Most people on dialysis use Xylocaine which is supposed to be an anesthetic before cannulation.
This is because the needles used for dialysis can be quite painful. So, before putting the needles, a small amount of Xylocaine is injected into the site where the needles need to be put.
So far, so good. The problem is that the Xylocaine itself is quite painful! Granted that it reduces the pain that would have otherwise been there if Xylocaine was not used. But why would something that is supposed to reduce the pain cause pain itself?
I read somewhere that ultrasound waves are being tried with some success for local anesthesia. I wonder how that research is going. Let's hope we see some good results soon.