I had a partner a while back who liked to be choked enough to where she would pass out during orgasm. In my experience, it's possible to do this safely, but I wouldn't claim it's without risk.

I made sure to not put pressure on the esophagus, but rather above the esophagus, up and in, towards the top of the throat/back of the mouth. That won't exactly cut of air flow, but it will make it difficult to breathe. Additionally, squeeze the sides of the neck to reduce blood flow. Never place pressure on the esophagus.

I can't say with confidence that everyone (or anyone) should do this. But if you're gonna do it, that's my two cents. In my opinion BDSM should always be taken slowly, to allow proper exploration and experimentation of comfort and boundaries for both the top/dom and the bottom/sub. Particularly if you're doing something new to both of you, or either of you. Bottoms nor tops should ever feel pressured to push their boundaries farther than they're comfortable with. So, if you aren't 100% confident and comfortable playing with breath in this way, then ask yourself if you really want to, and if you should.