Materiały źródłowe

• #1 Arteriovenous Fistula – StatPearls – NCBI Bookshelf

  https://www.ncbi.nlm.nih.gov/books/NBK559213/

  Arteriovenous fistulas were originally described by William Hunter as early as 1757. Much of the experience in managing AVFs originated out of traumatic injuries resulting in AVFs from the Second World War, the Korean War, and the Vietnam War. 215 AVFs and aneurysms were reported as a result of the Korean War. In the civilian population, traumatic AVFs of the abdomen and extremities are equally distributed, unlike in the military, where the majority of traumatic AVFs occur in the extremities. This difference is likely due to the body armor worn by the military. Demonstrably, traumatic fistulas are much more common than congenital fistulas and are more frequently discussed. Congenital fistulas are generally rare and found in case reports and small studies. […] The National Institute of Diabetes and Digestive and Kidney Diseases reported that, as of 2013, over 468,000 patients were on hemodialysis. Twenty percent of those patients receive dialysis via a surgically created AVF. In the HEMO Study published in 2000, AVF prevalence varied between dialysis centers from 4-77%. The authors discovered a decreased prevalence of AVF compared to other means of hemodialysis in females, blacks, obese, elderly, and patients with peripheral arterial disease. Geographically, the rate of AVF creation varies greatly, with the highest rates being in the Northeast and the lowest in the Southwest of the United States.

• #2 Dural arteriovenous fistula | Radiology Reference Article | Radiopaedia.org

  https://radiopaedia.org/articles/dural-arteriovenous-fistula?lang=us

  Most dural arteriovenous fistulas present in adulthood and account for 10-15% of all cerebral vascular malformations 6. […] Dural arteriovenous fistulas (dAVF) are a heterogeneous collection of conditions that share arteriovenous shunts from dural vessels. They present variably with hemorrhage or venous hypertension and can be challenging to treat.

• #3 Dural Arteriovenous Fistula Manifested as Rapid Progressive Dementia Successfully Treated by Endovascular Embolization Only

  https://neurointervention.org/journal/view.php?number=138

  A dural arteriovenous fistula (DAVF) is an uncommon type of intracranial vascular malformation. Though the true incidence of DAVF is unknown, the reported incidence is approximately 10-15% of all intracranial vascular malformations. […] As far as we know, a DAVF case with cognitive impairment and transient memory loss is uncommon. […] Therefore, early intervention through surgery or endovascular embolization is important. […] In addition to emphasizing the importance of a quick diagnosis, our case showed that endovascular therapy alone can completely obliterate a DAVF located in the posterior fossa.

• #4 Arteriovenous Fistulas: The Pathological Bridge | IntechOpen

  https://www.intechopen.com/chapters/69798

  An intracranial dural arteriovenous fistula (DAVF) is a type of intracranial vascular malformation in which there is a connection between an intracranial artery and a dural venous sinus. It accounts for 1015% of all intracranial arteriovenous malformations. […] The true incidence of DAVFs is unknown. However, the reported incidence of intracranial DAVFs is approximately 1015% of all intracranial vascular abnormalities. […] The presence of a CVD (Borden type II and III, Cognard types IIbV) or absence (Borden type I, Cognard types I, IIa) and the pattern of the venous drainage all are considered major factors by the previous classification systems and were used to assess the risk of hemorrhage or any neurologic deficits. […] The absence of a CVD has been recognized as a favorable factor and the patients are usually asymptomatic or have symptoms like pulsatile tinnitus or exophthalmos.

• #5 Intracranial Dural Arteriovenous Fistula: Microneurosurgery Basics and Tricks | SpringerLink

  https://link.springer.com/chapter/10.1007/978-981-10-8950-3_25

  Intracranial dural arteriovenous fistulas (DAVFs) are acquired lesions characterized by a region of abnormal arteriovenous fistulous connection within the dura. DAVFs contribute to 10-15% of all AVM intracranially as reported by Newton et al. from 1969. In common population the probable rates were 0.15-0.29 per 100,000 people per year. Median age of DAVF patients is between 50 and 60 years, but it may present at any age. […] The primary method for verification of DAVF occlusion postoperatively is DSA, because all the small feeding arteries may not show in ICG-VA or CTA. Later during follow-up, MRA and/or TRICKS is used to verify the occlusion of the fistula.

• #6 Dural Arteriovenous Fistula (dAVF): Symptoms & Treatment

  https://my.clevelandclinic.org/health/diseases/dural-arteriovenous-fistula-davf

  In the United States, a dural arteriovenous fistula affects an estimated 0.15 to 0.19 out of 100,000 people each year. […] A dural arteriovenous fistula can affect anyone at any age. The condition is most common among adults between ages 40 and 60. […] Complications of dAVF can be life-threatening and may include: Bleeding within your brain tissue (hemorrhage). […] If you dont have symptoms, your healthcare provider may not immediately treat the condition but offer regular monitoring to prevent complications. […] Theres no known way to prevent a dural arteriovenous fistula (dAVF). You may be able to reduce your risk by managing any underlying health conditions that may lead to this condition, like blood clotting conditions. […] As dural arteriovenous fistulas arent common, research is still ongoing to learn more about survival rates. Current studies report that the annual mortality rate (the number of people who die due to this condition) is between 11% and 19%. This estimates the annual survival rate to be above 80% in certain cases.

• #7 Dural Arteriovenous Fistulas: Epidemiology and Clinical Presentation | Neupsy Key

  https://neupsykey.com/dural-arteriovenous-fistulas-epidemiology-and-clinical-presentation/

  DAVFs present at a mean age of 50 to 60 years, but individual presentation is highly heterogeneous. […] In the past, DAVFs were relatively uncommon, but are now being diagnosed with increased frequency. This increased frequency of incidentally diagnosed DAVFs has been attributed to the wide availability of MRI. These lesions account for approximately 10% to 15% of intracranial vascular malformations. Among supratentorial and infratentorial vascular malformations, they account for 6% and 35% of lesions, respectively. […] These lesions seem to have no gender preponderance, but several studies have reported an increased incidence of hemorrhage in men in comparison with women. No linkages to family history or genetics have been identified.

• #8 Spinal dural arteriovenous fistula | Radiology Reference Article | Radiopaedia.org

  https://radiopaedia.org/articles/spinal-dural-arteriovenous-fistula?lang=us

  Spinal dural arteriovenous fistulas (SDAVF) are the most common type of spinal vascular malformation, accounting for ~70% of all such lesions. […] The incidence of SDAVF peaks in the 5th and 6th decades and males are more commonly affected than females.

• #9 Spinal Dural Arteriovenous Fistulas | American Journal of Neuroradiology

  http://www.ajnr.org/content/30/4/639

  SDAVFs are the most frequent vascular malformation of the spine and account for approximately 70% of all vascular spinal malformations. An estimation based on the retrospective series of the major German referral center for spinal vascular diseases (Prof Thron, Aachen, Germany), arrived at 510/million/year in the general population. However, the disease seems to be underdiagnosed. Usually, SDAVFs become symptomatic in elderly men. A recent meta-analysis of all series larger than 5 patients concluded that men are affected 5 times more often than women and that the mean age at the time of diagnosis is 55-60 years. Patients younger than 30 years of age constituted less than 1% of patients with a DAVF, whereas, to our knowledge, no patient younger than 20 years of age has ever been reported. Most fistulas are solitary lesions and are found in the thoracolumbar region. In our experience, 80% of all DAVFs are located between T6 and L2. Sacral lesions occur in approximately 4% of patients, whereas high cervical lesions (at the level of the foramen magnum) occur in 2% of patients. Low cervical DAVFs (below C2 and above T1) are extremely rare. In approximately 2% of patients, double spinal DAVFs or an association of a spinal dural with a spinal pial AV shunt may be present, raising the possibility of a potential etiologic connection.

• #10 Traumatic Arteriovenous Fistula: A Literature Review – Clinical Surgery Journal (ISSN 2767-0023)

  https://clinicalsurgeryjournal.com/article/1000121/traumatic-arteriovenous-fistula-a-literature-review

  ArterioVenous Fistulas (AVF) can be described as abnormal communication between the artery and vein. Traumatic AVF (TAVF) is present in about 4% of vascular traumas among its etiologies. TAVF was prevalent in men at the mean age of 41.6 years. The primary etiology was a gunshot wound, and the predominant topography was the head. […] In the epidemiology context, articles with full information on age, gender, and country of origin were considered. A total of 74 cases were gathered. The masculine gender was predominant (n = 54; 72.97%) in comparison to the female counterpart (n = 20; 27.03%). The age range was 7 years to 87 years, with an average of 41, 62, a variance of 380,95, and a standard deviation of 19,51. […] The TAVF topography, reported in 118 cases, varied significantly, with greater head area incidence (38.9%), mostly related to the carotid-cavernous fistula.

• #11 Traumatic Arteriovenous Fistula: A Literature Review – Clinical Surgery Journal (ISSN 2767-0023)

  https://clinicalsurgeryjournal.com/article/1000121/traumatic-arteriovenous-fistula-a-literature-review

  Regarding the time between the trauma and the development of the arteriovenous fistula, 43 articles that possessed this information available were considered. Most cases (76.7%) took more than one day to develop this vascular complication. […] In the selected articles, 48 had entire clinical history described, among which only 5 (10.4%) were discovered in the first moments after trauma and did not develop specific symptoms of the complication. […] The most used method to establish diagnosis was conventional angiography, reported in 34 patients (41.4%). […] The most common technical complication that hindered the intravenous approach was the impossibility of advancing the guidewire. […] TAVF is an uncommon condition, and it can have a clinically significant evolution. Thus it is necessary to search for this complication in patients with a traumatic history or victim of traumas since the majority of the cases had a penetrating etiology.

• #12 Clinical monitoring and surveillance of the mature hemodialysis arteriovenous fistula – UpToDate

  https://www.uptodate.com/contents/clinical-monitoring-and-surveillance-of-the-mature-hemodialysis-arteriovenous-fistula

  Clinical monitoring and surveillance of the mature hemodialysis arteriovenous fistula […] INTRODUCTION […] Arteriovenous (AV) fistulas are capable of providing rapid extracorporeal blood flow that is necessary for hemodialysis; however, vascular stenosis is common and can lead to inadequate hemodialysis or AV fistula thrombosis if not identified and treated in a timely fashion. […] Issues surrounding monitoring and surveillance of hemodialysis AV fistulas are reviewed here. Similar issues for hemodialysis AV grafts are discussed separately. […] RATIONALE FOR MONITORING AND SURVEILLANCE OF AV FISTULAS […] Nearly all thrombosed mature AV fistulas have an underlying stenotic lesion. This was shown in a series of 93 consecutive clotted AV fistulas in which 100 percent had an underlying stenosis.

• #13 Clinical monitoring and surveillance of the mature hemodialysis arteriovenous fistula – UpToDate

  https://www.uptodate.com/contents/clinical-monitoring-and-surveillance-of-the-mature-hemodialysis-arteriovenous-fistula

  Although angiography is the most sensitive and specific imaging modality to identify and characterize stenotic vascular lesions, it is expensive and invasive. For screening, noninvasive assessment is preferred to first identify AV fistulas with a high likelihood of stenosis. AV fistulas with sufficiently abnormal screening tests would then undergo diagnostic angiography and, if indicated, treatment. Clinical monitoring and surveillance are currently used to screen for vascular stenotic lesions. […] Clinical monitoring

• #14 Arteriovenous Fistula Flow Dysfunction Surveillance: Early Detection Using Pulse Radar Sensor and Machine Learning Classification

  https://www.mdpi.com/2079-6374/11/9/297

  Arteriovenous Fistula Flow Dysfunction Surveillance: Early Detection Using Pulse Radar Sensor and Machine Learning Classification […] The National Kidney Foundation Kidney Disease Outcomes Quality Initiative (NKF-K/DOQI) guidelines suggest two monitoring methods for VA flow surveillance, physical examination, and the measuring of arteriovenous VA flow through special equipment. Guideline 13 of the NKF-K/DOQI specifically states that the underlying cause of AV access flow dysfunction is either stenosis or thrombosis. Hence, the purpose of flow dysfunction surveillance is to detect stenosis early on before the development of thrombosis, which then requires surgical intervention to replace the AV access. […] Amongst the current monitoring instruments available, the Ultrasound Dilution (UD) flow monitoring instrument has been extensively studied. For example, the benefits of AV Fistula (AVF) flow surveillance using the UD measurement was studied, where the effectiveness of UD measurement in detecting stenosis and predicting thrombosis was investigated. Our clinical experience regarding the application of the UD measurement technique shows that it is limited due to its cost, the disposable consumables used, and its dependence on the operator’s experience with the instruments. However, through the use of skillful operation techniques, it has been accepted as a reference standard for AV access flow surveillance.

• #15 Arteriovenous Fistula Flow Dysfunction Surveillance: Early Detection Using Pulse Radar Sensor and Machine Learning Classification

  https://www.mdpi.com/2079-6374/11/9/297

  Studies have been performed surrounding the use of optical sensor and machine learning algorithms for the detection of stenosis or flow dysfunction. However, either two finger Photoplethysmography (PPG) sensors were used, which may cause measurement uncertainties or additional physiological measurements other than the PPG signal were required as input features for classification of the algorithm. Therefore, for the most part, detection sensitivity and specificity of the aforementioned methods do not meet the requirements for them to be reliable monitoring instruments. A qualified monitoring technique should possess standardized diagnostic thresholds, as well as sufficient sensitivity and specificity for the detection of flow dysfunction. […] As mentioned in the NKF-K/DOQI guidelines, there exists a need for standardized diagnostic thresholds with sufficient sensitivity as well as specificity. In the present work, the ROC curve analysis was performed with the results showing that the Area Under the Curve (AUC) was 0.994. The specificity and positive prediction value for the detection thresholds of 750, 650, 600, and 500 mL/min were all 100%, with the maximum sensitivity being 95.2% at a detection threshold of 750 mL/min. This result indicates that the VWM monitor-based AVF flow dysfunction detector provides an excellent correlation with the UD flow monitor within a large range of AVF flow. However, a single optimal detection threshold could not be determined solely on the value of sensitivity. Instead, two levels of detection thresholds, e.g., first level at 750 mL/min and second level at 600 mL/min, may be more reliable for the early detection of flow dysfunction before proceeding to pre-emptive angioplasty.

• #16 Surveillance and monitoring of early failing arteriovenous fistula using Doppler assessment in children on regular hemodialysis | Egyptian Journal of Radiology and Nuclear Medicine | Full Text

  https://ejrnm.springeropen.com/articles/10.1186/s43055-022-00912-y

  A well-functioning vascular access is a mainstay to perform an efficient hemodialysis procedure. Limited lifespan of arteriovenous accesses is one of the major challenges of the current long-term hemodialysis therapy. The pediatric vascular access clinical guidelines published by the National Kidney Foundation Kidney Disease Outcome Quality Initiative recommend establishing a surveillance strategy to detect access stenosis and direct patients for early intervention. […] The performance of color Doppler ultrasonography in the regular surveillance of AVF patency has been widely described in the literature. This safe, non-invasive and reproducible technique has been found useful for pre-operative vascular mapping, evaluation of AVF maturation and surveillance of AVF flow, providing direct evidence for the presence, localization and severity of stenosis.

• #17 Surveillance and monitoring of early failing arteriovenous fistula using Doppler assessment in children on regular hemodialysis | Egyptian Journal of Radiology and Nuclear Medicine | Full Text

  https://ejrnm.springeropen.com/articles/10.1186/s43055-022-00912-y

  The pediatric vascular access clinical guidelines published by the National Kidney Foundation Kidney Disease Outcome Quality Initiative (KDOQI) recommends establishing a surveillance strategy to detect access stenosis and direct patients for early intervention. The CDU is minimally invasive, while fistulography was costly, required radiation exposure and, in younger children, sedation and anesthesia. […] The current study demonstrated the role of CDU as a non-invasive surveillance method for detection of AVF different dysfunctions. Among pediatric patients, CDU can detect early stenosis of AVF which can affect the dialysis adequacy.

• #18 Arteriovenous Fistula Surveillance Using Tomographic 3D Ultrasound – PubMed

  https://pubmed.ncbi.nlm.nih.gov/33896727/

  Objective: A well functioning arteriovenous fistula (AVF) is essential for haemodialysis. Despite regular duplex ultrasound (DUS) a significant number of AVFs fail. Tomographic 3D ultrasound (tUS) creates a 3D image of the AVF that can be interpreted by the clinician. DUS, tUS, and fistulograms were compared for the identification and measurement of flow limiting stenosis. […] Methods: Patients with AVF dysfunction on routine Transonic surveillance, defined as (1) 15% reduction in flow on two consecutive occasions, (2) 30% reduction in flow on one occasion, (3) flow of 600 mL/sec, (4) presence of recirculation, underwent DUS. AVF tUS imaging was performed prior to fistulography. All fistulograms were reported by the same consultant radiologist and tUS images by the same vascular scientist blinded to the fistulogram results. Maximum diameter reduction in all stenoses were measured using all three imaging techniques. […] Conclusion: DUS and tUS were equally accurate at detecting AVF complications but tUS investigation requires less skill and was significantly quicker than DUS. […] Keywords: Arteriovenous fistula surveillance; Duplex imaging; Fistulography; Tomographic 3D ultrasound (tUS).

• #19 Clinical monitoring and surveillance of hemodialysis arteriovenous grafts to prevent thrombosis – UpToDate

  https://www.uptodate.com/contents/clinical-monitoring-and-surveillance-of-hemodialysis-arteriovenous-grafts-to-prevent-thrombosis

  Clinical monitoring refers to assessments that can be performed by physical examination of the access or by using readily available information that is collected in the course of treating dialysis patients. A number of studies have observed that a hemodynamically significant (>50 percent) stenosis is present in approximately 70 to 90 percent of patients identified to have abnormalities of clinical monitoring.

• #20 Arteriovenous fistula surveillance: Everyone’s responsibility | CCLHD Research Repositories

  https://centralcoast.intersearch.com.au/centralcoastjspui/handle/1/143?mode=full

  The arteriovenous fistula, as opposed to arteriovenous grafts and central venous dialysis catheters, remains the dialysis access of choice for haemodialysis patients, due to its superior long term patency, low incidence of stenosis, thrombosis and infection. […] The basic tenant of vascular access monitoring and surveillance is that stenosis develops over a variable amount of time in a majority of arteriovenous fistula, and if detected and corrected, inadequate dialysis can be prevented, maturation can be facilitated and thrombosis and access loss can be avoided. […] Large randomised controlled trials are lacking to clearly identify the ideal surveillance strategies and benefits of surveillance, often only supported by observational studies and small single -centre randomised controlled trials.

• #21

  https://journals.lww.com/ijvs/fulltext/2021/08010/systematic_surveillance_of_arteriovenous_fistula.13.aspx

  Does systematic surveillance help improve arteriovenous fistula (AVF) patency and health economics in renal failure patients? […] A surveillance program would reduce the morbidity and mortality associated with AVF complications by enabling the early detection and prompt intervention for high-risk fistulas. […] The records were accessed to see if the surveillance helped improve patency, reduced number of emergency admissions, and its effect on health economics. […] The quality initiative project, despite its limitations of small numbers has encouraged us to change our practice since we observed positive outcomes in individuals with early fistula complications. […] Centers managing patients requiring renal replacement therapy should have an open channel of communication between the vascular, interventional radiology, nephrology, and RDU to identify high-risk patients enabling improved patency rates of AVF created and a CNS plays a key role in orchestrating the smooth timely transfer of care for such patients.

• #22 Arteriovenous fistula surveillance: Everyone’s responsibility | CCLHD Research Repositories

  https://centralcoast.intersearch.com.au/centralcoastjspui/handle/1/143?mode=full

  Cost effective ways to improve outcomes in these types of vascular accesses involves formalised training of staff and other healthcare professionals to better identify dysfunctional fistulas by physical examination, with the addition of surveillance studies to support these findings and pre-emptive intervention when stenosis is found. […] In this review, we examine the physiology of a dysfunctional fistula and evaluate available studies in the surveillance of arteriovenous fistulas.

• #23 Journal of Medicine and Life Science

  https://www.e-jmls.org/m/journal/view.php?number=523

  Arteriovenous fistula flow dysfunction is the leading cause of vascular access thrombosis and loss in patients undergoing hemodialysis. […] This study aims to identify accesses at a high risk of thrombosis and loss among patients undergoing hemodialysis by measuring the access flow rate and exploring an optimal threshold value for predicting future access thrombosis. […] Access thrombosis and loss were higher in the low-flow group than in the high-flow group. […] This study revealed that low access flow rates are strongly associated with access thrombosis occurrence and subsequent loss of arteriovenous fistulas in patients undergoing hemodialysis. […] The 2019 K/DOQI guidelines recommend regular physical examination of the AVF by a trained dialysis provider instead of routine AVF surveillance by measuring access blood flow as there is inadequate evidence on its measurement.

• #24 Journal of Medicine and Life Science

  https://www.e-jmls.org/m/journal/view.php?number=523

  Thus, the 2019 guidelines commented on the complementary role of surveillance in routine clinical monitoring, as the well-timed identification of VA with flow dysfunction is vital for preserving their function. […] Among VA surveillance methods, measuring Qa using UDM has been a readily applicable tool owing to its sensitivity and accuracy and can be performed at the bedside more frequently and regularly without a heavy workload on the dialysis staff compared with other methods such as Doppler ultrasonography. […] Our findings suggested that regular AVF flow measurements using UDM can identify a subset of patients at an increased risk of future VA thrombosis and loss. […] In the present study, an ROC curve analysis showed that a Qa of 400 mL/min had a high predictive ability for imminent thrombosis, with an AUC of 0.908, indicating that measuring Qa is helpful in clinical practice for identifying patients at a high risk of VA thrombosis.

• #25 Surveillance arterioveNous fistulAs using ultRasound (SONAR) trial in haemodialysis patients: a study protocol for a multicentre observational study | BMJ Open

  https://bmjopen.bmj.com/content/9/7/e031210

  Arteriovenous fistulas (AVFs) are considered the best modality for providing haemodialysis in patients with end-stage renal disease. Only 20% of UK centres achieve the recommended 80% target for achieving dialysis of the prevalent dialysis population via permanent access (as opposed to a central venous catheter). This is partly due to the relatively poor maturation rate of newly created fistulas, with as many as 50% of fistulas failing to mature. […] The Surveillance Of arterioveNous fistulAe using ultRasound study will examine whether a protocolised programme of Doppler ultrasound (US) surveillance can identify, early after creation, potentially correctable problems in those AVFs that subsequently fail to mature. […] The literature relating to ultrasound (US) surveillance of AVFs is conflicting. This may reflect variations in the type of surveillance adopted, the type of fistula under surveillance and the precise US scanning method.

• #26 Surveillance arterioveNous fistulAs using ultRasound (SONAR) trial in haemodialysis patients: a study protocol for a multicentre observational study | BMJ Open

  https://bmjopen.bmj.com/content/9/7/e031210

  Few studies have attempted to use US to characterise early maturation, immediately after fistula creation, but those that do suggest that successful fistula maturation is associated with rapid increase in fistula blood flow, even by the first day after formation. […] Only 20% of UK dialysis centres manage to meet the Renal Association guidelines to dialyse their prevalent population via an AVF. Numerous factors contribute to this, but the high early failure rate, with as many as 50% of nascent fistulas failing to mature, is undoubtedly a major factor. […] This study aims to fill this gap in knowledge by determining whether US surveillance of newly formed AVFs can be used to identify failing fistulas. […] We aim to demonstrate whether a structured programme of Doppler ultrasound (US) surveillance will accurately predict structural abnormalities (such as venous intimal hyperplasia) that lead to the failure of a newly created fistula to adequately develop and provide effective access for dialysis.

• #27 Surveillance arterioveNous fistulAs using ultRasound (SONAR) trial in haemodialysis patients: a study protocol for a multicentre observational study | BMJ Open

  https://bmjopen.bmj.com/content/9/7/e031210

  Doppler US surveillance can reliably predict failing nascent AVFs by identifying potentially correctable anatomical defects. […] If Doppler US accurately identifies anatomically correctable lesions that are preventing maturation (salvageable fistula), this will be used to power and justify a second phase interventional study that addresses whether timely surgical and/or radiological intervention improves fistula patency rates.

• #28 Development and Validation of a Machine Learning Model Predicting Arteriovenous Fistula Failure in a Large Network of Dialysis Clinics

  https://www.mdpi.com/1660-4601/18/23/12355

  The controversy concerning the best surveillance strategy to ascertain and evaluate venous stenoses has not yet been solved. The rationale for surveillance is based on the hypothesis that progressive stenosis can be accurately detected by reduced Qa and increased venous pressure (VP) before VA thrombosis occurs. […] Even though both Qa surveillance and ultrasound examination, coupled with pre-emptive correction of hemodynamically significantly reduces the risk of thrombosis and access loss, false positive tests would lead to unnecessary intervention procedures which may ultimately promote further neointimal hyperplasia. No current surveillance method is without pitfalls. Major concerns for Qa surveillance relate to low reproducibility in clinical practice which corresponds to a minimal detectable change as large as 25%, questionable cost-effectiveness as the sole surveillance strategy and suboptimal inter-rater agreement across different measurement techniques.

• #29 Development and Validation of a Machine Learning Model Predicting Arteriovenous Fistula Failure in a Large Network of Dialysis Clinics

  https://www.mdpi.com/1660-4601/18/23/12355

  An excellent surveillance method should be quick, easy, accurate, non-invasive, non-operator-dependent and cost-effective. It is clear, that none of the existing methods can fulfil such expectations alone and a one-fits-all approach is not be able to adequately capture the diversity of AVF functional trajectories between and within patients. […] To this end, we sought to develop and validate a risk model based on the machine learning methods predicting the occurrence of AVF failure within three months. […] The AVF Failure Model (AVF-FM) aims at predicting the occurrence of a composite AVF failure endpoint within three months based on routinely recorded clinical information readily available in health information systems for dialysis patients. […] The model is based on the XGBoost algorithm, an iterative method where, at each iteration, a new sub-model is added to correct the prediction error of the previous iteration.

• #30 Development and Validation of a Machine Learning Model Predicting Arteriovenous Fistula Failure in a Large Network of Dialysis Clinics

  https://www.mdpi.com/1660-4601/18/23/12355

  The AVF-FM was derived using the information collected in the European Clinical Database (EuCliD, Fresenius Medical Care, Deutschland GmbH, Wendel, Germany), a large, multinational, database including in-centre dialysis patients. […] The final dataset consisted of 13,369 patients, which provided 113,592 patients-quarters. AVF failure incidence density was 6.6 events/100 patient-quarters or 26.4 events/100 patient years. […] The final model had a very good discrimination accuracy. The Area Under the ROC Curve (AUC-ROC) for the AVF-FM was 0.80 (95% CI 0.79–0.81). Model calibration showed excellent representation of observed failure risk. […] The AVF Failure Model has shown promising discrimination performance by combining routinely collected clinical as well as sensor data; therefore, the AVF Failure Model can potentially enable risk-based personalization of AVF surveillance strategies.

• #31 Doppler ultrasound surveillance of recently formed haemodialysis arteriovenous fistula: the SONAR observational cohort study | NIHR Journals Library

  https://www.journalslibrary.nihr.ac.uk/hta/YTBT4172

  Arteriovenous fistulas are considered the best option for haemodialysis provision, but as many as 30% fail to mature or suffer early failure. […] To assess the feasibility of performing a randomised controlled trial that examines whether, by informing early and effective salvage intervention of fistulas that would otherwise fail, Doppler ultrasound surveillance of developing arteriovenous fistulas improves longer-term arteriovenous fistula patency. […] A prospective multicentre observational cohort study of adult patients undergoing formation of AVF for haemodialysis was performed to test the hypothesis: Doppler US surveillance early after AVF creation can reliably identify those AVFs that will not mature or will fail early. […] The primary outcome measure was fistula maturation at 10 weeks.

• #32 Doppler ultrasound surveillance of recently formed haemodialysis arteriovenous fistula: the SONAR observational cohort study | NIHR Journals Library

  https://www.journalslibrary.nihr.ac.uk/hta/YTBT4172

  Primary fistula patency at 6 months for all fistulas was 76.6% (95% CI: 69.9% to 82.4%) and was higher at 6 months for elbow fistula than for wrist fistula (elbow: 83.0%, 95% CI 73.8% to 89.9%; wrist: 70.4%, 95% CI 60.3% to 79.2%). […] Although early US can predict fistula maturation and longer-term patency very effectively, it was only moderately good at identifying those unlikely to mature or to fail within 6 months.

• #33

  https://discovery.ucl.ac.uk/id/eprint/10186699

  Early Ultrasound Surveillance of Newly-Created Hemodialysis Arteriovenous Fistula. […] We assess if ultrasound surveillance of newly-created arteriovenous fistulas (AVFs) can predict nonmaturation sufficiently reliably to justify randomised controlled trial (RCT) evaluation of ultrasounddirected salvage intervention. […] Of 333 AVFs created, 65.8% matured by 10 weeks. […] Wrist and elbow AVF non-maturation could be optimally modelled from the week four ultrasound parameters alone, but with only moderate positive predictive values (wrist, 60.6% (95% CI 43.9 77.3); elbow, 66.7% (48.9 – 84.4)). […] Moreover, 40 (70.2%) of the 57 AVFs that thrombosed by week 10 had already failed by the week 4 scan, thus limiting the potential of salvage procedures initiated by that scans findings to alter overall maturation rates. […] Early ultrasound surveillance may predict fistula maturation, but is likely, at best, to result in only very modest improvements in fistula patency. […] Power calculations suggest that an impractically large number of participants (1700) would be required for formal RCT evaluation.

• #34 Importance of monitoring and treatment of failed maturation in radiocephalic arteriovenous fistula in predialysis: Role of ultrasound | Nefrología

  https://www.revistanefrologia.com/en-importance-monitoring-treatment-failed-maturation-in-radiocephalic-arteriovenous-fistula-in-articulo-S2013251416300281

  The aim of the study was to analyse outcomes of AVF-RC in predialysis stage in which a clinical and radiological follow up of its maturation had been done and primary failure had been treated. […] In this retrospective study, we analysed the 127 RC-AVFs that were placed from January 2009 to March 2013 in 117 consecutive patients with G4 and G5 chronic kidney disease (CKD) without dialysis. […] Monitoring of the maturation of the RC-AVFs was performed in 2 ways: a physical examination, within the first 72h post-surgery, at the time of ultrasound examination and at each follow-up visit. […] The RC-AVF was considered to be suitable if it was the VA both at the start of HD and throughout the first 3 months of dialysis, without requiring another VA or a central venous catheter (CVC), even if radiological treatment was required during this time.

• #35 Importance of monitoring and treatment of failed maturation in radiocephalic arteriovenous fistula in predialysis: Role of ultrasound | Nefrología

  https://www.revistanefrologia.com/en-importance-monitoring-treatment-failed-maturation-in-radiocephalic-arteriovenous-fistula-in-articulo-S2013251416300281

  In summary, ultrasound was very useful in the study of maturation of VA in predialysis since it allowed us: A) To determine the patient’s vascular status regardless of his or her potential comorbidities. B) To diagnose an immature AVF and its potential causes and guide its treatment. C) To diagnose, in mature AVFs, potential associated lesions, which may initially have no functional repercussions but may progress and require treatment. D) To diagnose a maturation pseudo-delay. E) To quantify the vascular flow rate. F) To diagnose in some cases lesions that did not have clinical expressivity. Therefore, all the above contingencies show that ultrasound in the follow-up of maturation offers advantages over exclusively clinical follow-up, such that they should complement each other. […] In conclusion, with our approach to the VA in predialysis we have achieved that 80% of our patients were able to start HD using a distal AVF (76% radiocephalic and 4% cubitalbasilic), potential complications of more proximal VA have been prevented and therefore we have saved venous resources that may be vital for our patients future.

• #36 Development and Validation of a Machine Learning Model Predicting Arteriovenous Fistula Failure in a Large Network of Dialysis Clinics

  https://www.mdpi.com/1660-4601/18/23/12355

  Arteriovenous fistula (AVF) represents the gold standard vascular access (VA) for haemodialysis (HD). Over time, AVFs may develop dysfunction and lower blood flow due to a series of biological changes that can lead to the formation of a stenosis and subsequent thrombosis. This event has a severe impact on the clinical status of dialysis patients; in the best scenario, endovascular and surgical interventions can restore a satisfactory AVF flow; if not, a central venous catheter (CVC) needs to be placed for interim dialysis access. […] Considering the strong negative impact of AVF failure on patient survival, morbidity and quality of life, recent guidelines focused on potential strategies for AVF preservation. The National Kidney Foundation’s (NKF) (KDOQI) Guidelines recommend AVF periodical physical examination (PE), or ultrasound evaluation as primary monitoring methods to detect access dysfunction. However, there is no evidence on the advantages to routine AVF surveillance by measuring intra access blood flow (Qa) to improve access patency; nevertheless, its assessment should be considered.

• #37 Combined functional and anatomical diagnostic endpoints for assessing arteriovenous fistula dysfunction

  https://www.wjgnet.com/2220-6124/full/v4/i1/6.htm

  Monitoring strategies mainly include physical examination (PE) and other clinical evidences of access dysfunction for stenosis detection, while surveillance programs were intended to supplement clinical monitoring by measuring variations in blood flow rate and venous access pressure. […] NKF-KDOQI guidelines have recommended that both AVGs and AVFs undergo routine surveillance for blood flow and venous access pressure measurements. […] The new functional diagnostic endpoints (resistance index, R, and pressure drop coefficient, Cp) have been recently used in a pilot study on a pig model. […] The new functional diagnostic endpoints are based on fundamental fluid dynamics concepts and are primarily presented in two major forms including: (1) resistance index (a ratio of pressure drop by flow); and (2) pressure drop coefficient (the pressure drop normalized by the dynamic pressure).

• #38 Monitoring and Surveillance of Vascular Access

  https://www.e-jkda.org/journal/view.html?pn=myread&uid=8&vmd=Full

  Physical examination is a simple but critical test with symptoms such as increased post-dialysis hemodialysis time, urea reduction ratio, decreased Kt/V levels, and increased pressure during dialysis in monitoring. Surveillance is an important test that maintains the function of the arteriovenous fistula, avoiding dialysis through unnecessary conduits and reducing the length of hospital stay, thereby improving the quality of life of dialysis patients. Future research into the proper combination of active clinical monitoring and additional surveillance would be expected to create a formalized program of monitoring and surveillance to provide a way to maintain arteriovenous fistulas and prevent unnecessary procedures.

• #39 Pharmaceutical prevention strategy for arteriovenous fistula and arteriovenous graft failure | Renal Replacement Therapy | Full Text

  https://rrtjournal.biomedcentral.com/articles/10.1186/s41100-019-0210-2

  Several guidelines recommend both monitoring and surveillance to facilitate the early detection of VAF after VA construction. […] VA nurses, also called VA coordinators or VA managers, play a crucial role in the prevention of VAF. […] An aggressive, multidisciplinary access program conducted by VA nurses is recommended by ERBP (Grade C1) and European Society for Vascular Surgery (ESVS) guidelines (Class IIa).

• #39 Pharmaceutical prevention strategy for arteriovenous fistula and arteriovenous graft failure | Renal Replacement Therapy | Full Text

  https://rrtjournal.biomedcentral.com/articles/10.1186/s41100-019-0210-2

  Vascular access failure (VAF) is a critical problem in patients undergoing hemodialysis (HD). […] Strategies for preventing VAF are scarce. […] This review proposes the following three aspects for developing strategies for preventing VAF: (i) early identification of risk factors of VAF (e.g., preoperative vascular conditions, age, sex, ethnicity, and clinical backgrounds), (ii) prophylactic drugs to reduce the risk of VAF, and (iii) early VAF detection through monitoring and surveillance of vascular access, particularly at frequent stenotic sites. […] The prevention of VAF is crucial for all healthcare providers involved in RRT. […] This review proposed the prevention of VAF based on the following criteria: (i) preoperative examination, (ii) prophylactic drugs for VAF, and (iii) maintenance of VA by monitoring and surveillance.

• #40 Should arteriovenous fistulas and synthetic grafts undergo surveillance with pre-emptive correction of stenosis? | Nature Reviews Nephrology

  https://www.nature.com/articles/ncpneph0878

  This Practice Point commentary discusses Tonelli et al.’s systematic review and meta-analysis of randomized controlled trials that evaluated surveillance of hemodialysis accesses. […] Tonelli et al. found that fistula surveillance reduced the risk of thrombosis without prolonging fistula life, and that graft surveillance showed no benefit. […] Larger multicenter randomized trials are needed to establish the role of surveillance. […] Tonelli et al.’s study will encourage reconsideration of the current recommendation in clinical practice guidelines that grafts should undergo routine flow surveillance.

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