Dialysis graft hemorrhage

Overheard a call regarding bleeding of a graft. The crew had a (frankly) horrible radio report and a probably pretty pissed off receiving nurse. Of course I wasn't there, so I don't know the whole story.

Im still a newbie so I'm curious how difficult a call this is. Has anyone experienced open bleeding from a graft before? How severe is it? Bad enough to consider a tourniquet?