I remember being taught, in our First Aid class, that anytime you had an injured individual lying on their back...
you should
"roll them over" on their side so that the vomit, blood, etc. can escape to prevent them from choking to death.
Does this have anything to do with the discussion?
More "roll over" stuff...
http://youtube.com/watch?v=PXvg8uCy0KE