100% Oxygen damages our brains ?!

Brainx3

Hi guys,


I have found this new report about breathing 100% oxygen. I would be interested to know your point of view on the report as this might be redefining what we think about using 100%.

UCLA Study Reveals Why Bad Things Happen Inside the Brain When We Inhale Pure Oxygen / UCLA Newsroom


Best Regards. Wael

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Ben Field

Interesting...

Thanks for posting.

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EBT

Interesting indeed, but it just goes to highlight the fact that when diving we're in an alien environment and not everything is predictable/understood (hell this study shows not everything is understood in our normal environment). Bear in mind this study was also normobaric, so its results may/may not reflect what happens in our exposure.

Interesting reading for a wet swedish winter though

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Abbo

It would be nice if it gave us some idea of what hormones and neurotransmitters it was talking about, what damage they cause and over what time period they start to have an appreciable impact; without that it is tough to judge. I would have thought that PCO2 in a rebreather is significantly higher than in the hospital mask, even when the scrubber is working well and the flow rate is low. My understanding is that the problems we have in long dives with high PO2 are primarily related to the superoxide radical: that's the bull in the china shop.

Ben Field

One wonders if its CO2 that is required or just a.n.other gas, our loops are commonly also carrying Helium, Nitrogen etc. I guess what follows from that is what happens if you breath Heliox, Trimix, Nitrox.

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nigelh

You read it?

They put masks on children and they hyperventilated.
They detected problems to do with the hyperventilation.
So they want to add CO2 to pretend they aren't hyperventilating.

Did they put a mask on a child and let them breath air?
My kids would have hyperventilated a bit because it's 'different'.
Kids either love or hate 'different' but it's always hyperventilate a bit time.

Somebody is mistaking an undergrad project for science. A friend of mind, a Research Fellow at a local university, complains that he often only just manages to stop them publishing abject stupidity by luck some times. He complains of Physicists who know no basic Chemistry, Biologists who know no statistics, Med students who know nothing. etc. This sounds like one of them.

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Marc

I doubt any other gas would cause this response as it's CO2 that triggers the breathing response (that's why you should not hyperventilate when freediving; similarly why people breath from a bag when hyperventilating to get more CO2 in)....

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York

BTW. the original article can be accessed here: http://medicine.plosjournals.org/arc....0040173-L.pdf

J.

Ant Slegg

If I read this correctly the concern is that if a person is breathing 100% O2 at normal atmospheric pressure then the levels of CO2 in the body drop (not new). This drop causes the blood vessels to narrow. I suppose one of the questions then is - Does the fact that the gas being breathed contains 5x the normal levels of O2 compensate to any degree for the narrower blood vessels? and the answer appears to be no.

I don’t quite follow the statement “When the children inhaled pure oxygen, their breathing quickened” as this is not an effect I associate with breathing 100% O2 but the paper identifies a number of causes including the release of CO2 from haemoglobin (see the intro). I suppose this free CO2 triggers the desire to breathe and as a result the CO2 gets flushed out. Oddly although the haemoglobin is carrying more O2 it appears to want to hang on to it more.


As far as the relevance to diving is concerned I suppose one question is how this relates to ppO2. With a 1.3bar set point at 40m the percentage of O2 in the gas I breathe is 26% i.e. nowhere near the 100%. If the ppO2 is itself significant then we are operating way beyond this experiment and I suppose there is a possible scenario where the level of O2 triggers the various responses described the brain gets less and less O2 and unconsciousness occurs.

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chunter

It is still better than getting bent.

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