I've seen one of these firsthand...
January 2018, Canisius hosting North Dakota at HarborCenter for the very first time. There's a collision near the NoDak bench and all of a sudden, I see one of my (Canisius's) defensemen making a beeline to the Griffs bench, where he's met IMMEDIATELY by the trainer - like, the trainer was about to jump over the dasher board to help him.
I didn't see very much in the way of blood, but word got up to us pretty quickly that it was a skate blade to the neck. They went right down the tunnel, where the EMTs met them. We did not restart the game until we received word that he was in stable condition (and we had to wait for another EMT crew to arrive).
I'll never take an AT staff for granted. They're heroes.