded on the triage electronic spreadsheet, with 214 total clinical events and an event-free time of 224.5 ± 172 days (range 4–713). The VA-related events were 150 (70.1%) with an event-free time of 230 ± 160 days (range 11–713). As of today, we have the association of VA triage with VA events in a subgroup of 300 patients (66.1 ± 11.7 years; HD vintage 28 ± 18; diabetes 27.6%; 180 with AVF and 120 had CVC) who are not different from the remaining 457. In this subgroup, 54% had G VA triage, 39% Y and 7% R. In the subgroups distinguished by VA type, AVF cases (64.5 ± 12.1 years; HD since 30.3 ± 27.2; 24.4% diabetics) were triaged as G in 54%, Y in 41% and R in 5%, while CVC cases (66.5 ± 11.7 years; HD since 28.8 ± 36.5 months; 34.3% diabetics) were G in 54%, Y in 34% and R in 11%. 83 patients had VA-related events VA during 16.3 ± 2.2 months of follow-up (range 3–23), with an event-free time of 237.8 ± 195.9 days. Figure 1 shows how both AVF and CVC patients, stratified into only two triage groups (G versus Y and R together) according to their average triage, had significantly different time-free from events, which was higher in both populations (AVF P = 0.04; CVC P = 0.001) in the green triage groups. CONCLUSION Our VA triage system identifies 40% of vascular accesses as yellow-red triage, thus deserving clinical surveillance. This score has increased the rate of clinical complications which, according to the time survival curve could be detectable roughly 237.8 days before the event developed.

MO771: Haemodialysis Access Flow Measurement: Comparison of Ultrasound Dilution and Ultrafiltration Method on Nikisso DBB-EXA™ Dialysis Machine

Abstract BACKGROUND AND AIMS The regular measurement of the haemodialysis vascular access (VA) flow demonstrates a protective effect over thrombotic complications [1]. Transonic® Ultrasound dilution technique was first introduced in 1995 and progressively became a method of reference for recirculation and blood flow measurement on haemodialysis VA [2]. It is based on the technique of haemodilution with a certain volume of 0.9% NaCl and the measure of recirculation with inversed lines using the ultrasound technique. Consecutively the VA flow is estimated with a certain formula. Nikisso DBB-EXA™ dialysis machine has the capacity to measure the VA recirculation rate by photometry performing a controlled rise on ultrafiltration rate. The aim of the present study is to compare the VA flow rate between the Transonic® Ultrasound dilution technique and the Nikisso DBB-EXA™ Ultrafiltration method. METHOD The primary outcome of the study is the association of VA flow measured by Transonic® and the Nikisso DBB-EXA™. During the first half of the same dialysis session, we measured the VA recirculation and flow rate twice with the two methods under a constant dialysis blood pump flow of 250–300 mL/min with the ultrafiltration and haemodiafiltration interrupted during the procedure after having reversed the dialysis lines. RESULTS The values are represented as mean ± SD. A total of 18 chronic haemodialysis patients (13 male: 5 female, mean age: 70 ± 14 years) participated in the study. They were haemodynamically stable without acute clinical conditions and were dialysed with a well-functioning arteriovenous fistula for at least 6 months. The mean value of recirculation with inverted dialysis lines for the Transonic® method was 20.79 ± 7.58% and for the Nikisso DBB-EXA™ was 24.43 ± 7.77. The mean values of VA blood flow with the Transonic® method were 1229 ± 588 mL/min and for the Nikisso DBB-EXA™ 1096 ± 490 mL/min. The measured values of the two methods presented a significant positive correlation (by Pearson) (R = 0.920, P < 0.001) (Figure). CONCLUSION There is a significantly positive correlation concerning the VA flow measurement between the reference method of Transonic® and the Ultrafiltration method offered by the Nikisso DBB-EXA™. Larger studies are needed to confirm this correlation with an additional comparative analysis of the reproducibility of measurements.

MO964: High Urgency Renal Transplantation for Patients With Exhaustion Of Vascular Access for Haemodialysis: Experience from A Tertiary Center

Abstract BACKGROUND AND AIMS When faced with exhaustion of vascular access for haemodialysis (EVAH), allocation for High Urgency Renal Transplantation (HURT) is the appropriate solution. Patients with EVAH usually have multiple comorbidities and an increased risk of cardiovascular and thrombotic events. The aim of this study is to analyze the characteristics and outcomes of patients undergoing HURT due to EVAH. METHOD Data from the Renal Transplant Unit since January 2006 were retrospectively analyzed. Eleven patients undergoing HURT were identified. RESULTS In the population studied, 45.5% (n = 5) were male, 63.6% (n = 7) were Caucasian and the mean age at the time of transplantation was 41.6 ± 7.8 years. Ninety % (n = 10) were hypertensive, 27.3% (n = 3) were diabetic and 27.3% (n = 3) had previous cardiovascular disease. Patients were on renal replacement therapy for 5.8 ± 2.7 years prior to transplantation. The mean transplant time was 75.5 ± 53.7 months. The mean follow-up period was 90.6 ± 51.9 months. During this period, 63.6% (n = 7) of patients lost their renal graft and mortality was 63.6% (n = 7). Renal graft survival was 81.8% (n = 9) at the first year, 72.7% (n = 8) at the third year and 63.6% (n = 7) at the fifth year of follow-up. At discharge, mean creatinine was 1.8 ± 1.1 mg/dL. At the first year, mean creatinine was 1.9 ± 0.8 mg/dL, at the third year was 2.3 ± 1.9 mg/dL and was 1.6 ± 0.4 mg/dL at the fifth-year post-transplant. The mean time to graft loss was 54.1 ± 49.3 months. Overall survival was 90.9% (n = 10) at the first year, 90.9% (n = 10) at the third year and 81.5% (n = 9) at the fifth-year post-transplantation. Two patients died from a cardiovascular event, one from neoplasia and other from an infectious cause. Two patients died with a functioning kidney allograft. CONCLUSION Kidney graft survival in patients undergoing HURT was significantly lower. Portuguese Transplantation Society reporting an overall graft survival of 92.9% at the first year and 85.0% at the fifth year. The mortality of these patients is quite high; however, the fact that they are patients with EVAH, whose life expectancy would be greatly reduced if they were not transplanted, makes HURT continue to be an indicated option in this population of more vulnerable patients.

MO765: Should We have to Create A Proximal Fistula in First Instance for Patients ≥75 Years Old?

Abstract BACKGROUND In France, the Network Epidemiology and Information in Nephrology evaluated the incidence of cases of chronic end-stage renal disease (ESRD), treated by dialysis, of patients aged ≥75 years at 39.8% (2015). Timely placement and development of functional fistulas for haemodialysis remain difficult logistical problems along with their high failure rate. Cardiovascular (CV) morbidity-mortality increases when patients initiate catheter-based treatment. The recommendations call for a glomerular filtration rate (GFR) between 15 and 30 mL/min/1.73m² (EBPG 2007 and Canadian 2006) to implement a fistula. The older the patients, the more the quality of the venous network deteriorates. In this population, clinicians face a simple problem: creating a too early fistula and preparing patients for an adequate supply. The surgery of vascular approaches tries to avoid two pitfalls: ‘too much to preserve’ the vascular capital, ‘too much to privilege’ the permeability of the first by creating proximal approaches (Barrou B.). The guidelines [Kidney Disease Outcomes Quality Initiative (K/DOQI) 2006] recommend the most distal vascular approach possible. Since 2016, CKD patients aged ≥75 years, have been implanted with arteriovenous fistula (native or prosthetic), localized in the first line of the humero-cephalic vein, huméro-basilique, or humero-axillary. Our primary objective is to assess primary permeability in a population of patients aged ≥75 years with stage IV/V chronic kidney disease (CKD) after the first-line proximal fistula. METHOD All patients aged ≥75 years for which a first-line proximal VA was created between 1 January 2016 and 31 December 2019 have been retrospectively reviewed in an observational study. They were followed for 12 months. A quarterly compilation of data has been produced. RESULTS A total of 31 patients (74% of men) benefit from the creation of a native fistula (90.3%) or prosthetic. During follow-up, 8 patients were excluded. 29% of patients had started catheter haemodialysis treatment prior to the creation of their first fistula. A total of 7 changed fistula from initial surgery during the study, of which 2 after the first use. At the creation of the vascular access, the median age of patients is 81 years, of which 35.5% have vascular nephropathy and 19.4% have diabetic nephropathy. The location of the anastomosis is as follows: 84% FAV brachiocephalic, 10% FAV brachiobasilic and 6% FAV axillary. At 12 months, 16 patients were still under observation. A total of 5 patients had thrombosis of their VA (80% of native fistulas). The average interval between the creation of the first, and the thrombosis is 2.18 months. Patients dialyzed with VA were 68%. On a scale from 0 (no difficulty) to 10 (puncture not performed), the average difficulty score of the first puncture is 2.2. The average time in the day between the first puncture and first ‘effective’ dialysis on the first 13.9 days and the average weekly duration of dialysis at the first effective puncture is 11.29 hours. There are 28 hospitalizations, 21% of which are related to VA, 37 ultrasound, 9 angiography and 4 surgical repairs were performed on VA. Only one ischaemia of the hand is observed, treated medically. Estimates of the risk of thrombosis associated with diabetes are confirmed [P = 0.02; 95% confidence interval (95%CI); hazard ratio (HR): 0.054–0.332]. At 12 months, 94% of the surroundings are permeable without any thrombosis. CONCLUSION This study confirms the interest in a proximal vascular approach in people aged ≥75. We have voluntarily included patients from the creation of their VA and for the majority before the time of starting haemodialysis. The average age is high in a high-risk epidemiological context (HTA, diabetes) and the number of early deaths (16%). The quality of the surroundings is confirmed by the percentage of native fistula at nearly 90% in accordance with the guidelines. The surgical team is motivated and sensitized in this collaborative project. A total of 52% of patients remained in observation at M12 and 94% had a permeable first with satisfactory dialysis quality. These results are encouraging and require a broader multicentre prospective and comparative study like other problems in managing vascular access for haemodialysis.