Was Carter ever chief of the ER??

I'm not sure if he was chief because Weaver was there when he was the senior guy and I think she was chief of staff at the time. (I could be wrong though)

I was surprised to see him on dialysis...did we already know about this? If so...I don't remember. I am hoping that they don't kill him now. I hate that ER is ending and I would like a happy sappy ending

Anyone know if Abby and Luka are returning?