Unassisted Maturation Research Articles

Unexpected identification of peak systolic velocity in the radial artery as a risk factor for functional primary patency of radiocephalic fistulas.

As radiocephalic fistula is not necessarily appropriate for all patients with advanced kidney disease, our aim was to investigate the sensitive indicators that affect the functional primary patency of radiocephalic fistulas. This prospective observational study included consecutive patients referred to the Second Hospital of Dalian Medical University for initial creation of radiocephalic fistula from July 2017 to December 2019. Preoperative ultrasound parameters, demographic characteristics, serum indicators and comorbidities were recorded. The functionality of radiocephalic fistulas would be assessed every 6 months until March 2023, following their unassisted maturation, unless AVF dysfunction, kidney transplantation, mortality or loss to follow-up occurred. Kaplan-Meier analysis was employed to illustrate differences in functional primary patency of radiocephalic fistulas, while log-rank tests were utilized to compare survival curves. Univariate and multivariable Cox proportional hazard models were performed, yielding hazard ratios and 95% confidence intervals. The significance level was set at 5% for a two-sided test. The studies included a total of 182 patients who successfully underwent radiocephalic fistulas with primary unassisted maturation. The mean age of the study population was 58 years, with 66 percent being male. All AVFs were placed on the forearm, with 84% located on the left side. The primary patency rates of eleven parameters exhibited significant differences between groups stratified by cut-off values at different time points. Notably, the group with a peak systolic velocity of the radial artery near the elbow ≤59cm/s demonstrated a higher primary patency rate compared to the >59cm/s group at 2 years (78.4% vs 57.5%, P=0.026). In the univariate Cox proportional hazard models, the P values for gender, the diameter of radial artery near the elbow, the peak systolic velocity of radial artery near the elbow, the diameter of brachial artery near the elbow were less than 0.1. The multivariable Cox proportional hazard model revealed that only the peak systolic velocity of radial artery near the elbow exhibited a significant impact on the functional primary patency of radiocephalic fistula (HR=1.017, 95%CI 1.002-1.031, P=0.021). The peak systolic velocity of the radial artery near the elbow is a significant risk factor for functional primary patency of radiocephalic fistula. Preoperative evaluation of the peak systolic velocity could allow to identify patients with a lower likelihood of long-term radiocephalic fistula patency, facilitating improved selection of candidates for radiocephalic fistula creation.

Vein distensibility is superior to vein diameter for predicting unassisted maturation of arteriovenous fistulae

Vein distensibility is superior to vein diameter for predicting unassisted maturation of arteriovenous fistulae

Efficacy of ultrasonography and color-Doppler for early prediction of hemodialysis arteriovenous fistula unassisted maturation.

Arteriovenous fistula (AVF) failure is a prevalent concern for patients with end-stage kidney disease on hemodialysis. Recognizing the efficacy of ultrasound Doppler in post-operative AVF evaluation, this study sought to discern the predictive capabilities of various ultrasonographic and color-Doppler metrics for early AVF outcomes. This single-center, prospective cohort study spanned 1 year and, post ethical clearance, included all patients who underwent native AVF creation surgery and were subsequently referred for standard post-operative ultrasound Doppler assessment. Parameters such as fistula size, cephalic vein area and diameter, and AVF flow velocity and rates were assessed on post-operative day 2, week 2, and week 6. These initial findings were juxtaposed with later outcomes to determine unassisted AVF results. Of the initial cohort of 40 patients, 75% encountered AVF failure, whereas 25% realized successful unassisted AVF maturation. A notable observation was the significant variance in AVF flow rates as early as post-operative day 2. A threshold of >246 ml/min was indicative of successful unassisted AVF maturation, leading to a sensitivity of 80% and a specificity of 70%. Although the cephalic vein diameter on post-operative day 2 lacked a robust association with AVF outcomes, a cut-off of >3.4 mm, when combined with flow rate testing, augmented the cumulative sensitivity to 92%. Ultrasound Doppler stands out as a valuable quantitative imaging modality, adept at prognosticating AVF outcomes from as early as post-operative day 2. In particular, a flow rate exceeding 246 ml/min and a cephalic vein diameter surpassing 3.4 mm are salient indicators for the early prediction of successful AVF outcomes.

Vein distensibility is superior to vein diameter for predicting unassisted maturation of arteriovenous fistulae

BackgroundA mature arteriovenous fistula (AVF) is the preferred hemodialysis access owing to its durability and lower risk of complications. Various factors have been implicated as predictors for maturation, including vein diameter and access type. Vein distensibility, which refers to the ability of the vein to dilate in response to changes in blood flow and pressure, has been proposed as a potential predictor for maturation, but its utility remains poorly studied. MethodsThis is a single-institution retrospective study of AVFs performed under regional anesthesia. Vein distensibility was defined as the absolute and relative difference in target vein diameter (TVD) between the preoperative ultrasound vein mapping performed with tourniquet and a repeat ultrasound examination after a regional block before AVF creation and without a tourniquet. ResultsForty-six patients underwent first-time AVF surgery with distensibility recorded in a prospectively maintained database. The mean initial preoperative TVD was 2.7 mm, and after the block 3.4 mm. The unassisted maturation rate for the entire cohort was 76%. In patients with an absolute change of TVD of <0.5 mm (Δ<0.5), the unassisted maturation rate was 63% (12/19), even though 95% of the group had a preoperative TVD of >3 mm. In those with ≥0.5 mm, the unassisted maturation rate was 85% (23/27; P = .08), even though the preoperative vein map TVD was 2.3 mm and 75% had a vein map TVD of <3 mm. For radiocephalic AVFs (n = 26), the unassisted maturation rate was 75% for Δ<0.5 vs 94% for Δ≥0.5 (P = .16), despite a preoperative vein map TVD of >3 mm in 92% vs 75%, respectively. The receiver operatring characteristic area under the curve for unassisted maturation with a Δ≥0.5 mm was 0.68 (P = .26). ConclusionsQuality in dialysis access surgery requires optimizing the unassisted maturation rate. A physiological measure that accounts for the dynamic process of maturation may be more informative than anatomic measurements alone. The results shown here demonstrate that vein distensibility may be a better predictor than absolute vein diameter on standard vein mapping ultrasound examinations.

Unexpected identification of peak systolic velocity in the radial artery as a risk factor for functional primary patency of radiocephalic fistulas

ObjectiveAs radiocephalic fistula is not necessarily appropriate for all patients with advanced kidney disease, our aim was to investigate the sensitive indicators that affect the functional primary patency of radiocephalic fistulas. MethodsThis prospective observational study included consecutive patients referred to the Second Hospital of Dalian Medical University for initial creation of radiocephalic fistula from July 2017 to December 2019. Preoperative ultrasound parameters, demographic characteristics, serum indicators and comorbidities were recorded. The functionality of radiocephalic fistulas would be assessed every 6 months until March 2023, following their unassisted maturation, unless AVF dysfunction, kidney transplantation, mortality or loss to follow-up occurred. Kaplan–Meier analysis was employed to illustrate differences in functional primary patency of radiocephalic fistulas, while log-rank tests were utilized to compare survival curves. Univariate and multivariable Cox proportional hazard models were performed, yielding hazard ratios and 95% confidence intervals. The significance level was set at 5% for a two-sided test. ResultsThe studies included a total of 182 patients who successfully underwent radiocephalic fistulas with primary unassisted maturation. The mean age of the study population was 58 years, with 66 percent being male. All AVFs were placed on the forearm, with 84% located on the left side.The primary patency rates of eleven parameters exhibited significant differences between groups stratified by cut-off values at different time points. Notably, the group with a peak systolic velocity of the radial artery near the elbow ≤59cm/s demonstrated a higher primary patency rate compared to the >59cm/s group at 2 years (78.4% vs 57.5%, P=0.026).In the univariate Cox proportional hazard models, the P values for gender, the diameter of radial artery near the elbow, the peak systolic velocity of radial artery near the elbow, the diameter of brachial artery near the elbow were less than 0.1. The multivariable Cox proportional hazard model revealed that only the peak systolic velocity of radial artery near the elbow exhibited a significant impact on the functional primary patency of radiocephalic fistula (HR=1.017, 95%CI 1.002–1.031, P=0.021). ConclusionsThe peak systolic velocity of the radial artery near the elbow is a significant risk factor for functional primary patency of radiocephalic fistula. Preoperative evaluation of the peak systolic velocity could allow to identify patients with a lower likelihood of long-term radiocephalic fistula patency, facilitating improved selection of candidates for radiocephalic fistula creation.

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

Differentiating between arteriovenous fistula (AVF) maturation and failure can help determine which AVF will undergo successful canulation and which ones will require immediate rescue. A prospective observational study was conducted at Vajira Hospital in Bangkok, Thailand, between October 2020-November 2022. A single vascular surgeon performed a physical examination on patients with chronic kidney disease undergoing AVF placement, and a radiologist conducted Doppler ultrasonography during the second and sixth postoperative weeks. Dialysis nurses determined AVF maturity by performing cannulation. The study compared the accuracy of physical examination and Doppler ultrasonography. A model was developed to predict the success of AVF use. Out Of the 125 recruited patients, 81% demonstrate unassisted maturation of their AVF. The male sex and brachiocephalic type are associated with AVF maturation. The physical examination findings of palpable thrill and the absence of a strong pulse at the 6th week show an area under the receiver operating curve (AUC) value of 0.79. Similarly, arterial end-diastolic velocity on ultrasonography at the 6th week also demonstrates a comparable predictive value with an AUC of 0.82 (p=0.697). Meanwhile, the model that combined end-diastolic velocity and venous volume flow yields the best results for predicting AVF maturation, with an AUC of 0.92. These models provide more accurate predictions compared to physical examination alone (AUC: 0.92 vs. 0.79; p<0.01). Although a prudent physician predicts AVF maturation through a thorough physical examination, Doppler ultrasonography is preferred in anticipating the success of postoperative AVF placement.

Nomogram-based prediction of the risk of AVF maturation: a retrospective study.

Early identification of autogenous arteriovenous fistula (AVF) maturation failure in patients with end-stage renal disease (ESRD) is crucial, as it enables early interventions that can enhance AVF maturation rates and reduce the duration of catheter use. This study aimed to identify factors that may predict arteriovenous fistula maturation in patients undergoing maintenance hemodialysis. This retrospective study included a cohort of 532 ESRD patients who underwent AVF creation and routine follow-up at the Beijing Haidian Hospital (Haidian Section of Pecking University Third Hospital) from August 2018 to March 2022. A total of 532 patients were randomly divided into a training cohort (389 cases) and a validation cohort (143 cases). Patients in each cohort were categorized into mature and non-mature groups based on whether they met clinical or ultrasound criteria 3 months after AVF creation. The timing of early intervention for non-maturation AVF was preliminarily discussed after a risk prediction nomogram for non-maturation in newly AVF creation was constructed. Of the 532 patients, 379 (73.24%) achieved fistula maturation at 3 months postoperatively. We randomly divided the total study population using computer-generated randomization into a training cohort (n = 389) and a validation cohort (n = 143) in an approximately 7:3 ratio. Analysis of the training cohort revealed that the anastomotic diameter (anas1), the internal diameter of the anastomotic vein (V1), brachial artery blood flow (F1) at 1 month, and brachial artery blood flow (F3) at 3 months postoperatively were associated with AVF maturation. A maturation nomogram was developed for the training cohort, yielding an area under the curve (AUC) of 0.938 (95% confidence interval [CI], 0.908-0.967), with a sensitivity of 0.911 and a specificity of 0.856. The model was validated in the validation cohort, showing an AUC of 0.927 (95% CI, 0.879-0.975), with a sensitivity of 0.870 and specificity of 0.886. The calibration curve showed strong agreement between nomogram predictions and actual observations. The anastomotic diameter (anas1), the internal diameter of the anastomotic vein (V1), brachial artery blood flow (F1) at 1 month, and brachial artery blood flow (F3) at 3 months postoperatively can predict the unassisted maturation of AVF.

Performance Characteristics of Candidate Criteria for Hemodialysis Arteriovenous Fistula Maturation.

Twenty to 60% of newly created hemodialysis arteriovenous fistulas do not mature adequately for use. One barrier to developing interventions to improve fistula outcomes is a lack of standardized criteria for maturation. Using data from the multicenter, prospective Hemodialysis Fistula Maturation (HFM) Study, we determined sensitivities, specificities, and positive and negative predictive values of multiple candidate maturation criteria using the HFM Study maturation criteria as the reference. We also compared, across the maturation criteria, relationships between maturation and fistula survival using Cox proportional hazards models. We included 535 of the 602 HFM Study participants. The median (interquartile range) age was 57 (47-65) years, 70% were men, and 45% were Black participants. Depending on the criterion and time frame for ascertainment (3, 4, 5, 6, or 9 months), sensitivities ranged from 57% to 100%, specificities ranged from 85% to 100%, positive predictive values ranged from 88% to 100%, and negative predictive values ranged from 65% to 100%. For all criteria, areas under the curve for the 6-month (0.90-0.97 for unassisted maturation and 0.89-0.95 for overall maturation) and 9-month time frames were similar. Attainment of unassisted maturation was associated with lower risks of fistula abandonment, with hazard ratios ranging from 0.10 to 0.40 depending on the criterion and time frame. Eliminating dialysis adequacy indicators, or simplifying the criteria in other ways, had little effect on performance characteristics. High performance characteristics are maintained with maturation criteria that are simpler and less burdensome to ascertain than the HFM Study outcome measure.

#4066 EARLY EXPERIENCE OF ENDOVASCULAR CREATION OF ARTERIOVENOUS FISTULA IN SOUTHEAST ASIA

Abstract Background and Aims Creation of native arteriovenous fistulae(AVF) has been traditionally through open surgical technique. Endovascular creation of AVF (EndoAVF) has been shown to be an effective alternative to open surgery in Europe and North America. In Asia, EndoAVF creation is a novel technique and we report our early experience of EndoAVF creation in a case series of 18 patients. Method Between Nov 2021 to Aug 2022, ultrasound vein mapping was performed in a total of 39 patients. Eighteen patients were deemed suitable for EndoAVF and proceed for the procedure. EndoAVF creation was attempted by multidisciplinary team comprising of vascular surgeon, interventional radiologists and nephrologists. The patients were prospectively followed-up for at least 6-months. Baseline demographics, vascular characteristics, unassisted maturation, functional patency and freedom from intervention were studied. Results Table 1 shows the baseline demographics of the participants. Twelve patients (67%) were already initiated on hemodialysis via tunneled dialysis catheters during the procedure. EndoAVF was successfully created in 16 (89%) patients. Of which, 13 (72%) were WavelinQ while the remaining 5 (28%) were Ellipsys EndoAVF. The reasons of failures were inability to cannulate artery (n = 1) and vein (n = 1). Minor complications occurred in 6 patients: extravasation in 5 cases and hematoma in 1 patient. The brachial artery flow rates at creation and 1-month post-creation were 558 ± 328 and 583 ± 215 mls/min, respectively. Two participants (11%) underwent interventions to facilitate maturation of the EndoAVF. The median time to maturation was 70 (IQR 49 – 106) days while the median time to first successful 2-needle cannulation was 77 (56 – 127) days. At 6-months, 8 (50%) of EndoAVFs that were successfully created required further intervention to maintain patency, while 1 EndoAVF was abandoned from failure to mature despite intervention Conclusion EndoAVF can be created successfully in a Southeast Asian population. Further studies with more patients and longer follow-up periods are needed to assess long-term outcomes.

Sex Disparities in Arteriovenous Fistula Maturation Outcomes

The end-stage kidney disease life-plan aims to individualize hemodialysis (HD) access selection in patients requiring renal replacement therapy. Paucity of data on risk factors for poor arteriovenous fistula (AVF) outcomes limits the ability of physicians to guide their patients on this decision. This is especially true for female patients, who are known to have worse AVF outcomes when compared to male patients. The goal of this study was to identify risk factors associated with poor AVF maturation outcomes in female patients that will help guide individualized access selection. A retrospective review of 1,077 patients that had AVF creation between 2014 and 2021 at an academic medical center was performed. Maturation outcomes were compared between 596 male and 481 female patients. Separate multivariate logistic regression models were created for the male and female cohorts to identify factors associated with unassisted maturation. AVF was considered mature if it was successfully used for HD for 4-week sessions without need for further interventions. Unassisted fistula was defined as an AVF that matured without any interventions. The male patients were more likely to receive more distal HD access; 378 (63%) male versus 244 (51%) female patients had radiocephalic AVF, P<0.001. Maturation outcomes were significantly worse in female patients; 387 (80%) AVFs matured in females and 519 (87%) in male patients, P<0.001. Similarly, the rate of unassisted maturation was 26% (125) in female patients versus 39% (233) in male patients, P<0.001. Mean preoperative vein diameters were similar in both groups; 2.8±1.1mm in male versus 2.7±0.97mm in female patients, P=0.17. Multivariate logistic regression analysis of the female patients revealed that Black race (odds ratio [OR]: 0.6, 95% confidence interval [CI]: 0.4-0.9, P=0.045), radiocephalic AVF (OR: 0.6, 95% CI: 0.4-0.9, P=0.045), and preoperative vein diameter <2.5mm (OR: 1.4, 95% CI: 10.33-0.901.1-1.7, P=0.014) were independent predictors of poor unassisted maturation in this cohort. In male patients, preoperative vein diameter <2.5mm (OR: 1.4, 95% CI: 1.2-1.7, P<0.001) and need for HD prior to AVF creation (OR: 0.6, 95% CI: 0.3-0.9, P=0.018) were independent predictors of poor unassisted maturation. Black women with marginal forearm veins may have worse maturation outcomes, and upper arm HD access should be considered when advising patients on their end-stage kidney disease life-plan.

Arterial Diameter and Percentage of Monocytes are Sex-Dependent Predictors of Early Arteriovenous Fistula Maturation

Arteriovenous fistulae mature less frequently in women than in men, leading to inferior patency and decreased fistula utilization in women. We hypothesized that both anatomic and physiologic sex differences explain reduced maturation. The electronic medical records of patients who had a primary arteriovenous fistula created from 2016 to 2021 at a single center were reviewed; sample size was determined using a power calculation. Postoperative ultrasound and laboratory tests were obtained at least 4weeks after fistula creation. Primary unassisted fistula maturation was determined up to 4years postprocedure. A total of 28 women and 28 men with a brachial-cephalic fistula were analyzed. The inflow brachial artery diameter was smaller in women than in men, both preoperatively (4.2±0.9 vs. 4.9±1.0mm, P=0.008) and postoperatively (4.8±0.8 vs. 5.3±0.9mm, P=0.039). Despite similar preoperative brachial artery peak systolic velocity, women had significantly lower postoperative arterial velocity (P=0.027). Fistula flow was reduced in women, particularly in the midhumerus (747.0±570.4 vs. 1,117.1±471.3cc/min, P=0.003). Percentages of neutrophils and lymphocytes were similar among women and men 6weeks after fistula creation. However, women had reduced monocytes (8.5±2.0 vs. 10.0±2.6%, P=0.0168). Among 28 men, 24 of 28 (85.7%) achieved unassisted maturation, whereas only 15 of 28 (53.6%) women had fistulae that matured without intervention. Secondary analysis using logistic regression suggested that postoperative arterial diameter was associated with maturation in men, while postoperative monocyte percentage was associated with maturation in women. Sex differences during arteriovenous fistula maturation are present in arterial diameter and velocity, suggesting that both anatomic and physiologic differences in arterial inflow contribute to sex differences in fistula maturation. In men, postoperative arterial diameter is correlated with maturation, whereas in women, the significantly lower proportion of circulating monocytes suggests a role for the immune response in fistula maturation.

Comparison between radiocephalic and brachiocephalic arteriovenous fistula in octogenarians: A retrospective single center study.

The number of older patients who need vascular access for end-stage renal disease is rapidly increasing. However, determining the optimal vascular access for older patients is difficult. We aimed to compare the outcomes of radiocephalic (RC) and brachiocephalic (BC) arteriovenous fistula (AVF) in patients aged >80 years. This study included 94 patients undergoing hemodialysis who underwent the procedure for the first time between 2013 and 2019 in Korea University Guro Hospital. The primary outcomes were primary patency (PP) and cumulative patency (CP). The secondary outcome was maturation failure and death with functional vascular access. Of the 94 patients (mean age, 83.9 ± 2.97 years), 66 (70.2%) and 28 (29.8%) patients belonged to the RC and BC AVF groups, respectively. One-year PP was worse in the RC AVF group than in the BC AVF group (59.6% vs. 87.4%, p = 0.013). However, no significant difference was observed in 1-year CP between the groups (87.4% vs. 91.2%, p = 0.441). The unassisted maturation rate was higher in the BC AVF group than in the RC AVF group (74.2% vs. 96.4%, p = 0.011). During follow-up (649 ± 612 days), only 6 (6.4%) patients required secondary fistula placement. Eighteen patients (19.1%), all of whom had functional AVF, died. BC AVF showed better PP and a smaller number of interventions than RC AVF in octogenarians. Therefore, BC AVF could be a primary choice of vascular access in the octogenarian patient. However, further research is warranted to confirm these findings.

Differential hemodynamics between arteriovenous fistulas with or without intervention before successful use.

A significant number of arteriovenous fistulas (AVFs) fail to maturate for dialysis. Although interventions promote maturation, functional primary patency loss is higher for AVFs with interventions (assisted maturation) than AVFs without interventions (un-assisted maturation). Although blood flow-associated hemodynamics have long been proposed to affect AVF remodeling, the optimal hemodynamic parameters for un-assisted maturation are unclear. Additionally, AVF maturation progress is generally not investigated until 6 weeks after AVF creation, and the examination is focused on the AVF's venous limb. In this exploratory study, patients (n = 6) underwent magnetic resonance imaging (MRI) at 1 day, 6 weeks, and 6 months after AVF creation surgery. Before successful use for hemodialysis, three AVFs required intervention and three did not. MRI of the AVFs were used to calculate lumen cross-sectional area (CSA) and perform computational fluid dynamics (CFD) to analyze hemodynamics, including velocity, wall shear stress (WSS), and vorticity. For the venous limb, the no-intervention group and intervention group had similar pre-surgery vein diameter and 1-day post-surgery venous CSA. However, the no-intervention group had statistically larger 1-day venous velocity (0.97 ± 0.67 m/s; mean ± SD), WSS (333 ± 336 dyne/cm2) and vorticity (1709 ± 1290 1/s) than the intervention group (velocity = 0.23 ± 0.10 m/s; WSS = 49 ± 40 dyne/cm2; vorticity = 493.1 ± 227 1/s) (P < 0.05). At 6 months, the no-intervention group had statistically larger venous CSA (43.5 ± 27.4 mm2) than the intervention group (15.1 ± 6.2 mm2) (P < 0.05). Regarding the arterial limb, no-intervention AVF arteries also had statistically larger 1-day velocity (1.17 ± 1.0 m/s), WSS (340 ± 423 dyne/cm2), vorticity (1787 ± 1694 1/s), and 6-month CSA (22.6 ± 22.7 mm2) than the intervention group (velocity = 0.64 ± 0.36 m/s; WSS = 104 ± 116 dyne/cm2, P < 0.05; vorticity = 867 ± 4551/s; CSA = 10.7 ± 6.0 mm2, P < 0.05). Larger venous velocity, WSS, and vorticity immediately after AVF creation surgery may be important for later lumen enlargement and AVF maturation, with the potential to be used as a tool to help diagnose poor AVF maturation earlier. However, future studies using a larger cohort are needed to validate this finding and determine cut off values, if any.

Association between anaesthesia type and arteriovenous fistula maturation.

Background:Whereas general anaesthesia is commonly used for haemodialysis fistula creation, regional or local anaesthesia has been posited to lead to better fistula maturation outcomes. We sought to measure the association between anaesthesia type and arteriovenous fistula maturation.Methods:We performed a secondary analysis of data from the Hemodialysis Fistula Maturation study, a multicentre prospective cohort study of advanced chronic kidney disease patients who underwent single-stage upper extremity fistula creation between 2010 and 2013. We evaluated the relationship between anaesthesia type and unassisted (without maturation-facilitating interventions) or overall (unassisted or assisted) fistula maturation using multivariable logistic regression.Results:Among 602 participants, 336 (55.8%) received regional/local anaesthesia and 266 (44.2%) received general anaesthesia. Unassisted maturation occurred in 164/309 patients (53.1%) after regional/local vs 91/226 patients (40.3%) after general anaesthesia (P=0.003). After adjustment for patient factors and fistula type, regional/local anaesthesia was associated with greater odds of unassisted maturation than general anaesthesia (odds ratio 1.72, 95% confidence interval 1.24–2.39; P=0.001). However, after further adjustment for clinical centre fixed effects, odds of unassisted maturation did not differ by anaesthesia type (odds ratio 1.03, 95% confidence interval 0.78–1.36; P=0.830). Similar findings were observed for overall maturation and composite endpoints accounting for potential survivorship bias.Conclusions:Regional/local anaesthesia was associated with increased odds of fistula maturation when adjusting for patient factors and fistula type. However, this association did not persist after adjusting for centre fixed effects. Future research is needed to better understand the relationship between anaesthesia type and centre factors to optimise outcomes after fistula surgery.

Arteriovenous Fistula Maturation, Functional Patency, and Intervention Rates

National initiatives have emphasized the use of autogenous arteriovenous fistulas (AVFs) for hemodialysis, but their purported benefits have been questioned. To examine AVF usability, longer-term functional patency, and remedial procedures to facilitate maturation, manage complications, or maintain patency in the Hemodialysis Fistula Maturation (HFM) Study. The HFM Study was a multicenter (n = 7) prospective National Institutes of Health National Institute of Diabetes and Digestive and Kidney Diseases cohort study performed to identify factors associated with AVF maturation. A total of 602 participants were enrolled (dialysis, kidney failure: 380; predialysis, chronic kidney disease [CKD]: 222) with AVF maturation ascertained for 535 (kidney failure, 353; CKD, 182) participants. All clinical decisions regarding AVF management were deferred to the individual centers, but remedial interventions were discouraged within 6 weeks of creation. In this case series analysis, the primary outcome was unassisted maturation. Functional patency, freedom from intervention, and participant survival were summarized using Kaplan-Meier analysis. Most participants evaluated (n = 535) were men (372 [69.5%]) and had diabetes (311 [58.1%]); mean (SD) age was 54.6 (13.6) years. Almost two-thirds of the AVFs created (342 of 535 [64%]) were in the upper arm. The AVF maturation rates for the kidney failure vs CKD participants were 29% vs 10% at 3 months, 67% vs 38% at 6 months, and 76% vs 58% at 12 months. Several participants with kidney failure (133 [37.7%]) and CKD (63 [34.6%]) underwent interventions to facilitate maturation or manage complications before maturation. The median time from access creation to maturation was 115 days (interquartile range [IQR], 86-171 days) but differed by initial indication (CKD, 170 days; IQR, 113-269 days; kidney failure, 105 days; IQR, 81-137 days). The functional patency for the AVFs that matured at 1 year was 87% (95% CI, 83.2%-90.2%) and at 2 years, 75% (95% CI, 69.7%-79.7%), and there was no significant difference for those receiving interventions before maturation. Almost half (188 [47.5%]) of the AVFs that matured had further intervention to maintain patency or treat complications. The findings of this study suggest that AVF remains an accepted hemodialysis access option, although both its maturation and continued use require a moderate number of interventions to maintain patency and treat the associated complications.

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

Arteriovenous fistulas created for hemodialysis often fail to become usable and are frequently abandoned. This prospective trial evaluated the efficacy of vonapanitase, a recombinant human elastase, in increasing radiocephalic fistula use for hemodialysis and secondary patency. PATENCY-2 was a randomized, double-blind, placebo-controlled trial in patients on or approaching the need for hemodialysis undergoing radiocephalic arteriovenous fistula creation. Of 696 screened, 613 were randomized, and 603 were treated (vonapanitase n = 405, placebo n = 208). The study drug solution was applied topically to the artery and vein for 10 min immediately after fistula creation. The primary endpoints were fistula use for hemodialysis and secondary patency (fistula survival without abandonment). Other efficacy endpoints included unassisted fistula use for hemodialysis, primary unassisted patency, fistula maturation and unassisted maturation by ultrasound criteria, and fistula procedure rates. The proportions of patients with fistula use for hemodialysis was similar between groups, 70% vonapanitase and 65% placebo, (p = 0.33). The Kaplan-Meier estimates of 12-month secondary patency were 78% (95% confidence interval [CI], 73-82) for vonapanitase and 76% (95% CI, 70-82) for placebo (p = 0.93). The proportions with unassisted fistula use for hemodialysis were 46% vonapanitase and 37% placebo (p = 0.054). The Kaplan-Meier estimates of 12-month primary unassisted patency were 50% (95% CI, 44-55) for vonapanitase and 43% (95% CI, 35-50) for placebo (p = 0.18). There were no differences in the proportion of patients with fistula maturation or in fistula procedure rates. Adverse events were similar between groups. Vonapanitase was not immunogenic. Vonapanitase treatment did not achieve clinical or statistical significance to meaningfully improve radiocephalic fistula surgical outcomes. Outcome in the placebo group were better than in historical controls. Vonapanitase was well-tolerated and safe. clinicaltrials.gov: NCT02414841 (https://clinicaltrials.gov/ct2/show/NCT02414841).

Early Predictors of Arteriovenous Fistula Maturation: A Novel Perspective on an Enduring Problem.

Preoperative ultrasound mapping is routinely used to select vessels meeting minimal threshold diameters for surgical arteriovenous fistula (AVF) creation but fails to improve AVF maturation rates. This suggests a need to reassess the preoperative ultrasound criteria used to optimize AVF maturation. We retrospectively identified 300 catheter-dependent patients on hemodialysis with a new AVF created between 2010 and 2016. We then evaluated the associations of preoperative vascular measurements and hemodynamic factors with unassisted AVF maturation (successful use for dialysis without prior intervention) and overall maturation (successful use with or without prior intervention). Multivariable logistic regression was used to identify preoperative factors associated with unassisted and overall AVF maturation. Unassisted AVF maturation associated with preoperative arterial diameter (adjusted odds ratio [aOR], 1.50 per 1-mm increase; 95% confidence interval [95% CI], 1.23 to 1.83), preoperative systolic BP (aOR, 1.16 per 10-mm Hg increase; 95% CI, 1.05 to 1.28), and left ventricular ejection fraction (aOR, 1.07 per 5% increase; 95% CI, 1.01 to 1.13). Overall AVF maturation associated with preoperative arterial diameter (aOR, 1.36 per 1-mm increase; 95% CI, 1.10 to 1.66) and preoperative systolic BP (aOR, 1.17; 95% CI, 1.06 to 1.30). Using receiver operating curves, the combination of preoperative arterial diameter, systolic BP, and left ventricular ejection fraction was fairly predictive of unassisted maturation (area under the curve, 0.69). Patient age, sex, race, diabetes, vascular disease, obesity, and AVF location were not associated with maturation. Preoperative arterial diameter may be an under-recognized predictor of AVF maturation. Further study evaluating the effect of preoperative arterial diameter and other hemodynamic factors on AVF maturation is needed.

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

Introduction:The goal of arterio-venous fistula (AVF) creation is to achieve a well-functioning access that can be cannulated repetitively and can provide adequate flow for the dialysis. The objective of this study was to assess the role of far infrared (FIR) therapy in the unassisted maturation of newly created AVF in patients with chronic kidney disease (CKD).Materials and Methods:In this prospective open labeled randomised control trial, 107 patients were randomized. Participants in the control arm received oral clopidogrel 75 mg once daily for 30 days along with isometric hand exercise, whereas those in the test arm received FIR therapy twice weekly, 40 min session each, for 4 weeks. A biopsy from venous end was taken during fistula surgery. Doppler study of AVF was done at the end of the 4th and 12th week to assess AVF. Vascular access guidelines proposed by National Kidney Foundation –Kidney Disease Outcomes Quality Initiative (NKF- KDOQI) in 2006 were adapted to define the maturation of AVF.Results:Out of 107 patients, 51 were randomized to the test arm and 56 to the control arm. During follow-up, the blood flow rate through AVF (Qa) and the diameter of the cephalic vein draining (CVd) the AVF were measured. At the end of 3 months, Qa in Radio-Cephalic Fistula (RCF) was high in the test arm (p–0.003). The AVF failures were 5 (10.2%) and 14 (28%) in the test and control arms, respectively (p: 0.025). However, when adjusted for AVF failure within 6 h of surgery (may be related to surgical technique) this difference in AVF patency was statistically insignificant (p: 0.121). The mean Qa was high in patients with an arterial intimal medial thickness (AIMT) <0.5 mm. The IMT of the anastomosed artery had statistically significant correlation with the primary failure rate of AVF (P < 0.001).Conclusion:In patients with CKD, FIR therapy was effective in increasing the AVF blood flow rate at the end of 3 months, though the difference in primary failure rate was statistically insignificant.

Postoperative Ultrasound, Unassisted Maturation, and Subsequent Primary Patency of Arteriovenous Fistulas.

Postoperative ultrasound is commonly used to assess arteriovenous fistula (AVF) maturation for hemodialysis, but its utility for predicting unassisted AVF maturation or primary AVF patency for hemodialysis has not been well defined. This study assessed the predictive value of postoperative AVF ultrasound measurements for these clinical AVF outcomes. We queried a prospective vascular access database to identify 246 patients on catheter-dependent hemodialysis who underwent AVF creation between 2010 and 2016 and obtained a postoperative ultrasound within 90 days. Multivariable logistic regression was used to evaluate the association of clinical characteristics and postoperative ultrasound measurements with unassisted AVF maturation. A receiver operating characteristic curve estimated the predictive value of these factors for unassisted AVF maturation. Finally, multivariable survival analysis was used to identify factors associated with primary AVF patency in patients with unassisted AVF maturation. Unassisted AVF maturation occurred in 121 out of 246 patients (49%), assisted maturation in 55 patients (22%), and failure to mature in 70 patients (28%). Using multivariable logistic regression, unassisted AVF maturation was associated with AVF blood flow (odds ratio [OR], 1.30; 95% confidence interval [95% CI], 1.18 to 1.45 per 100 ml/min increase; P<0.001), forearm location (OR, 0.37; 95% CI, 0.08 to 1.78; P=0.21), presence of stenosis (OR, 0.45; 95% CI, 0.23 to 0.88; P=0.02); AVF depth (OR, 0.88; 95% CI, 0.77 to 1.00 per 1 mm increase; P=0.05), and AVF location interaction with depth (OR, 0.50; 95% CI, 0.28 to 0.84; P=0.02). The area under the receiver operating characteristic curve, using all these factors, was 0.84 (95% CI, 0.79 to 0.89; P<0.001). Primary AVF patency in patients with unassisted maturation was associated only with AVF diameter (hazard ratio, 0.84; 95% CI, 0.76 to 0.94 per 1 mm increase; P=0.002). Unassisted AVF maturation is predicted by AVF blood flow, location, depth, and stenosis. AVF patency after unassisted maturation is predicted only by the postoperative AVF diameter.

Effect of Anti-Hypertensive Medication History on Arteriovenous Fistula Maturation Outcomes

Background: The arteriovenous fistula (AVF) is the preferred vascular access for hemodialysis. However, approximately half of AVFs fail to mature. The use of angiotensin converting enzyme inhibitors (ACE-Is), angiotensin receptor blockers (ARBs), and calcium channel blockers (CCBs) exerts favorable endothelial effects and may promote AVF maturation. We tested associations of ACE-I and ARBs, CCBs, beta-blockers, and diuretics with the maturation of newly created AVFs. Methods: We evaluated 602 participants from the Hemodialysis Fistula Maturation Study, a multi-center, prospective cohort study of AVF maturation. We ascertained the use of each medication class within 45 days of AVF creation surgery. We defined maturation outcomes by clinical use within 9 months of surgery or 4 weeks of initiating hemodialysis. Results: Unassisted AVF maturation failure without intervention occurred in 54.0% of participants, and overall AVF maturation failure (with or without intervention) occurred in 30.1%. After covariate adjustment, CCB use was associated with a 25% lower risk of overall AVF maturation failure (95% CI 3%–41% lower) but a non-significant 10% lower risk of unassisted maturation failure (95% CI 23% lower to 5% higher). ACE-I/ARB, beta-blocker, and diuretic use was not significantly associated with AVF maturation outcomes. None of the antihypertensive medication classes were associated with changes in AVF diameter or blood flow over 6 weeks following surgery. Conclusions: CCB use may be associated with a lower risk of overall AVF maturation failure. Further studies are needed to determine whether CCBs might play a causal role in improving AVF maturation outcomes.