Sunday, April 26, 2009

Retrograde / Antegrade cannulation

One thing which Dr. Agar suggested was to have both my needles pointing towards my shoulder rather than my hand after cannulation.

Currently neither does that. Here's a pic of my cannulated fistula:

Shoulder this side
Hand this side

As you can see my arterial needle points towards my hand and the venous is at right angles to my arm. This is because during the surgery they realized that there was some kind of obstruction and they had to make it like this!

Also, I was told that the way the arterial needle is now positioned, it is in the direction of the blood flow. This means that the arterial needle which takes the blood from the artery and sends it to the machine is in the right position so that the blood flows right into the needle and out into the machine. Similarly, the venous needle is in a direction that the blood coming from the machine goes into the vein in the direction of the blood flow.

I then do not understand where the disconnect is. Why should the arterial needle point towards the shoulder? Have I got my blood directions wrong?

1 comment:

Rich Berkowitz said...

Kamal, I can see why you think the arterial needle should face the arm, or the direction from where the blood flows. But that's not the reason for antegrade-antegrade.

It has more to do with what happens when you pull the needle after treatment. When you insert a needles it creates a flap. With a retrograde insertion, the flap is opened against the flow. When you pull it blodd will escape throught the flow and contribute more to the formation of a pseudo-aneurism. The more times you pull the larger the pseudo-aneurism will grow.

If you look at a Medisystems back-eye fistula needle, you'll notice a hole near the tip. The hole is there to allow blood flowing against the needle to more easily go up. In the two needle set, one has the hole the other not.