100% Oxygen damages our brains ?!

teksimple

Thanks for the article!!

What is new here in this study is the brain activity analysis. But the described "phenomena" of what happens when exposed to 100% oxygen--or carbon dioxide--are nothing new.

Oxygen is a vasoconstrictor.

CO2 is a vasodilator.

We all know of course why oxygen cause our vessels to constrict...because oxygen is a poison. It kills all living things given the chance...including brain cells. Vasoconstriction (and seizing) are our bodies' defense mechanisms to keep this life killer from killing us.

Maybe someone should send this article to George "anyone deco'ing on anything but 100% oxygen is a stroke" Irvine III.

Perhaps holding one's breath every few minutes and driving up the CO2 while deco'ing might be beneficial.

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chunter

It is still better than getting bent.

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"Hobgoblin is a cool word."
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teksimple

Apparently the voice of experience?

Dead brain cells....hughhhmmmm....bad. Bent body...hughhhmmmm.....not so bad .

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"I don't know the percentage of the Internet that's valid, do you? Jesus, it's scary." - Hunter S. Thompson

duffmiver

Primary symptoms of O2 damage seem to be forgetfulness, short term memory loss, and repeating oneself

tibby

I tried to take the time and read through the original document and although I don't understand a lot of it, I couldn't find a clear statement where the brain activity caused by the 100% O2 (shown in yellow on MRI scans) causes brain damage or kills brain cells. Is it because I missed that verbage or it's hidden in fancy neuro-talk? Does activity = brain damage?
In contrast, the summary clearly states that adding CO2 to hyperoxia mitigates the above mentioned brain activity. That's it! I would expect them to say something like -breathing non-rebreathing 100% O2 causes so and so damage which is mitigated by CO2...
Am I missing something?
Tibby

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Does the voice of reason change when you add helium to the mix?...hmm

divelermentov

well, the issue why 100% O2 is used in resus. is mainly as the victims 02 saturation is usually highly compromised.
in this study healthy individuals did breath the O2 - this is a massive difference towards a real med emergency situation. I therefrore would quantify this study.
I personally have seen the O2 saturation dropping very fast in some patients when we were in theatre, and coming right after O2 was administered.
Disclaimer: I am not an anaestehsist but have some exopereinece in maxillo-facial surgery.

With regards to diving - well some question here are of interest
a) how much CO2 do we have in the loop?

b) what is our O2 saturation like


At this point i would asume as hyperventilation does not occur that we either do have a significant CO2 concentration in the loop anyway, or the physiology of a child does not apply to a middled aged, overweight heavy smoking and drinking guy sitting in a dry suite in cold water and waiting for the time to go past getting bored his a@#$% off.

but these are only my .02

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Simon Mitchell

No, you have hit the nail on the head. I would take this study with a huge pinch of salt, particularly in the context of diving.

All they have done is identify some physiological responses to oxygen breathing that they appear to assume are detrimental. They have not demonstrated actual harm in so far as I can tell. Moreover, these authors would benefit from reading the diving medicine literature which clearly describes marked potentiation of cerebral oxygen toxicity if you elevate the CO2 during oxygen breathing (rather than amelioration as they imply).

I am not really familiar with the pediatric implications of this study, but I think you can largely ignore it from a diving point of view.

Warm regards,

Simon M

chunter

I thought it was from all the drugs I used to do. I thought it was from all the drugs I used to do.

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"Foolish consistency is the hobgoblin of little minds." - Emerson

"Hobgoblin is a cool word."
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tibby

Hi Simon,
Thanks for the reply. I wasn't exactly worried as much as curious. Now I wonder what was the main driver for this study. Someone's project, a thesis maybe? Was there an issue to address...
Tibby

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Does the voice of reason change when you add helium to the mix?...hmm

Marc

Gets a little more complicated than that. Yes, rel. high CO2 can increase chances of an O2 hit BUT you are talking tests with pO2 usually greater than 1. Breathing pure O2 at 1 atm does not really increase O2 tissue content.

At higher pressures, significantly more gas will be able to dissolve into solution, i.e. you will be able to increase O2 levels in tissues independent of O2-binding to haemoglobin blood flow / blood flow. This is one of the principles of HBO therapy and separate issue from this.

As pointed out by others, and I think they are right, MRI observations seem more related to hyperventilating, i.e. instead of making them breath into a paper bag to ramp up CO2 they mixed a little it through the O2.

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