Dean launches himself out of the booth the second the waitress starts screaming. He's by Castiel's side in a heartbeat, muttering completely useless but hopefully encouraging words to him. See? Everything's fine. Sort of.

"Sam." It's an acknowledgement and a plea. "Come on, Cas. We'll get you up and to a hospital. You'll be fine." How he'll manage to do any lifting with a bum arm is beside the point.