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Cannulation Methods

By Laminate Medical
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Since first used for hemodialysis in 1966, the Arteriovenous Fistula (AVF) has been established in the medical community as the preferred method of vascular access,

providing clear clinical benefits compared to currently available alternatives for most patients requiring hemodialysis.

An extended long-term usability of the AVF is one of these benefits, with some patients receiving hemodialysis using the same AVF for many years. If we consider a standard hemodialysis routine consists of 3 weekly sessions in which the AVF is cannulated by two needles, over the course of 5 years it would be cannulated more than 1500 times! As each cannulation carries a risk for adverse effects including development of stenosis, hematomas, pain and infection, the importance of the correct cannulation technique to the long term “health” of the AVF becomes evident.

Currently, there are 3 cannulations techniques most commonly used in dialysis centers:

  1. Rope Ladder
  2. Area (Regional)
  3. Buttonhole

The Rope Ladder technique In this method, several cannulation sites along the entire length of the fistula are used in rotation.

In each dialysis treatment, a sharp needle is used to puncture a new site. In other words, in the Rope Ladder technique a new cannulation site along the vein would be chosen for each hemodialysis session in a systematic manner, ensuring uniform use of the full length of the AVF. The Rope Ladder represents the current gold standard in cannulation techniques, as numerous studies have shown it is associated with reduced risks of infection, cannulation related pain and vascular access interventions.

In the Area (Or “Regional”) cannulation, once a convenient location for cannulation is found, adjacent locations in the same region will be used in subsequent hemodialysis sessions. The region would often be no more than 5 cm in length, and overtime the entire circumference of the AVF in this segment would be used for cannulation, exploiting both the sides as well as the central section of the access. This cannulation method is generally not recommended and should be avoided, as it increases the risk of aneurysm formation, is associated with a shorter AVF life span and a higher risk of hemorrhage.

The Buttonhole technique

In this technique, tunnel tracts (or “Buttonholes”) are first established by an experienced cannulator at carefully selected locations along the AVF, using sharp needles. After the “Buttonholes” have been created, after about 10 cannulations using sharp needles, they are used to cannulate the AVF using blunt needles during Hemodialysis sessions. As blunt needles are less likely to infiltrate the AVF and can be less painful to the patient, their use requires less technical skill, thus making this technique useful as a salvage procedure if an AVF is difficult to cannulate, or for patients who receive hemodialysis at home and self-cannulate. However, alongside these potential benefits, an increased risk of bacteremia, a potentially fatal condition has been associated with this technique, while hard evidence supporting many of its’ proclaimed benefits has been scarce. Of note, cannulation related pain, a major parameter affecting patient quality of life, was not significantly improved using this technique.

To summarize, it is important to remember that correct cannulation of the AVF is paramount to successful, long term hemodialysis therapy. As each of the techniques mentioned here presents its’ own set of advantages and disadvantages, they might be right for some of the patients but not others. You should always consult your healthcare provider to determine the right technique for you.

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