Breathing O2 during surface interval

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Hortondon

Registered
Messages
15
Reaction score
2
Location
Bend, OR
# of dives
200 - 499
I read an earlier thread about breathing O2 during surface interval after deep dives. I have been bent once without the need of a deco chamber. After an hour on the phone with DAN they saw no apparent reason that I got bent. No apparent mistake was made on my dive. A deco diver suggested breathing O2 during surface interval so I’m in the research mode. If I were to do this between deep dives as a precautionary measure and not to reduce surface interval time, what percent O2 is recommended and for what length of time.
 
Unfortunately that’s a hugely vague question, with many variables. How long a dive? What GF? How deep? Repetitive dives? Deco dive or within NDL?

if I breathe oxygen on the surface it’s 100%. Usually I try to just get on my rebreather so I waste less oxygen.
 
Some agencies recommend breathing o2 for at least six minutes before ascending after completing the last deco stop. I think that is suppose to perform the same purpose.
 
Unfortunately that’s a hugely vague question, with many variables. How long a dive? What GF? How deep? Repetitive dives? Deco dive or within NDL?

if I breathe oxygen on the surface it’s 100%. Usually I try to just get on my rebreather so I waste less oxygen.
Good point. I should have been more specific. I’m referring to non-deco dives of 100-130’ depth. Diving Nitrox. No more than 32% at 100’ and less than 32% on dives greater than a depth of 110’.
 
Good point. I should have been more specific. I’m referring to non-deco dives of 100-130’ depth. Diving Nitrox. No more than 32% at 100’ and less than 32% on dives greater than a depth of 110’.
Thrse are not "deep" dives. They are "normal" dives.
Hence if done to the boundary of NDL they give more Nitrogen to tissues with longer hemisaturation times, compared with deep dives, which mostly affect fast tissues.
Hence during the surface interval you need more time for offgassing.
Breathing pure oxygen can provide faster offgassing.
However after an "undeserved" DCS I would first look for a medical explanation of the event, before evaluating a strategy such as breathing oxygen before or after the dive.
Have you been checked for a pervious oval foramen?
 
Even if the benefit is dubious is there any reason NOT to breath pure O2, aside from the trouble and expense? There’s no side effects from it at around one bar are there?
 
If I were to do this between deep dives as a precautionary measure and not to reduce surface interval time, what percent O2 is recommended and for what length of time.
How high is up?

The higher the percentage and longer the period, the greater the safety margin. At least until all nitrogen is purged from your body, which takes around 2 hours on 100%. But that doesn't answer the question of when to stop. I'll give some made up examples. Is lowering your DCS risk from 1 in 10,000 to 1 in 50,000 worth 15 minutes on 100% O2? How about extending that another 30 minutes to lower it to 1 in 100,000?

Except you don't know any of these numbers.
 
Thrse are not "deep" dives. They are "normal" dives.
Hence if done to the boundary of NDL they give more Nitrogen to tissues with longer hemisaturation times, compared with deep dives, which mostly affect fast tissues.
Hence during the surface interval you need more time for offgassing.
Breathing pure oxygen can provide faster offgassing.
However after an "undeserved" DCS I would first look for a medical explanation of the event, before evaluating a strategy such as breathing oxygen before or after the dive.
Have you been checked for a pervious oval foramen?
Interesting you brought up the possibility of a pervious oval foramen. I know of someone that was having decompression sickness symptoms when she should not have experienced them and this was in fact the issue. After repairing the hole she no longer experiences these conditions. I have a regurgitative aortic heart valve that will one day need to be replaced, but does not currently affect quality of life. The cardiologist and cardiac surgeon do not believe this condition would be of concern and are more concerned about Oxygen Toxicity. However, finding a doctor that really understands diving has been difficult and I’m not convinced they are correct.
 

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