We were taught two choke holds in class (arm chokes, I mean)—one for blood, and one for air. Why does everyone do the bar (air) choke on TV? That's the really dangerous one that can kill the victim—your forearm is pulled tight against the victim's throat and you risk damaging the trachea—I took a hit to the cartilage there once (edge of a desk, as I fell running across them) and that's no fucking shit. If someone maintains that pressure...
But if you tuck their chin in your elbow, you can constrict their blood supply to their brain and have them pass out—as long as you don't keep it on too long, you probably won't break them, but it's much easier to knock them out.
You don't want to end up like these two:
Just a thought for the next fight scene you choreograph.