Devices placed directly on a semi-electric or total electric hospital bed frame. They utilize alternating pressure, low air loss or powered flotation without air loss. An air pump or blower provides either sequential inflation and deflation or a low interface pressure throughout. The mattresses have an inflated cell height of 5 inches or greater and a surface designed to reduce friction and shear. Indicated for patients with stage II, III and IV pressure ulcers or post-operative myocutaneous flaps or skin grafts.