Vincent asks excellent questions - dehydration, high muscle wastage, poor nutrition, amount of time she has been bedridden, continence issues, age, sheet fabric used, do they really turn her OFF the bed sore frequently or just lessen the amount of pressure (and if incontinent does she lay in urine for an hour or more because she isn't checked except 2 hourly to be turned).
Pressure ulcers are a true threat to all PALS once they cannot reposition themselves, they are best prevented as treatment is difficult.
My Chris had a threatening pressure sore on one buttock for his last 6 months or so. I would work hard on it by having health professionals really go on at him about it and nearly get rid of it, then he would refuse to be repositioned off it again (he had FTD). In his last weeks it broke down and became an actual sore, but his breathing was so compromised he could not tolerate anything but a pillow or wedge to just relieve pressure a tiny bit. I still shudder to think what was going to happen with it had he not been set free altogether when he was.
Deb has talked of this in depth, if you check either posts by her, or read through the pity party thread in the CALS section ...