Orgasms are said to be much more intense when the brain is deprived of oxygen, but this practice can also be dangerous and even deadly.
So those who play with breath are literally only minutes away from playing with death.
This is definitely one of those things where pretty much even the slightest thing gone wrong can cause lasting damage to the brain or spine; in fact, the list of possible injuries is as long as the different types of breath-play.
The lower the oxygen gets, the greater the risk.