Anti-decubitus pneumatic mattress

The mattress includes a main assembly, a pair of bolsters, and a bottom assembly. The main assembly is adapted to overlay the conventional mattress of the bed, and has opposing longitudinal sides, and comprises a plurality of cells that are selectively inflatable for moving the patient in the preselected ways so as to prevent the patient from having the skin breakdowns. The pair of bolsters are replaceably attached to, and extend along, the opposing longitudinal sides of the main assembly, and are inflatable, and when inflated, form barriers that prevent the patient from falling off the bed when the patient is turning. The bottom assembly is adapted to overlay the conventional mattress of the bed and underlie the main assembly, and when inflated, forms a static air space between the main assembly and the conventional mattress of the bed that prevents the patient from bottoming out on the low side of the turning, while suspending the patient in the cushion of static air if the power to the main assembly fails.