Wrist Fistula – Surprisingly, Ready to Use after the first Post-Operative Visit
This wrist fistula was created approximately two weeks before the image was taken, and it was surprisingly ready to be used at the first post-operative visit. On the average, our wrist fistulas take about two months to be usable, but in this case the vein was large, the radial artery was capable of delivering enough flow right away, and the patient was both slender with healthy tissues.
The raw picture taken in the office.
An ultrasound guided digital photo diagram created to guide cannulation.
A few important points:
In this slender patient with very little subcutaneous tissue to protect the fistula, the fistula is right under the skin. We ordinarily consider these fistulas not suitable for buttonholes due to the risk of local skin erosion and bleeding (see my previous post on buttonholes).
This particular fistula is long, with three easily identifiable zones of cannulation: (1) the distal fistula in the forearm from just above the wrist incision up several inches to the spot where it divides into smaller medial and larger lateral branches, (2) the dominant lateral branch in the upper forearm, separating from the smaller medial branch and coursing laterally over the brachioradialis muscle where it is supported by the muscle and is easy to feel, and (3) the cephalic vein in the upper arm where the medial and lateral branches come back together.
There is much variation in venous anatomy. In some cases the lateral branch in the forearm is not well developed, and the medial branch in the upper forearm can be hard to feel. In other cases, the cephalic vein in the upper arm is not well developed, and the main outflow is up the unusable basilic vein on the inside of the arm (most often the basilic is too deep without a transposition procedure). This patient happens to have good veins in a fortunate pattern.
Knowing when to clear a fistula for use can be very subjective. In general, the “rule of sixes” says that a fistula is not ready to be used unless it is at least 6mm in diameter, not more than 6mm deep, has at least 6cm of usable length, and can provide 600 cc/min of blood flow. Just feeling a good thrill is not enough to guarantee successful cannulation.
Whenever possible, we would like the fistula to grow and toughen a bit before use. The Dialysis Outcomes Quality Initiative (DOQI) guidelines suggest waiting 6–8 weeks to lessen the incidence, severity and consequences of potential early infiltration. In my practice (our review done in 2009), the average time to release of a wrist fistula was72 days, although this obviously varies widely.
If the patient has a catheter, there is a risk of infection and central venous damage as long as the catheter is in place, so there may be urgency to use the fistula sooner and get the catheter out.
In our practice, nearly every fistula is released with an “Ultrasound guided digital photo diagram” (see previous post from June 2016), which is designed to make initial cannulation easier.
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