Prisma, sort of a vent

The other day I was taking care of my pt who was on the Prisma. We were taking her off because she is going to start HD the next day. I called another Rn to help me just read the screen and go through the steps. I had the NS bag attatched and had begun to clamp my lines. So the next step is to begin to give the blood back, so in my ingenious ways I hit continue instead og return blood - I felt like such an idiot because the dialysis nurse came by to "oversea" - So once I hit continue it was to the point of no return and the pt could not get her blood back - wow did I feel like a true idiot. I wonder why there is this point of no return on wuch a "high tech" machine. I guess my little vent is why does this machine not have a little safety check. Other nurses have made this same mistake. It is easy to do because the return blood button is in the far left corner and the continue button is directly below the instructions on the screen. Sorry for the vent, this happened after I had told people that I actually enjoed taking care of pts on the CVVH and I like the theory of how the machine worked. I even was explaining to people about the different pressures on the machine.