02 at depth ??

[Gilldiver]

Many of the plexiglass single place chambers have no mask and you are in a 100% O2 atmosphere and at 3 ATM/60'. The biggest risk is O2 fires so they are very picky about what you you have on in them or bring in with you.

But, As other have said, a quick visit to 1.7 to 2.0+ ATM will not kill you, say if you had a full gas failure and no option but deco gas to get up to deco depths. A number of years ago it was common practice to teach new commercial divers about Ox Tox by taking them to 60' in a chamber, putting them on 100% and make them do push ups till they toxed. It was to show the student that OxTox could sneak up on you without warning and what it looked like.

 

[AshTray]

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[Dr Deco]

Hello Readers:

Medical Treatment

Many readers have responded that elevated pressures of oxygen are administered to individuals undergoing medical treatment. In such cases, the treatment risks are considered justified proportional to the problem. Many things are done to ill people that would be considered unacceptable risks to those who in good health.

Multiplace chambers have attendants who can remove the masks (or head hoods) if a problem arises. in such cases, a good whack of the head against the camber wall is about the greatest risk. Drowning is not a possibility – of course.

Monoplace Chambers

In monoplace chambers, attendants will wait until the oxygen convulsion passes, and then bring the chamber to atmospheric pressure. Again, drowning in not a problem.

A few decades ago, monoplace chambers had a button that could be pressed to reduce the chamber pressure and bring the patient back to 1 ATM. Since convulsing individuals will close their glottis, one individual experienced a fatal lung overexpansion injury and died. The system was redesigned such that rapid venting to the surface was not possible.

Toxicity In Chambers

There are aspects of treatment chambers that appear to render high oxygen pressures more tolerable for patients.

- Chambers are warmer and oxygen is better tolerated.
- Exercise is eliminated. Arterial carbon dioxide is reduced and does not act as a vasodilator in the brain. Brain tissues thus “sees” less oxygen.


Dr Deco :doctor:

 

[T-Dog]

Here is a good article by DAN on OxTox.
DAN Divers Alert Network : OXTOX: If You Dive Nitrox You Should Know About OXTOX

 

[dumpsterDiver]

All this information was very interesting, however when I read it I feel that someone might get the impression that maintaining 20 feet while deco on 100% is really not THAT critical.

My personal feeling is that I do NOT want to be below 18-20 feet on 100% and I always have a SMB or a weighted rope or some other means to allow me to maintain my depth should I be distracted. I don't want to be doing a drifting deco and simply watching a depth guage without a physical, tactile barrier to help me avoid sinking.

 

[ChrisA]

Ok, this may be obvious, but I don't know the answer and I'm asking. Call me stupid if you must.

When doing decompression, I use 100% at 20' and above. I've been taught and told numerous times that breathing pure 02 deeper than 20' is a death sentence. SO, how do they get away with giving someone in a recompression chamber 100% at chamber depths of 66' ?

Thanks,

Dave.

I've been to lectures from people who run chambers and an MD who specializes in this. Simple answer. The reason divers die is downing when the high O2 causes convoltions and loss of concieness. It is not the O2 that kills them, it's the water. In a chamber an O2 hit is not so much of a problem it it happenthereis plenty of time to turn down the O2.

O2 is dangerous underwater because there is no warnning. One minute you are OK the next not OK so they teach us to keep a very wide saftey margin

 

[Couv]

Hello Readers:

snip....

Toxicity In Chambers

There are aspects of treatment chambers that appear to render high oxygen pressures more tolerable for patients.

- Chambers are warmer and oxygen is better tolerated.
- Exercise is eliminated. Arterial carbon dioxide is reduced and does not act as a vasodilator in the brain. Brain tissues thus “sees” less oxygen.


Dr Deco :doctor:

Plus *some* chamber operators were known to get a sleepy diver's attention by "ringing the chamber bell" with a small brass hammer. Wouldn’t want him to miss the onset of tunnel vision, twitching etc….

 

[ArcticDiver]

During a chamber dive we got to talk to the hyperbaric consultant and asked similar things.

He said routinely people were put at ppO2 of 2.1 or so in the chamber and he'd not yet in his career seen a convulsion.
However the reason 1.6 is chosen for underwater is due to cold, more exertion and as others have said, if they DO oxtox in a chamber its really not a serious problem and they'd just come off the O2. Also peoples tolerance varies so underwater partial pressures are chosen to err on the very conservative side to be "safe" for just about all members of the group not just most.

One of our group actually asked could he test a 2.0 or higher in the chamber just to see if he had issues or not but was told no.

That is quite a buggy post, eh?

 

[Diver Dennis]

Excellent question and answers. Thanks.