Breathing up with pure O2

[Hank49]

I believe thats how some of the free divers or world record breath holders. are able to hold there breath for the extended amount of time is they breath pure Oxygen before diving. I could be wrong but I believe that is what I had heard.

That's interesting. I was thinking that if you saturate yourself, you're starting at a partial pressure oxygen of 1.0 (.2 x 5) and if you dive down 10 meters quickly, the gas in your lungs will go to 2.0...then 3.0 at 20 meters. How could deep free divers stay conscious?

 

[danvolker]

In case anyone starts getting excited about breathing pure O2 and then going underwater for 5 or 6 minutes, there are several huge problems with this..

1. The O2 will get toxic to a typical human not much past 30 feet...this toxicity could occurr at shallower depths if CO2 levels built up to a critical point.
2. I think part of the mechanism for the increased time prior to feeling the need to breathe, is the drastically reduced volume of CO2 this leaves in the bloodstream( after breathing the pure O2) .... when you blackout, you may have depleted blood oxygen to the point that CPR may not even be successful. I don't think there is a great body of skilled scientific research that has been done on this ( in-water effects, of breathing pure O2 prior, to Freediving to depths). There is a large body of research that was done on tech divers breathing O2 at 20 feet, in a relaxed, non-working mode. Much has to do with CNS clock which will not relate to freedivers, and much has been done on the pure tox from the absolute depth itself--this will apply to freedivers...and there is also alot on the very negative health effects of massively increasing oxidative forces in your body chemistry---the high O2 is a great way to create massive increases in free radicals ( the things we take Vitamin C and E to get rid of) and also a great way to cause lung inflamation and mild damage.
3. Nobody NEEDS to stay down longer than 3 minutes. If you don't screw with your CO2 mechanism--the thing that allows us to have a sense of when we need to breathe to stay alive....Freediving is unlikely to ever cause you to blackout. You can see and do alot in 2 to 3 minutes, and this will not require you to dive without having any sense

Regards,
DanV

 

[lowviz]

Don't let me stop you, but breathing pure O2 and holding your breath as long as you can will cause partial lung collapse. Just a little oxygen to breathe as you go off to sleep?is it always a good idea? ? Br J Anaesth Actually, not really a big deal if you are healthy. Smokers may want to pass on this activity...

Application to diving:

"Collectively, these studies offer good evidence that the amount of atelectasis during anaesthesia increases significantly with increasing FiO2 and that the use of oxygen 100% at any stage of an anaesthetic is associated with significant pulmonary collapse. Reducing FiO2, even by a small amount to 0.8, seems to be substantially better than using oxygen alone. " (from reference above)

I do my decompressions on 80% instead of 100% mostly for this reason.

I'm just saying...

 

[danvolker]

That's interesting. I was thinking that if you saturate yourself, you're starting at a partial pressure oxygen of 1.0 (.2 x 5) and if you dive down 10 meters quickly, the gas in your lungs will go to 2.0...then 3.0 at 20 meters. How could deep free divers stay conscious?

I have heard of tech divers who have acidentally gone on pure O2 at 110 feet deep, and not known about it for quite a while..I know of one that did this who toxed and died from it over 10 minutes after going on it. Death and tox does not have to happen instantly, for breathing this to be foolish....

Regards,
DanV

 

[Arubandi07]

What is the point of boosting your natural capability by breathing O2? IMO, this approach to enhancing one's limits constitutes doping, and goes contrary to the spirit and philosophy of free diving. You might as well use a tank...

 

[Thalassamania]

In case anyone starts getting excited about breathing pure O2 and then going underwater for 5 or 6 minutes, there are several huge problems with this..

1. The O2 will get toxic to a typical human not much past 30 feet...this toxicity could occurr at shallower depths if CO2 levels built up to a critical point. - Dan, I don't know if this is true for bound oxygen and dissolved oxygen during apnea, do you?
2. I think part of the mechanism for the increased time prior to feeling the need to breathe, is the drastically reduced volume of CO2 this leaves in the bloodstream( after breathing the pure O2) .... when you blackout, you may have depleted blood oxygen to the point that CPR may not even be successful. If you black out, not when you black out. I don't think there is a great body of skilled scientific research that has been done on this ( in-water effects, of breathing pure O2 prior, to Freediving to depths). There is a large body of research that was done on tech divers breathing O2 at 20 feet, in a relaxed, non-working mode. Much has to do with CNS clock which will not relate to freedivers, and much has been done on the pure tox from the absolute depth itself--this will apply to freedivers I don't know about that, I'd like to though ... got a reference?...and there is also alot on the very negative health effects of massively increasing oxidative forces in your body chemistry---the high O2 is a great way to create massive increases in free radicals ( the things we take Vitamin C and E to get rid of) and also a great way to cause lung inflamation and mild damage as far as I know that is only over prolonged periods of time.
3. Nobody NEEDS to stay down longer than 3 minutes. If you don't screw with your CO2 mechanism--the thing that allows us to have a sense of when we need to breathe to stay alive....Freediving is unlikely to ever cause you to blackout. You can see and do alot in 2 to 3 minutes, and this will not require you to dive without having any sense Agreed

Regards,
DanV

Don't let me stop you, but breathing pure O2 and holding your breath as long as you can will cause partial lung collapse. Just a little oxygen to breathe as you go off to sleep?is it always a good idea? ? Br J Anaesth Actually, not really a big deal if you are healthy. Smokers may want to pass on this activity...

Application to diving:

"Collectively, these studies offer good evidence that the amount of atelectasis during anaesthesia increases significantly with increasing FiO2 and that the use of oxygen 100% at any stage of an anaesthetic is associated with significant pulmonary collapse. Reducing FiO2, even by a small amount to 0.8, seems to be substantially better than using oxygen alone. " (from reference above).

I do my decompressions on 80% instead of 100% mostly for this reason.

I'm just saying...

I think you are misreading the study if it is creating that sort of a concern for you

I'd suggest that is not a good reason and that you'd greatly benefit from stepping up to 100%.

 

[lowviz]

That's interesting. I was thinking that if you saturate yourself, you're starting at a partial pressure oxygen of 1.0 (.2 x 5) and if you dive down 10 meters quickly, the gas in your lungs will go to 2.0...then 3.0 at 20 meters. How could deep free divers stay conscious?

The nitrogen in your lungs helps keep the alveoli from collapsing since your blood does not actively bind with nitrogen. With pure oxygen you can empty the alveoli to the point of collapse in areas of poor ventilation in your lungs. The external pressue experienced in breath-hold freediving causes lung collapse. Combining both sounds like a bad idea (to me). Thus, my post.

In case anyone starts getting excited about breathing pure O2 and then going underwater for 5 or 6 minutes, there are several huge problems with this......

Adding one more to your list...

I think you are misreading the study if it is creating that sort of a concern for you

I'd suggest that is not a good reason and that you'd greatly benefit from stepping up to 100%.

I agree with you about not being much of a concern during deco, overstated it a bit. My real reason for posting is given above. (I refuse to hijack this thread to the 80/100 debate, and suspect that you aren't going there either.) For me, accelerated off-gassing on 80% is a personal choice for several minor reasons. Debating these would be about as useful as restarting another MOF/NMOF thread. Been done, nothing will change.

 

[danvolker]

Thal,
My ideas of O2 toxicity are really from tech diving, where lots of research has been done. The freediving applications are only guesses..at least as far as I am concerned.
This is the kind of thing where if I was to be guessing wrong, I would want it to be on the safe side, not the blacking out side...

As to the specifics of your first point to me, there has been some research on pinnipeds and whales, where air is exhaled prior to the huge descents into deep ocean depths, and scientists postulated this was effective in both decreasing DCS potential and O2 tox....which would relate to your point. And there are human freedivers who are using a technique where after breathing up for a few minutes on the surface, they exhale most air from their lungs, and then do drops to 80 feet deep and far beyond....

In the study of Sperm Whales, they found that after the 3500 foot or so big drops these whales would do, after surfacing for a minute or so ( less time than required for hypersaturation/bubbling) they would drop back down to 40 feet or so and languish their for 10 minutes or so....essentially a deco stop !!!!

Regards,
DanV

 

[danvolker]

I agree with you about not being much of a concern during deco, overstated it a bit. My real reason for posting is given above. (I refuse to hijack this thread to the 80/100 debate, and suspect that you aren't going there either.) For me, accelerated off-gassing on 80% is a personal choice for several minor reasons. Debating these would be about as useful as restarting another MOF/NMOF thread. Been done, nothing will change.

So you read the Baker's Dozen post and still don't think 80/20 is the wrong mix for final deco on a tech dive? I won't argue it here, but I felt that post was dramtically effective in explaining why the benefits of 100% for deco made this the only real choice.

Regards,
DanV

 

[Hank49]

[*]I think part of the mechanism for the increased time prior to feeling the need to breathe, is the drastically reduced volume of CO2 this leaves in the bloodstream( after breathing the pure O2) .... when you blackout, you may have depleted blood oxygen to the point that CPR may not even be successful. I don't think there is a great body of skilled scientific research that has been done on this
[/LIST]Regards,
DanV

I would guess that in breathing up on pure O2 that you do decrease the CO2 dramatically. You do that hyperventilating on just air, which is dangerous also before a free dive. (remember, I wasn't free diving after this and PLEASE, DON'T ANYONE TRY THIS FOR FREE DIVING.. I was just experimenting to see if it would really lengthen my breath hold time....out of....boredom on a bad weather day)

But even though you breathed in pure O2, your body cells would still be producing and releasing CO2 back into your bloodstream, wouldn't they?
This is why I THINK my diaphragm began to spasm. I was experiencing the build up of CO2 telling me to breath, but I had enough O2 left in my blood and countered that demand which negated the urgent feeling of needing to breath.