Systems, methods, and apparatus are provided for preventing and treating pressure ulcers in bedfast patients. The invention includes providing a non-powered mattress having a first zone adapted to conform to a first body part and a second zone adapted to provide support to a second body part, and off-loading interface pressure on the first body part to the second body part by dynamically increasing the support provided to the second body part by the second zone based on a weight of the first body part on the first zone. The off-loading of interface pressure from the first body part to the second body part equalizes blood oxygen saturation in tissue of the first and second body parts. Numerous additional aspects are disclosed.
