Apparatus and/or instruments: A commercial full-length LiquiCell® anti-shear mattress overlay (ASMO) (Birchwood Laboratories, Eden Prairie MN) was placed on the standard ambulance stretcher mattress. Shear force and tissue interface pressure was measured during a full stop, acceleration, travelling at 30 mph, deceleration, and a full stop by a PREDIA device (Molten Corporation, Hiroshima Japan) through reusable sensors attached to the sacrum, ischial tuberosity, and heel.