Hi Jolly... in the sense that dialysis is LIFESUPPORT for these patients, whether outpt./chronic or in the acute setting, then yes, it could well be seen as critical care.
However, critical care background is by no means essential in an outpatient/chronic setting.
I started in dialysis as a tech, and while working there, persued my RN, much as AmyLiz is doing above.
Have been in dialysis going on ten years now, and have loved every minute of it. Just when you think things are getting "routine", something changes with another new challenge.