Asphyxia
From wipipedia.org
Asphyxia is a condition of severely deficient supply of oxygen to the body. In the absence of remedial action it will very rapidly lead to unconsciousness and death. Asphyxia is the same as suffocation. Asphyxia is a very real danger in scenes involving bondage and/or gags for this reason victims should never be left alone whilst bound. Further more, the Dom should always have a mechanism for releasing the sub quickly if they get into difficulties.
