Brain damage

[alpha_wolf]

On average, how long can a human brain survive without oxigen without being noticably damaged? Thanks.

[Moonbear]

Usually *they* say it's about 5 min. I don't have a reference on hand, that's just what I've been taught from CPR courses and stuff like that. Though, I do know all bets are off when hypothermia is involved.

[alpha_wolf]

It's somewhat difficult to google for this, since I'm not sure which keywords to enter. But I did manage to find this site (http://www.biology-online.org/8/4_brain_damage.htm), which states that:

A human can survive for four minutes without oxygen before the brain damage becomes so severe there is no realistic chance of survival.
Ovbiously, the time limit for unnoticable damage is shorter than that... But how much shorter?

[Marijn]

Like moonbear said, it depends for a great deal on the temperature of the body.
But basicaly damage starts to be done the moment the brain is deprived of oxigen.
Also the parts that are effected matter greatly in the question when you start to notice damage.

During freediving i've had the "pleasure" of being witness to several cases of cardiac-arrest, in all cases the time had been more than 2 minutes.
In all cases there was no noticable change in the victims, not even on the long run (ok several of them stopped going to extreme depths).
Ofcourse in these cases the body temperature is lower than normal, possibly contributing to their good survival.
But these are just observations from the side, i don't know to what extend the damage was done.

But again, damage starts being done once the hart stops (and thus the oxigen stream to the brain)

[alpha_wolf]

Like moonbear said, it depends for a great deal on the temperature of the body.
Ok, to focus the question a bit, let's assume cardiac arrest at normal body temperature. Would there be any noticable damage after ~2.5 minutes?
But basicaly damage starts to be done the moment the brain is deprived of oxigen.
Yes, that's why I didn't say "no damage".