Our local protocols are pretty much against the use of either the fistulas or the grafts. We have to go throught medical control to get authorization to even try. Our area is warming up to IO's being used more and more and not just for pediatric pt's. Critical pt's are given a couple attempts at IV access then we don't hesistate to go to our EZ IO's.
In my medic class we had a very good presention from a dialysis nurs explaining why they don't like anyone to access the either of the dialysis sites:
In the case of the permcaths the thinking was that some people don't realize that there is heparin in the lines and a flush would push an excess of heparin into the pt's system.
With the grafts, there is a very high risk of infection. So they would just rather avoid that all together.
Like I said though, I'm still a medic student and this is what I learned haven't had any critical dialysis pt's in the field yet. However, during my in hospital time, most of the dialysis pt's that needed an IV I was able to find a suitable vein and place one unless they had other major health problems that caused a lack of good potential IV sites.
Don't know if this helps but this is what I've noticed in my area.