Cardboard contraption

I spent last night stuck in an emergency room and a man (or what was left of him) was brought in and temporily parked near my cubicle. He was strapped to a gurney as accident victims generally are and he had some cardboard box type contraption over his head. It appeared to have some sort of clear plastic on the face and it could have been some kind of restraining device, but I was afraid to look too closely as he was surrounded by police (he may have died in a police chase.) I had to walk past him and the cardboard just looked a little odd to me; I’ve seen enough of what goes on in ERs to know about restraining devices and why they’re used but this is the first time I’ve seen a cardboard box type thing used. Quadgop, do you know anything about this sort of thing?

Maybe it was to prevent head movement in case of a spinal injury?

My guess would be something to stop the spray of saliva from a possibly contagious and combative person.