To extricate an MVA patient while trying to maintain full spinal immobilize, a KED is useful to go from a sitting position to transition them to a flat lay on a full spine board. Also the tension of the chest straps can help stabilize any rib or sternal injuries. For the past several years they've had KEDs that can be x-rayed through.
If need be, once layed flat and properly secured onto the spine board, you can undo the chest straps to expose the chest to place a monitor or to auscultate the chest or any other examination.
All in all, a KED can be very versatile.
In this case, we were fortunate to have used a KED on her. Her breast implant was an older one made of the kind of silicone that they don't even use anymore. By applying pressure as we did prevented more of the silicone from leaking out.