In the video below two BJJ instructors discuss the incident, including some of the surprising symptoms of unconsciousness. If you practise this technique, please watch this video.
It is always advisable that if any partner work is done, it is best to do so with a supervisor watching. Even then accidents could happen. Martial arts are, after all, occupied with the act of hurting and killing; of course as a pretence ritual -- that is what martial arts are. However, just because we are pretending, i.e. applying safety precautions, doesn't mean that these things are not lethal. Likewise, just because many of the things we are doing are in fact performed with layers of safety precautions in place--especially by the traditional martial artists, this doesn't mean that they are not dangerous. There are often important reasons for practising techniques, including traditional techniques, in certain "unrealistic" ways.
I saw the following from another blog and thought it well worth it to include here:
Chokes are no joke. Which makes you look more like a chump? Tapping out and patting your cousin on the back. “Wow that was awesome you really got me there I was starting to see stars”. Or being killed by a 14 year old? No one knows why Arcenaux didn’t tap, but if you find yourself in a simular situation just tap. Your not tapping doesn’t impress anyone. Nor does tapping ruin your status, even in competition. There is a reason the tap exists! Better to tap and learn from your experience than break an elbow and be out for 6 months learning nothing.
Again, Chokes are no joke. A 110 lb 14 year old ended a guy twice his size with out trying in 30 seconds. A subject putting their hands around your neck is a lethal force situation. When lethal force is justified USE LETHAL FORCE, you can ease back if control can be gained, but you don’t have time to try less effective lower force options.