O2 after dive

[vincent54]

Are there any benefits of breathing pure 02 after any SCUBA dive. I notice that some divers switch to 02 at shallow depths in their deco dives, but what about shallow(less than 100') Other than cost, what would be the negatives of breathing pure 02 at surface immediately after the dive? I also notice athletes like to huff 02 after a strenuous activity, so why not apply this to dive activities. In emergencies, 02 is one of the first things done if there is a question of DCS, heart, or any other thing for that matter. Could it help get rid of the Nitrogen in blood faster, give me super powers, or just give me one more piece of equipment to trip over? I am sure it's been covered before, but haven't found it yet. Thanks

 

[Wookie]

I'm not a doctor, nor do I play one on TV, but the spearfisherman's term for it is "washing out", and the use of O2 at 20 feet and on the surface is part of their procedure after a deep bounce dive. It seems to work for them. After a particularly strenuous working dive, when I get this funny rash on my right forearm, use of surface O2 seems to make the rash go away. Yes, I know what the rash is. Yes, I know how to stop the rash. I find that use of surface O2 makes me think more clearly if I know I've loaded up on N2 in a way my computer can't account for.

 

[Steve_C]

I have had the same thought but no answer. You can get too much O2. If you breathed pure O2 for your SI and after you last dive that might be pushing your overall O2 exposure. Just another question to add to the mix.

 

[Doppler]

I have had the same thought but no answer. You can get too much O2. If you breathed pure O2 for your SI and after you last dive that might be pushing your overall O2 exposure. Just another question to add to the mix.

Oxygen at one bar/atmosphere is going to take a long, long time to "PUSH" any limit. Pulmonary exposure for oxygen at that level is one OTU per minute... the REPEX tables "allow" more than 800... 350 for multiple days.

... Could it help get rid of the Nitrogen in blood faster... Thanks

I wrote an article about breathing O2 to lessen "no fly time" after staged decompression dives... this application is clearly outside the one you're asking about, but all things being equal, surface "therapy" with a spell on oxygen could buck you up!

 

[Akimbo]

… Other than cost, what would be the negatives of breathing pure 02 at surface immediately after the dive?...

As mentioned, the negative is mostly exceeding OTU limits (Oxygen Toxicity Units) resulting in what is basically a lung irritation that is easily healed. The consensus I have read is the efficacy of breathing pure O2 on the surface as a prophylactic treatment against DCS is fairly limited where pure oxygen at 15-20' is much greater. You might find this thread interesting:

http://www.scubaboard.com/forums/diving-medicine/402490-increasing-safety-margin.html

Any decent multi-gas Nitrox computer will track your OTUs if you decompress on O2 or complete a dive and make a second dive to 10-15' on O2 as a reped “safety stop”. The computer will give you “Nitrogen credit” towards repeds in both cases. I don’t know of any computers that track OTUs for breathing O2 on the surface.

Another strategy is to track your OTUs manually and don’t tell the computer that you switched to pure O2. This would not reduce your decompression or safety stop time but adds what I understand to be a significant safety margin.

 

[vincent54]

Thanks for the link. Cheers

 

[Dr. Lecter]

Oxygen at one bar/atmosphere is going to take a long, long time to "PUSH" any limit.

But it seems safe to assume that both time at 1.0 pO2 after the dive should be added manually to CNS calculations (0.33%/min isn't huge, but it does add up and I'm not aware of any computer that has a SI O2 function) and no SI half-life/new 24 hr count can start until you're off the surface O2.

 

[Doppler]

But it seems safe to assume that both time at 1.0 pO2 after the dive should be added manually to CNS calculations (0.33%/min isn't huge, but it does add up and I'm not aware of any computer that has a SI O2 function) and no SI half-life/new 24 hr count can start until you're off the surface O2.

It would be safe to make that assumption but bear in mind three factors:

1) NOAA limit for CNS at 1.0 bar is 300 minutes (single exposure and 24-hour)

2) Few people would breathe from a demand regulator for five hours (300 minutes) (especially on the surface!)

3) Constant flow face-masks, which are usually set at a constant 4-6 litres per minute mass flow, are around 50-60 percent efficient (at most... hence a PO2 of 0.6 which is well below tolerances for CNS (but not pulmonary if the user spends 12 hours or so on the device))


Combined, these three factors seem to reduce the initial assumption (CNS Toxicity) to a moot point.

A P.S. Added later... when else would a post script be added (!?) I am unaware of ANY CNS episodes at 1 bar ambient DRY environment. I will research to see what I can find but it seems unlikely... so make that FOUR FACTORS to bear in mind! LOL

 

[Dr. Lecter]

I only mean to raise it as an issue if one is planning a repetitive staged deco dive after SI O2. That is very unlikely if you're doing it to get on a plane sooner, but quite possible if you're doing it as a form of washing out like Wookie mentioned.

 

[BRT]

But it seems safe to assume that both time at 1.0 pO2 after the dive should be added manually to CNS calculations (0.33%/min isn't huge, but it does add up and I'm not aware of any computer that has a SI O2 function) and no SI half-life/new 24 hr count can start until you're off the surface O2.

Didn't some UWATEC nitrox computers have an error in programming that assumed continued nitrox use on the SI thus reducing the divers apparent nitrogen load? Seems there was a recall over that.