Arteriovenous access in hemodialysis: A multidisciplinary perspective for future solutions

Dialysis Access-Associated Steal Syndrome in High-Risk Patients Undergoing Surgery for Hemodialysis Access: A Systematic Review and Meta-Analysis of Preventive Operative Techniques

This systematic review and meta-analysis examine preventive operative techniques in high-risk patients undergoing surgery for hemodialysis access to mitigate the risk of Dialysis Access-Associated Steal Syndrome (DASS). Chronic kidney disease often leads to end-stage renal disease (ESRD), necessitating dialysis. Successful vascular access is crucial for efficient dialysis, but complications, such as DASS, pose significant challenges. DASS redirects arterial blood flow, affecting populations undergoing arteriovenous access surgery. This study aims to assess preventive strategies, including distal revascularization with interval ligation (DRIL) and extension techniques. A systematic search of PubMed, Cochrane Library, EMBASE, and Web of Science until 2022 identified 11 relevant studies. The inclusion criteria comprised non-pediatric hemodialysis patients reporting outcomes related to patency and complications. The data were analyzed using Review Manager 5.3.5 (The Nordic Cochrane Centre, The Cochrane Collaboration, Copenhagen). Meta-analysis indicated a significant association between DASS and arteriovenous fistula (AVF) or arteriovenous graft (AVG) procedures. Radiocephalic AVF (RC-AVF) and distal endovascular AVF procedures were favored. Various interventions addressed venous narrowing, including simple plication and loop interposition. The Modified by Inserted Latex Link for Endovascular Repair (MILLER) technique, DRIL, Extension Technique, and Proximalization of Arterial Inflow (PAI) were assessed for arterial bypass graft and blood supply preservation. This study underscores the importance of individualized strategies in preventing DASS during hemodialysis access surgery. Prophylactic measures, such as the extension technique, show promise, while DRIL remains effective in treatment. Ongoing research is imperative for optimizing outcomes in this complex patient population.

Multiparametric ultrasound for upper extremity dialysis access evaluation

The evolution of ultrasound (US) techniques has greatly improved the evaluation of many parameters in dialysis vascular access, which is typically achieved through an arteriovenous fistula (AVF) or graft (AVG). These techniques include grayscale B-mode, color Doppler, power Doppler, spectral Doppler, non-Doppler US flow imaging techniques, contrast-enhanced US, and elastography. In conjunction with a patient's medical history and physical examination, US provides crucial information about the native vascular bed prior to the surgical creation of an arteriovenous anastomosis. It also tracks the maturation progress of the newly created AVF or AVG and aids in diagnosing potential complications of the vascular access. These complications include thrombosis, steal syndrome, aneurysms, pseudoaneurysms, hematomas, infection, ischemic neuropathy, exacerbation of preexisting congestive heart failure, and stenosis.

Deep learning analysis of blood flow sounds to detect arteriovenous fistula stenosis

For hemodialysis patients, arteriovenous fistula (AVF) patency determines whether adequate hemofiltration can be achieved, and directly influences clinical outcomes. Here, we report the development and performance of a deep learning model for automated AVF stenosis screening based on the sound of AVF blood flow using supervised learning with data validated by ultrasound. We demonstrate the importance of contextualizing the sound with location metadata as the characteristics of the blood flow sound varies significantly along the AVF. We found the best model to be a vision transformer trained on spectrogram images. Our model can screen for stenosis at a performance level comparable to that of a nephrologist performing a physical exam, but with the advantage of being automated and scalable. In a high-volume, resource-limited clinical setting, automated AVF stenosis screening can help ensure patient safety via early detection of at-risk vascular access, streamline the dialysis workflow, and serve as a patient-facing tool to allow for at-home, self-screening.

Intradialytic techniques for automatic and everyday access monitoring

Vascular access dysfunction is associated with reduced delivery of dialysis, unplanned admissions, patient symptoms, and loss of access, making assessment of vascular access a fundamental part of routine care in dialysis. Clinical trials to predict the risk of access thrombosis based on accepted reference methods of access performance have been disappointing. Reference methods are time-consuming, affect the delivery of dialysis, and therefore cannot repeatedly be used with every dialysis session. There is now a new focus on data continuously and regularly collected with every dialysis treatment, directly or indirectly associated with access function, and without interrupting or affecting the delivered dose of dialysis. This narrative review will focus on techniques that can be used continuously or intermittently during dialysis, taking advantage of methods integrated into the dialysis machine and which do not affect the delivery of dialysis. Examples include extracorporeal blood flow, dynamic line pressures, effective clearance, dose of delivered dialysis, and recirculation which are all routinely measured on most modern dialysis machines. Integrated information collected throughout every dialysis session and analyzed by expert systems and machine learning has the potential to improve the identification of accesses at risk of thrombosis.

Strategies to counteract adverse remodeling of vascular graft: A 3D view of current graft innovations

Vascular grafts are widely used for vascular surgeries, to bypass a diseased artery or function as a vascular access for hemodialysis. Bioengineered or tissue-engineered vascular grafts have long been envisioned to take the place of bioinert synthetic grafts and even vein grafts under certain clinical circumstances. However, host responses to a graft device induce adverse remodeling, to varied degrees depending on the graft property and host's developmental and health conditions. This in turn leads to invention or failure. Herein, we have mapped out the relationship between the design constraints and outcomes for vascular grafts, by analyzing impairment factors involved in the adverse graft remodeling. Strategies to tackle these impairment factors and counteract adverse healing are then summarized by outlining the research landscape of graft innovations in three dimensions-cell technology, scaffold technology and graft translation. Such a comprehensive view of cell and scaffold technological innovations in the translational context may benefit the future advancements in vascular grafts. From this perspective, we conclude the review with recommendations for future design endeavors.

The evolving panorama of vascular access in the 21st century

There are three major types of hemodialysis vascular access: hemodialysis catheters, arteriovenous grafts, and arteriovenous fistulas. Arteriovenous fistulas provide the best access due to their reliability and long-term patency. They are recommended by the current Kidney Disease Outcomes Quality Initiatives (K-DOQI) guidelines; however, not all patients benefit from arteriovenous fistulas due to poor maturation or a lack of adequate vasculature. Currently, hemodialysis is initiated via catheters in the majority of patients. Catheters are associated with high morbidity and mortality due to infection, lower quality of dialysis, and the development of central vein stenosis. The varied responses of patients to the different access types exemplify the need to choose the "right access for the right patient" based on scores that can predict death risk and progression of chronic kidney disease. Additionally, vascular access, often referred to as the "Achilles' heel" of hemodialysis patients, represents a significant percentage of the Medicare budget that continues to increase yearly. The purpose of this paper is to review the current literature on the management of vascular access complications and infection treatment and prevention. The paper also explores emerging research regarding the devices and methods to improve access outcomes such as early cannulation arteriovenous grafts, endovascular arteriovenous fistula creation, and regenerative grafts with resorbable scaffolds, among others. The data were collected through literature searches via PubMed, Athens and web search engines.

Novel electrospun polyurethane grafts for vascular access in rats

OBJECTIVES

The purpose of this study is to develop a new and improved polyurethane (PU) graft using electrospinning and chemical modifications for hemodialysis patients, which will replace the current standard, polytetrafluoroethylene (PTFE) graft. The chemical modifications aim to improve hemocompatibility and reduce thrombogenicity and neointimal hyperplasia.

METHOD

The study population was randomized and divided equally into four groups; one control group received a PTFE graft, and three treatment groups received three different types of polyurethane grafts. Two duplex measurements were performed directly on the graft on the same locations, followed by a histologic examination.

RESULTS

In the first few days after the implantation animals lost some weight, it took a week to recover to pre-surgical weight. Throughout the 28 days, there was no significant difference between animals in wound, activity, and the general appearance. PTFE and PU A groups have lower compliance or reduced graft diameter due to neointimal hyperplasia development on Doppler interrogation. The histological analysis showed limited neointimal hyperplasia development and no excessive inflammatory response to any of the grafts.

CONCLUSION

This study demonstrates that animals with polyurethane grafts show better blood flow because the developed NIH was inconspicuous, as indicated by the different velocity measure than controls on Duplex and minimal NIH development microscopically.

Patient specific approach to analysis of shear-induced platelet activation in haemodialysis arteriovenous fistula

Shear-induced platelet activation (SIPAct) is an important mechanism of thrombosis initiation under high blood flow. This mechanism relies on the interaction of platelets with the von Willebrand factor (VWF) capable of unfolding under high shear stress. High shear stress occurs in the arteriovenous fistula (AVF) commonly used for haemodialysis. A novel patient-specific approach for the modelling of SIPAct in the AVF was proposed. This enabled us to estimate the SIPAct level via computational fluid dynamics. The suggested approach was applied for the SIPAct analysis in AVF geometries reconstructed from medical images. The approach facilitates the determination of the SIPAct level dependence on both biomechanical (AVF flow rate) and biochemical factors (VWF multimer size). It was found that the dependence of the SIPAct level on the AVF flow rate can be approximated by a power law. The critical flow rate was a decreasing function of the VWF multimer size. Moreover, the critical AVF flow rate highly depended on patient-specific factors, e.g., the vessel geometry. This indicates that the approach may be adopted to elucidate patient-specific thrombosis risk factors in haemodialysis patients.

Wearable and implantable artificial kidney devices for end-stage kidney disease treatment-Current status and review

BACKGROUND

Chronic kidney disease (CKD) is a major cause of early death worldwide. By 2030, 14.5 million people will have end-stage kidney disease (ESKD, or CKD stage 5), yet only 5.4 million will receive kidney replacement therapy (KRT) due to economic, social, and political factors. Even for those who are offered KRT by various means of dialysis, the life expectancy remains far too low.

OBSERVATION

Researchers from different fields of artificial organs collaborate to overcome the challenges of creating products such as Wearable and/or Implantable Artificial Kidneys capable of providing long-term effective physiologic kidney functions such as removal of uremic toxins, electrolyte homeostasis, and fluid regulation. A focus should be to develop easily accessible, safe, and inexpensive KRT options that enable a good quality of life and will also be available for patients in less-developed regions of the world.

CONCLUSIONS

Hence, it is required to discuss some of the limits and burdens of transplantation and different techniques of dialysis, including those performed at home. Furthermore, hurdles must be considered and overcome to develop wearable and implantable artificial kidney devices that can help to improve the quality of life and life expectancy of patients with CKD.

In-plane guided upper arm arteriovenous fistula cannulation with color ultrasound

BACKGROUND

The blood vessel in the upper extremity arteriovenous fistula (AVF) is deep in the tissue, and cannulation in AVF is frequently associated with blood oozing, hematoma, or aneurysm. This study evaluated the performance of color ultrasound in-plane guided cannulation technique during upper extremity high-AVF cannulation in patients with hemodialysis.

METHODS

A total of 40 patients with hemodialysis who needed cannulation in upper extremity AVF were recruited in the study, and the patients were randomly divided into observation group and control group. Color Doppler ultrasound was used to guide cannulation in the observation group and in the control group blind cannulation method was applied. The success rate of one-time cannulation, the incidence of subcutaneous hematoma, oozing, and pain caused by incorrect fistula cannulation as well as the satisfaction score of the patients were compared to evaluate the effect and advantages of color ultrasound-guided cannulation.

RESULTS

The one-time success rate of internal fistula cannulation in the observation group (98.71%) was significantly higher than that in the control group (88.27%). The incidence rates of hematoma, oozing, pain, and total failure events were significantly reduced in the observation group. The average satisfaction degree in the observation group was also significantly higher than that of the control group.

CONCLUSION

Ultrasonic-guided cannulation effectively enhances the success rate of cannulation in upper extremity AVF, reduces the incidence of cannulation failures, and improves the satisfaction level in the patients.

Quantification of dissolved H2 and continuous monitoring of hydrogen-rich water for haemodialysis applications: An experimental study

The prevalence of oxidative and inflammatory stress in end-stage renal disease (ESRD) patients has often been associated with chronic haemodialysis therapies. Over the past decades, several reports have shown the potential of hydrogen molecule as an antioxidant in the treatment of various medical conditions in animal models, as well as in pilot studies with human patients. Recently, a hydrogen-enriched dialysate solution has been introduced, holding promise in reducing the oxidative and/or inflammatory complications arising during haemodialysis. To this end, a standardised measuring method to determine the levels of hydrogen in dialysate and subsequently in blood is required. This study explores the possibility of quantifying hydrogen concentration using a novel contactless sensor that detects dissolved hydrogen in liquids. An experimental circuit is assembled to validate the sensitivity and accuracy of the hydrogen monitoring system (Pureron Japan Co., Ltd) through in vitro investigations with physiological solutions. Measurements of dissolved molecular hydrogen concentration are corroborated by an established oxygen sensor providing continuous partial pressure readings. The relationship between the applied H₂ content in the gaseous mixture and the H₂ concentration value at equilibrium is linear. At the same time, the hydrogen monitoring system has a rather long response time, and its readings seem to slightly diverge from sensor to sensor as well as at different temperatures. For this reason, a sensor recalibration might be necessary, which could become part of the product's ongoing development. Nevertheless, the aforementioned minor deficiencies can be mostly considered negligible in applications such as haemodialysis.

An unusual case of femoral arteriovenous fistula associated with acute limb ischemia following femoral vein catheterization for hemodialysis

Co-occurrence of acute limb ischemia (ALI) and arteriovenous fistula (AVF) as a manifestation of inadvertent arterial injury during percutaneous femoral vein dialysis catheter insertion is a rare and dangerous, but preventable complication. Iatrogenic femoral AVF commonly presents late, with leg swelling or high output cardiac failure. However, the co-occurrence of a femoral AVF with both progressive leg swelling, and acute thromboembolism has not been previously reported. We report the case of an iatrogenic femoral AVF with superficial femoral artery (SFA) thrombosis and distal embolism in a 53-year-old female who underwent percutaneous femoral access for temporary hemodialysis. Both the SFA and AVF were managed with open surgical repair.

A family-centred perspective on the arteriovenous fistula in end-stage renal disease: Findings from dyadic interviews

INTRODUCTION

The preservation of a well-functioning arteriovenous fistula (AVF) is crucial for successful dialysis in patients with end-stage renal disease (ESRD); nonetheless, complications are frequent which leads to lower quality of life, hospitalisations and death. Self-care behaviours help to reduce the risk of complications and family caregivers can play an important role as partners for behaviour change. However, the patient and family caregiver's experiences with such an invasive intervention are largely unknown.

AIMS

This study aimed to explore the experiences of patients with ESRD and their family caregivers with the AVF through joint interviews.

METHODS

A qualitative exploratory study was conducted with a purposive sample. Semi-structured joint interviews were conducted with 14 dyads (28 participants) composed of patients on haemodialysis with AVF and their respective family caregivers. Interviews were audiotaped, transcribed verbatim and submitted to thematic analysis.

FINDINGS

Four major themes were identified: (i) AVF negative impacts; (ii) (un)presence of self-care behaviours; (iii) AVF self-management facilitators and (iv) AVF self-management barriers.

DISCUSSION

The findings suggested that more attention needs to be paid to patients' and their family caregivers' support needs (e.g. fears, concerns, knowledge, adherence barriers and facilitators) regarding AVF self-management. The dyads seem to be aware of how to take care of the AVF; however, self-care behaviours still need to be improved.

CONCLUSION

Innovative interventions need to follow an interdisciplinary approach with an educational and support component. The integration of family caregivers should also be considered, since this study evidenced their lack of knowledge and skills, and willingness to participate in these initiatives.

Using two-holed needles for both arterial and venous accesses to the arteriovenous fistula to improve flow during hemodialysis

This prospective study compared methods using both arterial and venous needles with back eyes with those using only arterial needle with back eye for arteriovenous fistula cannulation. Sixty-one patients receiving hemodialysis (HD) via an arteriovenous fistula were evaluated. All patients underwent arteriovenous fistula puncture using only arterial needle with back eye in first 3 months and both arterial and venous needles with back eyes in following 3 months. Arterial and venous pressures, blood flow velocities, total blood volume cleared, and Kt/V values were compared. Mean blood flow velocity, arterial pressure, Kt/V, and cleared total blood volume values were higher and venous pressure was lower in patients who underwent cannulation using both needles with back eyes than in those with only the arterial needle with back eye. For arteriovenous fistula cannulation, using both arterial and venous needles with back eyes provides adequate HD more successfully.

The association of erythropoietin-stimulating agents and increased risk for AV-fistula dysfunction in hemodialysis patients. A retrospective analysis

BACKGROUND

Patients in maintenance hemodialysis (HD) need a patent vascular access for optimal treatment. The recommended first choice is a native arteriovenous fistula (AVF). Complications of AVF are frequent and include thrombosis, stenosis and infections leading to worsening of dialysis efficacy. Some known risk factors are age, gender and the presence of diabetes mellitus. The aim was to investigate if further risk variables are associated with dysfunctional AVF.

METHODS

This retrospective observational study included 153 chronic HD patients (Cases) referred to a total of 473 radiological investigations due to clinically suspected complications of their native AVF. Another group of chronic HD patients (n = 52) who had a native AVF but were without history of previous complications for at least 2 years were controls. Statistical analyses included ANOVA, logistic regression, parametric and non-parametric methods such as Student's T-test and Mann-Whitney test.

RESULTS

Among Cases, at least one significant stenosis (> 50% of the lumen) was detected in 348 occasions. Subsequent PTA was performed in 248 (71%). Median erythropoiesis-stimulating agent (ESA) weekly doses were higher in Cases than in Controls (8000 vs 5000 IU, p < 0.001). Cases received higher doses of intravenous iron/week than the Controls before the investigation (median 50 mg vs 25 mg, p = 0.004) and low molecular weight heparin (LMWH, p = 0.028). Compared to Controls, Cases had a lower level of parathyroid hormone (median 25 vs 20 ρmol/L, p = 0.009). In patients with diabetes mellitus, HbA1c was higher among Cases than Controls (50 vs 38 mmol/mol, p < 0.001). Multiple regression analysis revealed significant associations between Cases and female gender, prescription of doxazocin, and doses of ESA and LMWH. There was no difference between the groups regarding hemoglobin, CRP or ferritin.

CONCLUSION

In conclusion, the present study indicated that the factors associated with AVF problems were high doses of ESA, iron administration, and tendency of thromboembolism (indicated by high LMWH doses); the use of doxazocin prescription, however, requires further investigation.