YM- re the air matress bed - if you cannot get one of those, you can go on ebay and goto the med section - they sell air mattress overlays which could be used in the same way, also if she is using a wheelchair a lot, you can get a ROJO cushion - it is essentially a air seat that does not allow for skin breakdown - which she may need anyway after the operation..
I was unable to get a air matress overlay so I purchased dense foam about 2 inches thick and that seemed to work for the interim.
Skin integrity is of the utmost importance and it doesnt take long for bedsores to develop. Zinc ointment is a great healer for skin breakouts...
Just a few thoughts to help if I can