Hemodialysis vascular access morbidity

Early access flow rate predicts vascular access patency-related intervention in the first year: A retrospective cohort study

INTRODUCTION

Arteriovenous fistulas and grafts are lifelines for most hemodialysis patients, and a low access flow rate often requires patency-related intervention, such as angioplasty or thrombectomy, to prevent access failure. We examined whether early access flow rate, measured after initial fistula/graft cannulation, predicts vascular access patency-related intervention within 1 year.

METHODS

This was a single-center retrospective cohort study. Among 172 patients undergoing surgical creation of a fistula/graft, 52 (30.2%) had documented access flow rates measurement by the Transonic™ ultrasound dilution technique, performed within an average of 48 days from initial access cannulation. The need for a patency-related intervention, defined as undergoing a fistulogram, angioplasty, thrombectomy, or surgical revision, was ascertained within 1 year. A receiver-operating characteristic curve (ROC) was generated to evaluate the diagnostic performance of first and average access flow rates for predicting patency-related intervention within 1 year.

FINDINGS

Twenty-eight (53.8%) of the 52 study subjects required a patency-related intervention within 1 year. Their characteristics were not significantly different from those who did not require patency-related interventions. However, first access flow rates were significantly lower in patients requiring patency-related intervention compared to those who did not (898 vs. 1471 mL/min; p = 0.003), as were average access flow rates (841 vs. 1506 mL/min; p < 0.001). The ROC analyses revealed that first access flow rates and average access flow rates predicted the need for patency-related intervention within 1 year, with an area under-the-ROC curve of 0.743 (95% confidence interval [CI] 0.608, 0.877) and 0.775 (95% CI 0.648, 0.903), respectively, demonstrating acceptable discrimination.

DISCUSSION

In adults undergoing hemodialysis, early access flow rate measurement can predict patency-related intervention within 1 year after initial vascular access cannulation. Additional studies are required to confirm these findings and identify optimal access flow rate cut-off values to predict vascular accesses at higher risk of stenosis.

Functioning tailor-made 3D-printed vascular graft for hemodialysis

BACKGROUND

The two ends of arteriovenous graft (AVG) are anastomosed to the upper limb vessels by surgery for hemodialysis therapy. However, the size of upper limb vessels varies to a large extent among different individuals.

METHODS

According to the shape and size of neck vessels quantified from the preoperative computed tomography angiographic scan, the ethylene-vinyl acetate (EVA)-based AVG was produced in H-shape by the three-dimensional (3D) printer and then sterilized. This study investigated the function of this novel 3D-printed AVG in vitro and in vivo.

RESULTS

This 3D-printed AVG can be implanted in the rabbit's common carotid artery and common jugular vein with ease and functions in vivo. The surgical procedure was quick, and no suture was required. The blood loss was minimal, and no hematoma was noted at least 1 week after the surgery. The blood flow velocity within the implanted AVG was 14.9 ± 3.7 cm/s. Additionally, the in vitro characterization experiments demonstrated that this EVA-based biomaterial is biocompatible and possesses a superior recovery property than ePTFE after hemodialysis needle cannulation.

CONCLUSIONS

Through the 3D printing technology, the EVA-based AVG can be tailor-made to fit the specific vessel size. This kind of 3D-printed AVG is functioning in vivo, and our results realize personalized vascular implants. Further large-animal studies are warranted to examine the long-term patency.

Obesity drives secondary procedures to achieve access maturation in end-stage renal disease

BACKGROUND

Establishing long-term arteriovenous access is an important component in the long-term care of a patient with end-stage renal disease. The increasing frequency of obesity is reported to impact the access management of end-stage renal disease patients. This study aims to evaluate the outcomes of arteriovenous fistulae (AVF) in obese and nonobese patients.

METHODS

A retrospective review of all patients over ten years with primary autogenous AVF (radiocephalic, brachiocephalic, and brachial-basilic) was undertaken at a single center. Patients were subcategorized by body mass index into nonobese, class I, II, and III obesity. Outcomes of maturation (successful progression to hemodialysis), reintervention, functional dialysis (continuous hemodialysis for 3 consecutive months), and patency were examined.

RESULTS

From January 1999 to December 2019, 2311 patients (67% female; mean age, 61 ± 15 years) underwent primary AVF placement (12% radiocephalic, 53% brachiocephalic, and 35% brachial basilic). Forty-one percent were nonobese, 29% had class I obesity, 19% had class II obesity, and 11% had class III obesity. The majority of patients were diabetic and Hispanic. The 30-day major adverse cardiovascular event rate was elevated in class II (0.20%) and class III (0.50%) obesity compared with class I obesity (0.15%) and nonobese (0.05%). The 30-day morbidity rate was higher in all classes of obesity (0.5% vs0.3% vs 0.2% vs 0.05% for class III vs class II vs class I obesity and nonobese, respectively). Early thrombosis was significantly increased in class II (9%) and class III obesity (12%) compared with class I obesity (5%) and nonobese (3%). There was a two-fold increase in procedures to effect maturation in class II (51%) and class III (74%) obesity compared with class I obesity (22%) and nonobese (34%). Secondary patency at 3 years was significantly lower in class III (62 ± 4%) and class II (79 ± 3%) compared with class I obesity (87 ± 2%) and nonobese (93 ± 4%). All classes of obesity required significantly more secondary Interventions per year compared with nonobese (3.9 vs 3.1 vs 2.5 vs 1.4 secondary interventions per year for class III vs class II vs class I obesity and nonobese, respectively).

CONCLUSIONS

Advancing obesity class is associated with an increased number of procedures to achieve AVF maturation and is associated with poorer patency and functionality as the category of obesity advances.

Guidelines on vascular access for hemodialysis from the Brazilian Society of Angiology and Vascular Surgery

Chronic kidney disease is a worldwide public health problem, and end-stage renal disease requires dialysis. Most patients requiring renal replacement therapy have to undergo hemodialysis. Therefore, vascular access is extremely important for the dialysis population, directly affecting the quality of life and the morbidity and mortality of this patient population. Since making, managing and salvaging of vascular accesses falls within the purview of the vascular surgeon, developing guideline to help specialists better manage vascular accesses for hemodialysis if of great importance. Thus, the objective of this guideline is to present a set of recommendations to guide decisions involved in the referral, evaluation, choice, surveillance and management of complications of vascular accesses for hemodialysis.

Trans-radial percutaneous intervention for thrombosed hemodialysis access: A single-center experience

BACKGROUND

Traditionally, percutaneous transluminal angioplasty (PTA) is a first-line approach for stenosed dialysis accesses and has been performed through the non-thrombosed vein segment. For thrombosed accesses, thrombectomy (whether open or percutaneous) is a standard approach. The primary objective of our study is to determine the clinical and technical outcomes of the trans-radial approach of PTA among thrombosed dialysis accesses, in terms of safety and feasibility, technical and clinical aspects and factors influencing them, as well as assisted primary patency, secondary patency at 6 and 12 months.

METHODS

This is a single-center retrospective study that included 150 patients over 3 years. About 123 patients underwent successful percutaneous balloon angioplasty through the radial access.

RESULTS

We report an overall technical and clinical success rate of 82%, assisted primary patency rate of about 90.25% at 3 months, 82.93% at 6 months, 73.18% at 1 year, and secondary patency rate of 94% at 1 year. Twenty-seven patients were referred for surgical revisions/creation of a new fistula for reasons like inability to pass wire (6 patients), unfavorable anatomical variations like aneurysms at the proximal segments (5 patients), inability to cross the fistula (5 patients), and persistent fistula dysfunction with no flow after initial balloon dilatation (11 patients). Three patients had hematoma at the radial access site (2.5%) while two patients had the AV fistula segment rupture and were successfully treated conservatively.

CONCLUSION

We conclude that PTA through the trans-radial approach to completely thrombosed hemodialysis accesses is a good alternative to transvenous access and has a very good assisted primary patency and secondary patency at 1 year without major complications.

Single-centre experience with endovascular rotational thrombectomy for single session salvage of thrombosed arteriovenous fistulas and grafts

OBJECTIVES

This paper documents our experience and outcomes of using a relatively new endovascular rotational thrombectomy device for salvage of thrombosed vascular access.

METHODOLOGY

A retrospective study reviewing patients with thrombosed native AVF or AVG who underwent endovascular declotting using a rotational thrombectomy device between November 2018 and May 2020 at a tertiary university hospital in Southeast Asia. We evaluated demographics, procedural data, technical and procedural success, patency rates and complications.

RESULTS

A total of 40 patients underwent single session endovascular declotting of thrombosed vascular access. The mean follow-up period was 21.6 months (range 13.4-31 months). The technical success was 92.5% and clinical success was 80%. About 50% of patients had concomitant thrombolysis for pharmacomechanical thrombectomy. One patient had a myocardial infarction during the post-operative period. There were no other major complications within 30 days. The primary patency was 45.5% at 6 months and 22.7% at 12 months. Assisted primary patency was 68.1% at 6 months and 61.6% at 12 months, which was maintained up to 2 years. The secondary patency was 84.1% at 6 and 12 months.

CONCLUSION

Our study shows that rotational thrombectomy device for single session thrombectomy of thrombosed arteriovenous fistulas and grafts is safe and effective. A high technical and clinical success rate was achieved, with low complication rates and specific advantages compared to other techniques, including reduced length of hospital stay. Our reported mid-term outcomes are reasonable with an assisted primary patency of 62% at 12 and 24 months. The use of newer techniques and novel dedicated thrombectomy devices show promise.

Tensor decomposition and machine learning for the detection of arteriovenous fistula stenosis: An initial evaluation

Duplex ultrasound (DUS) is the most widely used method for surveillance of arteriovenous fistulae (AVF) created for dialysis. However, DUS is poor at predicting AVF outcomes and there is a need for novel methods that can more accurately evaluate multidirectional AVF flow. In this study we aimed to evaluate the feasibility of detecting AVF stenosis using a novel method combining tensor-decomposition of B-mode ultrasound cine loops (videos) of blood flow and machine learning classification. Classification of stenosis was based on the DUS assessment of blood flow volume, vessel diameter size, flow velocity, and spectral waveform features. Real-time B-mode cine loops of the arterial inflow, anastomosis, and venous outflow of the AVFs were analysed. Tensor decompositions were computed from both the 'full-frame' (whole-image) videos and 'cropped' videos (to include areas of blood flow only). The resulting output were labelled for the presence of stenosis, as per the DUS findings, and used as a set of features for classification using a Long Short-Term Memory (LSTM) neural network. A total of 61 out of 66 available videos were used for analysis. The whole-image classifier failed to beat random guessing, achieving a mean area under the receiver operating characteristics (AUROC) value of 0.49 (CI 0.48 to 0.50). In contrast, the 'cropped' video classifier performed better with a mean AUROC of 0.82 (CI 0.66 to 0.96), showing promising predictive power despite the small size of the dataset. The combined application of tensor decomposition and machine learning are promising for the detection of AVF stenosis and warrant further investigation.

A Comparative Study of Continuous Versus Interrupted Suturing Technique in Creating a Vascular Access for Hemodialysis: An Institutional-Based Experience

Background Arteriovenous fistulas (AVFs) are considered the first and best access for patients with end-stage renal disease who need permanent vascular access for hemodialysis over arteriovenous grafts and central venous catheters for reasons that have been well-established. Poor early patency rates pose the biggest challenge in creating vascular access as they cause increased morbidity and economic/psychological concerns among patients. To minimize such effects, it is critical to use a patient-centered approach and carefully choose patients for AVF access creation. This study aimed to compare the primary patency of distal vascular access provided by continuous suturing versus that provided by interrupted suturing. Methodology This prospective study was conducted in the urology department of a superspecialty, tertiary care center from November 2021 to November 2022. Patency was assessed immediately after surgery (on the table), one month later, and six months later by palpating thrill and auscultating bruit. A total of 50 patients between the ages of 18 and 70 years who met the inclusion criteria were randomly assigned to two groups of 25 each. Results The baseline characteristics of both groups were comparable. At six months (p = 0.09), the continuous suturing group was observed to be somewhat better than the interrupted suturing group, with no significant difference in immediate and one-month patency rates. When compared to the continuous suturing group, the primary patency failure rate was significantly higher in the interrupted suturing group. Conclusions Thus, under appropriate circumstances, continuous sutures can be performed with greater ease, resulting in anastomosis that is as patent as that performed with interrupted sutures.

Early identification of bloodstream infection in hemodialysis patients by machine learning

Background

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

Methods

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

Results

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

Conclusions

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

Fate mapping RNA-sequencing reveal Malat1 regulates Sca1+ progenitor cells to vascular smooth muscle cells transition in vascular remodeling

Regeneration of smooth muscle cells (SMCs) is vital in vascular remodeling. Sca1⁺ stem/progenitor cells (SPCs) can generate de novo smooth muscle cells after severe vascular injury during vessel repair and regeneration. However, the underlying mechanisms have not been conclusively determined. Here, we reported that lncRNA Metastasis-associated lung adenocarcinoma transcript 1 (Malat1) was down-regulated in various vascular diseases including arteriovenous fistula, artery injury and atherosclerosis. Using genetic lineage tracing mice and veingraft mice surgery model, we found that suppression of lncRNA Malat1 promoted Sca1⁺ cells to differentiate into SMCs in vivo, resulting in excess SMC accumulation in neointima and vessel stenosis. Genetic ablation of Sca1⁺ cells attenuated venous arterialization and impaired vascular structure normalization, and thus, resulting in less Malat1 down-regulation. Single cell sequencing further revealed a fibroblast-like phenotype of Sca1⁺ SPCs-derived SMCs. Protein array sequencing and in vitro assays revealed that SMC regeneration from Sca1⁺ SPCs was regulated by Malat1 through miR125a-5p/Stat3 signaling pathway. These findings delineate the critical role of Sca1⁺ SPCs in vascular remodeling and reveal that lncRNA Malat1 is a key regulator and might serve as a novel biomarker or potential therapeutic target for vascular diseases.

Chameleon™ PTA balloon catheter: A single device in managing thrombosed AV access

Thrombectomy is a common procedure for maintenance of arteriovenous (AV) access and is critical to prolong access life. Techniques for performing thrombectomy are incredibly diverse, ranging from open surgical procedures to percutaneous interventions. Percutaneous interventions include a combination of thrombectomy devices to clear the thrombus and balloon angioplasty to treat the underlying lesion. In this case report we describe a novel technique using a single device, the Chameleon™ PTA balloon catheter (Medtronic, Minneapolis, MN) balloon catheter, to safely and efficiently perform a percutaneous intervention.

Plasma Interleukin-6 Level Predicts the Risk of Arteriovenous Fistula Dysfunction in Patients Undergoing Maintenance Hemodialysis

Systemic inflammation has been proposed as a relevant factor of vascular remodeling and dysfunction. We aimed to identify circulating inflammatory biomarkers that could predict future arteriovenous fistula (AVF) dysfunction in patients undergoing hemodialysis. A total of 282 hemodialysis patients were enrolled in this prospective multicenter cohort study. Plasma cytokine levels were measured at the time of data collection. The primary outcome was the occurrence of AVF stenosis and/or thrombosis requiring percutaneous transluminal angioplasty or surgery within the first year of enrollment. AVF dysfunction occurred in 38 (13.5%) patients during the study period. Plasma interleukin-6 (IL-6) levels were significantly higher in patients with AVF dysfunction than those without. Diabetes mellitus, low systolic blood pressure, and statin use were also associated with AVF dysfunction. The cumulative event rate of AVF dysfunction was the highest in IL-6 tertile 3 (p = 0.05), and patients in tertile 3 were independently associated with an increased risk of AVF dysfunction after multivariable adjustments (adjusted hazard ratio = 3.06, p = 0.015). In conclusion, circulating IL-6 levels are positively associated with the occurrence of incident AVF dysfunction in hemodialysis patients. Our data suggest that IL-6 may help clinicians identify those at high risk of impending AVF failure.

HD, Sarma P, Srikanth L, V. SK. Thrombophilic risk factors and ABO blood group profile for arteriovenous access failure in end stage kidney disease patients: a single-center experience

INTRODUCTION

Thrombosis of fistula occurs most frequently in end-stage kidney disease (ESKD) patients receiving hemodialysis. However, the role of thrombophilia in arteriovenous fistula (AVF) failure has not been well established. Hence, this study was aimed at assessing the roles of hereditary and acquired thrombophilic factors in association with AVF failure among patients with ESKD undergoing hemodialysis.

METHODS

A cross-sectional study was conducted on 100 ESKD patients, of whom 50 patients with well-functioning AVFs with no fistula failures earlier were enrolled as Group 1, and 50 patients who have had AVF failure were enrolled as Group 2. The hereditary factors as factor V Leiden, factor XIII, prothrombin, and methylene tetrahydrofolate reductase and the acquired factors as lipoprotein (a), fibrinogen, homocysteine, and anticardiolipin antibodies IgG and IgM were studied.

RESULTS

Among the hereditary factors, no statistically significant difference was observed in relation to factor V Leiden and Prothrombin (p > 0.05). However, for factor XIII and methylene tetrahydrofolate reductase, a statistically significant difference was observed between patients with well-functioning AVFs and patients who have had AVF failure (p < 0.05). We found a statistically significant increase in all the acquired factors in patients who have had AVF failure in comparison with patients with well-functioning AVFs (p < 0.001). Association between ABO blood groups and thrombophilic factors showed significant association between factor V Leiden, anticardiolipin antibody IgG and IgM and ABO blood groups (p < 0.05), whereas none of the other thrombophilic factors showed significant association (p > 0.05).

CONCLUSION

Thus, our study suggests significant role of acquired factors in causing AVF failure.

Effect of anesthetics on postoperative nausea and vomiting after peripheral vascular surgery in end-stage renal disease patients: A retrospective observational study

Background

Propofol-based total intravenous anesthesia (TIVA) is considered a prophylactic approach to decrease postoperative nausea and vomiting (PONV). Despite general anesthesia commonly being performed in end-stage renal disease (ESRD) patients, PONV in ESRD patients has not been well-described. We investigated PONV in peripheral vascular surgery under general anesthesia in ESRD patients.

Methods

To compare PONV between propofol-based TIVA and anesthesia with volatile anesthetics, we collected retrospective data from patients who underwent peripheral vascular surgery under general anesthesia from July 2018 to April 2020. We performed univariable and multivariable analyses, including factors that could be associated with PONV and those previously shown to affect PONV.

Result

A total of 1,699 peripheral vascular surgeries under general anesthesia in ESRD patients were eligible for analysis. Based on the multivariable analysis, TIVA (odds ratio [OR], 0.45; 95% confidence interval [CI], 0.35-0.60; P < 0.001) significantly decreased PONV. Female sex (OR, 1.85; 95% CI, 1.44-2.38; P < 0.001) and anesthetic duration (OR, 1.01; 95% CI, 1.00-1.01; P < 0.001) were associated with increased PONV.

Conclusion

Propofol-based TIVA is the most influential factor decreasing PONV after peripheral vascular surgery in ESRD patients. Anesthesiologists can apply propofol-based TIVA as an alternative to anesthesia with volatile anesthetics.

Nurses' Use of Ultrasound Location for Puncturing Arteriovenous Fistulas in Hemodialysis

Puncturing an arteriovenous fistula (AVF) in chronic hemodialysis (HD) patients is a source of difficulty even for experienced dialysis nurses. The objective of this study was to compare the failure rate of AVF puncture by the usual technique (visual or by palpation) and after ultrasound location. This nonrandomized prospective single-center study was carried out at the Safi HD Hospital Center for 16 weeks in two successive phases, with the time between each phase dedicated to training nurses in locating punctures by ultrasound. We first evaluated 30 HD patients (300 HD sessions, i.e., 600 punctures) without ultrasound location, then the same patients (300 sessions, i.e., 600 punctures) using ultrasound location for all punctures. Ultrasound location carried out by a single nurse did not show a significant reduction in the rate of failure to puncture the AVF compared with the standard method (2.6% vs. 4%, P = 0.07). However, the rate of complications at the puncture site, recourse to medical advice, or mobilization of a second nurse were significantly reduced (P < 0.05). This single-center study showed no advantage of this approach for the effective cannulation of AVF in HD patients known to be not difficult to cannulate.

Functionality of Flexible Pressure Sensors in Cardiovascular Health Monitoring: A Review

As the highest percentage of global mortality is caused by several cardiovascular diseases (CVD), maintenance and monitoring of a healthy cardiovascular condition have become the primary concern of each and every individual. Simultaneously, recent progress and advances in wearable pressure sensor technology have provided many pathways to monitor and detect underlying cardiovascular illness in terms of irregularities in heart rate, blood pressure, and blood oxygen saturation. These pressure sensors can be comfortably attached onto human skin or can be implanted on the surface of vascular grafts for uninterrupted monitoring of arterial blood pressure. While the traditional monitoring systems are time-consuming, expensive, and not user-friendly, flexible sensor technology has emerged as a promising and dynamic practice to collect important health information at a comparatively low cost in a reliable and user-friendly way. This Review explores the importance and necessity of cardiovascular health monitoring while emphasizing the role of flexible pressure sensors in monitoring patients' health conditions to avoid adverse effects. A comprehensive discussion on the current research progress along with the real-time impact and accessibility of pressure sensors developed for cardiovascular health monitoring applications has been provided.

Pentraxin 3 Predicts Arteriovenous Fistula Functional Patency Loss and Mortality in Chronic Hemodialysis Patients

INTRODUCTION

Viable vascular access is the lifeline for hemodialysis patients. In the nondialysis population, emerging evidence suggests that circulating pentraxin 3 (PTX3), neutrophil gelatinase-associated lipocalin (NGAL), and chitinase-3-like protein 1 (CHI3L1) are associated with cardiovascular inflammation and endothelial injury. However, predictive values of these three biomarkers on arteriovenous fistula (AVF) outcomes are unknown.

METHODS

This prospective observational cohort study enrolled 135 hemodialysis patients using AVF and then followed them for 3 years. Plasma levels of PTX3, NGAL, and CHI3L1 were measured. Patients were followed up prospectively for two clinical outcomes, including AVF functional patency loss and death. Cox proportional hazards regression models were used to analyze hazard ratios for the commencement of AVF functional patency loss and mortality.

RESULTS

Among 135 patients, the mean age was 66.0 ± 15.7 years old and 48.1% were male. The plasma level of PTX3, NGAL, and CHI3L1 was 2.8 ± 2.3 ng/mL, 349.2 ± 111.4 ng/mL, and 185.5 ± 66.8 ng/mL, respectively. During a 3-year follow-up period, the plasma level of PTX3 was an independent predictor for AVF functional patency loss (per 1 ng/mL increase, HR 1.112 [95% CI: 1.001-1.235], p = 0.048). Besides, patients with higher plasma levels of PTX3 were more likely to suffer from cardiovascular mortality (per 1 ng/mL increase, HR 1.320 [95% CI: 1.023-1.703], p = 0.033), infectious mortality (per 1 ng/mL increase, HR 1.394 [95% CI: 1.099-1.769], p = 0.006), and all-cause mortality (per 1 ng/mL increase, HR 1.233 [95% CI: 1.031-1.476], p = 0.022).

CONCLUSIONS

The plasma level of PTX3, not NGAL or CHI3L1, was associated with higher risks of AVF functional patency loss in chronic hemodialysis patients, showing its value in reflecting AVF endothelial dysfunction. Furthermore, PTX3 also predicts mortality in chronic hemodialysis patients.

The outcome of radiocephalic after brachiocephalic and redo arteriovenous fistula

Introduction:

When created in appropriately selected patients, arteriovenous fistula requires fewer interventions and costs compared to arteriovenous graft. The outcome of radiocephalic after brachiocephalic and redo arteriovenous fistula is not studied well in the literature, and this study highlights the outcome of these arteriovenous fistulae.

Methods:

The retrospective, single-center study, based on patient record analysis of 1040 arteriovenous fistula, was created between January 2017 and October 2021. Thirty-nine (3.37%) patients met the inclusion criteria for radiocephalic after brachiocephalic arteriovenous fistula group, and 42 (4.04%) met the inclusion criteria for the redo arteriovenous fistula group. Preoperative Doppler ultrasound was performed by the operating surgeon in all patients. All patients were scheduled for a visit 2 months after surgery for assessment—only 34 of radiocephalic after brachiocephalic arteriovenous fistula and 35 of redo arteriovenous fistula patients presented for follow-up. The arteriovenous fistula was assessed for patency, maturation, and complications. SPSS version 22 (Chicago, USA) was used for data entry and analysis.

Results:

The redo arteriovenous fistula has a significantly lower maturation rate at 2 months of follow-up (62.85%) when compared to other brachiocephalic arteriovenous fistula (79.18%) ( p-value = 0.0245). The radiocephalic after brachiocephalic arteriovenous fistula has no significant difference in maturation rate at 2 months of follow-up (61.67%) when compared to other distal forearms radiocephalic arteriovenous fistula (68.18%) ( p-value = 0.5173). The incidence of some early complications was higher in the redo group.

Conclusion:

The feasibility of doing radiocephalic arteriovenous fistula after failed brachiocephalic arteriovenous fistula is generally overlooked. The redo arteriovenous fistula is more technically challenging, associated with higher complications, but it provides reliable access in a specific group of patients.

Nitric oxide releasing nanomatrix gel treatment inhibits venous intimal hyperplasia and improves vascular remodeling in a rodent arteriovenous fistula

Vascular access is the lifeline for hemodialysis patients and the single most important component of the hemodialysis procedure. Arteriovenous fistula (AVF) is the preferred vascular access for hemodialysis patients, but nearly 60% of AVFs created fail to successfully mature due to early intimal hyperplasia development and poor outward remodeling. There are currently no therapies available to prevent AVF maturation failure. First, we showed the important regulatory role of nitric oxide (NO) on AVF development by demonstrating that intimal hyperplasia development was reduced in an overexpressed endothelial nitric oxide synthase (NOS3) mouse AVF model. This supported the rationale for the potential application of NO to the AVF. Thus, we developed a self-assembled NO releasing nanomatrix gel and applied it perivascularly at the arteriovenous anastomosis immediately following rat AVF creation to investigate its therapeutic effect on AVF development. We demonstrated that the NO releasing nanomatrix gel inhibited intimal hyperplasia formation (more than 70% reduction), as well as improved vascular outward remodeling (increased vein diameter) and hemodynamic adaptation (lower wall shear stress approaching the preoperative level and less vorticity). Therefore, direct application of the NO releasing nanomatrix gel to the AVF anastomosis immediately following AVF creation may enhance AVF development, thereby providing long-term and durable vascular access for hemodialysis.

Update on the creation and maintenance of arteriovenous fistulas for haemodialysis in children

Arteriovenous fistulas (AVFs) are widely used for haemodialysis (HD) in adults with stage 5 chronic kidney disease (CKD 5) and are generally considered the best form of vascular access (VA). The 'Fistula First' initiative in 2003 helped to change the culture of VA in adults. However, this cultural change has not yet been adopted in children despite the fact that a functioning AVF is associated with lower complication rates and longer access survival than a central venous line (CVL). For children with CKD 5, especially when kidney failure starts early in life, there is a risk that all VA options will be exhausted. Therefore, it is essential to develop long-term strategies for optimal VA creation and maintenance. Whilst AVFs are the preferred VA in the paediatric population on chronic HD, they may not be suitable for every child. Recent guidelines and observational data in the paediatric CKD 5 population recommend switching from a 'Catheter First' to 'Catheter Last' approach. In this review, recent evidence is summarized in order to promote change in current practices.

Predialysis nephrology care amongst Palestinian hemodialysis patients and its impact on initial vascular access type

Referral time for end-stage renal disease (ESRD) patients to nephrologists and initial vascular access method are considered significant factors that impact health outcomes at the time of hemodialysis (HD) initiation. Native arteriovenous fistula (AVF) is strongly recommended as initial access. However, little is known about the referral rate among ESRD receiving HD in Palestine and its correlation with AVF creation. In Ramallah Hemodialysis Center, we investigated the pre-dialysis nephrology care and AVF usage in 156 patients. Type of access at HD initiation was temporary central venous catheter (CVC) in 114 (73%), tunneled hemodialysis catheter (TDC) in 21 (13%) and AVF in 21 (13%). Out of all participants, 120 (77%) were seen by nephrologist prior to dialysis. Of the participants who initiated dialysis with a CVC, 36 (31%) had not received prior nephrology care. All participants who initiated dialysis with functional AVF had received prior nephrology care. Patients who were not seen by a nephrologist prior to HD initiation had no chance at starting HD with AVF, whereas 17% of those who had nephrology care >12 months started with AVF. In conclusion, a relatively large percentage of Palestinian HD patients who were maintained on HD did not have any predialysis nephrology care. In addition, patients who received predialysis nephrology care were significantly more likely to start their HD through AVF whereas all those without predialysis nephrology care started through CVC. More in-depth national studies focusing on improving nephrology referral in ESRD patients are needed to increase AVF utilization.

Hypoxia and hypoxia-inducible factors promote the development of neointimal hyperplasia in arteriovenous fistula

KEY POINTS

Patients with end-stage renal failure need arteriovenous fistulas (AVF) to undergo dialysis. However, AVFs present a high rate of failure as a result of excessive venous thickness. Excessive venous thickness may be a consequence of surgical dissection and change in oxygen concentration within the venous wall. We show that venous cells adapt their metabolism and growth depending on oxygen concentration, and drugs targeting the hypoxic response pathway modulate this response in vitro. We used the same drugs on a mouse model of AVF and show that direct or indirect inhibition of the hypoxia-inducible factors (HIFs) help decrease excessive venous thickness. Hypoxia and HIFs can be targets of therapeutic drugs to prevent excessive venous thickness in patients undergoing AVF surgical creation.

ABSTRACT

Because the oxygen concentration changes in the venous wall, surrounding tissue and the blood during surgical creation of arteriovenous fistula (AVF), we hypothesized that hypoxia could contribute to AVF failure as a result of neointimal hyperplasia. We postulated that modulation of the hypoxia-inducible factors (HIF) with pharmacological compounds could promote AVF maturation. Fibroblasts [normal human fibroblasts (NHF)], smooth muscle cells [human umbilical vein smooth muscle cells (HUVSMC)] and endothelial cells [human umbilical vein endothelial cells (HUVEC)], representing the three layers of the venous wall, were tested in vitro for proliferation, cell death, metabolism, reactive oxygen species production and migration after silencing of HIF1/2-α or after treatment with deferioxamine (DFO), everolimus (Eve), metformin (Met), N-acetyl-l-cysteine (NAC) and topoisomerase I (TOPO), which modulate HIF-α stability or activity. Compounds that were considered to most probably modify intimal hyperplasia were applied locally to the vessels in a mouse model of aortocaval fistula. We showed, in vitro, that NHF and HUVSMC can adapt their metabolism and thus their growth depending on oxygen concentration, whereas HUVEC appears to be less flexible. siHIF1/2α, DFO, Eve, Met, NAC and TOPO can modulate metabolism and proliferation depending on the cell type and the oxygen concentration. In vivo, siHIF1/2α, Eve and TOPO decreased neointimal hyperplasia by 32%-50%, 7 days after treatment. Within the vascular wall, hypoxia and HIF-1/2 mediate early failure of AVF. Local delivery of drugs targeting HIF-1/2 could inhibit neointimal hyperplasia in a mouse model of AVF. Such compounds may be delivered during the surgical procedure for AVF creation to prevent early AVF failure.

Association of early failure of arteriovenous fistula with mortality in hemodialysis patients

Arteriovenous fistula (AVF) is prone to early dysfunction and relates to poor outcome. However, little is known about the role of early AVF dysfunction as an independent risk factor for death in hemodialysis patients. A retrospective cohort study was performed using data of patients who underwent initial AVF surgery at a single institution. Demographic, clinical, biochemistry and AVF parameters were extracted from the electronic records, and the association between these variables and mortality was analyzed by Cox proportional hazards model. A total of 501 patients on hemodialysis (63.4 ± 12.7 years, 57.3% male) were included, and the median observation period was 3.66 years. In multivariate analysis, early failure of AVF (hazard ratio (95% confidence interval): 1.54 (1.06–2.24); p = 0.023) was associated with overall mortality but not cardiovascular mortality. Other identified predictors of overall mortality included older age, peripheral artery disease (PAD), cardiomegaly, higher white blood cell (WBC) count and corrected calcium level, and lower total cholesterol level, while predictors of cardiovascular mortality included older age, coronary artery disease (CAD), PAD and lower hemoglobin level. In conclusion, patients with early AVF failure were associated with increased risk of overall mortality.

Perceived barriers and attitudes toward arteriovenous fistula creation and use in hemodialysis patients in Palestine

In the dialysis center in Ramallah, we investigated the attitudes and perceived barriers to having arteriovenous fistula (AVF) in 156 patients. The current method of HD access was AVF in 52% and central venous catheter in 47%. Perceived causes of no or delayed AVF were: patient’s refusal of AVF in 54.5%, late referral to a surgical evaluation in 31.3% and too long to surgical appointments in 14.2%. Among those who refused AVF, reasons were: concern about the surgical procedure in 42.5%, poor understanding of disease/access in 23.3%, fear of needles in 15.1%, denial of disease or need for HD in 17.8%, and cosmetic reasons in 1.4%. Forty six percent of patients believed they received education about AVF prior to the creation of HD access, and 73.7% would recommend AVF as the method of access due to the lower risk of infection (96%), easier to care for (16%), easier showering (14%), and better-associated hygiene (3%). In conclusion, the majority would recommend an AVF as the mode of vascular access for HD. The most common barrier to having an AVF was patient’s refusal to undergo AVF creation because of their concern about the surgical procedure. A systematic evaluation of the process that precedes the creation of AVF may allow for better utilization.

[Complications of permanent vascular access for haemodialysis]

Permanent vascular access is the basis of renal replacement therapy by the method of programmed haemodialysis, on whose stable functioning depends the life of patients with end-stage renal disease. At the present time, there is significant deficit of scientific and methodological Russian-language literature on this problem, with no Russian consensus documents concerned. This article is a review of the contemporary world literature dedicated to the problem of permanent vascular access, including currently in force European (2018) and North American (2019) guidelines for good clinical practice, also discussing the problems of strategy and tactics of creating a permanent vascular access, monitoring its dysfunction, pathophysiology of functioning of arteriovenous fistulas. Presented herein are unified approaches to diagnosis and treatment of thrombolytic and haemorrhagic complications associated with the access, as well as local infectious and non-infectious complications. Special attention is paid to indications for the operation and rational therapeutic decision-making.

A Randomized Clinical Trial of Low-dose Warfarin Therapy for Improving the Longevity of Permanent Arteriovenous Catheters

BACKGROUND

The patency of a permanent arteriovenous catheter plays a significant role in the functioning of the catheter among patients dependent on the hemodialysis. Thrombosis formation is one of the most critical reasons for the short-term efficacy of the embedded catheters. The present study aimed to evaluate the efficacy and safety of warfarin for hemodialysis catheter failure prevention.

METHODS

This randomized clinical trial has been conducted on patients under hemodialysis using a permanent arteriovenous catheter. The patients were randomly allocated to the control group and the intervention group. The intervention group was treated with warfarin to achieve a target international normalized ratio (INR) of 1.5-2. The control group did not receive any treatment. The patients were followed for 12 months to assess the efficacy defined as the incidence of catheter clotting and safety defined as warfarin-related hemorrhage.

RESULTS

Eighty-six patients with end-stage renal disease under hemodialysis were included, among which 43 ones were allocated to the intervention group and the latter ones to the control group. The participants of both groups were similar in terms of demographic, clinical, and baseline laboratory characteristics. Four patients (9.3%) presented with warfarin-induced hematoma, among which the warfarin administration stopped for 5.33 ± 1.44 days and then restarted again. None of the patients was forced to cease warfarin therapy because of significant hemorrhages. The mean duration of catheter functioning was 8.30 ± 1.75 months in the intervention group versus 3.90 ± 1.12 months in the controls (P-value<0.001).

CONCLUSIONS

Based on the findings of the present study, the use of warfarin to achieve an INR level of 1.5-2 could effectively lead to a longer duration of permanent hemodialysis catheter functioning.

Challenges and novel therapies for vascular access in haemodialysis

Advances in standards of care have extended the life expectancy of patients with kidney failure. However, options for chronic vascular access for haemodialysis - an essential part of kidney replacement therapy - have remained unchanged for decades. The high morbidity and mortality associated with current vascular access complications highlights an unmet clinical need for novel techniques in vascular access and is driving innovation in vascular access care. The development of devices, biological approaches and novel access techniques has led to new approaches to controlling fistula geometry and manipulating the underlying cellular and molecular pathways of the vascular endothelium, and influencing fistula maturation and formation through the use of external mechanical methods. Innovations in arteriovenous graft materials range from small modifications to the graft lumen to the creation of completely novel bioengineered grafts. Steps have even been taken to create new devices for the treatment of patients with central vein stenosis. However, these emerging therapies face difficult hurdles, and truly creative approaches to vascular access need resources that include well-designed clinical trials, frequent interaction with regulators, interventionalist education and sufficient funding. In addition, the heterogeneity of patients with kidney failure suggests it is unlikely that a 'one-size-fits-all' approach for effective vascular access will be feasible in the current environment.

Vascular access placement and mortality in elderly incident hemodialysis patients

BACKGROUND

Arteriovenous fistulas (AVFs) are the preferred vascular access type in most hemodialysis patients. However, the optimal vascular access type in octogenarians and older (≥80 years) hemodialysis patients remains widely debated given their limited life expectancy and lower AVF maturation rates.

METHODS

Among incident hemodialysis patients receiving care in a large national dialysis organization during 2007-2011, we examined patterns of vascular access type conversion in 1 year following dialysis initiation in patients <80 versus ≥80 years of age. Among a subcohort of patients ≥80 years of age, we examined the association between vascular access type conversion and mortality using multivariable survival models.

RESULTS

In the overall cohort of 100 804 patients, the prevalence of AVF/arteriovenous graft (AVG) as the primary vascular access type increased during the first year of hemodialysis, but plateaued thereafter. Among 8356 patients ≥80 years of age and treated for >1 year, those with initial AVF/AVG use and placement of AVF from a central venous catheter (CVC) had lower mortality compared with patients with persistent CVC use. When the reference group was changed to patients who had AVF placement from a CVC in the first year of dialysis, those with initial AVF use had similar mortality. A longer duration of CVC use was associated with incrementally worse survival.

CONCLUSIONS

Among incident hemodialysis patients ≥80 years of age, placement of an AVF from a CVC within the first year of dialysis had similar mortality compared with initial AVF use. Our data suggest that initial CVC use with later placement of an AVF may be an acceptable option among elderly hemodialysis patients.

Determining the incidence of needle-related complications in hemodialysis access: We need a better system

INTRODUCTION

Hemodialysis access complications are common. We hypothesize that many of these complications can be traced back to needle-related injury from routine cannulation practices or inadvertent cannulation injuries. We set out to compare the rates of hemodialysis access complications under prior and current diagnosis coding systems, determine the incidence of needle-related complications for hemodialysis access, and describe the association of needle-related complications and resulting interventions.

METHODS

Arteriovenous graft and arteriovenous fistula placements occurring in the first 6 months of 2014 and 2016 were identified in the United States Renal Data System Medicare claims data. Placements were followed until end of hemodialysis access life or end of the calendar year. Diagnoses and resulting interventions occurring during placement life were identified and mapped to needle-related complication terms.

RESULTS

Almost 30,000 placements for 27,000 patients were followed in each year, with 67% of all accesses placed being arteriovenous fistula and 33% arteriovenous graft. In both years, 75% of arteriovenous fistulae and arteriovenous grafts required one or more interventions. Stenosis and thrombosis were the most common complications diagnosed and treated (41% and 16%, respectively); however, potential needle-related complications accounted for 6% of this dataset.

DISCUSSION

International Classification of Diseases, 9th Revision, was inadequate for determining the incidence of specific hemodialysis access complications or needle-related complications. International Classification of Diseases, 10th Revision, introduced several more hemodialysis access diagnoses but is still subject to coding confusion and catch-all coding for a variety of common and otherwise well-defined complications, suggesting that the true incidence of needle-related complications is buried in the non-specific diagnosis codes. These findings mark the clear need for an improved diagnosis coding system that consistently represents all common hemodialysis access complications.

The Effect of Geometric Graft Modification on Arteriovenous Graft Patency in Haemodialysis Patients: A Systematic Review and Meta-Analysis

OBJECTIVE

Arteriovenous grafts (AVGs) are the second best option for haemodialysis access when native arteriovenous fistulae placement is not possible, because they have a lower patency owing to neointimal hyperplasia at the venous anastomosis. This review aimed to evaluate the effect of geometric graft modification to the graft-vein interface on AVG patency.

DATA SOURCES

The MEDLINE and Embase (OvidSP) databases were systematically searched for relevant studies analysing the effect of geometrically modified AVGs on graft patency and stenosis formation (last search July 2019).

REVIEW METHODS

Data regarding AVG type, patency, and graft outlet stenosis was extracted for further evaluation. Data were pooled in a random effects model to estimate the relative risk of graft occlusion within one year. Follow up, number of patients, and relevant patient characteristics were extracted for the quality assessment of the included studies using Newcastle-Ottawa Scale and Cochrane Risk of Bias Tool. The quality of the evidence was determined according to the Grading of Recommendations, Assessment, Development and Evaluations (GRADE) system.

RESULTS

Search strategies produced 2772 hits, of which eight articles met predetermined inclusion criteria. Overall, the included articles had low to moderate risk of bias. In total, 414 expanded polytetrafluoroethylene AVGs (232 geometrically modified and 182 standard) were analysed, comprising two modified AVG types: a prosthetic cuff design (Venaflo®) and grafts with a Tyrell vein patch. Overall, modified grafts did not show a statistically significantly higher one year primary (relative risk [RR] 0.86, 95% confidence interval [CI] 95% 0.64-1.16; GRADE: "low to very low") or secondary patency (RR 0.57, 95% CI 0.32-1.02; GRADE: "low to very low") when compared with standard AVGs. Analysis of prosthetic cuffed grafts (112 patients) separately demonstrated a statistically significantly higher one year primary (RR 0.75, 95% CI 0.61-0.91) and one year secondary patency (RR 0.47, 95% CI 0.30-0.75) compared with standard grafts (92 patients). The results on stenosis formation were inconclusive and inadmissible to quantitative analyses.

CONCLUSION

The meta-analysis showed that a prosthetic cuff design significantly improves AVG patency, while a venous cuff does not. Although the heterogeneity and low number of available studies limit the strength of the results, this review shows the potential of grafts with geometric modification to the graft-vein anastomosis and should stimulate further clinical and fundamental research on improving graft geometry to improve graft patency.

The Role of Peritoneal Dialysis as the First-Line Renal Replacement Modality

Twenty years after its introduction, peritoneal dialysis (PD) is a well-established alternative to hemodialysis (HD) as a modality of renal replacement therapy. Much debate and research is apparent in the literature, comparing hemodialysis and PD as “opposite” modalities and trying to ascertain which modality should be more optimal.

In our opinion, HD and PD are two distinct modalities, each with its own advantages and disadvantages. In addition, it is clear that for both HD and PD, rates of technique failure are high, causing patients to transfer between modalities. The question is thus not which modality is best, but rather, which flow-chart of modalities makes best use of the advantages of each modality, while avoiding its disadvantages. In this respect, HD and PD appear to be complementary modalities.

The better preservation of residual renal function, lower risk of infection with hepatitis B and C, better outcome after transplantation, preservation of vascular access, and lower costs are arguments to promote PD as a good initial treatment. When PD-related problems arise (adequacy, ultrafiltration, peritonitis, patient burnout), a timely transfer to HD has to be planned.

This editorial tries to review arguments supporting the complementary nature of both modalities, and especially the role of PD as the first-line renal replacement therapy.

Flexible, Skin Coupled Microphone Array for Point of Care Vascular Access Monitoring

Point-of-care screening for hemodialysis vascular access dysfunction requires tools that are objective and efficient. Listening for bruits during physical exam is a subjective examination which can detect stenosis (vascular narrowing) when properly performed. Phonoangiograms (PAGs)-mathematical analysis of bruits-increases the objectivity and sensitivity and permits quantification of stenosis location and degree of stenosis (DOS). This work describes a flexible and body-conformal multi-channel sensor and associated signal processing methods for automated DOS characterization of vascular access. The sensor used an array of thin-film PVDF microphones integrated on polyimide to record bruits at multiple sites along a vascular access. Nonlinear signal processing was used to extract spectral features, and cardiac cycle segmentation was used to improve sensitivity. PAG signal processing algorithms to detect stenosis location and severity are also presented. Experimental results using microphone arrays on a vascular access phantom demonstrated that stenotic lesions were detected within 1 cm of the actual location and graded to three levels (mild, moderate, or severe). Additional PAG features were also used to define a simple binary classifier aimed at patients with failing vascular accesses. The classifier achieved 90% accuracy, 92% specificity, and 91% sensitivity at detecting stenosis greater than 50%. These results suggest that point-of-care screening using microphone arrays can identify at-risk patients using automated signal analysis.

Operative Techniques to Prevent Dialysis Access-associated Steal Syndrome in High-risk Patients Undergoing Surgery for Hemodialysis Access: A Systematic Review

Up to 10% of patients suffer from various degrees of dialysis access-associated steal syndrome (DASS) after surgery for hemodialysis access. This systematic review was conducted to find out optimal intra-operative techniques to prevent DASS in high-risk patients.

This systematic review is registered with PROSPERO (2017:CRD42017060804). It was conducted at Department of Surgery, Aga Khan University Hospital, Karachi. All types of studies conducted on intra-operative techniques to prevent DASS in high-risk population (Age > 60 years, female gender, diabetes mellitus, peripheral arterial disease and previous DASS) undergoing access creation from January 1990 till April 2019 were included in the systematic review. Thorough search was conducted on Pubmed, Google Scholar and Cochrane databases to identify relevant articles. Included studies reviewed for success of various techniques to prevent dialysis access steal syndrome are summarized.

Out of 125 studies in the initial search, six met the inclusion criteria. Five were retrospective case series while one was a case report. The largest study sample size was 32. All but one study had arterio-venous access creation on an arm. “Proximalization of arterial inflow” was described in three and “prophylactic distal revascularization and interval ligation (DRIL) procedure” in two studies to prevent DASS. Only one patient out of these studies developed DASS at an overall follow-up of 7-42 months.

Proximalization of inflow has been reported as the most common procedure performed to prevent DASS followed by extension technique and DRIL procedure. All three procedures have satisfactory outcome with no clear superiority of one over the other.

Use of dehydrated human amnion chorion membrane allograft on infected ruptured arteriovenous fistula: revision and closure

OBJECTIVE

Over two million individuals worldwide, with end-stage renal disease (ESRD), depend on dialysis therapy or a kidney transplant for survival. Every haemodialysis patient requires vascular access. The arteriovenous fistula (AVF) is preferred for long-term hemodialysis vascular access due to long-term primary patency rates. Given the limited options for haemodialysis access and placement, preservation of existing AVF sites is always a clinical priority. This case report describes a novel approach to wound closure with the application of dehydrated amnion chorion human membrane (dHACM) at an AVF surgical site known to be complicated with issues of scarring and tissue breakdown. The patient was treated successfully with the imperative preservation of his AVF given that he had few other vascular access options.

Thrombophilic risk factors in hemodialysis: Association with early vascular access occlusion and patient survival in long-term follow-up

Objective

Thrombophilic risk factors (TRFs) occur rather frequently in hemodialysis (HD) patients. However, little is known about their significance in HD patients, besides their potential impact on arteriovenous (AV) access failure, with varying results. We examined the effects of a wide variety of TRFs on both early AV fistula occlusion and survival among HD patients in long-term follow-up.

Methods

In this single-center, observational study, 70 consecutive HD patients from our dialysis center were examined with respect to shunt occlusion within the first 2 years after fistula creation and patient survival in a long-term follow-up (at least 16 years). We examined the presence of factor V, prothrombin, and MTHFR mutations using real-time fluorescence polymerase chain reaction. Furthermore, antithrombin (AT), protein C, protein S, and antiphospholipid antibodies (APL-Abs) were assessed.

Results

Among the 70 patients, 32 had MTHFR mutations, 10 had heterozygous factor V Leiden mutations, 4 had prothrombin mutations, 4 had protein S deficiency, 2 had protein C deficiency, 9 had AT deficiency, and 14 had APL-Abs. 40 patients had shunt occlusion. TRFs were associated with a significantly increased risk for shunt thrombosis (P<0.02). Kaplan–Meier analysis with a log-rank test revealed significantly shorter survival in HD patients with TRFs (P<0.02). Cox regression analysis showed that the presence of TRFs (P<0.05; hazard ratio, 1.94; 95% CI: 1.07–3.56), but not early shunt occlusion, was associated with short patient survival.

Conclusions

TRFs in hemodialysis patients have a strong impact on patient survival and early AV fistula failure; however, patient survival is not significantly affected by early shunt occlusion.

Hemodialysis access cost comparisons among incident tunneled catheter patients

Background:

Arteriovenous fistula is the ideal hemodialysis access, but most patients start with tunneled dialysis catheter. Arteriovenous fistula and arteriovenous graft surgery may reduce tunneled dialysis catheter use and also increase procedural expenses. We compared Medicare costs associated with arteriovenous fistula, arteriovenous graft, and tunneled dialysis catheter.

Methods:

Using the US Renal Data System, we identified incident hemodialysis patients in 2008 who started with tunneled dialysis catheter, survived at least 90 days, and had adequate Medicare records for analysis. We followed them until death or end of 2011; access modality was based on billing evidence of arteriovenous fistula or arteriovenous graft creation. We assumed patients without such records remained with tunneled dialysis catheter. We generated multivariate linear regression models predicting Medicare expenditures, censoring costs when patients died; we included all payments to physicians and institutions. We also created algorithms to identify access-related costs.

Results:

There were 113,505 patients in the US Renal Data System who started hemodialysis in 2008, of whom 51,002 Medicare patients met inclusion criteria. Of that group, 41,532 (81%) began with tunneled dialysis catheter; 27,064 patients were in the final analysis file. In the first 90 days after hemodialysis initiation, 6100 (22.5%) received arteriovenous fistula, 1813 (6.7%) arteriovenous graft, and 19,151 (70.8%) stayed with tunneled dialysis catheter. Annualized access costs by modality were tunneled dialysis catheter US$13,625 (95% confidence interval: US$13,426–US$13,285); arteriovenous fistula US$16,864 (95% confidence interval: US$16,533–US$17,194); and arteriovenous graft US$20,961 (95% confidence interval: US$20,967–US$21,654; p < .001). Multivariate linear regression demonstrated that staying with tunneled dialysis catheter had lowest access-related costs, arteriovenous fistula was intermediate, and those who underwent arteriovenous graft surgery were highest (p < .021). Access type was not significantly associated with total costs. Additional arteriovenous fistula and arteriovenous graft creation (US$3525 and US$3804 per access per year, respectively) and open and endovascular access-related interventions (US$3102 and US$3569 per procedure per year, respectively; all p < .001) were important predictors of increased cost.

Conclusions:

Among patients starting hemodialysis with tunneled dialysis catheter, continued tunneled dialysis catheter use is associated with lowest access-related cost. Both endovascular and open interventions are associated with significant additional costs. Further investigation is warranted to develop efficient patient-centered strategies for hemodialysis access.

Outcomes of endovascular salvage of clotted arteriovenous access and predictors of patency after thrombectomy

OBJECTIVE

This study aimed to report the outcomes of endovascular salvage of clotted arteriovenous (AV) accesses and to determine potential predictors of poor patency rates after thrombectomy.

METHODS

Records of hemodialysis patients who underwent endovascular salvage of clotted AV access were reviewed retrospectively. Technical and clinical success rates, complication rates, and 3- and 6-month patency rates were determined. Multivariate analysis was performed to determine the predictors of patency after thrombectomy.

RESULTS

A total of 294 patients underwent endovascular salvage of clotted AV access during the study period; 156 patients had arteriovenous fistula, whereas the remaining 138 were arteriovenous grafts (AVGs). The technical and clinical success rates were 96.3% and 93.2%; the major and minor complication rates were 0.7% and 9.9%. Post-thrombectomy primary, assisted primary, and secondary patency rates were 62.9%, 76.2%, and 77.6% at 3 months and 43.9%, 59.5%, and 61.6% at 6 months. The patency rates were significantly better for arteriovenous fistula than for AVG except for 6-month assisted primary and secondary patency. Multivariate Cox regression analysis showed that prior thrombosis within 90 days was significantly associated with loss of primary patency (hazard ratio [HR], 1.90; 95% confidence interval [CI], 1.21-2.98; P < .01), assisted primary patency (HR, 2.42; 95% CI, 1.42-4.13; P < .01), and secondary patency (HR, 2.52; 95% CI, 1.40-4.53; P < .01). Having an AVG was also negatively associated with primary patency.

CONCLUSIONS

Most clotted AV accesses can be salvaged by endovascular technique. Recurrent thrombosis within 90 days is associated with poor short- and long-term patency even after successful endovascular reinterventions.

The Influence of Age on the Likelihood of Catheter-Free Fistula Use in Hemodialysis Patients

Background:

Clinical practice guidelines recommend arteriovenous fistulas as the preferred form of vascular access for hemodialysis. However, some studies have suggested that older age is associated with poorer fistula outcomes.

Objective:

We assessed the impact of age on the outcomes of fistula creation and access-related procedures.

Design:

This was a prospective cohort study using data collected as part of the Dialysis Measurement Analysis and Reporting (DMAR) system.

Setting:

Participating Canadian dialysis programs, including Southern Alberta Renal Program, Manitoba Renal Program, Sunnybrook Health Sciences Centre (Toronto, Ontario), London Health Sciences Centre (London, Ontario), and The Ottawa Hospital (Ottawa, Ontario).

Patients:

Incident hemodialysis patients aged 18 years and older who started dialysis between January 1, 2004, and May 31, 2012.

Measurements:

The primary outcome was the proportion of all first fistula attempts that resulted in catheter-free fistula use, defined as independent use of a fistula for hemodialysis (ie, no catheter in place). Secondary outcomes included the time to catheter-free fistula use among patients with a fistula creation attempt, total number of days of catheter-free fistula use, and the proportion of a patient’s hemodialysis career spent with an independently functioning fistula (ie, catheter-free fistula use).

Methods:

We compared patient characteristics by age group, using t tests or Wilcoxon rank sum tests, and chi-square or Fisher exact tests, as appropriate. Logistic and fractional logistic regression were used to estimate the odds of achieving catheter-free fistula use by age group and the proportion of dialysis time spent catheter-free, respectively.

Results:

A total of 1091 patients met our inclusion criteria (567 age ≥ 65; 524 age < 65). Only 57% of first fistula attempts resulted in catheter-free fistula use irrespective of age (adjusted odds ratio [OR]_≥65vs<65: 1.01; P = .93). The median time from hemodialysis start to catheter-free use of the first fistula did not differ by age when grouped into fistulas attempted pre- and post-dialysis initiation. The adjusted rates of access-related procedures were comparable (incidence rate ratio [IRR]_≥65vs<65: 0.95; P = .32). The median percentage of follow-up time spent catheter-free was similar and low in patients who attempted fistulas (<65 years: 19% vs ≥65 years: 21%; P = .85).

Limitations:

The relatively short follow-up time may have underestimated the benefits of fistula creation and the observational study design precludes inferences about causality.

Conclusions:

In our study, older patients who underwent a fistula attempt were just as likely as younger patients to achieve catheter-free fistula use, within a similar time frame, and while requiring a similar number of access procedures. However, the minority of dialysis time was spent catheter-free.

Ischemic Monomelic Neuropathy after Arteriovenous Fistula Surgery: Clinical Features, Electrodiagnostic Findings, and Treatment

Ischemic monomelic neuropathy (IMN) is a rare complication of vascular access in the hemodialysis patients, characterized by multiple mononeuropathies in the absence of clinical ischemia. Most commonly seen in the female gender, diabetes mellitus, and it must be differentiated from vascular steal syndrome, where we see clinical ischemia as the main pathognomonic feature. Early recognition of the symptoms and prompt intervention was shown to be beneficial. A delay in the treatment can lead to irreversible damage to the nerves and muscles. This article is depicting a case of an elderly male patient who presented with signs and symptoms of IMN which developed after arteriovenous (AV) fistula graft surgery.

Evidence-Based Strategies and Recommendations for Preservation of Central Venous Access in Children

Children with chronic illness often require prolonged or repeated venous access. They remain at high risk for venous catheter-related complications (high-risk patients), which largely derive from elective decisions during catheter insertion and continuing care. These complications result in progressive loss of the venous capital (patent and compliant venous pathways) necessary for delivery of life-preserving therapies. A nonstandardized, episodic, isolated approach to venous care in these high-need, high-cost patients is too often the norm, imposing a disproportionate burden on affected persons and escalating costs. This state-of-the-art review identifies known failure points in the current systems of venous care, details the elements of an individualized plan of care, and emphasizes a patient-centered, multidisciplinary, collaborative, and evidence-based approach to care in these vulnerable populations. These guidelines are intended to enable every practitioner in every practice to deliver better care and better outcomes to these patients through awareness of critical issues, anticipatory attention to meaningful components of care, and appropriate consultation or referral when necessary.

C-reactive protein as a prognostic risk factor for loss of arteriovenous fistula patency in hemodialyzed patients

BACKGROUND

Inflammation is a cardiovascular risk factor in hemodialysis patients, but its influence on vascular access patency is still debatable. Our prospective study investigated this issue.

METHODS

A total of 258 patients receiving an arteriovenous fistula (AVF) between 2006 and 2016 at the Municipal Hospital Arad were included. Demographic, clinical, and laboratory characteristics were collected at the time of creation of the AVF. The primary study end point was AVF patency loss, defined as an event occurring at least 2 months after AVF formation and requiring surgical revision or replacement of the fistula. The patients were followed up for a median time of 26 months.

RESULTS

In our group, the mean age was 59.7 ± 13.2 years (median, 62 years), and 60.1% were male. During follow-up, 134 patients (51.9%) maintained AVF patency, whereas 124 (48.1%) lost AVF patency within a mean time of 23.3 ± 28.1 months (median, 10.5 months). We found that age (hazard ratio [HR], 1.015; P = .035) and C-reactive protein (CRP) level (HR, 1.17; P < .0001) were associated with a higher risk of loss of AVF patency. The protective factors for AVF patency were autosomal dominant polycystic kidney disease (HR, 0.336; P = .009), pre-emptive AVF (HR, 0.648; P = .031), and higher level of triglycerides (HR, 0.998; P = .035). In the multivariate adjusted Cox model, CRP level remained an independent predictor for loss of AVF patency (HR, 1.17; 95% confidence interval, 1.1-1.3; P < .0001).

CONCLUSIONS

In our study, CRP level was an independent predictor of AVF patency loss, whereas better AVF survival was independently associated with autosomal dominant polycystic kidney disease and pre-emptive AVF. As a simple noninvasive marker of chronic inflammation, CRP level may be a useful tool to predict AVF outcomes. Further research is needed to assess the protective effects of inflammation reduction on AVF survival.

Preventing arteriovenous shunt failure in hemodialysis patients: a population-based cohort study

Essentials Uncertainty remains about antiplatelets for vascular access patency in hemodialysis patients. 95 971 people under hemodialysis were followed in a claims database in Taiwan. Aspirin reduced vascular access failure rate and did not increase major bleeding rate. Clopidogrel, Aggrenox, and warfarin might increase major bleeding rate. SUMMARY: Background Dialysis adequacy is a major determinant of survival for patients with end-stage renal disease. Good vascular access is essential to achieve adequate dialysis. Objectives This study evaluated the impacts of different drugs on the vascular access failure rate of an arteriovenous fistula or an arteriovenous graft and the rate of major bleeding in hemodialysis patients. Patients and methods We studied patients with end-stage renal disease registered in the Taiwan National Health Insurance program from 1 January 1997 to 31 December 2012. A total of 95 971 patients were enrolled in our study. Vascular access dysfunction was defined as the need for thrombectomy or percutaneous angioplasty. Major bleeding was defined as emergency department visits or hospitalization with a primary diagnosis of gastrointestinal bleeding or intracerebral hemorrhage. The adjusted odds ratios between person-quarters with or without antiplatelet or oral anticoagulant use were calculated using a generalized estimating equation. Results The odds ratio of vascular access failure was 0.21 (0.11-0.39) for aspirin, 0.76 (0.74-0.79) for clopidogrel, 0.67 (0.59-0.77) for dipyridamole, 0.67 (0.53-0.86) for Aggrenox and 0.96 (0.90-1.03) for warfarin. The highest odds ratio for intracerebral hemorrhage was 5.33 (1.25-22.72) in younger patients using Aggrenox. The highest odds ratio for gastrointestinal bleeding was 1.34 (1.10-1.64) for clopidogrel. Conclusion Antiplatelet agents, but not warfarin, might reduce the vascular access thrombosis rate. The gastrointestinal bleeding rate was increased in the group using clopidogrel. Aggrenox should be used with caution in young individuals because it might increase the rate of intracerebral hemorrhage.

Stenosis Characterization and Identification for Dialysis Vascular Access

Vascular access dysfunction is the leading cause of hospitalization for hemodialysis patients and accounts for the most medical costs in this patient population. Vascular access flow is commonly hindered by blood vessel narrowing (stenosis). Current screening methods involving imaging to detect stenosis are too costly for routine use at the point of care. Noninvasive, real-time screening of patients at risk of vascular access dysfunction could potentially identify high-risk patients and reduce the likelihood of emergency surgical interventions. Bruits (sounds produced by turbulent blood flow near stenoses) can be interpreted by skilled clinical staff using conventional stethoscopes. To improve the sensitivity of detection, digital analysis of blood flow sounds (phonoangiograms or PAGs) is a promising approach for classifying vascular access stenosis using non-invasive auditory recordings. Here, we demonstrate auditory and spectral features of PAGs which estimate both the location and degree of stenosis (DOS). Auditory recordings from nine stenosis phantoms with variable DOS and hemodynamic flow rate were obtained using a digital recording stethoscope and analyzed to extract classification features. Autoregressive modeling and discrete wavelet transforms were used for multiresolution signal decomposition to produce 14 distinct features, most of which were linearly correlated with DOS. Our initial results suggest that the widely-used auditory spectral centroid is a simple way to calculate features which can estimate both the location and severity of vascular access stenosis.