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Surveillance for New AV Fistulas

Surveillance for New AV Fistulas

What is your practice for monitoring new fistulas and grafts for success?  Are you using all the best tools to help ensure your patient’s access has matured successfully and can provide adequate dialysis treatments?

It is well known that the AV fistula (AVF) is the preferred vascular access for dialysis patients over the AV graft and central venous catheter since it has more benefits associated with it.  Some of those benefits include lower risk of infection and reduced rates of stenosis thus leading to longer-term patency rates.  What is also known is that all AV accesses, both fistula and graft, are at some risk of developing stenosis and requiring intervention.  

The Journal of American Medical Association (JAMA) Surgery published a study that concluded that intervention is commonly required to foster maturation of AVFs, maintain patency, and treat complications.  The study included patients both with kidney failure and chronic kidney disease.  In the kidney failure group 37.7%...required interventions to foster maturation or manage complications before maturation’ which ‘was defined as access use for effective dialysis using 2 needles for 75% or more of the dialysis sessions over 4 weeks.1

There are many ways to assess the functionality of an AV access being used for dialysis.  For example, one of the most common ways is to perform a physical assessment.  During a physical assessment, a clinician will palpate for thrill as well as listen for consistent bruit throughout the AV access.  Once cannulation with needles has been initiated the access should be monitored to ensure appropriate blood flow rates are being achieved and venous and arterial pressures are within normal limits on the dialysis machine.  If the patient is experiencing out of range pressures or not achieving prescribed blood flow rates, one should consider that the AV access has possibly not matured properly, or the access has stenosis and may require intervention.  

While this study focused on AVF maturation and use, it is known that AVGs also require monitoring and intervention to maintain patency.  An additional tool for monitoring AVF and AVG accesses is to review surveillance data such as Vasc-Alert.  Vasc-Alert provides online reporting that is available to view whenever it is convenient for the clinician.  The reports contain consistent intra-access pressure monitoring as well as efficient access risk scores for each patient and are available for review by any user with access to the system.  

Below are some graphics that show how Vasc-Alert can help indicate if a new access is functional and patent or has signs of potential complication.  Each graphic is a display of the calculated Venous Access Pressure Ratio (VAPR) for each treatment using a patented algorithm that has been cleared by the FDA.   Vertical green or red lines represents an individual dialysis session’s averaged VAPR for the patient. 

Examples of new accesses without indications of complication:

Screen Shot 2022 08 22 at 2.18.41 PM

The VAPR pressure trend for this access is below the FDA approved threshold and remains steady indicating the access is patent and without indication of developing stenosis.

Screen Shot 2022 08 22 at 2.17.47 PM

It is not uncommon to see slightly elevated pressure in the early stages of cannulation due to continued maturation and the use of smaller needles when first using the access.  The important thing to note is the consistent decreasing trend indicating patency of the access.

Screen Shot 2022 08 22 at 2.16.45 PM

In this example the intra-access pressure is just below threshold when cannulation was implemented.  After about a month the trend begins to increase consistently indicating there is a complication developing and that the patient should be referred for further evaluation.

Examples of new accesses that have required intervention to remain functional:

Screen Shot 2022 08 22 at 2.15.35 PM

The VAPR trend was increasing from the beginning of use with this access indicating early stenosis development.  An intervention is noted in the Vasc-Alert record (red arrow) and evidence of success is seen by the drastic decrease in the VAPR.

Screen Shot 2022 08 22 at 2.13.20 PM

Consistently elevated intra-access pressure occurs from the time cannulation is implemented with this access.  An intervention is noted in the Vasc-Alert record (red arrow) followed by a brief time period with decreased pressure.  Shortly after the pressure increases indicating a potential complication is developing and the patient should again be referred for further evaluation.

According to the study one-third of the fistulas that were mature at 6 months required some type of intervention to facilitate maturation and/or manage complications. Knowing this increases the need for good monitoring practices for new accesses.  Vasc-Alert provides useful data for clinical staff allowing the ability to proactively identify complications so that the patient can be referred for further evaluation before the access is lost to a severe complication such as thrombosis.  

Is your dialysis center using Vasc-Alert?  Are you familiar with your patients’ intra-access pressure trends?  If not, contact Vasc-Alert support staff at www.vasc-alert.com.  We would be happy to discuss how Vasc-Alert can help you protect your patients’ vascular accesses.  

 
Source:
JAMA Surg. 2021;156(12):1111-1119. doi:10.1001/jamasurg.2021.4527
Published online September 22,2021. Corrected on June 22,2022.