Breathing pure oxygen

[rbsub]

I just wonder what happens with all the oxygen in your lung when you do such a record attemp like Tom Sitas did (Static with pure oxygen).

What I mean: If you inhale 5 l of pure oxygen what is in your exhalation? Still 5 l of "gas"? What about the amount of CO2 in the exhalation? 4 %?

Or is a lot of the oxygen only absorbed by the body and you can't even do an exhalation?

[Kimmo]

Nice question. I have been doing couple of tests with O2. After 8 min static I had CO2 so much that it took about 8 mins after the attempt that CO2 level was measurable with CO2 meters (PCO2 meter). O2 level was 100% (SaO2 meter). This test was done without proper O2 breathing before attempt. Only couple of breaths and then inhale.
So I do not recommend to test O2 static and specially O2 dynamic due risk of CO2 black out. CO2 black out is a scary thing. I have seen one and it is pretty difficult to rescue (tap, talk, blow or similar did not work).

- kimmo

[rbsub]

Oh, don't panic! I don't want to do O2 statics.

When you write about your CO2 level, does that means that the CO2 was not in your exhalation but a lot of it still in your body?

What happend with the O2? Did you exhale less air as at the inhale? Was the O2 consumed but not replaced be CO2? So there must be less air in your lung at the end of your breathhold?!?!?!?!

[sanso]

I wonder if the effect of change of volume is measureable.

To my understanding, when You inhale lots of O₂, You will obviously be able to supply Your brain with O₂ for a very long time. But while You do that, CO₂ is created and will accumulate in Your body, in the end creating the effect of a very hard CO₂ table, the used O₂ in Your lungs will be replaced by CO₂, but with increasing amounts of CO₂ in the lungs, the concentration of CO₂ in Your blood and thus in all other tissues will rise.

I have never breathed pure oxygen, so I can't speak from experience here. This is a theory only.

[Kimmo]

I just wonder what happens with all the oxygen in your lung when you do such a record attemp like Tom Sitas did (Static with pure oxygen).

In the lungs there will be less O2 in the end of the attempt. Body will use part of it. This is just a wild guess but I guess that it may be logical one?

What I mean: If you inhale 5 l of pure oxygen what is in your exhalation? Still 5 l of "gas"? What about the amount of CO2 in the exhalation? 4 %?

Amount of CO2 in the end of the attempt depends of time, body size and the absorbtion capability of the body and the temperature, I guess.

Or is a lot of the oxygen only absorbed by the body and you can't even do an exhalation?

Normally O2 level in the body is about 98% I guess, but by packing we can cheat SpO2 meters a bit (most of the meters may show 100% after full packing). And in my 8 min case SpO2 was 100% (like I mentioned earlier) and I had a lot of gas for exhaling. But maybe I measure also amount of O2 next time with a PO2 meter. I guess that the amount of O2 in the exhale will be pretty high because in the body it is still 100% anyway. Gas changements in the body is based on the pressures (from higher pressure to the lower pressure) if I can remember right.

- kimmo

[rbsub]

Originally Posted by sanso

the used O₂ in Your lungs will be replaced by CO₂

This means that if you use 20% of the oxygen in your lung, you will have 20% CO2 in your lung. Can't imagine!

[alexrom1207]

After David Blane did the pure 02 breath hold before Tom, I started looking into 02 because I thought it was interesting. Even while breathing 02, CO2 is the limiting factor in breath holds. Some scientists figured out that if humans could figure out a way to either rid themselves of CO2 while under water, or just eliminate CO2 production to begin with, a human breathing pure 02 would be able to stay submerged for nearly an hour. I thought that was a pretty cool study and wanted to pass it along.

[Kimmo]

My best guess is that it is possible to stay underwater for years and some people has already done it as I have read it right. Although it is not recommended in the pool. It is pretty dirty job.

- kimmo

[Nitas]

After a long O2 static you will definitely have less gas in your lungs than at the beginning. A friend of mine after 17-20 minutes O2 statics felt totally “empty”. Before the attempts I suggested him to exhale a little bit at the end to get rid of CO2, but he couldn’t - he felt as if he had no gas in his lungs.

I guess that the reason of it is that CO2 (which replaces O2 in your body) is much more soluble in the water than O2, so a lot of CO2 stay dissolved in your tissues rather than as a gas in your lungs.

The other reason may be that respiratory coefficient is usually less than 1. Normally, when your diet is balanced, it is about 0.8 which means that when you consume 1 liter of O2 then you produce only 0,8 liter of CO2.

Correct me if I am wrong.

nitas

[IronLung]

I have done a few statics on O2, my longest was 14:16. At the end my lungs felt as full of air as they did at the start. Alex, it seems you are thinking of something I've wondered about myself for a while. Where does C come from? Our body uses O2 and CO2 is the byproduct. How can that Carbon molecule be eliminated from the equation, if possible?

[Mullins]

The carbon atom comes from glucose

[apneaboy]

Originally Posted by Kimmo

Nice question. I have been doing couple of tests with O2. After 8 min static I had CO2 so much that it took about 8 mins after the attempt that CO2 level was measurable with CO2 meters (PCO2 meter). O2 level was 100% (SaO2 meter). This test was done without proper O2 breathing before attempt. Only couple of breaths and then inhale.
So I do not recommend to test O2 static and specially O2 dynamic due risk of CO2 black out. CO2 black out is a scary thing. I have seen one and it is pretty difficult to rescue (tap, talk, blow or similar did not work).

- kimmo

As a matter of interest what did you do to revive them. I have read about the complications of this before.

When i did an O2 hold at the end of the dive my bouyancy was slightly more negative than the start, presumably the Oxygen dissipated into the body. Only did one, no complications and one of my freediving buddies was a GP.

What additional safety measures and techniques could you put in place to make an O2 hold safer?