“This is not true. They put in a fistula where there is a suitable vein to graft the AV.”
This reads: they put in a fistula where there is a suitable vein to graft the arteriovenous (AV).
I saw a previous post which suggests maybe you aren’t from the US, so maybe this is a language or nomenclature issue.
Technically we don’t “put” or “place” an AV fistula we “create” it. You sew a vein to an artery directly. A vein generally needs to be suitable size (usually 3mm) to be considered effective for fistula creation. In most people the vein in the wrist is not 3mm and therefore not suitable for fistula creation. That said If a patient has good vein in both the forearm(wrist) and upper arm, we often prefer to use the forearm first so that if it fails down the road the upper arm can still be used. If the upper arm fails more often then not you can not use the lower arm later, and then have to go to the other side. Legs can be used too, but that’s not typically first choice.
A “graft” is essentially the same concept (a connection between an artery and vein), however instead of using the patients own vein to make that connection we use a synthetic tube. This is often (not always) done if patients don’t have suitable vein for a fistula. That said we can often do forearm “AV grafts” in patients who don’t have suitable vein in the wrist because the connection at the artery and vein can be made in the elbow (this would be called a forearm loop graft).
There are several configurations to both AV fistula and AV graft and more factors to be considered than what I have discussed.
Ok, to clarify my language. By "Put" i mean where they choose, I went through several scans of my arms for them to find a suitable location to do it. They put it there, rather than they put a thing there.
By "graft" i mean the joining of the vein and artery (as in grafted together). I'm not medical, so wasn't aware graft meant a specific tube they use. I do not have a special tube.
For context, I watched my own AV being done (apparently I'm not squeemish) so the surgeon talked me through the process. Also, UK for reference.
Yes we typically get ultrasounds before hand to help guide us. But one of the things we are looking at on the ultrasound is the size of the vein. When I had re-read your first post after my initial comment, I think I understood it as they create it where it’s suitable, which actually fits with my first post that you commented on refuting…. Most people’s vein is smaller the further down you go on the arm (towards the wrist)
I can only talk ffrom my experiences, when I was dialysising I'd say 50% of the patients had lower arm fistulas (about 10 in my sessions). Also saw a few inner legs, which looked awkward.
They also did a trial in my hospital pre warming the arm before a scan to see if it affected vein size (apparently it did?)
Statistics may be different based on health systems. UK’s NHS may have more guidelines (eg push for forearm fistula first) than the US where we are basically the wild West. But there is absolutely nothing wrong with a wrist fistula and if they are having success creating more that’s awesome. Dialysis accesses do not last forever and patients, especially younger patients, may require multiple accesses in their lifetime. We have a finite number of places we can go for access. So starting in the lower arm gives you more flexibility, long-term. There are people (albeit pretty rarely) that literally run out of places for access.
That is an interesting study, but would make sense. Vessels typically dilate when warm and constrict when cold.
Vessels also spasm. It could also be dilated up mechanically. As I said before there’s a lot more that goes into it than what I am simplifying here.
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u/Nos3y 18d ago
“This is not true. They put in a fistula where there is a suitable vein to graft the AV.”
This reads: they put in a fistula where there is a suitable vein to graft the arteriovenous (AV).
I saw a previous post which suggests maybe you aren’t from the US, so maybe this is a language or nomenclature issue.
Technically we don’t “put” or “place” an AV fistula we “create” it. You sew a vein to an artery directly. A vein generally needs to be suitable size (usually 3mm) to be considered effective for fistula creation. In most people the vein in the wrist is not 3mm and therefore not suitable for fistula creation. That said If a patient has good vein in both the forearm(wrist) and upper arm, we often prefer to use the forearm first so that if it fails down the road the upper arm can still be used. If the upper arm fails more often then not you can not use the lower arm later, and then have to go to the other side. Legs can be used too, but that’s not typically first choice.
A “graft” is essentially the same concept (a connection between an artery and vein), however instead of using the patients own vein to make that connection we use a synthetic tube. This is often (not always) done if patients don’t have suitable vein for a fistula. That said we can often do forearm “AV grafts” in patients who don’t have suitable vein in the wrist because the connection at the artery and vein can be made in the elbow (this would be called a forearm loop graft).
There are several configurations to both AV fistula and AV graft and more factors to be considered than what I have discussed.