Oxygen Toxicity...

[mars2u]

I've recently become Nitrox certified and was unable to get an answer from my instructor and other places concerning oxygen toxicity.

My question is as follows:

When can you continue to dive after experiencing oxygen toxicity?

Let's imagine that you feel fine after a "hit" and are not any worse for the wear, would it be 24hrs. per the Nitrox tables? As we all know, this is very different than getting the "bends", but it seems to me that if you were feeling fine and since the Nitrox tables basically state that your PO2 level readings start over after 24hrs., would this not be the case?

Any personal experiences or thougths that you could share?

uke:

Hope this is the right place to be asking this.

 

[dmdalton]

I would want to find out how and why I got hit before I dove again.

Dave D

 

[mars2u]

Well that's understandable. Again, all the info I have is based on my training from this last weekend. I didn't want the thread to imply I had encountered oxygen toxicity so sorry for the confusion, if any. I just find it interesting that many non-nitrox divers are apprehensive to use it because of the toxicity factor.

I'm just trying to learn more about this.

I did get a pretty interesting e-mail from a diver so here's the info:

"Oxtox was common in the Brit navy prior to the end of WW II, because we
wouldn't give them helium for deep diving. It was also common among the
Brit "frogmen" who were using oxygen rebreathers. Their procedure was to
keep the diver out of the water for 24 hours because that was how long
the headache took to wear off. They were also very careful on subsequent
dives because they observed that oxtoxed divers were increasingly
sensitive to further hits if they went deep too soon.

Oxtox has been rare in the US, as we started using helium in 1919. As a
result, it is here still shrouded in ignorance, myth, and fear."

 

[dmdalton]

Keep your PPO2 level below 1.4 for the working portion of the dive (better 1.1-1.2) and the deco portion 1.6 and you should avoid it. Better to figure ways to avoid it than figure how to recover from it.

Dave D

 

[jbd]

an interesting e-mail that you recieved. Maybe more of the resident Brit could elaborate more about this if indeed they have more info based on history thatn we have here in the states.

Just based on what you recieved in that e-mail it would seem that possibly waiting 48 to 72 hours would be prudent for the recreational diver.

 

[mars2u]

Yes, I'd like to get more info, especially from those it's happened to and/or know someone it's happened to.

 

[rmediver2002]

We used to do O2 tolerance testing to determine suceptability to central nervous system oxygen toxicity, it was determined after quite some time running these tests that individual variations from day to day would determine suceptability. (Any one could get an o2 hit on any given day) These tests were determined to be completely inconclusive and are no longer conducted

Another finding was that below a oxygen partial pressure of 1.3 there was no incidents of O2 tox.

As far as waiting period after a hit, in the chamber (when more time at depth is needed for decompression or treatment the protocol is to go off o2 until symptoms subside (unless the first symptom is convulsions), wait an additional 15 minutes and start the treatment at the point of interuption.

The NOAA dive manual has a table for determining one time exposure and 24 hour exposure periods for O2, might be worth a read...

Jeff Lane

 

[rmediver2002]

During surface decompression in the chamber, symptom is most often twitching of the facial muscles.

The diver is breathing 100% o2 at 40 feet sea water... or 2.21 pp O2

Jeff

 

[boomx5]

Have you ever taken an O2 hit, or seen someone else take one on a working dive? Also what's the lowest ppO2 that you have heard anybody tox from?

 

[Doppler]

Hi Mars: Great question... strange because it brings up some very interesting discussion material!

I don't want to assume that your question is regarding CNS oxygen toxicity. Because if it is, I'd am surprised and dismayed to think that your nitrox instructor did not make this clear during your course. CNS toxicity kills. Plan carefully to manage the risk... that's the purpose of a nitrox class. Discussions about how long after an episode can one dive indicate an unrealistic understanding of the issue... sorry to rant.

My experience with in-water episodes with this unhappy type of episode is two buddies dead zero survived. The straight facts are that the changes of surviving a Tonic-Clonic event while inwater on open-circuit-scuba and in a recreational community are very slim... even in a "technical" environment (as was the case with my two friends) the chances of survival are really not much greater. So the amount of time to rest before diving again is academic.

The good news is that as long as a diver stays within the limits set for us by NOAA and now almost universally accepted as appropriate, CNS toxicity is highly unlikely.



Pulmonary toxicity is another issue. It is highly unlikely that you will ever run across this type of oxygen loading as a recreational diver; however, you should be familiar with its causes and its signs and symptoms. I think Dr Deco will be able to answer the question of Pulomonary or Whole Body toxicity so....


take care...

DD