You can also crush the larynx if you're not careful mm- a good idea to find out about the whole thing.
I've never done it in a D/s context, but my wife & I used to do some pretty wild stuff, including breath play. It can sure be intense.
My comment would be for anyone looking to do such things, is to learn CPR.
Imagine calling an ambulance while he or she is chained to the bed & turning blue??![]()