Methodology and grading of recommendations
Purpose
The European Society for Vascular Surgery (ESVS), in line with its mission, appointed the Vascular Access (VA)
Writing Committee (WC) to write the current clinical practice guidelines document for surgeons and physicians who are involved in the care of patients with haemodialysis
The purpose of these Guidelines is to summarize and evaluate the existing evidence to support physicians in choosing the most effective management strategies for patients requiring VA or related pathologies.
VA However, each physician must make the ultimate de- cision regarding the particular care of an individual patient 1,2
Patients with vascular access (VA) for hemodialysis (HD) present complex challenges and experience considerable variability in clinical practice However, a robust evidence base exists to inform guidelines for their management Recent advancements in VA technology and medical practices have strengthened the supporting evidence for these guidelines As the adoption of new treatment options driven by industry and public demand may lead to increased healthcare costs and risks, adhering to updated guidelines has become essential for ensuring optimal patient care.
Many clinical situations involving patients with HD and
VA have not been studied by randomised clinical trials.
In situations where extensive level A evidence is lacking, it is crucial to ensure that patient care continues and clinical decisions are made effectively This document aims to offer guidance by relying on the best available evidence to inform recommendations in such circumstances.
Understanding the significance and reliability of evidence quality enables readers to access crucial, evidence-based information tailored to the individual patient's needs.
This guide offers flexible recommendations for the clinical care of patients with HD and VA, encompassing pre-operative, peri-operative, post-operative, and long-term maintenance care, rather than strict rules tailored to individual patient circumstances.
Methodology
The VA WC was established by members from the ESVS and Vascular Access Society (VAS) across Europe, comprising vascular surgeons, nephrologists, radiologists, and clinical nurses from diverse academic and private hospitals, to enhance the effectiveness of vascular access practices.
In September 2012, the Working Committee (WC) convened for the first time to outline the purpose, content, methodology, and timeline for the forthcoming recommendations The VA WC conducted a systematic literature review across MEDLINE, EMBASE, and the COCHRANE Library for various topics included in the guidelines document, with the most recent search completed by August 31, 2017 The evidence collected adhered to specific eligibility criteria to ensure its relevance and quality.
Only peer reviewed published literature has been considered
Published abstracts or congress proceedings have been excluded
The search prioritized randomized clinical trials (RCTs), along with meta-analyses and systematic reviews, while also incorporating non-RCTs, non-controlled trials, and well-conducted observational studies, including cohort and case-control studies.
NIH Neointimal hyperplasia (Synonym: Myointi- mal hyperplasia)
NKF-KDOQI National Kidney Foundation for Kidney dis- ease outcome quality initiative
NPWT Negative pressure wound therapy
NSF Nephrogenic systemicfibrosis ntCVC Non tunnelled central venous catheter (Syn- onym: indwelling catheter without cuff)
PAVA Proximalisation of the arteriovenous anastomosis
PICC Peripherally inserted central venous catheter
PTA Percutaneous transluminal angioplasty (Syn- onym: balloon angioplasty)
Qb Blood pumpflow delivered to the dialyser
RCAVF Radiocephalic AVF (Synonoym: Brescia-
RCT Randomised controlled trial RRT Renal replacement therapy RUDI Revision using distal inflow SFA Superficial femoral artery
FV Femoral vein (formerly superficial femoral vein) FVT Femoral vein transposition Stent graft Former covered stent tcCVC Tunnelled cuffed central venous catheter
(Synonym: indwelling catheter with cuff) UDT Ultrasound dilution technique
VAILI Vascular access induced limb ischaemia VAS Vascular Access Society
VP/MAP Venous pressure adjusted for the mean arterial pressure
Previous guidelines, position papers and published consensus documents have also been included as part of the review process when new evidence was absent
Minimising the use of reports of a single medical device or from pharmaceutical companies reduced the risk of bias across studies A grading system based on the European
The methodology of the Society of Cardiology (ESC) guidelines was utilized, with a classification system for levels of evidence that details the study characteristics underpinning the recommendations and expert consensus, as outlined in Table 1.
The recommendation grade indicates the strength of a recommendation Definitions of the classes of recommen- dation are shown inTable 2.
The recommendations were independently assessed for strength and supporting evidence by two members of the writing committee (WC), with a master copy of the manuscript circulated and approved by all members Consensus-driven discussions and votes were conducted for recommendations requiring agreement, allowing strong recommendations to be made even with low-quality evidence if a general consensus was reached Meta-analyses were referenced based on the quality of recommendations, with original data examined for mixed findings in contentious areas Each section of the guidelines was prepared by two WC members, followed by an internal review before submission to the ESVS Guidelines Committee and external reviewers, who provided critical feedback on preliminary versions The final document received approval from the ESVS Guidelines Committee and was submitted to the European Journal of Vascular and Endovascular Surgery (EJVES), with plans for periodic updates as new evidence or clinical practices emerge.
field, which could occur every three years.
To optimise the implementation of the current docu- ment, the length of the guidelines has been kept as short as possible to facilitate access to guideline information Con-
Prior to the writing process, conflicts of interest from each member of the working committee (WC) were collected, assessed, and accepted This document reports these conflicts, ensuring transparency Furthermore, the WC affirmed that all intellectual contributions would be made freely, guided solely by the honesty and professionalism of its members throughout the writing process.
1.3.1 Definition of vascular access Patients with acute renal failure or end stage renal disease require renal replacement therapy, which includes peritoneal dialysis (PD), haemodialysis (HD) or kidney transplantation (Fig 1) A VA is essential for patients on HD and can be accomplished with central venous catheters (CVC), but also with arterialisation of a vein or by interposition of a graft between an artery and a vein for the insertion of HD needles The bloodflow available for HD should reach at least 300 ml/min and preferably
500 ml/min depending on the VA modality to allow a suffi- cient HD.
1.3.2 Other definitions Arteriovenous fistulas (AVFs) and arteriovenous grafts (AVGs) are established terms to charac- terise a special kind of VA in patients on HD An AVF is defined as an autogenous anastomosis between an artery and a vein and an AVG is defined as a VA using a prosthetic graft.
At the start of the 21st century, interventional radiologists and vascular surgeons worked to clarify terminology related to hemodialysis (HD) access, leading to revised definitions and ongoing discussions among vascular access specialists Despite these debates, certain definitions are widely accepted by clinicians in the field Incidence refers to the proportion of a specific population that develops a new condition or experiences an event within a defined timeframe, such as the number of patients undergoing vascular access creation divided by the total population.
Table 2.Grades of strength of recommendations according to the
ESC grading system 7 population (e.g the number of patients undergoing HD).
For a disease, incidence can be expressed as the number of patients per million population per year.
Prevalence refers to the total number of existing cases of a disease within a specific population, encompassing both new and ongoing patients It is quantified as the number of patients per million individuals and is influenced by the incidence of new cases as well as the outcomes, including recovery or mortality.
Point prevalence is calculated by taking the number of patients using a specific type of visual aid (VA) at a particular moment, multiplying that figure by 100, and then dividing it by the total number of patients utilizing a VA at that same time This percentage provides insight into the current usage of visual aids among patients.
Period prevalence is calculated by taking the average number of patients utilizing a specific visual aid (VA) over a one-year period, multiplying that figure by 100, and then dividing it by the total number of patients using any VA during the same timeframe.
The rate of hospitalisation days per 1000 access days is determined by dividing the total number of hospitalisation days for the study population by the total number of vascular access (VA) days, which is calculated from the creation of the VA or the start of the study period until permanent VA failure, the end of the study period, patient death, transfer from the dialysis unit, or a change in renal replacement modality This rate is then multiplied by 1000 to express the number of hospitalisation days per 1000 VA days.
Access abandonment:The day on which a VA is deemed to be permanently unusable or not suitable for cannulation.
Primary VA: Creation of a functioning VA for thefirst time.
Secondary VA: Ordinary VA creation with AVF or AVG at any location after a failed primary VA (tertiary VA excluded).
Tertiary VA: VA using great saphenous vein (GSV) or femoral vein (FV) translocated to the arm or leg Unusual
VA procedures such as upper or lower limb arterio-arterial loops are included in this category.
Transposition: Relocation of an autogenous vein to a new
(more superficial) position in the soft tissues of the same anatomical area (e.g an upper arm AVF with transposition of the basilic vein).
Translocation involves detaching a prepared vein and repositioning it in a new anatomical location to form an arteriovenous fistula (AVF) Superficialisation refers to the process of transposing the index vein into the subcutaneous tissue, bringing it closer to the skin's surface Kaplan-Meier life table analysis is a statistical technique used to assess time-dependent clinical outcomes, including vascular access patency rates and infection-free survival rates.
Primary patency: The interval between VA creation and the first re-intervention (intervention free VA survival) for
VA dysfunction or thrombosis, the time of measurement of patency or the time of its abandonment.
Assisted primary patency: The interval between VA cre- ation and thefirst occlusion (thrombosis free VA survival) or measurement of patency including operative/endovascular interventions to maintain the VA.
Primary functional patency refers to the time from the initial use of a newly created vascular access (VA) until the first intervention is required to either salvage the VA or abandon it In contrast, secondary patency encompasses the duration from VA creation to its abandonment due to thrombosis, which may occur after one or more interventions, or it may be measured at the time of a censored event, such as death, a change in hemodialysis modality, or loss of follow-up.
Definitions
the prescribed bloodflow throughout the HD and achieved adequate HD (usually at least 300 ml/ min) Therefore, it is a post-cannulation definition.
Monitoring: Examination and evaluation of the VA by means of physical examination to detect physical signs that suggest the presence of VA dysfunction.
Surveillance:Periodic evaluation of a VA using haemody- namic tests This may trigger further diagnostic evaluation.
VA-induced limb ischemia refers to extremity malperfusion following the creation of a vascular access This condition can be categorized into four distinct stages: Stage 1 presents with slight coldness, numbness, pale skin, and no pain; Stage 2 involves loss of sensation and pain during hemodialysis or exercise; Stage 3 is characterized by rest pain; and Stage 4 indicates tissue loss affecting the distal parts of the limb, typically involving the digits.
This definition is more appropriate than ‘steal’ which describes the physiological phenomenon of (even retro- grade) bloodflow recruitment towards the AVF/AVG.
Recirculation: The return of dialysed blood to the sys- temic circulation without full equilibration (NKF-DOQI definition).
Kt/V: A parameter to quantify the adequacy of the HD:
KẳDialyser clearance of urea, tẳeffective time of HD
Vẳvolume of urea distribution, approximately equal to the patient’s body water (60% of the body mass).
Early VA failure: A VA that has occluded within 24 hours of creation.
Early dialysis suitability failure: A VA that cannot be used by the third month following creation despite radiological or surgical intervention.
Late dialysis suitability failure: A VA that is not usable after more than 6 months despite radiological or surgical intervention.
Cannulation failure: Failure is defined as the inability to place and secure two dialysis needles.
Non-tunnelled CVC (ntCVC): An uncuffed catheter providing temporary VA for HD.
Tunnelled cuffed CVC (tcCVC): A subcutaneously tunnelled dual lumen catheter with a cuff that can be used for VA if HD is expected to last for more than two weeks.
Bacteraemia is confirmed when there is at least one positive blood culture from a peripheral vein, and either the same pathogen is identified from the catheter tip or a catheter blood culture shows a bacterial colony count more than three times higher than that from the peripheral vein.
Probable: Bacteraemia with positive blood cultures ob- tained from a catheter and/or peripheral vein in a patient where there is no clinical evidence of an alternative source of an infection.
Proven: The presence of a purulent discharge or ery- thema, induration/and or tenderness at the catheter exit site with a positive bacteriological culture of the serous discharge.
Probable: The clinical signs of infection with negative cultures from the discharge or blood without signs of irri- tation from gauze, stitches or the cleansing agent.
Proven: The presence of purulent discharge from the tunnel or erythema, induration and/or tenderness over the catheter tunnel with a positive culture.
Clinical signs of infection may be present around the catheter site, despite negative cultures from discharge or blood samples The primary catheter site patency refers to the time elapsed between catheter insertion and the first intervention aimed at restoring the catheter’s function.
Secondary catheter site patency: Interval between cath- eter insertion and exchange or removal of the catheter for any reason.
The continuous catheter site refers to the duration from the initial catheter insertion until its removal, including any exchanges made within the same target vessel, which are documented (e.g., 12 months with 3 catheters) Catheter dysfunction is defined as the first instance where the peak flow drops to 200 ml/minute or lower for a period of 30 minutes.
HD, a mean bloodflow of 250 ml/minute or less during two consecutive dialyses or the inability to initiate HD resulting from an inadequate bloodflow, despite attempts to restore patency.
Epidemiology of chronic kidney disease (CKD) stage 5
Epidemiology of chronic kidney disease
Chronic kidney disease (CKD) is a significant global public health issue, categorized into five stages Renal insufficiency specifically applies to stages 3 to 5, characterized by a glomerular filtration rate (GFR) of less than 60 ml/min per 1.73 m² persisting for three months or longer, regardless of the underlying cause.
The true incidence and prevalence of CKD within a com- munity are difficult to ascertain as early to moderate CKD is usually asymptomatic Most studies point to a prevalence of
Table 3 Classification of chronic kidney disease based on glomerularfiltration rate (GFR) 8e11
Stage Description GFR mL/min/1.73 m 2
Stage 1 Kidney damage with normal or elevated GFR
Stage 2 Kidney damage with mildly decreased GFR
Stage 3 Moderately decreased GFR 30e59 Stage 4 Severely decreased GFR 15e29 Stage 5 End stage renal disease (ESRD)
CKD of around 10%, albuminuria of around 7%, and GFR below 60 ml/min per 1.73 m 2 of around 3% 13e15
CKD stage 5 (ESRD) is characterised by GFR below
The treatment process for renal failure involves two phases: initially, patients are managed conservatively without dialysis, and if necessary, the second phase requires the initiation of renal replacement therapy (RRT) through dialysis or transplantation to ensure survival This approach is based on a renal function threshold of 15 ml/min per 1.73 m².
The incidence of chronic kidney disease (CKD) stage 5, which indicates the number of patients with end-stage renal disease (ESRD) starting renal replacement therapy (RRT), often overlooks those not receiving treatment, leading to an underestimation of the true incidence of ESRD In the dialysis population, the prevalence of ESRD is influenced by both the incidence of new cases and the outcomes related to transplantation or mortality.
2.1.1 Epidemiology of end stage renal disease
2.1.1.1 Incidence.The number of patients per year starting
The rapid increase in the number of patients requiring dialysis for chronic kidney disease (CKD) can be attributed to three primary factors: patient selection criteria, competitive health risks, and an actual rise in the incidence of CKD.
1 Selection of patients for RRT:the steep increase in the incidence of older patients suggests that those very old and/or those affected by particularly severe comorbidities were not given access to dialysis in thefirst decades of RRT, compared with the more recent years.
2 Competitive risks: a study suggested that the number of deaths where CKD is the underlying cause of death increased by 82% between 1990 (27 th in the global death rank) and 2010 (18 th in the global death rank) 17 A high risk of death exists even in patients in the early stages of CKD, with many individuals in stages 3 and 4 dying before starting RRT 18,19 In fact, a reduced GFR is considered one of the most important risk factors for coronary heart dis- ease 20 Substantial improvements in the treatment of car- diac diseases and in survival have occurred in recent decades and this has allowed many patients to survive in the more advanced CKD stages and to require RRT.
3 The true increase in CKD incidence: it may also be possible that the increased incidence of ESRD reflects increases in the underlying prevalence of CKD The Framingham Heart Study has shown that the incidence of type 2 diabetes has doubled from the 1970s to the 1990s 21 Furthermore, potentially nephrotoxic drugs, such as non-steroidal anti-inflammatory drugs, antibiotics and chemotherapy agents are used more commonly Finally, reduced mortality from cardiovascular diseases and cancer may be associated with an increase in the number of patients reaching ESRD.
2.1.1.2 Prevalence.Data related to the prevalence of CKD stage 5 are lacking, except for those of registries of ESRD patients treated by dialysis or transplantation In the USA, of the 547,982 prevalent ESRD patients in 2008, 70 percent were being treated by dialysis while 30 percent had a functioning kidney transplant In 2008 alone, 112,476 patients entered the US ESRD program Adjusted rates for incident and prev- alent ESRD are 351 and 1,699 cases per million population, respectively Diabetes and hypertension account for 44% and
27.9% of all causes of incident ESRD, respectively 22
The increasing prevalence of treated End-Stage Renal Disease (ESRD) can be linked to either a rise in the number of patients initiating Renal Replacement Therapy (RRT) annually or an improvement in the survival rates of existing ESRD patients With incidence rates of treated ESRD stabilizing in recent years, the prolonged lifespans of current patients may account for the ongoing growth of this population It is crucial to maintain global efforts focused on preventing and treating acute and chronic conditions, particularly diabetes and hypertension, which can lead to ESRD.
Demographics of end stage renal disease
The global epidemiology of end-stage renal disease (ESRD) varies significantly across different countries due to various influencing factors This results in notable differences in both the incidence and prevalence of ESRD, which are shaped by racial and ethnic diversity, as well as the prevalence of diabetes and hypertension in specific regions Populations such as African Americans, Native Americans, and Aboriginal peoples in Australia and New Zealand exhibit a higher incidence of ESRD, with diabetes being a common underlying cause In contrast, disparities observed in developing countries are more likely linked to the availability and access to renal replacement therapy (RRT) rather than a lower incidence of chronic kidney disease (CKD) In the United States, diabetes remains the primary contributor to CKD among newly diagnosed patients.
The elderly are a substantial and growing fraction of the RRT population worldwide, reaching 25e30% in most ESRD regis- tries 22,24 In the United States, the proportion of patients
>65 years of age starting dialysis has increased by nearly 10% annually, representing an overall increase of 57% between
Table 4 Global incidence and prevalence of RRT (per million population) in different parts of the world in 2002 and 2006.
1996 and 2003 22 In Canada, from 1990 until 2001, the incident dialysis rate among patients aged 75 and older increased
74% 25 Researchers have speculated that more liberal accep- tance of the very elderly (80 years) into dialysis programs has contributed to the increase in patients with ESRD 27,28
CKD is expected to be a major 21 st century medical challenge In developing nations, the growing prevalence of
Chronic Kidney Disease (CKD) poses significant health and economic challenges, particularly in developing nations The increasing prevalence of risk factors like diabetes, hypertension, and obesity, especially among low-income populations, is expected to exacerbate these burdens, overwhelming the capacity of these countries to manage the crisis effectively.
Epidemiology of vascular access for dialysis
Significant variations in vascular access (VA) practices are observed between Europe, Canada, and the United States, even when accounting for patient characteristics While similar challenges exist in VA care across these regions, the extent of these issues varies The rising prevalence of obesity, type 2 diabetes, and peripheral vascular disease—key independent predictors of central venous catheter (CVC) use—poses a global health concern that may complicate the creation and survival of native arteriovenous fistulas (AVFs).
Nevertheless, in the USA following the establishment of the Fistula First Initiative, AVF use among prevalent HD patients increased steadily from 34.1% in December 2003 to
In April 2012, the prevalence of vascular access types among incident patients starting chronic hemodialysis (HD) was reported, with 14.3% utilizing arteriovenous fistulas (AVF), 3.2% using arteriovenous grafts (AVG), and a significant 81.8% relying on central venous catheters (CVC) Additionally, 15.8% of patients had maturing AVFs, while 1.9% had maturing AVGs, with similar statistics observed in 2014.
International data from the Dialysis Outcomes and Practice Patterns Study (DOPPS) reveals significant variations in vascular access (VA) practices, indicating that hemodialysis (HD) patients using catheters face higher mortality risks compared to those with usable arteriovenous fistulas (AVF), who experience the lowest risk.
VA practices have been observed within the DOPPS from
Between 2005 and 2007, the use of native arteriovenous fistulas (AVF) among prevalent patients varied significantly across countries, with rates reaching 67-91% in Japan, Italy, Germany, France, Spain, the UK, Australia, and New Zealand, while Belgium, Sweden, and Canada reported lower usage rates of 50-59% This data highlights the disparities in AVF adoption for dialysis treatment during this period.
From 2007, the use of arteriovenous fistulas (AVF) in the USA increased from 24% to 47%, while it declined in Italy, Germany, and Spain Data collected over three phases revealed that certain factors, including female gender, older age, higher body mass index, diabetes, and peripheral vascular disease, were associated with a lower likelihood of AVF usage compared to other vascular access types Additionally, countries with higher diabetes prevalence among hemodialysis patients had significantly fewer patients utilizing AVFs Despite the known poorer outcomes associated with central venous catheters (CVCs), their use surged by 1.5 to 3 times among prevalent patients globally from 1996 to 2007, including non-diabetic individuals aged 18 to 70 years.
In five countries, 58-73% of incident patients initiated dialysis using a central venous catheter (CVC), despite 60-79% having consulted a nephrologist over four months before reaching end-stage renal disease (ESRD) The median time from referral to vascular access (VA) creation ranged from 5-6 days in Italy, Japan, and Germany, to 40-43 days in the UK and Canada Delays in surgery and the time from VA creation to the first cannulation significantly impacted the likelihood of commencing hemodialysis with a permanent vascular access.
Patient preference for central venous catheters (CVC) shows significant international variation, with only 1% of hemodialysis patients in Japan favoring CVCs, compared to 18% in the United States and 42-44% in Belgium and Canada Factors positively influencing the preference for CVCs include older age, female gender, and previous or current catheter use This highlights the diverse attitudes towards CVCs among patients across different countries.
Patient preferences regarding central venous catheters (CVCs) may be shaped by socio-cultural factors, making them potentially modifiable While peripherally inserted central venous catheters (PICCs) have become increasingly popular among non-renal patients due to their perceived benefits, their use is not recommended for patients with chronic kidney disease (CKD) This is because CKD patients experience significantly poorer outcomes, including a reduced likelihood (15%-19%) of maintaining a functioning fistula or graft when PICC lines are utilized.
Early referral of patients with end-stage renal disease (ESRD) to a nephrologist is crucial for minimizing catheter use and associated complications, as well as reducing hospitalizations This proactive approach facilitates timely interventions to slow renal damage progression, manage hypertension and anemia, and address the metabolic impacts of renal failure It also allows for discussions about renal replacement therapy options, including living donor transplantation and peritoneal dialysis, while ensuring psychological readiness for dialysis When hemodialysis is indicated, it is essential to minimize the time between referral and the creation of a vascular access (VA) to optimize patient outcomes.
Clinical decision making
Choice of type of vascular access
The preferred method for creating a vascular access (VA) is the establishment of an autogenous arteriovenous fistula (AVF), as it is associated with fewer postoperative complications and a lower need for revisions compared to prosthetic arteriovenous grafts (AVGs) and central venous catheters (CVCs) Observational studies indicate that the use of CVCs significantly increases morbidity and mortality rates, particularly due to higher hospitalization risks for infections in patients undergoing hemodialysis (HD) To optimize venous preservation, it is advisable to perform the most distal AVF possible, ideally in the non-dominant upper extremity for new HD patients If a distal VA fails, a more proximal AVF can be considered.
Timing of referral for vascular access surgery
functioning autogenous AVFs, while late referral results in a greater chance of AVF non-maturation and the need for a
Timely referral for hemodialysis (HD) using a central venous catheter (CVC) can slow the decline of estimated glomerular filtration rate (eGFR) However, initiating HD with a CVC and a prolonged arteriovenous fistula (AVF) maturation time is linked to lower long-term AVF patency rates Additionally, the same factors that indicate poorer primary AVF survival are also associated with an increased risk of eventual failure.
The presence of cardiovascular disease, use of catheters at
HD initiation, and early cannulation are independent pre- dictors offinal failure A short time to cannulation is asso- ciated with the greatest risk offinal failure 45 (Figs 2 and 3)
Regular pre-nephrology visits every three months are linked to enhanced patient survival in the first year following the start of hemodialysis, especially benefiting elderly and diabetic patients Additionally, the DOPPS data reveals notable disparities in referral practices and the timing of vascular access (VA) creation across European countries, with planning for VA surgery ranging from less than five days in Italy to over 42 days in the UK after referral to a VA surgeon.
The expertise of a vascular access (VA) surgeon is crucial for the successful creation of arteriovenous fistulas (AVFs), significantly influencing surgical outcomes However, there are notable regional disparities among hospitals regarding the volume of autogenous AVFs performed and their likelihood of successful maturation.
Selection of vascular access modality
3.3.1 Primary option for vascular access e autogenous arteriovenousfistula.The radiocephalic AVF (RCAVF) at the level of the wrist is thefirst choice for VA creation When successfully matured, the RCAVF can function for years with a minimum of complications, revisions and hospital admissions.
The RCAVF is typically created in the non-dominant arm, although the dominant arm may be used if the non-dominant vessels are unsuitable The decision to perform a wrist RCAVF is based on a physical examination, including the inspection and palpation of distal veins and arteries, along with ultrasound assessment For successful fistula creation and maturation, both the radial artery and cephalic vein should have a minimum internal diameter of 2.0 mm when a proximal tourniquet is applied In the case of brachiocephalic (BCAVF) and brachiobasilic (BBAVF) AVFs, a minimum arterial and venous diameter of 3 mm is deemed sufficient.
The major disadvantages of vascular access include the risk of early thrombosis, non-maturation, and eventual access failure, with a meta-analysis indicating a mean early failure rate of 17% Recent studies have reported even higher failure rates, reaching up to 46%, and one-year patency rates ranging from 52% to 83% These elevated early failure rates are primarily attributed to the elderly dialysis population, which often presents with concurrent comorbidities and suboptimal upper extremity vessels.
When wrist radial-cephalic arteriovenous fistulas (RCAVFs) are not feasible or have failed, alternative access points can be created in the forearm, antecubital region, or upper arm These access types include mid-forearm, brachial/radial-deep perforating vein, brachial-median cubital vein, brachial-cephalic arteriovenous fistula (BCAVF), and brachial-basilic arteriovenous fistula (BBAVF) Brachial artery-based AVFs provide high access flow, which is beneficial for effective hemodialysis (HD).
Arteriovenous fistulas (AVFs) can lead to decreased distal arterial perfusion and increased cardiac workload However, these AVFs demonstrate favorable one-year patency rates, as indicated by low thrombosis occurrences at 0.2 events per patient per year and a minimal infection rate of 2%.
When direct arteriovenous anastomoses are not feasible, vein transposition or translocation may be utilized This involves redirecting a suitable vein to an accessible artery, such as creating a forearm radial or ulnar-basilic arteriovenous fistula (AVF) Alternatively, great saphenous vein (GSV) harvesting from the leg can be performed, followed by its implantation between an artery and vein in the arm.
Basilic vein transposition (BVT) in the upper arm is an effective alternative when radial-cephalic arteriovenous fistulas (RCAVFs) or brachiocephalic arteriovenous fistulas (BCAVFs) are unsuccessful or impractical BVT can be executed through either a one-stage or two-stage surgical procedure.
Figure 2.Kaplan-Meier curves of time to AVF failure (primary patency fromfirst cannulation) by use of catheters (CVC) at the initiation of
HD (left) and by the time to maturation in days (right) Reproduced with permission from Ravani et al 45
3.3.1.1 Patient variables and outcome of vascular access.
Research indicates that patient characteristics significantly impact the selection and success of vascular access (VA) Specifically, factors such as age and diabetes mellitus adversely affect fistula maturation and heighten the likelihood of arteriovenous fistula (AVF) failure.
A systematic review indicates a higher risk of deep vein thrombosis and a lower risk of catheter occlusion associated with peripherally inserted central catheters (PICCs) The antecubital fossa is identified as a high-risk anatomical area for thrombosis Elbow veins are particularly beneficial for creating vascular access for hemodialysis in obese, elderly, diabetic patients, and those with peripheral artery disease, highlighting the importance of preserving these veins.
Women typically possess smaller blood vessels than men, which may lead to challenges in vascular access maturation and long-term patency While some research indicates that females require more vascular access revisions and the creation of additional arteriovenous grafts (AVGs), other studies, including a meta-analysis, have found no significant differences in vessel diameters or maturation rates between genders Additionally, diabetes mellitus and arteriosclerosis are major contributors to renal failure and hemodialysis treatment, adversely affecting the successful use of vascular access.
Figure 3.Risk factors associated with primary and secondary access failure Hazard ratios plotted using a logarithmic scale Reproduced with permission from Ravani et al 45
Table 5.Early failure and one year secondary patency rate of the radiocephalic AVF.
Reference No RCAVF Early failure (%)
Table 6.Early failure (within one month of access creation) and one year secondary patency rate of brachiocephalic AVF
(including brachiocephalic/perforating vein AVF).
Reference No BCAVF Early failure (%)
Table 7.Early failure (within one month of access creation) and one year secondary patency rate of brachiobasilic AVF.
Reference No BBAVF Early failure (%)
Other variables that influence fistula use are: lower ex- tremity atherosclerotic disease (LEAD), race and obesity 90
Patients using calcium channel blockers, aspirin and ACE inhibitors, enjoy better AVF and AVG patency 91
3.3.2 Secondary options for vascular access.When there are no options for creating an autogenous AVF, an AVG VA with the implantation of synthetic (expanded polytetrafluoro- ethylene [ePTFE]; polyurethane; nanograftẳelectrospun ePTFE graft) or biological material (ovine graft/Omniflow Ò ) can be created ePTFE is frequently used as an AVG with reasonable short-term patency but long-term patency is hampered by thrombotic occlusions, due to stenoses caused by progressive neointimal proliferation One and two year primary patency varies between 40e50% and 20e30%, respectively The secondary patency varies from 70 to 90% (at one year) and 50 to 70% at two years Multiple interventions to prevent and treat thrombosis are required to achieve these outcomes 92e96
Elderly patients may benefit from the use of AVGs, because of the high primary autogenous AVF failure rate in these patients 97 An important consideration for AVG use
(in particular“early stick grafts”) might be the avoidance of
CVCs with their inherent high risk of infection, in particular when (sub)acute HD treatment is necessary and AVF crea- tion/maturation is problematic.
3.3.3 Lower extremity vascular access.The indications for lower extremity VA are bilateral central venous occlusive disease (CVOD) or inability to create access in the upper extremity Primary options are autogenous GSV 98 and FV transpositions, and prosthetic graft implantation Thigh VAs have acceptable patency rates but the handicap of an increased risk of ischaemia and infection 100
In a meta-analysis the results of femoral vein trans- positions and AVGs are described The one year primary and secondary patency was 83% and 48% and 93% and 69%, for
In a comparison of FV transpositions and AVGs, it was found that VA loss due to infection was significantly higher in AVGs at 18% compared to just 1.6% for FV transpositions (p