My wife is a nurse and has been training with a product called Maxi Slide Sheets. They are a really neat product for transferring immobile patients from one bed to another or for just moving a patient up in the bed for repositioning. Here is their PDF showing the product in use, however the training video does it more justice.
For us, this would have been great on several occasions as we needed to reposition Macayla for bath (which required that we spin her completely around with her head at the foot of the bed) or to just move her up closer to the head of the bed. Macayla grew to be a very tall and was heavy to move. She was dead weight much of the time and it was not always comfortable for her when we moved her. These sheets would have been great! Unfortunately, I cannot seem to find any American suppliers carrying them on their websites. Several European companies seem to though. Obviously, it is for sale here for hospitals but not the home yet.