free diving on 100% o2

[lowviz]

Thanx.

 

[Mr Carcharodon]

question 1:
if i were to breath 100% o2 on the surface would i reduce my chances on a black out.
question 2:
if i dived down to 40 meters after having breathing 100% o2 on the surface could i suffer oxygen toxicity. as i swim down my body would use o2 and reduce the % in my lungs.

I would think breathing pure O2 would significantly increase the oxygen supply for free divers. There is something like 20 ml/dl of oxygen in arterial blood and about 5 liters of blood total so about a liter of oxygen total at a best case. Total lung volume is maybe 5 liters so without doing any detailed book keeping that seems like a lot more. Of course not all gas in the lungs is at interfaces where gas exchange can occur, and not all blood is arterial. Still it seems like a 2x increase in O2 is reasonable. This also ignores the role of carbon dioxide in black out.

Ox Tox risk seems low except possibly for many dives in a row. You wont get to 5 ATA for surface breathed gas unless your lungs compress to one fifth their initial volume which seems unlikely. That is a very different situation than breathing compressed gas at higher ambient pressure. Also recall that ox tox risk is a function of depth, and time, and the free dives are pretty short relative to the conventional limits

 

[Seaduced]

Isn't Shallow Water Blackout exacerbated by hyperventilating before a dive? The low level of CO2 fails to trigger breathing before the O2 is consumed causing the blackout. Wouldn't breathing 100% O2 be 'super' hyperventilation? Then again, maybe the CO2 would build up sufficiently because the available O2 level is well above normal.

Not intrigued enough to try it...

 

[cascas]

No nitrogen to offgas? The body will be SATURATED with nitrogen at the surface, at depth, the body and blood will still be carrying a lot of nitrogen and I see no reason why it would not diffuse into the lungs which would presumably be filled with oxygen (under this scenario). The nitrogen would diffuse from a high PP to a lower PP area, right?

Depends on how long O2 has been breathed doesn't it ?

 

[ianr33]

Depends on how long O2 has been breathed doesn't it ?

How much deco do you need to do after a saturation dive? Probably no more than a couple of days??