Fistula Creation Research Articles

Comparative study on efficacy of ultrasound-guided supraclavicular versus costoclavicular brachial plexus block in patients for arteriovenous fistula surgery

Background: Patients with end-stage renal failure (ESRF) who require arteriovenous fistula (AVF) creation often have multiple comorbidities, making the brachial plexus block a suitable choice for anaesthesia. The objective of this study is to compare the efficacy of ultrasound-guided supraclavicular and costoclavicular brachial plexus blocks for AVF creation. Methods: A total of 70 patients scheduled for the creation of AVF in the distal upper extremity were randomly assigned to 2 groups: supraclavicular block (SCB), Group A: n = 35, and costoclavicular block (CCB), Group B: n = 35. Both groups received 20 ml of 0.5% ropivacaine and 10 ml of 1% lidocaine. The measured parameters included the speed of onset of motor and sensory blockade, the quality of blockade, procedural-related pain score, patient satisfaction, and regional perfusion. Results: The costoclavicular block demonstrated a significantly faster onset to achieve complete paralysis (p = 0.01) in all sensory and motor nerves compared to the supraclavicular block. Additionally, there was a significant difference in regional perfusion, with higher perfusion observed in the supraclavicular block (p = 0.013). However, there were no significant differences in the quality of block (p = 0.573), and procedural-related pain score (p = 0.117) between the 2 groups. Conclusion: The costoclavicular block offers a faster onset of sensory and motor blockade compared to the supraclavicular block. However, they are comparable in terms of the quality of the block and procedural-related pain. This new technique can be considered as an alternative for providing anaesthesia in patients with ESRFundergoing AVF creation.

Heterogeneous gene expression during early arteriovenous fistula remodeling suggests that downregulation of metabolism predicts adaptive venous remodeling

Clinical outcomes of arteriovenous fistulae (AVF) for hemodialysis remain inadequate since biological mechanisms of AVF maturation and failure are still poorly understood. Aortocaval fistula creation (AVF group) or a sham operation (sham group) was performed in C57BL/6 mice. Venous limbs were collected on postoperative day 7 and total RNA was extracted for high throughput RNA sequencing and bioinformatic analysis. Genes in metabolic pathways were significantly downregulated in the AVF, whereas significant sex differences were not detected. Since gene expression patterns among the AVF group were heterogenous, the AVF group was divided into a ‘normal’ AVF (nAVF) group and an ‘outliers’ (OUT) group. The gene expression patterns of the nAVF and OUT groups were consistent with previously published data showing venous adaptive remodeling, whereas enrichment analyses showed significant upregulation of metabolism, inflammation and coagulation in the OUT group compared to the nAVF group, suggesting the heterogeneity during venous remodeling reflects early gene expression changes that may correlate with AVF maturation or failure. Early detection of these processes may be a translational strategy to predict fistula failure and reduce patient morbidity.

Changes of Dissociative Properties of Hemoglobin in Patients with Chronic Kidney Disease.

Background: The ability of hemoglobin to bind and dissociate oxygen is crucial in delivering oxygen to tissues and is influenced by a range of physiological states, compensatory mechanisms, and pathological conditions. This may be illustrated by the oxyhemoglobin dissociation curve (ODC). The key parameter for evaluating the oxygen affinity to hemoglobin is p50. The aim of this study was to evaluate the impact of hemodialysis on p50 in a group of patients with chronic kidney disease (CKD). An additional goal was to assess the correlation between p50 and the parameters of erythropoiesis, point-of-care testing (POCT), and other laboratory parameters. Methods: One hundred and eighty patients (106 male, 74 female), mean age 62.5 ± 17 years, with CKD stage G4 and G5 were enrolled in this cross-sectional study. Patients were divided into two groups, including 65 hemodialysis (HD) patients and 115 patients not receiving dialysis (non-HD). During the standard procedure of arteriovenous fistula creation, blood samples from the artery (A) and the vein (V) were taken for POCT. The causes of CKD, as well as demographic and comorbidity data, were obtained from medical records and direct interviews. Results: The weekly dose of erythropoietin was higher in HD patients than in non-HD patients (4914 ± 2253 UI vs. 403 ± 798 UI, p < 0.01), but hemoglobin levels did not differ between these groups. In the group of non-HD patients, more advanced metabolic acidosis (MA) was found, compared to the group with HD. In arterial and venosus blood samples, the non-HD group had significantly lower pH, pCO2 and HCO3-. This group had a higher proportion of individuals with MA with HCO3- < 22 mmol/L (42% vs. 24%, p < 0.01). The absolute difference of p50 in arterial and venous blood was determined using the formula Δp50 = (p50-A) - (p50-V). Δp50 was significantly higher in the HD group in comparison to non-HD (0.08 ± 2.05 mmHg vs. -0.66 ± 1.93 mmHg, p = 0,02). There was a negative correlation between pH and the p50 value in arterial (pH-A vs. p50-A, r = -0.56, p < 0.01) and venous blood (pH-V vs. p50-V, r = -0.45, p < 0.01). In non-HD patients, hemoglobin levels correlated negatively with p50 (r = -0.29, p < 0.01), whereas no significant relation was found in HD patients. Conclusions: The ODC in pre-dialysis CKD (non-HD) patients is shifted to the right due to MA, and this is an additional factor influencing erythropoiesis. Hemodialysis restores the natural differences in hemoglobin's dissociation characteristics in the arterial and venous circulation.

Incremental hemodialysis and vascular access complications: a 12-year experience in a hospital hemodialysis unit.

Incremental hemodialysis (HD) is considered a valid alternative for patients with residual kidney function. Evidence concerning its effect on vascular access is scarce. We present our 12-year experience of an incremental hemodialysis program with the aim of evaluating survival and complications of arteriovenous fistula in these patients compared to the thrice-weekly scheme. From January 1st, 2006 to December 31st, 2017, 220 incident patients startedhemodialysis, 132 (60%) of whom began hemodialysis with two sessions per week and 88 (40%) with three sessions per week. Demographic and clinical variables were assessed at the start of treatment. Data regarding arteriovenous fistula survival and complications were collected. Both groups had similar baseline sociodemographic and clinical characteristics. A total of 188 (85%) patients were dialyzed with an arteriovenous fistula during follow-up. Eighty-three patients had one or more fistula complications, with no differences between incremental and conventional groups (p = 0.55). Fistula survival rates showed no significant difference between the two groups, whether analyzed from the date of fistula creation (Log Rank p = 0.810) or from the date of initial fistula cannulation (Log Rank p = 0.695). We found no differences in arteriovenous fistula survival or complication rate between patients who started HD with an incremental versus a conventional treatment scheme. Randomized controlled clinical trials may be warranted to achieve a higher degree of evidence.

Multi-Center Two-Year Patency Outcomes of Endovascular Arteriovenous Fistulas (endoAVF) Created with a 4 French System.

To assess multicenter two-year patency outcomes of endovascular arteriovenous fistulas (endoAVF) created with the WavelinQ device. Patients who had fistulas created at three centers from January 2018 to December 2020 were included in this retrospective study. In total, 112 patients underwent endoAVF creation [40 females, 72 males; mean age 60years (range 18-88)]. Data collected included patient demographics, location of fistula creation, interventions performed, and brachial artery flows pre- and post-creation. Two-year cumulative patency, functional patency, and primary patency were assessed with Kaplan-Meier methodology. Factors affecting patency and maturation were examined using the Cox proportional hazards model. Technical success defined as angiographically successful endoAVF creation was 97.3% (109/112). In 11 patients the fistula did not mature for dialysis use. For 98 patients (87%) with endoAVF maturation, 12- and 24-month cumulative patency was 94.3% and 91.7%. Functional patency (two-needle cannulation) at 12 and 24months was 95.7% and 92.7%, respectively. Median maturation time is 95days (IQR 51-231days). Male gender and brachial vein coiling at the time of endoAVF creation were predictive of maturation. There were 34 censored events (four patients undergoing renal transplantation; 30 patients deceased). Number of reinterventions per patient year was 0.73 where 43 were maturation procedures and 101 were maintenance procedures. One Grade 3 complication occurred of arterial access puncture site pseudoaneurysm. A high two-year functional and cumulative patency following endoAVF creation with the WavelinQ device was observed in this multicenter real-world experience Level of Evidence: 3 Level of Evidence III.

Effects to cerebral oxygenation by arteriovenous fistula creation in patients with chronic kidney disease.

Vascular access, including arteriovenous fistula (AVF), is essential in patients undergoing hemodialysis (HD). However, the presence of AVF is non-physiological in humans and could pose a burden to the systemic circulation or tissue microcirculation, potentially affecting tissue oxygenation, including in the brain. Recently, near-infrared spectroscopy has been used to measure regional oxygen saturation (rSO2) as a marker of cerebral oxygenation in various settings, including in patients undergoing HD. Thus far, no studies have reported changes in cerebral rSO2 before and after AVF creation. This study aimed to monitor the differences in cerebral oxygenation before and after AVF creation and to clarify the clinical factors affecting the changes in cerebral rSO2. Forty-eight patients (34 men, 14 women) with chronic kidney disease (CKD) who were not undergoing dialysis and newly created AVF were recruited. Cerebral rSO2 values before and after AVF creation were evaluated using near-infrared spectroscopy (INVOS 5100c). Cerebral rSO2 values were significantly changed from 60.3% ± 7.5% to 58.4% ± 6.8% before and after AVF creation in all patients (p < 0.001). Cerebral rSO2 were also lower in patients with diabetes mellitus (DM) than in those without DM (57.5 ± 7.1 vs 63.7 ± 6.5, p = 0.003) before surgery; however, no differences of changes in cerebral rSO2 were observed between the two groups after AVF creation. Additionally, multivariate regression analysis identified changes in HR (standardized coefficient: 0.436) as independent factors associated with changes in cerebral rSO2. Surgically created AVF was associated with the deterioration of cerebral rSO2 in patients with CKD not undergoing dialysis. Notably, AVF could cause cerebral hypoxia, and thus further studies are needed to clarify the clinical factors influencing changes in cerebral oxygenation after AVF creation.

Challenges of Predicting Arteriovenous Access Survival Prior to Conversion from Catheter

The decision to convert from catheter to arteriovenous access is difficult yet very important. The ability to accurately predict fistula survival prior to surgery would significantly improve the decision making process. Many previously investigated demographic and clinical features have been associated with fistula failure. However, it is not conclusively understood how reliable predictions based on these parameters are at an individual level. The aim of this study was to investigate the probability of arteriovenous fistula maturation and survival after conversion using machine learning workflows. A retrospective cohort study on multicentre data from a large North American dialysis organisation was conducted. The study population comprised 73 031 chronic in centre haemodialysis patients. The dataset included 49 variables including demographic and clinical features. Two distinct feature selection and prediction pipelines were used: LASSO regression and Boruta followed by a random forest classifier. Predictions were facilitated for re-conversion to catheter within one year. Additionally, all cause mortality predictions were conducted to serve as a comparator. In total, 38 151 patients (52.2%) had complete data and made up the main cohort. Sensitivity analyses were conducted in 67 421 patients (92.3%) after eliminating variables with a high proportion of missing data points. Selected features diverged between datasets and workflows. A previously failed arteriovenous access appeared to be the most stable predictor for subsequent failure. Prediction of re-conversion based on the demographic and clinical information resulted in an area under the receiver operating characteristic curve (ROCAUC) between 0.541 and 0.571, whereas models predicting all cause mortality performed considerably better (ROCAUC 0.662 - 0.683). While group level depiction of major adverse outcomes after catheter to arteriovenous fistula or graft conversion is possible using the included variables, patient level predictions are associated with limited performance. Factors during and after fistula creation as well as biomolecular and genetic biomarkers might be more relevant predictors of fistula survival than baseline clinical conditions.

Evaluating the Effectiveness of Systemic Heparin During Arteriovenous Fistula Creation by Emulating a Target Trial.

Most of the 800,000 people living with end-stage kidney disease in the United States rely on a functioning vascular access to provide life-sustaining hemodialysis, yet one-third of arteriovenous fistulas experience early failures. Determining the safety and effectiveness of systemic heparin during fistula creation could improve the quality and quantity of life for these vulnerable patients. In this paper, a pragmatic randomized trial was emulated to assess the effect of systemic heparin administration (vs. none) during radiocephalic arteriovenous fistula creation on early bleeding and thrombosis using data from two international multicenter randomized trials performed between 2014 and 2019. Marginal risks were estimated using inverse probability weighted parametric survival analysis and confidence intervals were generated with bootstrapping. A total of 914 patients were enrolled and 61% received systemic heparin; median (IQR) age was 58 (49, 67) years and 45% were on hemodialysis at enrollment. No difference in the risk of bleeding events was observed, with a risk difference (95% CI) at 14 days of -0.1% (-1.6, 1.4). The risk of access thrombosis was lower in the heparin group, with a risk of 3.7% (2.6, 4.8) after heparin and 5.3% (3.4, 7.4) without heparin at 14 days (risk ratio 0.72, 95% CI 0.50, 0.98).

Trends in clinical outcomes of older hemodialysis patients: data from the 2023 Korean Renal Data System (KORDS).

With an increasing aging population, the mean age of patients with end-stage kidney disease (ESKD) is globally increasing. However, the current clinical status of elderly patients undergoing hemodialysis (HD) is rarely reported in Korea. The current study analyzed the clinical features and trends of older patients undergoing HD from the Korean Renal Data System (KORDS) database. The patients were divided into three groups according to age: <65 years (the young group), n = 50,591 (35.9%); 65-74 years (the younger-old group), n = 37,525 (26.6%); and ≥75 years (the older-old group), n = 52,856 (37.5%). The proportion of older-old group undergoing HD significantly increased in incidence and decreased in prevalence from 2013 to 2022. The median levels of hemoglobin, serum creatinine, albumin, calcium, phosphorus, and intact parathyroid hormone significantly decreased in the older-old group. The proportions of arteriovenous fistula creation and left forearm placement showed decreased trends with age. Although the utilization of low surface area dialyzers increased with age, the dialysis adequacy, including urea reduction ratio and Kt/V was within acceptable range in the older-old group on HD. Over the past 20 years, the mortality rate in the older-old group has increased, with cardiovascular diseases decreasing and infectious diseases increasing. The incidence of elderly patients undergoing HD has increased over time, but the high mortality of the older-old group needs to be solved. Therefore, it is imperative to develop holistic strategies based on age and individual needs for patients with ESKD.

Simplifying the Creation of the Ulnar Basilic Arteriovenous Fistula: The Royal Wave Position – A Case Series

ABSTRACT While the radio-cephalic arterio-venous fistula (RCAVF) remains the procedure of choice for hemodialysis, the value of the ulnar-basilic arterio-venous fistula (UBAVF) is perhaps underappreciated. The challenge of placing the forearm in a suitable and comfortable position for both the surgeon and the patient during the creation of the UBAVF may be an important factor inhibiting its use. We present a new method of hand positioning in the creation of the UBAVF that we have termed the “Royal Wave” position, which facilitates both patient comfort and surgical access intraoperatively. Patients suffering from chronic kidney disease stage -V were operated upon for the creation of UBAVF following the standardized protocol in the Royal Wave position. Patency (by Color Doppler) was recorded before discharge. Patients were clinically followed up for a period of 3 months. A total of five patients (four males) with the age range of 43–66 years were studied. The position was found to be comfortable for patients and suitable for surgeons. All five patients had successful creation of fistulas that remained patent, which was documented by Doppler report prior to discharge. The patients were followed up till 3 months post fistula creation. Thrombosis was not seen in any patient, and the basilic veins arterialized and were used for dialysis in all five patients. This innovation in positioning, the “Royal Wave” position improves the comfort of both the operator and the patient during surgery, and merits consideration when creating a UBAVF.

#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.

#2795 In-silico assessment of arteriovenous fistula maturation with patient-specific computational hemodynamic models

Abstract Background and Aims Native arteriovenous fistula (nAVF) is the preferred access for haemodialysis (HD) treatment. Both the quality and complications of the haemodialysis technique are closely related to vascular access. nAVF maturation process includes several morphological changes affecting haemodynamics, with previous studies suggesting that it is highly related to AVF failure. Computational Fluid Dynamics (CFD) simulations by using idealized morphologies or the analysis of one patient-specific geometry have been proposed to understand the pathophysiology of maturation failure. However, it is difficult to correlate with clinical practice and therefore limits its use. The aim is to develop a patient-specific modelling time pipeline, incorporating the haemodynamics of the blood flow to real anatomical and morphological characteristics. Method Design: prospective computational simulation analysis of nAVF in 3 patients at 3 different stages: after fistula creation, (1 week), maturation (1 month) and post-maturation (6 months). Analysis: morphological and haemodynamic. Inclusion criteria: &amp;gt;18 years and end-stage chronic kidney disease. Variables and data: Once morphology was extracted from nAVF magnetic resonance imaging, generated meshes were refined and compiled to obtain a volumetric mesh. The boundary conditions of the model were defined and extracted using ultrasound nAFV data. Data were analyzed at the 3 stages. Models: A 3-element Windkessel model was used to simulate the pressure waveform to feed the vein of the system. In this model, clinical data were also considered to classify the patient as normotensive or hypertensive to estimate waveform parameters. The Windkessel model estimates wall shear stress (WSS), velocity and flow for all the points located in the mesh by making an analogy from an electric circuit resistance model. As validation, the flow obtained from the Windkessel model was compared with the one obtained from the ultrasound scan of the patient. Results Different temporal points were analyzed for each nAVF. Results from the simulations in Fig. 1, illustrating the evolution over time and development. The geometrical characteristics were found to significantly impact on flow dynamics. The area most affected by flow was the juxta-anastomotic section which showed higher magnitude distribution of WSS and velocity for all time-points. According to the analysis of the simulations, a perpendicular junction between the vein and the artery potentially resulted in less damage in this area (in WSS terms), being important to mitigate the AVF failure. At maturation stage (1 month) the analysis shows WSS distribution mainly located in the juxta-anastomotic section and decreased in magnitude regarding one week; therefore, this can be marked as the stabilization point for nAFV maturation. Conclusion

#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.

#1578 Left ventricular ejection fraction: association with risk of mortality and the incidence of AVF dysfunction

Abstract Background and Aims Ejection fraction (EF) and chronic heart failure (HF) are often considered as criteria for the possibility of arteriovenous fistula (AVF) creation in relation to an increased risk of death, without sufficient evidence for this. There is, however, rare but compelling evidence that low EF increases the risk of AVF dysfunction. Aims: to evaluate the association between EF at the time of AVF creation and the incidence of adverse cardiovascular events, all-cause mortality, as well as AVF dysfunction Method This retrospective cohort study included 962 adult patients who had a first-time created functioning AVF. Only patients with a more than three months period after AVF creation and within a five-year period were included. The mean follow-up period was 34 ± 13 months. Four groups were identified based on EF and the presence of HF at the time of AVF creation (transthoracic echocardiogram): HF with reduced EF (rEF) &amp;lt;40%, with mid-range (mrEF) of 40-49%, or with preserved EF (pEF) ≥50% + HF, and a “no HF” group with EF ≥50% and no HF. Results In the univariate analysis, a reduced EF was associated with an increased risk of mortality, with the hazard ratios (HRs) of 2.706 [95% CI 1.330; 5.507], p = 0.006 for mrEF and 8.250 [95% CI 2.621; 25.97], p &amp;lt; 0.001 for rEF, compared to the “no HF” group (here and thereafter)—Fig. 1. However, after adjusting for age, sex, and Charlson Comorbidity Index (CCI), the EF was not significantly associated with the risk of death. Only the CCI score remained a significant factor (HR = 1.748 [95% CI 1.482; 2.063], p &amp;lt; 0.001). A decreased EF was associated with the incidence of AVF dysfunction both in the univariate analysis and after adjustments. In the univariate analysis, the incidence rate ratios (IRRs) of 6.88 [95% CI 3.88; 12.1], p &amp;lt; 0.001 for mrEF, and 19.9 [95% CI 8. 64; 41.6], p &amp;lt; 0.001 for rEF, were shown. After adjusting for age, sex, and CCI, the IRR for mrEF was 8.96 [95% CI 5.81; 13.7], p &amp;lt; 0.001, and for rEF it was 23.4 [95% CI 13.8; 38.6], p &amp;lt; 0.001. Even in the presence of polycystic kidney disease and diabetes mellitus in the fully adjusted model, the association between EF and the incidence of AVF dysfunction remained statistically significant: the IRR was 8.61 [95% CI 5.61; 13.1], p &amp;lt; 0.001 for mrEF, and 33.4 [95% CI 19.5; 56.2], p &amp;lt; 0.001 for rEF. The findings were confirmed in a sensitivity analysis that included adjustments for unplanned onset of dialysis and competing risks survival analysis (death—outcome of interest, conversion of HD to PD or kidney transplantation and conversion of AVF to CVC—competing events). According to our results patients with EF&amp;lt;40% will inevitably lose AVF function for various reasons within 3.5 years—Fig. 2. Meanwhile, this approach will give the patient additional time of HD via AVF, but not CVC, without increasing the risk of death, subject to Qa monitoring. Conclusion In patients with CKD 5 who are initiating treatment with maintenance hemodialysis, a decreased EF is associated to a greater extent with a higher risk of AVF dysfunction than with an increased risk of mortality. The burden of comorbidities, rather than a standalone assessment of EF, is one of the major risk factors determining patient survival.

#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 (&amp;gt; 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

#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.

#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.

#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 (&amp;lt;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&amp;lt;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 &amp;lt; 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 &amp;lt; 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.

Predictors of Steal Syndrome After Brachiocephalic Fistula Creation in a Single Institution County Hospital

Predictors of Steal Syndrome After Brachiocephalic Fistula Creation in a Single Institution County Hospital