Abstract: A patient's head, chest and upper torso are supported on a first surface formed by a plurality of inflatable sacks disposed on an articulatable member. The patient's lower torso, buttocks, legs and feet are supported on a second surface formed by air fluidizing a mass of fluidizable material. A blower inflates the sacks and the fluidizable material via a network including manifolds, valves, and flexible tubing. A microprocessor controls actuation of the articulatable member, the various valves, and the blower, according to signals inputted by operating personnel or supplied by various monitoring sensors. The flow of air to the fluidizable material beneath the buttocks of the patient is reduced when the articulatable member is raised, thus increasing the density of support beneath the patient's buttocks and counteracting the tendency of the shifting weight of the patient's upper body to slide the patient toward the foot of the bed.