Reblogging for the very high percentage of people here who haven't received adequate sex education. No shame--this included me until a few years ago, I've participated many times myself, and I'm a nurse.
Choking is always edgeplay (i.e very risky). There is no safe way to choke someone. Even light pressure is not safe.
There is a nerve in the neck whose function is to lower heart rate. If you accidentally stimulate this nerve, it's possible to lower the heart rate to zero very quickly. This can result in sudden cardiac death in seconds. Sometimes symptoms can be minimal and they unfortunately also mimic the symptoms of low oxygenation, which are the sensations you're trying to provoke.
Also, if your partner has cholesterol buildup in the major artery leading to the brain--which there is no way to know except an angiogram--small chunks of cholesterol can break off, travel to the brain, and result in stroke. This too can initially cause minor symptoms the partner may not notice until it's too late to reverse the process.
Breathplay is no kidding my very favorite kink in the world, and I hated giving it up, but please think very, very seriously. This is a Risk Aware Consensual Kink activity, not a safe, sane, consensual one.