Why does Oxygen displacement (via inert gas) knock people out in seconds but people can hold their breath much longer?
In: Biology
Gas exchanges across the lung/blood membranes according to the relative concentrations in the air and blood. Hold your breath and the lungs are filled with air with 21% oxygen which goes down to about 15% as some of it moves into the blood, so they are reasonably balanced.
Fill the lungs with inert gas with no oxygen and the concentrations will tend to equalise, it will actually remove oxygen from the blood, dropping the level very quickly and causing oxygen deprivation in the brain.
Normally when you breath in air, the pressure of the oxygen in your lungs causes it to enter your blood stream and bond with the hemoglobin which carries it around and then when it gets back to your lungs it gives off its higher level of CO2 to the air in your lungs which has a lower level of CO2
When you breath in pure nitrogen it works like the high CO2 levels leaving your blood to join the low CO2 levels in the air, except that its all the oxygen in your blood leaving to join the low oxygen level air. The pure nitrogen in your lungs effectively sucks the oxygen out of your blood stream!
Normally you burn through oxygen at some fixed rate and when the CO2 builds up high enough your lungs begin to burn and make you need to take another breath, but the nitrogen pulls the oxygen out of your blood **wayyyyy** quicker than you would normally use it.
After 30 seconds you have basically no oxygen left in any of your blood because its all left to play with the nitrogen, and you don’t realize because your CO2 levels never built up so your body never warned you you were about to die. You’d likely pass out after 15-20 seconds.
After 60 seconds you have brain damage due to severe lack of oxygen(like wayyyyy less oxygen than drowning)
And after a couple minutes you’re dead and so is anyone who came in to retrieve you.
Because those breathing inert gas were not prepared, so unlike free divers and other breath holders, they didn’t take a bunch of deep breaths to get ready.
When you breathe out air, it still has most of its oxygen in it. That’s how mouth-to-mouth resuscitation works. Holding your breath is just ignoring the build up of CO2, there is still lots of O2 there. You can breathe for quite a while in an enclosed space with a CO2 scrubber. Removing the oxygen, that’s a problem.
Latest Answers