Arteriovenous Fistula Creation Research Articles

#1434 A study of the factors related to the change in eGFR after arteriovenous fistula creation in CKD patients and its impact on kidney prognosis

Abstract Background and Aims Occasionally, we observe cases of transiently increased estimated glomerular filtration rate (eGFR) after arteriovenous fistula (AVF) creation in patients with chronic kidney disease (CKD). However, there is limited research on the factors influencing the change in eGFR after AVF creation and its impact on kidney prognosis. Method In this single-center retrospective cohort study conducted from April 1, 2021, to July 31, 2023, 141 patients with CKD were enrolled. The participants were categorized into two groups: the increased eGFR group and the non-increased eGFR group after AVF creation. Factors contributing to increased eGFR after AVF creation were identified using through univariate and multivariate logistic regression analysis. Predictive variables included demographic and clinical variables such as sex, age, presence of diabetes mellitus (DM), history of cardiovascular diseases, urinary protein level, systolic blood pressure (SBP) on admission, the use of RAAS inhibitors and diuretics, and smoking history. Additionally, the period from AVF creation to dialysis induction was compared between both groups by the Mann-Whitney U test. Results Mean age was 69.3 ± 12.4. 75.9% were male, and 48.2% had DM. Among the 141 patients, 44 (31.2%) experienced an increase in eGFR after AVF creation. There was no significant difference in eGFR at the time of AVF creation between the increased eGFR group and the non-increased eGFR group (6.4 ± 1.5 vs. 6.2 ± 1.7 ml/min/1.73 m2, P = 0.56). Multivariate adjustment revealed that DM (Odds ratio [OR] 2.55, 95% confidence interval [95% CI] 1.01-6.45), hypertension (OR 0.97, 95% CI 0.95-0.99), and smoking history (OR 0.40, 95% CI 0.16–0.98) were associated with the eGFR increase after AVF creation. The time from AVF creation to dialysis induction was significantly longer in the increased eGFR group than in the non-increased eGFR group (median, 76.5 days vs. 42.0 days, P = 0.02). Conclusion Factors associated with accelerated atherosclerosis, such as hypertension and smoking, were significantly negatively correlated with increased eGFR. Conversely, DM was significantly associated with increased eGFR after AVF creation. Increased eGFR after AVF creation significantly prolonged the time to dialysis induction compared to the non-increased eGFR group.

#1703 Role of early AV fistula creation among elderly and its impact on estimated decline in GFR among pre dialysis patients

Abstract Background and Aims Recent evidence suggests that AVF creation may slow estimated glomerular filtration rate (eGFR) decline. The aim of the present study was to assess the impact of the pre dialysis AVF creation on eGFR decline and the need for dialysis, after controlling for key confounding factors among elderly population with advanced renal failure . Method A retrospective cohort study among patients attending Nephrology, Urology and General Surgery OPD between Jan 2019-Jan 2022 in Tertiary care hospital, Lucknow for AV fistula creation and assessed their stage of CKD and trajectory of fall in eGFR within a year's time and the time to initiation of dialysis from AV fistula creation was assessed. Results 34 men and 23 females (> 65 years ) of age who at time of AV fistula creation had an median eGFR at time of AVF creation of 15.5 (10.3–16.9) mL/min/1.73m2. The factors like frailty, diabetes, psychosocial issues were matched between the two genders . Males were more in age with better BMI .Baseline eGFRs were 14.4± 2.0 mL/min/1.73m2 in men and 13.8.0 ± 1.2 mL/min/1.73m2 in women. The crude annual eGFR decline rates were − 3.20 ± 2.50 mL/min/1.73 m2 pre- and − 2.45 ± 2.16 mL/min/1.73 m2 post-AVF. In a mixed effect linear regression model, monthly eGFR decline was − 0.43 mL/min/1.73m2/month.. The period after AVF creation was associated with a relatively higher eGFR . There was a significant association between follow-up time and the period pre/post AVF such that eGFR decline was more attenuated each month after AVF creation. There was better preservation of GFR from the pre AV fistula creation . Conclusion In this cohort, AVF creation was associated with a significant reduction of eGFR decline among elderly population . Further prospective studies are needed to confirm this association

#1922 Patterns and 2-year outcomes of preemptive vascular access creation in France

Abstract Background and Aims Most studies on clinical practices regarding the type and the timing of vascular access creation are limited to patients on kidney replacement therapy (KRT) from North American settings. Our aim was to describe patterns of preemptive vascular access creation in patients under nephrology care in France, and to assess the subsequent risks of hemodialysis (HD) initiation with arteriovenous (AV) access use, HD initiation with central venous catheter (CVC) use, initiation of other KRT modality, and competing death. Method From 2013 through 2016, the CKD-REIN cohort included 3033 adult patients with CKD stages 3 to 5 from 40 outpatient nephrology clinics in France, nationally representative geographically and in terms of facility legal status (public, private not for profit, and private for profit). Participants were followed for 5 years or until initiation of kidney replacement therapy (KRT) or death, whichever came first. Patients who underwent a first vascular access creation during follow-up were eligible for this analysis. We described the type, anatomical site and timing of the first vascular access created, as well as patients’ associated characteristics. The number and type of subsequent accesses were also described. Among patients who underwent AV fistula creation first, we used the cumulative incidence functions to estimate the 2-year probabilities of HD initiation with AV access use (independently of its type or order), HD initiation with CVC use, initiation of other KRT modality, and death. Results Over a median follow-up of 5.0 years (interquartile range [IQR], 4.6 to 5.2), 535 patients (18% of the total population) underwent a first vascular access creation. 408 patients (75%) had an AV fistula as their first vascular access, 7 patients (1%), an AV graft, and 127 patients (24%), a CVC. AV fistulas were predominantly located in the lower arm (76%). The median eGFR levels at access creation were 13 (IQR, 10 to 16), 12 (10 to 14) and 9 (6 to 13) ml/min/1.73 m2 for AV fistula, AV graft, and CVC, respectively. Groups defined by their first vascular access did not differ with regards to diabetes status, but patients who received AV fistula as their first vascular access stood out for being younger and having less cardiovascular comorbidities than their counterparts who received AV graft or CVC (Table 1). In contrast to the 7 patients with first AV graft who did not have any subsequent access creation, 22% of those with first AV fistula had at least one subsequent access creation before initiating KRT. The subsequent access was a fistula in 49% of cases (54% of them in the lower arm), a CVC in 48% and a graft in 2%. The 2-year cumulative incidences of HD initiation with AV access use, HD initiation with CVC use, preemptive kidney transplantation and pre-KRT death were 61%, 14%, 2% and 5%, respectively (Fig. 1); 18% of patients undergoing a first AV fistula creation did not experience any event within two years, and 25% did not start HD. No patients received peritoneal dialysis as other KRT modality. Conclusion In this nationwide description of patterns of preemptive vascular access creation, we highlight that lower arm AV fistula is largely prioritized, even after a first failed AV fistula creation. This may contribute to the higher use of AV fistula among HD patients in France compared to North American countries. Most patients who undergo a first AV fistula creation eventually start hemodialysis with an AV access within 2 years of this creation, but 1 out of 4 do not start HD at all (because of death, preemptive transplantation, or stable kidney function). Novel tools assisting clinical decision making in preemptive AV fistula creation are needed.

#2709 Genome wide association study regarding disturbed AVF patency

Abstract Background and Aims Veins are frequently exposed to arterial circulation, as coronary artery bypass grafts (CABG) and as a peripheral venous bypass to treat atherosclerotic disease, or in the case of arterio-venous fistulas (AVF) to provide a vascular access for hemodialysis. Therapeutic success is dependent on proficient venous remodeling after introduction in the arterial circulation to sustain the increased hemodynamic pressure. Frequently observed adverse outcomes after the aforementioned procedures include the stenosis or total occlusion of the vein, requiring surgical or interventional treatment or leading to bypass/ AVF failure. Hereditary factors associated with disturbed venous patency have been previously investigated in all three conditions. For example, distinct VEGF-A as well as TGF-beta polymorphisms have been identified to correlate with AVF failure. In the present analysis we aimed at investigating whether genetic polymorphisms associated with disturbed venous patency after AVF creation are similar to findings in CABG and peripheral bypass patients in a genome wide association study. Method The analyses were conducted in White Europeans (N= 425,406) in the UK Biobank using regenie software. This software employs a linear mixed model that accounts for the impact of population structure and individual relatedness. Out of approximately 805,000 variants, we selected 606,201 high-quality variants to construct a relatedness model for regenie. These selected variants were identified by a genotyping rate exceeding 80%, minor allele frequencies greater than 1%, and Hardy-Weinberg equilibrium p-values below 10^-8. We adjusted for age, sex, BMI, smoking, and history venous thromboembolism. We assessed the association of 9,757,417 imputed SNPs, each having a minimum allele count of 12 and a minimum info score of 0.3. Results In total, 768 patients underwent at least 1 surgery for AVF creation. Out of those, 341 (44.4%) had a recorded procedure or diagnosis associated with disturbed fistula patency. The controls included 6067 CABGs and 384 peripheral bypasses with 76 (1.3%) and 67 (17.4%) recorded events, respectively. We found no genome wide significant associations for the tested SNPs and patency-related AVF complications (Fig. 1). Additionally, we also found no genome wide significant associations after combining the phenotypes (Fig. 2). Conclusion Multiple studies have evaluated genetic associations and adverse clinical outcomes after AVF creation. Nevertheless, the generalizability of these findings might be limited at least partially due to small sample sizes. While the sample size of the present analysis is similar to previous research efforts and therefore also comparably low, the lack of consistency in results might be suggestive of the difficulties research in this field faces. Additionally, we found no indication that impaired venous patency after AVF creation is related to complications after coronary or peripheral bypass surgery regarding genetic patient profiles. However, whether this is due to differences in pathophysiology and related genetic predispositions or due to the limited sample size and incidence rates of the present study remains to be determined in follow-up investigations.

#2192 Aging dialysis population and late referral: two factors influencing the choice of vascular access

Abstract Background and Aims The decision on the type of vascular access for hemodialysis is based on several factors including the timing of renal replacement therapy initiation and certain patients’ clinical and demographic features. We hypothesized that the increasing age of patients on hemodialysis and the issue of "late referral" can be relevant in this context and favor the use of central venous catheter (CVC) over arteriovenous fistula (AVF), with a surge in catheter-related complications. Method We carried out a retrospective observational study of vascular access procedures (AVF creation and long-term CVCs placement) performed at the Nephrology Unit of the “Fondazione Policlinico Universitario Agostino Gemelli” between January 2020 and December 2023. Results A total of 415 procedures for AVF creation (median age 63.5, IQR 55.5 - 71.5 years), of which 59 (14,2%) in “late referral” patients (median age 61, IQR 47.5 - 72.5 years), were performed. During the same period, 343 CVCs were placed, of which 151 (44%) in patients with planned admission as previously evaluated by a nephrologist (median age 69, IQR 60 - 79 years). The remaining 192 CVC placements (56%) involved patients after an emergency admission (median age 69, IQR 57 - 80 years). In 56 (29%) of these patients an AVF was created concurrently or within 60 days from the emergency procedure. Such patients were significantly younger (median age 66, IQR 57 - 73 years) than those who underwent a CVC placement after a planned admission (p=0.01) or others with emergency admission (p=0.03). In a multivariate analysis (logistic regression) the use of CVC over AVF was significantly and independently correlated with both late referral and age. Conclusion These data suggest that the increasing use of CVCs in hemodialysis may be due to the age of incident patients and remark the importance of early evaluation in order to choose the most appropriate vascular access.

#3008 Very low protein diet with ketoanalogues supplementation could start haemodialysis with AVF without additional CVCs insertion

Abstract Background and Aims Nutritional interventions and a low-protein diet (LPD) are a critical point in the management of chronic kidney disease (CKD). Several protein-restricted dietary regimens have been proposed in patients with end stage kidney disease: a typical LPD provides around 0.6–0.7 g·kg meanwhile a very low-protein diet (VLPD) provides around 0.3–0.4 g·kg and it is basically a vegetarian diet which has to be supplemented with essential amino acids (EAA) to satisfy the body nitrogen need and with nitrogen-free ketoanalogues (KA) to recirculate the endogenous urea, whose serum levels are elevated in patients with CKD. KA and EAA reduce the rate of progression of chronic kidney disease and improve the inflammatory state; they reduce the absorption of phosphates and can maintain a good state of nutrition even if associated with diets with very low protein content. On the contrary, an excessively restrictive and inadequate diet in terms of EAA or calorie intake induces a negative nitrogen balance, therefore cachexia. The recommended vascular access to start dialysis treatment is represented by the arteriovenous fistula (AVF). An early referral to the vascular surgeon for vascular access creation is pivotal for deciding on a patient-specific strategy for planning access. Guidelines advise referral at least 3–6 months before the expected start of HD, because time is needed for AVF maturation and possible repeat interventions when it is impaired. An early referral results in more autologous AVFs, which have a better long-term patency, whereas late referral, results in a greater risk of AVF non-maturation and failure and therefore the need for additional central venous catheters (CVCs) to initiate dialysis. Recent studies have shown that pre-dialysis patients who undergo a VLDP + KA require less emergency dialysis access and have better elasticity of the arterial wall, better maturation rates and duration of the AVF and sometimes a reduction in the uremic toxins responsible of endothelial dysfunction. The aim of the study was to evaluate if patients could start haemodialysis with fistula cannulation, without central venous catheter insertion. Method 10 patients, late referral end stage renal disease were enrolled in a prospective, single arm study starting very low protein diet supplemented with ketoanalogues after arteriovenous fistula creation; they were followed with periodically assessment of renal function, uremic toxin, and acid-base balance until they need to start haemodialysis. It was evaluated AVF maturation and needs to additional CVC insertion. Results Patients (3 females, 7 males) mean age was 71.2 years; before AVF creation, baseline mean value was: sCr: 6.46 mg/dl, sUrea: 150 mg/dl, phosphorus: 4.45 mg/dl, bicarbonates: 19.8 mmol/l, eGFR: 8,37 ml/min. After 3 months of VLPD supplemented with KA, eGFR and sCr was stable to 8.25 ml/min and 6.69 respectively, sUrea and phosphorus reduced to 115 mg/dl and 3.8 mg/dl, and bicarbonate increased to 22.4 mmol/l. All 10 patients achieved AVF maturation within 3 months, no one needed CVC insertion. Conclusion In this small group we see how late referral ESRD patients, undergone AVF surgery, after 3 months of VLPD supplemented with KA, had stability of renal function, with reduction of urea and phosphorus, improvement of acid-base balance and achievement of AVF maturation, without needing of CVC insertion. For these reasons VLPD + KA could be useful in delaying haemodialysis start in late referral ESRD patients who have created AVF, without emergency placement of a central venous catheter.

#1465 Enhancing vascular access planning in CKD: validating the 40% KFRE threshold in a French retrospective cohort study

Abstract Background and Aims The optimal timing for dialysis vascular access creation remains a complex clinical decision, balancing the risk of early intervention against the prospect of starting dialysis with a central venous catheter. This study sought to compare the predictive capabilities of the Kidney Failure Risk Equation (KFRE) and estimated Glomerular Filtration Rate (eGFR) in determining the appropriate timing for arteriovenous fistula (AVF) creation in patients with advanced chronic kidney disease (CKD). Method A retrospective cohort of 238 patients referred for ultrasound vascular mapping from April 2013 to June 2023 was analyzed. Data on patient characteristics, laboratory results, and clinical outcomes were collected. The 4-variable and 8-variable KFRE and eGFR were assessed for their ability to predict end-stage kidney disease (ESKD) within a 2-year period. Discrimination was evaluated using receiver operating characteristic (ROC) curves, and calibration was assessed graphically. Net benefit decision curves were utilized to compare the net benefit of the KFRE models at various threshold probabilities. Results The cohort comprised 238 patients with an average age of 65.2 years and a mean eGFR of 13.3 mL/min/m²73. During the median 10.7-month follow-up, 178 patients (74.8%) progressed to ESKD, and 21 (9.2%) died prior to reaching ESKD. At the 1-year mark, the probability of progressing to ESKD was 77.6% (95% CI, 69.9-85.3%) when a 40% threshold for the 4-variable KFRE was applied, compared to 65.8% (95% CI, 58.3-73.3%) with an eGFR threshold of 15 mL/min/m²73. Discrimination analysis demonstrated a superior predictive performance for the 8-variable KFRE at 6 months, with a C-statistic of 0.82 (95% CI: 0.76-0.88). At 1 year, both KFRE models showed strong predictive abilities, with C-statistics of 0.835 (95% CI: 0.78-0.89) for the 4-variable KFRE and 0.82 (95% CI: 0.76-0.875) for the 8-variable KFRE. Sensitivity and specificity analyses underscored the benefits of utilizing the 40% KFRE threshold for predicting ESKD over the eGFR threshold. Conclusion The study demonstrates that both the 4-variable and 8-variable KFRE are valuable tools for predicting the need for vascular access in pre-dialysis patients, outperforming eGFR alone. The 8-variable KFRE, in particular, provides a significant improvement in 6-months ESKD prediction, with potential implications for clinical decision-making and patient management in advanced CKD. These findings advocate for the incorporation of KFRE in the clinical evaluation process for timely and appropriate vascular access planning.

#858 The efficacy of preoperative ultrasound mapping prior to arteriovenous fistula creation: a meta-analysis and systematic review

Abstract Background and Aims Current literature presents conflicting evidence regarding the benefits of Color Doppler Ultrasound (DUS) in the preoperative vascular mapping of arteriovenous fistula (AVF) for haemodialysis. Thus, we conducted a systematic review and meta-analysis of RCTs to evaluate differences in primary AVF failure between patients randomly assigned to routine preoperatory DUS and those randomly assigned to physical examination assessment alone or combined with DUS when physical examination provides limited information. Method We systematically searched PubMed, Google Scholar, Web of Science, and Scopus databases from their inception to November 30, 2023. The accessible text search terms were: “fistula” AND “arteriovenous” AND “dialysis” OR “haemodialysis” AND “Doppler” OR “ultrasound” OR “ultrasonography” AND “preoperative” OR “perioperative” OR “mapping”. No language restriction was applied. We also reviewed references from original papers and review articles to identify additional suitable studies not covered by our original database searches. Exclusion criteria were: (1) meeting abstracts, case reports, reviews, practice guidelines, case-control or cross-sectional or longitudinal studies; (2) RCTs that did not report any estimates of the outcomes of interest; (3) RCTs conducted in the paediatric population (<18 years of age). Two authors independently extracted data from eligible RCTs. Disagreements at this level were resolved by consensus and a third author if needed. The outcome was categorized into three groups: primary AVF failure within 48 hours, within six weeks or 40 months from the vascular procedure. AVF Failure was defined as intraoperative inadequate vessels, incomplete surgical procedure, absence of thrill, thrombosis detection, AVF unsuitability for cannulation at 90 days, inability to achieve Qb 200-300 ml/min at six months, or lack of maturation at 40 months. Statistical analysis was performed using STATA 17.0 software with the metanalysis package and R (version 4.2.2.) for all statistical analyses. This study was performed according to the updated Preferred Reporting Items for Systematic Reviews and Meta-Analysis statement. Results We included 6 RCTs involving 802 patients. Fig. 1 summarizes the results of the literature search and study selection. Table 1 shows the main clinical characteristics of RCTs. Compared to controls, the use of routine preoperative DUS was associated with a reduction in the risk of AVF failure within 48 hours [5 RCTs; OR 0.27, confidence interval 95% 0.16-0.45 for the common effect model (CEM); OR 0.27, CI 95% 0.16-0.46 for the random effects model (REM), no heterogeneity (I2 = 0%)]; within six weeks [2 RCTs (OR 0.33, CI: 95% 0.18-0.61 for CEM, and OR 0.34, CI 95% 0.18-0.63 for REM with I2 = 0%]; and within 40 months [4 RCTs, OR 0.51, CI 95% 0.35-0.75 for CEM; and OR 0.51, CI 95% 0.35-0.76 for the REM, with I2 = 0%] from surgical intervention (Figs 2–4). Conclusion Routine use of DUS in preoperative vascular mapping improves the survival AVF in the immediate to 40 months post-surgery, compared to relying solely on physical examination or using DUS only in cases of insufficient physical examination.

#1694 The Cl-/HCO3-ratio as a predictor of decompensated metabolic acidosis in CKD stages G4 and G5

Abstract Background and Aims Metabolic acidosis (MA) is a common disorder in patients with chronic kidney disease (CKD) and is associated with both a normal anion gap (AGMA) and a high anion gap (HAGMA). AGMA is typically detected early in the course of CKD, whereas HAGMA appears later in the course of CKD due to the accumulation of non-chloride anions such as phosphate, sulphate, and an array of organic acids. The anion gap (AG) is usually calculated as the difference between serum concentration of cations and anions using the formula AG=Na+-(Cl−+HCO3−). The most important anions in serum are chlorides (Cl−) and bicarbonates (HCO3−). The more advanced the CKD, the higher the AG. As eGFR decreases, a reciprocal decrease in HCO3− and an increase in chloride concentration is observed to correct the AG. The aim of this study is to determine whether the Cl−/HCO3− ratio can be used to predict decompensated metabolic acidosis with pH decline in CKD stages G4 and G5. Method A total of 115 patients (median age 63 ± 17 years), with CKD stage G4 or G5 were enrolled in this cross-sectional study. Demographic and comorbidity data was obtained from medical records, and the Charlson Comorbid Index (CCI) was calculated. A two-year clinical follow-up was conducted to assess the clinical status of each patient. The number of patients, the time dialysis was started, and deaths were all recorded. All patients were qualified for arteriovenous fistula creation in predialysis period. The arterial (A) and venous (V) blood samples were taken during surgery, directly after vessel dissection, and evaluated in a point of care testing analyzer (POCT). The ratio of arterial Cl− and HCO3− concentration were calculated. According to mean arterial pH (pH-A) the group was divided into Group A pH-A<7.33 and Group B pH-A≥7.33 (Table 1). Results In Group A was significantly lower pH-A, pH-V, HCO3−-A, HCO3−-V, pCO2-A, pCO2-V, and significantly higher both arterial and venous Cl− and the Cl−/HCO3− ratios compared to Group B. No such differences were observed in the case of AG. Cl−/HCO3−-A ratio negatively correlated with pH (r = −0.77, p < 0.01) (Fig. 1A). The discriminative power of Cl−/HCO3−-A ratio for predicting pH-A≤7.33 was 0.917 (95% confidence interval [CI] = 0.87–0.97; p < 0.01) which provided 87% sensitivity and 84% specificity (Fig. 1B). The best cut-off was 6.22 (mmol/l)/(mmol/l). Conclusion The Cl−/HCO3− ratio lower than 6.22 (mmol/l)/(mmol/l) may be used as predictor of decompensated metabolic acidosis.

Outcomes of brachial artery transposition in hemodialysis patients

ObjectiveIn hemodialysis patients with a difficult access extremity who are not suitable for an arteriovenous fistula or arteriovenous graft creation, the concept of cannulating a superficialized artery for arterial outflow in dialysis sessions has been adopted as a tertiary alternative. However, its long-term patency and complications have not been recognized widely. We report our 16-year experience with hemodialysis access creation using the brachial artery transposition (BAT) technique. MethodsThis single-center retrospective study included consecutive patients who underwent BAT for hemodialysis vascular access between June 1, 2006, and December 31, 2022. The patency of the whole access circuit and the transposed brachial artery itself was evaluated independently. ResultsIn total, 193 surgical procedures were included. The success rate was 93.2%. The mean operative time was 128 minutes. The median interval from access placement to first cannulation was 21 days. The primary patency rates for BAT were 92.3%, 91.3%, 90.3%, 86.1%, and 71.9% at 1, 2, 3, 5, and 10 years, respectively. The secondary patency rates for BAT were 96.3%, 96.3%, 95.0%, 90.1%, and 74.9% at 1, 2, 3, 5, and 10 years, respectively. The primary patency rates for the whole access circuit were 61.4%, 49.2%, 45.8%, and 26.9% at 1, 2, 3, and 5 years, respectively. The secondary patency rates for the whole access circuit were 85.1%, 83.3%, 82.0%, and 68.6% at 1, 2, 3, and 5 years, respectively. The overall patient survival rates were 79.6%, 69.6%, 54.6%, 36.5%, and 13.4% at 1, 2, 3, 5 and 10 years, respectively. The abandonments of BAT were brachial artery thrombosis (n = 6), pseudoaneurysm (n = 2), aneurysmal change (n = 1), and other reasons (n = 1). The abandonments of the whole access circuit were exhaustion of venous return (n = 26), abandonment of BAT (n = 7), and other reasons (n = 2). Complications were exhaustion of venous return (n = 26), aneurysmal change (n = 12), pseudoaneurysm (n = 6), brachial artery thrombosis (n = 7), impaired wound healing (n = 19), lymphorrhea (n = 9), skin infection (n = 5), hematoma on cannulation (n = 3), and reduced peripheral blood flow (n = 2). ConclusionsThe patency of BAT was excellent, and that of the whole access circuit was adequate, with a few complications. BAT is an effective alternative from a long-term perspective for patients who are unsuitable for conventional hemodialysis access creation.

The role of glomerular filtration rate in AVF success: Should we intervene earlier?

End-stage kidney disease (ESKD) patients require life-sustaining kidney replacement therapies, with the natural arteriovenous fistula (AVF) being the preferred vascular access due to its low infection risk, high patency, and fewer complications. Factors like vessel diameter, gender, diabetes, age, and surgical technique influence AVF maturation. Our study focused on short-term AVF creation success, specifically examining estimated glomerular filtration rate (eGFR) levels using the CKD-EPI formula. Patients were categorized according to their eGFR levels to observe the effects of fistula timing and the severity of kidney disease. No significant demographic or outcome differences between eGFR groups have been observed except for gender. AVF maturation was notably associated with distal vein diameter (>2mm), while other factors did not significantly impact maturation rates. As a secondary outcome, it was concluded that the recording of patients' blood pressure values at preoperative and perioperative levels led to the conclusion that blood pressure levels may have an impact on fistula maturation. To ensure vascular access effectiveness, optimizing blood pressure, determining vein diameter, strategic AVF timing, and reducing catheter usage are crucial. Our study aimed to identify eGFR levels conducive to optimal AVF outcomes. Although significant results could not be obtained in this regard, it is considered worthwhile to re-examine the effect of blood pressure in secondary outcomes. Additionally, prospective studies may be appropriate for reevaluating the effect of GFR.

Heat therapy preconditioning improves the skeletal muscle contractile and mitochondrial function in a mouse model of access-related hand dysfunction

Introduction: Hemodialysis via arteriovenous fistula (AVF) is a life-line treatment for patients with end-stage kidney disease. However, hemodialysis access-related hand dysfunction (ARHD) including ischemia, muscle weakness and alterations in mitochondrial function is prevalent following AVF placement. We tested the hypothesis that two-weeks of daily heat therapy prior to AVF surgery would improve hindlimb function in a mouse model of ARHD. Methods: Adult male C57BL/6J mice (N=9-11/group) were fed a 0.2% adenine diet to induce chronic kidney disease. Following two weeks of the initial adenine diet, animals were randomly allocated to heat therapy (HT) or control (CON) groups. Animals assigned to HT were exposed to environmental heat at 40°C in a climate chamber for 30 min/day, six days/week, for two weeks while the control mice were exposed to room temperature (~22°C). The AVF was created using the left common iliac artery and vein 24-48 hours after the last treatment session. Laser Doppler perfusion to the ventral paw was assessed post-operatively (POD) and AVF patency was verified using a high-frequency duplex ultrasound system three days prior to euthanasia. Following 14 days of recovery, in situ tibialis anterior (TA) muscle contractility and gastrocnemius muscle mitochondrial function were assessed. RNA sequencing analysis of the hindlimb skeletal muscle (N=4/group) was performed. Results: Compared to baseline, the level of blood urea nitrogen was similarly elevated ( P<0.05) in both groups following four weeks of adenine diet. In both groups, blood perfusion to the paw was decreased by ~50% immediately after AVF creation and progressively recovered to ~80% at POD13 without a treatment effect ( P=0.4467). No differences in body weight and muscle mass in the TA, extensor digitorum longus, and soleus muscles were observed (all P>0.05). Notably, however, the absolute ( P=0.0250) and specific force ( P=0.0101) frequency relationship of the TA muscle were significantly improved in the animals exposed to HT. In addition, compared with control animals, HT mice had significant improvement in oxidative phosphorylation (OXPHOS) in both pyruvate ( P=0.0145) and octanoylcarnitine ( P=0.0196) fueled conditions. RNA sequencing results revealed that genes involved in nervous system development and metabolism were significantly different between HT and CON groups. Conclusion: Daily application of heat therapy for two weeks prior to the AVF surgery has beneficial effects on both skeletal muscle contractile and mitochondrial function suggesting this pre-habilitation strategy may mitigate the risk of ARHD in patients undergoing AVF surgery. Funding Support: National Institutes of Health grant R01HL148597 and American Heart Association grant POST903198. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

A systematic review of prediction models on arteriovenous fistula: Risk scores and machine learning approaches.

Failure-to-mature and early stenosis remains the Achille's heel of hemodialysis arteriovenous fistula (AVF) creation. The maturation and patency of an AVF can be influenced by a variety of demographic, comorbidity, and anatomical factors. This study aims to review the prediction models of AVF maturation and patency with various risk scores and machine learning models. Literature search was performed on PubMed, Scopus, and Embase to identify eligible articles. The quality of the studies was assessed using the Prediction model Risk Of Bias ASsessment (PROBAST) Tool. The performance (discrimination and calibration) of the included studies were extracted. Fourteen studies (seven studies used risk score approaches; seven studies used machine learning approaches) were included in the review. Among them, 12 studies were rated as high or unclear "risk of bias." Six studies were rated as high concern or unclear for "applicability." C-statistics (Model discrimination metric) was reported in five studies using risk score approach (0.70-0.886) and three utilized machine learning methods (0.80-0.85). Model calibration was reported in three studies. Failure-to-mature risk score developed by one of the studies has been externally validated in three different patient populations, however the model discrimination degraded significantly (C-statistics: 0.519-0.53). The performance of existing predictive models for AVF maturation/patency is underreported. They showed satisfactory performance in their own study population. However, there was high risk of bias in methodology used to build some of the models. The reviewed models also lack external validation or had reduced performance in external cohort.

Mitochondrial targeted catalase improves muscle strength following arteriovenous fistula creation in mice with chronic kidney disease

Hand dysfunction is a common observation after arteriovenous fistula (AVF) creation for hemodialysis access and has a variable clinical phenotype; however, the underlying mechanism responsible is unclear. Grip strength changes are a common metric used to assess AVF-associated hand disability but has previously been found to poorly correlate with the hemodynamic perturbations post-AVF placement implicating other tissue-level factors as drivers of hand outcomes. In this study, we sought to test if expression of a mitochondrial targeted catalase (mCAT) in skeletal muscle could reduce AVF-related limb dysfunction in mice with chronic kidney disease (CKD). Male and female C57BL/6J mice were fed an adenine-supplemented diet to induce CKD prior to placement of an AVF in the iliac vascular bundle. Adeno-associated virus was used to drive expression of either a green fluorescent protein (control) or mCAT using the muscle-specific human skeletal actin (HSA) gene promoter prior to AVF creation. As expected, the muscle-specific AAV-HSA-mCAT treatment did not impact blood urea nitrogen levels (P = 0.72), body weight (P = 0.84), or central hemodynamics including infrarenal aorta and inferior vena cava diameters (P > 0.18) or velocities (P > 0.38). Hindlimb perfusion recovery and muscle capillary densities were also unaffected by AAV-HSA-mCAT treatment. In contrast to muscle mass and myofiber size which were not different between groups, both absolute and specific muscle contractile forces measured via a nerve-mediated in-situ preparation were significantly greater in AAV-HSA-mCAT treated mice (P = 0.0012 and P = 0.0002). Morphological analysis of the post-synaptic neuromuscular junction uncovered greater acetylcholine receptor cluster areas (P = 0.0094) and lower fragmentation (P = 0.0010) in AAV-HSA-mCAT treated mice. Muscle mitochondrial oxidative phosphorylation was not different between groups, but AAV-HSA-mCAT treated mice had lower succinate-fueled mitochondrial hydrogen peroxide emission compared to AAV-HSA-GFP mice (P < 0.001). In summary, muscle-specific scavenging of mitochondrial hydrogen peroxide significantly improves neuromotor function in mice with CKD following AVF creation.

Comparison of Outcomes of Drug-Coated Balloons versus Plain Balloons in Secondary Interventions on Percutaneous Arteriovenous Fistulae

PurposeTo compare patency and reintervention outcomes after either plain old balloon angioplasty (POBA) or drug-coated balloon angioplasty (DCBA) for venous stenoses after percutaneous arteriovenous fistula (pAVF) creation. Materials and MethodsOne-hundred ninety-five pAVFs were successfully created during the study period, 141 using Ellipsys and 54 using Wavelinq. After pAVF creation, 95 patients (48.7%) required secondary percutaneous transluminal angioplasty (PTA) with either POBA (n = 55, 58%) or DCBA (n = 40, 42.1%). The most common site for PTA was the juxta-anastomotic segment (75.5%; 74/98). Univariate and multivariate Cox regression analyses were used to compare target lesion primary patency, access circuit primary patency, secondary patency, and reintervention rates in the POBA and DCBA cohorts. ResultsThirty-four of 55 (62%) patients in the POBA cohort and 14 of 40 (35%) patients in the DCBA cohort required reinterventions for pAVF restenosis. Mean number of follow-up days among patients treated with POBA was 1,030.4 (SD ± 342.9) and among those treated with DCBA was 744.4 (SD ± 403.5). The use of POBA compared with DCBA was not associated with target lesion and access circuit primary patency loss in multivariate analysis (hazard ratio [HR], 1.81; 95% CI, 0.93–3.51; P = .080; and HR, 1.77; 95% CI, 0.73–4.28; P = .210, respectively). However, time from fistula creation to the first PTA (days) was statistically significantly associated with both outcomes (HR, 0.997; 95% CI, 0.994–0.999; P = .009; and HR, 0.997; 95% CI, 0.992–0.999; P = .021, respectively). There were no major adverse events. ConclusionsIn this retrospective single-center analysis of pAVFs, considerably more patients who underwent PTA with POBA after pAVF creation required reinterventions compared with PTA using DCBA, although the follow-up time of POBA was longer. In multivariate analysis, no differences were noted in the hazard of patency loss between POBA and DCBA.

Incidental AVF creation during unrelated hospitalization is associated with worse outcomes compared with outpatient AVF creation.

Arteriovenous fistula (AVF) creation during an inpatient hospitalization is often performed for patient convenience and to ensure compliance. We sought to evaluate whether this approach has comparable outcomes to outpatient AVF creation. We identified patients undergoing index AVF creation from the United States Renal Data System dataset (2012-2017). Patients were grouped into outpatient and inpatient. Outpatient included patients that were operated in either an outpatient setting, ambulatory surgical center or were admitted inpatient on the day of AVF creation. Inpatient included only patients with claims for an inpatient visit before access creation. Multiple safety outcomes were compared between groups using unadjusted and adjusted logistic regression methods generating odds ratios and 95% confidence intervals (95% CI). One-year maturation rates were compared using competing-risks regression methods generating sub-hazard ratios (sHR) and 95% CI. Outcomes were also compared after 1:1 propensity score matching. We identified 68,872 patients undergoing AVF creation, 4855 (7.1%) of which were created during inpatient hospitalization. Patients in the inpatient group were older (65.8 ± 13.8 vs 65.2 ± 13.8, p = 0.002), more likely to be of Black race (28.1% vs 26.8%, p = 0.02), and have cardiovascular comorbidities (all p < 0.05). Patients in the inpatient groups were more likely to be dialyzed at for-profit (88.1% vs 85.9%, p < 0.01) and freestanding (94.8% vs 92.9%, p < 0.01) dialysis centers. On both unadjusted and adjusted analysis, inpatient group was more likely to experience 30-day adverse events (e.g. pneumonia, COPD exacerbation, stroke, myocardial infarction), any complication, and all-cause mortality. On competing risks analysis, successful two-needle cannulation at 1 year was significantly less likely in the inpatient group (68.1% vs 76.8%, p < 0.01; sHR = 0.68 [95% CI, 0.65-0.71], p < 0.01). These trends were robust on 1:1 propensity matching. Incidental AVF creation in hospitalized patients is associated with worse outcomes, ranging from mortality to postoperative complications to fistula maturation, compared with outpatient AVF creation.

PICC insertion and veins of the arm size variation during dialysis treatment: A prospective observational study.

Peripherally Inserted Central Catheters play an increasingly important role in Central Venous Access Devices. However, the use of these devices should be carefully considered in specific situations such as central catheterisation in patients with chronic kidney disease. When evaluating the feasibility of placement for a patient undergoing dialysis, the relationship between changes in circulating volume before and after dialysis treatment, and potential variations in the size of deep veins in the upper limbs, should be considered. Upper limb veins, specifically the basilic or brachial veins, were identified and measured before and after dialysis treatment. Patient data and weight loss data during dialysis treatment were also collected. Linear regression analysis was performed to assess the correlation between the variables. The average variation in vein size for the entire sample was +0.17 ± 0.43 mm. The mean volume removed was 2.2 ± 0.8 l. In subgroup 1 (fluid volume loss <2000 ml), the population experienced a decrease in the measured vein size after dialysis. In subgroup 2 (fluid volume loss ⩾2000 ml), the population experienced an increase in the measured vein size after dialysis. Upper arm vascular access placement in dialysed patients with fluid removal of less than 2000 ml should be performed after the dialysis session. Conversely, in dialysed patients with fluid removal of more than 2000 ml, where a significant increase in vein size was observed, vascular access placement should be performed before the dialysis session when the veins are smaller. Additionally, it should be noted that in patients with chronic kidney disease, the venous system of the upper limbs should be preserved as much as possible to prevent thrombosis and stenosis in potential arteriovenous fistula creation.

Hemodialysis Patients with High-Flow Arteriovenous Fistulas: An Evaluation of the Impact on Cardiac Function.

: Patients undergoing hemodialysis often experience changes in cardiac function when they have a high-flow arteriovenous fistula (AVF). This study aimed to assess the effect of high-flow AVFs on cardiac function in patients undergoing hemodialysis. : A longitudinal study was conducted on hemodialysis patients with high-flow AVFs. Echocardiographic parameters, such as left ventricular ejection fraction (LVEF), left atrial diameter (LAD), left ventricular end-diastolic dimension (LVEDD), right ventricular end-diastolic dimension (RVEDD), inferior vena cava diameter (IVCD), systolic blood pressure, and diastolic blood pressure, were measured and compared before and after AVF creation. : One hundred hemodialysis patients with high-flow AVFs (mean age: 55.95±13.39 years, mean body mass index: 24.71±3.43 kg/m²) were studied. LVEF significantly decreased (51.10%±5.39% to 47.50%±5.79%), while LAD, LVEDD, and IVCD significantly increased after AVF creation (P<0.05). Systolic (132.49±16.42 mmHg to 146.60±17.43 mmHg) and diastolic (79.98±8.40 mmHg to 83.33±9.68 mmHg) blood pressure substantially rose post-fistularization (P<0.001). Notably, LVEF reduction was more significant in brachio-cephalic AVFs (46.29%±4.24%) compared to distal radio-cephalic or snuffbox AVFs (49.17%±7.15%) (P=0.014). : High-flow AVFs can significantly affect echocardiographic parameters in hemodialysis patients, thereby increasing the risk of cardiac failure. Close cardiac monitoring may be necessary for early intervention. Distal AVFs may be preferable in patients with decreased cardiac function.

Role of Doppler Evaluation in Assessing the Maturation of the Arteriovenous Fistula for Hemodialysis: An Observational Study.

Introduction Arteriovenous fistulas (AVFs) are the preferred type of vascular access for hemodialysis due to their lower risk of complications. This study aimed to determine the role of Doppler evaluation in assessing AVF. Materials and methods We conducted an 18-month prospective observational study of 33 hemodialysis patients who underwent a procedure for the creation of AVF at the Department of Radio-Diagnosis at Sri Devaraj Urs Academy of Higher Education and Research.Patients were evaluated using color Doppler ultrasound. Participants underwent a careful history and clinical examination to diagnose the disease. All relevant parameters were documented in a structured study proforma. AVF maturation was assessed postoperatively at four weeks using Doppler ultrasound color flow evaluation by looking for vascular components (flow volume, vein, and arterial diameter). Data were analyzed using CoGuide V 1.0.3 Statistical Software (CoGuide, Bangalore, India). Results A total of 33 patients, with a mean age of 54.6 ± 7.8 years, were evaluated. Of the 33 participants, 24 (72.7%) were male, and nine (27.3%) were female. The majority (47%, n=16) of participants had diabetes mellitus, eight (24%) had hypertension, and 10 (29%) had both diabetes mellitus and hypertension. A brachiocephalic fistula was created in 45.5% of participants, and 33.33% had radiocephalic anastomoses. Five participants were diagnosed with AVF complications: two had a pseudoaneurysm, and three had a cephalic vein thrombus. Clinical and demographic characteristics (age, vascular components, and complications) were not significantly related to AVF maturation. Conclusions Doppler ultrasound plays an important role in selecting vessels for AVF preoperatively and assessing AVF maturation postoperatively, thus reducing the primary fistula failure rate. The findings suggest that Doppler evaluation can be a reliable tool for assessing AVF maturation and predicting surgical success, which could help healthcare providers make informed decisions about the best course of treatment for their patients. Continued research is warranted in this area to further understand the role of Doppler ultrasound in evaluating AVF surgery.

Early experience with endovascular arteriovenous fistula creation

Background: Patients opting for haemodialysis as a form of renal replacement therapy require prompt and reliable vascular access. The gold standard for delivering high-quality and safe haemodialysis is through the creation of an arteriovenous fistula (AVF), typically formed at the wrist or elbow. This intervention promotes increased blood flow through superficial veins, fortifying them for repeated needle insertion during haemodialysis treatment. The emergence of percutaneous endovascular arteriovenous fistula (pAVF) introduces a non-surgical alternative for AVF creation. This method eliminates the need for incisions, reducing the likelihood of surgical scarring and changes in vein appearance. Advantages of pAVF encompass the potential for accelerated convalescence, enhanced comfort for the patient, and a diminished adverse effect on body image perception. These non-surgical options may motivate patients to undergo the procedure promptly, enhancing the timeliness of vascular access for haemodialysis and positively impacting overall health outcomes. These relatively new interventions are evolving, enabling the refinement of more efficient and safer techniques. Dialysis nurses play a crucial role in overall success, necessitating further training and development of their skills and knowledge for needling these new fistulas. With an increasing number of successful cases and more readily available information, these non-surgical techniques are gaining popularity among patients, particularly those conscious about their body image. Aim: The goal is to outline an early experience with a comprehensive approach to planning a percutaneous endovascular arteriovenous fistula service at King's College Hospital. Method: This article describes the referral process, screening, clinical assessments, procedural elements and cannulation. Insights are drawn from a single-centre experience in the UK with the WavelinQ System (BD). Emphasis will be placed on key staffing needs, particularly related to patient selection and dialysis nurse training. Conclusion: By addressing these essential considerations, a pAVF service can be successfully implemented.