Oxygen Toxicity vs Narcosis

[Chris66]

My dive buddy and I were on a wreck dive. We were using a 32% mixture and had a safety limit of 100 feet with 110 feet giving us an O2 pp of 1.39. He went down to 123feet for about a minute and came up to 110 feet for about another 5 mins. He then joined me at 100 feet. When we got to the surface I berated him for breaking our dive plan however he told me:" It gets worse". He told me that at 123 and 110 feet he began to feel seasick (nausea and just a little wierd). My reponse to him was that he had experienced O2 toxicity. He feels that it was narcosis. His computer stated his PO2 max was 1.53

I know he was not down there for very long but it seems to me that the symptoms are classic for O2 toxicity although I know that at depth either could have been an issue.

Any thoughts

Chris

 

[rockjock3]

**************Disclaimer*************I am not a doctor. I think he might have been feeling some O2 tox effects. Just because you go past 1.4 doesn't mean it happens to you (we deco at 1.6), but it also depends on duration of exposure and amount of work. O2 tox doesn't always start with convulsions and can have symptoms. Here are some symptoms from the DAN website:

"Some symptoms of CNS oxygen toxicity include flashing lights in front of the eyes, tunnel vision, loud ringing or roaring in the ear (tinnitus), confusion, lethargy, a feeling of nausea or vertigo, areas of numbness or tingling, and muscular twitching, especially of the lips."

Narcosis is more like being drunk (without the worshiping the porcelean god part). That would be more likely if he felt more at ease and had a hard time concentrating. It would not be out of the question that he was feeling a little of both, but I lean more towards the O2 with the nausea. Nobody, but a dive medic could be really sure, and even then some symptoms can cross over, so that might not be a 100% accurate diagnosis.

More importantly you did what I would have done, get on your buddy for breaking the plan. If you set up a plan and you both agree then you both dive it, unless you make a joint decision during the dive and you both follow it. What would have happened if he really was deep enough and suffering an O2 hit and had gone into convulsions. Now you have to make the decision to possibly risk your life going down to try and save him, or you have to go back to the boat to either change tanks to an appropriate gas/send another diver to go and retrieve the body.

 

[Thalassamania]

Taking EAN-32 to 123FSW is not a big deal. That said, breaking an agreed to depth limit on a dive is. Divers who can not control their depth should not be diving EAN.

 

[Rick Murchison]

Taking EAN-32 to 123FSW is not a big deal. That said, breaking an agreed to depth limit on a dive is. Divers who can not control their depth should not be diving EAN.

I concur 100%.
Thanks, though... I'm teaching Nitrox tonight & will use your example as a no-no.
Rick

 

[Walter]

I agree with Thal and Rick.

 

[biz_nate]

I agree with Thal and Rick (and thus, Walter). Though I too am neither a doctor nor an expert on O2 tox.

From what I can make of the times and depths of your dive profile, your buddy probably wasn't exposed enough to worry about toxing.

This leads me to another question though- the material I've read says that if you suspect you're toxing, to abort the dive immediately. That much is clear. What I'm unsure of, is whether the symptoms you've experienced to lead you to that conclusion would persist throughout the remainder of the dive? In other words, if this buddy was really showing early signs of tox and he came up a bit (say from his 123 ft to 80 ft), would he still feel the same symptoms? My suspicion is yes, since he's still contributing to his per dive CNS exposure, but I can see possible arguments against this. Anyone know?

Whatever it was that he was experiencing (could very well have been narcosis), it was absolutely wrong of him to exceed your planned max depth. He exposed not only himself, but you, to risk you had agreed (together) not to incur.

 

[rockjock3]

My understanding is that the effects should decrease (depending upon the profile) as you decrease your depth. Tox is combination of exposure time, ppO2 and will be different for each person due to their physiology. If somebody takes an "almost hit" as in not convulsing from a short time at a dangerous pp02 then they should abort the dive, but they should also feel the effect lessen/disappear as they ascend.

 

[aowdan]

rick, check my "spelling" but isn't there a acronym for o2 symptoms?

CONVENTID

CONvulsions
Visual disturbances
Ear disturbances
Nausea
Twitching
Irratability
Dizzyness

to me it sounds like a mild hit, but i'm no expert, i'm just learning the ropes here.
i don't remember CONVENTID from nitrox, just from my AOW(strange huh?)
dano

 

[Chris66]

Thanks to all, actually his mild nausea continued through the remainder of the dive including his safety stop and well into his surface interval - at an hour into his surface interval it finally cleared but we both decided a second dive (even though it was only to be a 40 ft reef) was a no-no and so we sat it out. I guess I am just confused as like posters have stated a hit should be a function of time and depth and 1 min at 123 feet and a total of 5 mins at 110 feet should not have led to the hit and yet clearly he felt the nausea that lasted for over and hour into the surface interval.

 

[Dr Deco]

This is less of a question of physiology and more one of poor dive technique.

PS. Many people who never dive experience nausea.