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Doesn't the brain start to die after 10-15 minutes without oxygen? How could he possibly go that long without breathing without suffering any brain damage? I re

Doesn't the brain start to die after 10-15 minutes without oxygen? How could he possibly go that long without breathing without suffering any brain damage? I remember when David Blaine was going for the records, the biggest concern was that he would irreversibly and severely damage his brain.

chronic1921 8y ago
Your brain still receives oxygen without you breathing.
rrauenza 8y ago
He does start with a lung full of pure oxygen.
- kazinator 8y ago
  That seems like a poor idea. https://en.wikipedia.org/wiki/Oxygen_toxicity https://en.wikipedia.org/wiki/Oxygen_toxicity
  - Shish2k 8y ago
    oxygen toxicity at sea level (1 atmosphere of pressure) would require a 140% oxygen mixture - it's only when you go to higher pressure environments (eg 10m underwater = 2 atm) that it becomes an issue (at 2atm, 70% oxygen is toxic; at 4atm, 35% oxygen is toxic, etc - regular air is 21% oxygen, which becomes toxic around 7atm aka 60m underwater)
    - matt_the_bass 8y ago
      You’re generally on the right track, just off slightly. In the scuba diving world 1.4atm partial pressure of Oxygen is generally considered the maximum safe partial pressure when working (ie swimming). 1.5 atm for rest. This makes the depth limit for regular air to be 216 feet. Though there are a lot of divers who dove deeper than that befor trimix became so common.
  - dgritsko 8y ago
    Watch the TED talk linked elsewhere in the thread, there are many, many things he talks about doing that are also poor ideas.
deleted 8y ago
[deleted]
user5994461 8y ago
Brains cells start dying in less than 5 minutes without oxygen.
toss1 8y ago
Yes, and the trick is to supersaturate your blood & tissues with vastly greater amounts of O2 than normal, and also to reduce your oxygen consumption rate. Of course, even with these preparations, freedivers have died and some have shown some damage.
- village-idiot 8y ago
  Also, humans cannot detect O2 levels, we detect CO2 levels. When you supersaturate your blood with O2, you're also purging CO2 levels. This can result in you holding your breath beyond the point where your O2 levels drop below the blackout threshold, which is typically a fatal experience if you're underwater when it happens.
village-idiot 8y ago
Your brain starts to die without any oxygen, but not breathing is not the same as not giving your brain any O2. Your blood cells buffer amount of O2 for use and CO2 ready for removal, which is how an untrained person is able to hold their breath and not die. When you stop breathing, consumption of O2 continues until CO2 builds up to a threshold point, triggering a desperate need to breathe (humans cannot actually detect O2 levels). If you try and hold your breath for too long, either the buildup of CO2 will cause the need to breathe, or lack of O2 will cause blackout and the autonomous nervous system to take over and resume normal breathing. While I am not a doctor, I don't see how it's possible to deprive your brain of enough O2 to damage it and not lose consciousness. It's possible to train long breath holding in two ways: increasing O2 stores and increasing efficiency. Hyperventilating can result in you purposefully purging extra CO2 and over oxygenating your blood. This will let you hold your breath for a very long time, I can comfortably go from a 30s hold to a 2m hold by pre-hyperventilating (see: Wim Hof Method). It also adds the risk of letting O2 levels drop before CO2 rises, causing blackout, which is basically one of the things that kills free divers. DO NOT DO THIS IN OR NEAR WATER, BLACKING OUT IN ANY AMOUNT OF WATER KILLS. The other thing is that our systems that consume O2 can be made much much more efficient. Training probably helps, but there are some autonomous systems capable of reducing O2 consumption that all of us carry around. The mammalian diving reflex appears to automatically cut O2 consumption and limit max heart rate once your face is under water, for example. tl:dr: You carry extra O2, and you can increase how much on purpose. The rate you use O2 isn't fixed, and if you run out of O2 you black out and start breathing normally (which kills you if your underwater).
- fpoling 8y ago
  I read that some free divers advised against hyperventilating. Instead they suggested to train to control urges to breathe despite rising CO2 in blood. This is much more difficult, but this way one keeps a solid indicator of dangerously low oxygen level.
  - village-idiot 8y ago
    That makes sense. I wonder if they do anything to add extra O2, or if that carries too high a risk of blackout due to low CO2 levels. I clearly am not a free diver. Either way, the all caps warning stands. And even experienced free divers black out on occasion, so be careful out there.

chronic1921 8y ago

Your brain still receives oxygen without you breathing.

rrauenza 8y ago

He does start with a lung full of pure oxygen.

kazinator 8y ago
That seems like a poor idea. https://en.wikipedia.org/wiki/Oxygen_toxicity https://en.wikipedia.org/wiki/Oxygen_toxicity
- Shish2k 8y ago
  oxygen toxicity at sea level (1 atmosphere of pressure) would require a 140% oxygen mixture - it's only when you go to higher pressure environments (eg 10m underwater = 2 atm) that it becomes an issue (at 2atm, 70% oxygen is toxic; at 4atm, 35% oxygen is toxic, etc - regular air is 21% oxygen, which becomes toxic around 7atm aka 60m underwater)
  - matt_the_bass 8y ago
    You’re generally on the right track, just off slightly. In the scuba diving world 1.4atm partial pressure of Oxygen is generally considered the maximum safe partial pressure when working (ie swimming). 1.5 atm for rest. This makes the depth limit for regular air to be 216 feet. Though there are a lot of divers who dove deeper than that befor trimix became so common.
- dgritsko 8y ago
  Watch the TED talk linked elsewhere in the thread, there are many, many things he talks about doing that are also poor ideas.

deleted 8y ago

[deleted]

user5994461 8y ago

Brains cells start dying in less than 5 minutes without oxygen.

toss1 8y ago

Yes, and the trick is to supersaturate your blood & tissues with vastly greater amounts of O2 than normal, and also to reduce your oxygen consumption rate. Of course, even with these preparations, freedivers have died and some have shown some damage.

village-idiot 8y ago
Also, humans cannot detect O2 levels, we detect CO2 levels. When you supersaturate your blood with O2, you're also purging CO2 levels. This can result in you holding your breath beyond the point where your O2 levels drop below the blackout threshold, which is typically a fatal experience if you're underwater when it happens.

village-idiot 8y ago

Your brain starts to die without any oxygen, but not breathing is not the same as not giving your brain any O2. Your blood cells buffer amount of O2 for use and CO2 ready for removal, which is how an untrained person is able to hold their breath and not die. When you stop breathing, consumption of O2 continues until CO2 builds up to a threshold point, triggering a desperate need to breathe (humans cannot actually detect O2 levels). If you try and hold your breath for too long, either the buildup of CO2 will cause the need to breathe, or lack of O2 will cause blackout and the autonomous nervous system to take over and resume normal breathing. While I am not a doctor, I don't see how it's possible to deprive your brain of enough O2 to damage it and not lose consciousness. It's possible to train long breath holding in two ways: increasing O2 stores and increasing efficiency. Hyperventilating can result in you purposefully purging extra CO2 and over oxygenating your blood. This will let you hold your breath for a very long time, I can comfortably go from a 30s hold to a 2m hold by pre-hyperventilating (see: Wim Hof Method). It also adds the risk of letting O2 levels drop before CO2 rises, causing blackout, which is basically one of the things that kills free divers. DO NOT DO THIS IN OR NEAR WATER, BLACKING OUT IN ANY AMOUNT OF WATER KILLS. The other thing is that our systems that consume O2 can be made much much more efficient. Training probably helps, but there are some autonomous systems capable of reducing O2 consumption that all of us carry around. The mammalian diving reflex appears to automatically cut O2 consumption and limit max heart rate once your face is under water, for example. tl:dr: You carry extra O2, and you can increase how much on purpose. The rate you use O2 isn't fixed, and if you run out of O2 you black out and start breathing normally (which kills you if your underwater).

fpoling 8y ago
I read that some free divers advised against hyperventilating. Instead they suggested to train to control urges to breathe despite rising CO2 in blood. This is much more difficult, but this way one keeps a solid indicator of dangerously low oxygen level.
- village-idiot 8y ago
  That makes sense. I wonder if they do anything to add extra O2, or if that carries too high a risk of blackout due to low CO2 levels. I clearly am not a free diver. Either way, the all caps warning stands. And even experienced free divers black out on occasion, so be careful out there.