alternating pressure air mattress

alt·er·nat·ing pres·sure air mat·tress

(awl'tĕr-nā-ting presh'ŭr ār mat'trĕs)

Air mattress that is placed on top of a regular bed mattress; used to promote skin integrity and prevent skin breakdown, has air-filled channels that alternately fill and empty to keep bearing weight off bony prominences of immobilized or weak patients who are unable to shift their weight frequently.