fistula needle research

Hi I'm currently tasked to research improvising fistula needles for dialysis patients and I was wondering if I could get some feedback. I've never seen an actual dialysis procedure in real life and I've only done research by watching videos about it. I did try to contact dialysis centers for a visit to get feedback or even tried sending them questionnaires but they were not receptive. I do hope you guys could help!

1) What are the disadvantages of current fistula needles used for dialysis patients?

2) What can be done to improve the fistula needle?

3) As the needle must remain in the artery during the whole duration of the dialysis procedure, does it pose as a threat to the patient? For example what if the patient becomes restless and moves his arms? Would that result in injury?

4) I've observed IV catheter cannulation where there is a blood flashback chamber to watch for blood flow and it helps the nurse locate the vein. Why don't fistula needles have the same concept to help the nurses locate and insert the needle successfully?

5) Also, the needle of an IV catheter can be removed which leaves a flexible tube in the vein which doesn't injure the patient if he moves. Will it help if the fistula needle could do the same?