PRESENTED BY
MAURIZIO GALLIENI

Presentation Summary

Written by Jasna Trbojevic-Stankovic
Reviewed by Maurizio Gallieni

The number of patients requiring renal replacement therapy has increased worldwide in the last decades. The most common replacement therapy is hemodialysis, which requires adequate vascular access as a key component to achieve high-quality treatment. However, the exact timing and choice of the type of vascular access remain elusive.

Evaluating the need for preemptive vascular access creation
Even though it undoubtedly represents the preferred approach, preemptive arterio-venous fistula (AVF) placement is linked to several concerns. The most challenging aspect is to choose the optimum timing for creation, as it is not an easy task to predict which patients shall live to start dialysis. This is especially true for the elderly, who, when compared to younger patients with similar levels of estimated glomerular filtration rate (eGFR), experience a slower decline of eGFR and higher mortality rates, thus having higher chances to die before reaching end-stage renal disease (ESRD) (1). It is estimated that in patients aged 65 to 75 years the risk of developing ESRD becomes higher than the risk of death only when eGFR falls to 15 ml/min (1). Therefore, it would not seem wise to invest in preemptive creation of vascular access at eGFR>15mL/min in this population.

All these data underline the importance of predicting the rate of progression of renal function decline to plan the adequate approach to creating the necessary vascular access. Among such tools is the predictive equation which quantifies the risk of progression to ESRD, freely available at The Kidney Failure Risk Equation (KFRE) site (2). An example of how to use this tool is presented in Figure 1.

Figure 1. Predicting the need for preemptive vascular access creation based on the estimated rate of progression of renal function decline (2, 3)

Based on the data obtained from this equation, the highest number of optimal dialysis onsets with functioning, mature vascular access was achieved when AVF had been placed in patients with KFRE of >20% annually, or 40% over 2 years. This useful prediction tool may help reduce the number of chronic renal disease patients who died with an unused AVF, thus minimizing the treatment costs and patient discomfort.

On the other hand, the AV access should be promptly created when needed, with the aim of reducing the number of patients who start dialysis with a central venous catheter (CVC).

Something old, something new
The 2006 KDOQI guidelines on vascular accesses for hemodialysis focused on promoting AVFs as the preferred vascular access in all ESRD patients (4). Current evidence-based recommendations, however, have moved past the well-known Fistula First – Catheter Last doctrine. The latest KDOQI guidelines on vascular accesses underline the importance of an individual approach to each patient when planning his/her treatment. The key concept, as presented in the guidelines, is creating an individual ESRD Life-Plan which should encompass all possible treatment options and related outcomes (5). Thus, the new principle when it comes to planning the vascular access is Right Access in the Right Patient at the Right Time for the Right Reasons (5). Furthermore, the new approach underlines the importance of at least quarterly reviews of vascular access functionality, complications risks, and other access options (5).

There are currently several possible approaches to choosing the optimum renal replacement therapy within the framework of the patients’ life plan, and then the right vascular access if hemodialysis is the treatment of choice. As for the permanent vascular accesses, the AVF remains the ultimate goal, but new creation strategies, namely the percutaneous approach, have been introduced into practice. Other options are AV grafts, either early or late cannulation ones, and tunneled central venous catheters. The previous doctrine to avoid long-term central venous catheter at any cost has been abandoned in the latest guidelines, which suggest that in certain, well-evaluated cases, it is reasonable to use tunneled central venous catheter for the short or long-term duration even as a first choice vascular access (5).

Adequate blood vessel preservation is crucial for creating a well-functioning AVF. Venipuncture and peripheral IV lines can damage the veins and jeopardize future AVF construction and function. Thus, preservation of forearm veins should start well before the patient needs access. The preferred and most often used superficial vein in the upper extremity for AVF creation is the cephalic vein. Radiocephalic AVFs are the first, and brachiocephalic AVF at the elbow the second choice for AVF creation (6). The other superficial veins in the forearm, the basilica vein on the ulnar side, and the median basilica vein near the elbow are occasionally used. The brachial veins in the upper arm are only used for vascular access creation as the last resort. Synthetic AV grafts are utilized for dialysis access creation in cases when the native vessels are not suitable for creating an AVF (6). The commonly used configurations include the forearm loop, upper arm straight and thigh loop grafts.

New development in the field of vascular access creation
The main obstacles associated with AVFs creation and use are protracted wait time for creation, poor maturation, and surgical dysfunction that can result in significant patient morbidity and preclude the optimum dialysis (7). The recent approval of minimally invasive endovascular devices designed to enable the percutaneous approach to the creation of AVFs may potentially reduce the wait and maturation time, provide more anatomical options for AVF creation and avoid surgery and related complications thus providing patients with more choice and better quality of life (7). The currently available percutaneous techniques for creating AVFs are presented in Figure 2. Ellipsys is an ultrasound-guided, single catheter device, while the WavelinQ, on the other hand, is a dual catheter device that is placed under fluoroscopy.

Figure 2. Devices for creating percutaneous AVF, along with the most common surgical option. – Image courtesy of Dr. Robert Shahverdyan (3)

Another novelty in the field of vascular accesses is early cannulation AV graft which can be punctured as early as 24 to 72 hours after the placement. These grafts have been specifically designed for dialysis and are currently indicated as early access in late referral patients, as a prompt solution to thrombosing AVFs, as an interposition for the repair of aneurysmal AVF, or to avoid the use of a central venous catheter (8). Their twelve-month primary patency rates range from 40 to 60%, which is similar to the regular AV grafts. However, their wider use is still hindered by their relatively high cost.

References

1. O’Hare AM, Allon M, Kaufman JS. Whether and when to refer patients for predialysis AV fistula creation: complex decision making in the face of uncertainty. Semin Dial. 2010;23(5):452-455.

2. The Kidney Failure Risk Equation (KFRE) Website https://kidneyfailurerisk.com/

3. Gallieni M. How to chose the dialysis access for an individual patient. Presented at the 57th European Reanal Association – European Dialysis Transplantation Association Congress (fully virtual), June 6, 2020. Available at Virtual Meeting

4. KDOQI National Kidney Foundation. 2006 Updates Clinical Practice Guidelines and Recommendations. Available at KDOQI Website

5. Lok CE, Huber TS, Lee T, et al. KDOQI Clinical Practice Guideline for Vascular Access: 2019 Update. Am J Kidney Dis 2020;75(4 Suppl 2):S1-S164.

6. Vachharajani TJ. Atlas of dialysis vascular access. Wake Forest University School of Medicine, 2010.

7. Wasse H, Alvarez AC, Brouwer-Maier D, et al. Patient selection, education, and cannulation of percutaneous arteriovenous fistulae: An ASDIN White Paper [published online ahead of print, 2019 Nov 29]. J Vasc Access. 2019;1129729819889793.

8. Al Shakarchi J, Inston N. Early cannulation grafts for haemodialysis: An updated systematic review. J Vasc Access. 2019;20(2):123-127.

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