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Rick, Thanks for the input... > The symptoms of your "cold narcosis" are classic oxygen toxicity symptoms. > From what I gather, your question is why does it effect you at different > depths under different conditions? Besides all the literature which is > pretty clear on the fact that O2 toxicity does in fact affect different > people at diffrent levels and within a given person at diffrerent levels > on different dives, I think it's valid to say that O2 toxicity symptoms > are related to exhertioon levels. I think it was Bret Gilliam who > related an incident where he was quite deep and doing fine until he > made several hard kicks and whammy! Well, supposedly there aren't any consistent pre-convulsion symptoms of true acute oxygen toxicity, other than perhaps facial twitching and maybe the tunnel vision. I agree, perhaps these are realted to the same physiology/biochemistry as acute or chronic O2 toxicity, but why haven't these symptoms been reported on experiments looking at O2 toxicity. Most often, the reports say the subjects were feeling just fine, right up until they convulsed. The reason I'm reluctant to just write it off as O2 toxicity is that it doesn't seem to happen when breathing equally high or even much higher PPO2 while breathing pure oxygen - hence my belief in the synergistic effect with nitrogen. Also, why haven't I or anyone else I know ever convulsed when experiencing these symptoms? Perhaps we've all just been lucky, but your talking about hundreds of dives, which is far beyond what I would suspect "luck" would allow for. (BTW, for those who missed my original disclaimer, I don't subject my body to this level of abuse anymore - at least not underwater. I think anyone who tries this sort of diving without an intimate understanding of their own limitations is relying on luck to keep them alive - and people who rely on luck to stay alive are often weeded out by natural selection). As for CO2, I think it plays a big role in all of this - my weird narcosis feelings, O2 toxicity, "deep water blackout" (whatever that really means), and many other deep diving complications. Hence the importance of remaining relaxed as much as possible. > One thing I've always wondered about is the effects of immersion on the > subject. I was texted in a chambr for O2 tolerence to 2.0 for 5 in > and 1.7 for several minutes, but on real dives if my levlels reached 1.6 > then I would begin the niggles in the extremities, even at rest. This is a REALLY interesting, and I think neglected topic. There has been some work on the effects of immersion on hypothermia, metabolism, and DCS incidence, but I think it requires further attention. I notice MANY different feelings between being at depth underwater and being at simulated depth in a chamber, and I can't attribute all of these things to warmth and level of exertion. I'm pretty sure that research on this topic is being done in wet-chambers, but others on this forum would know about it much better than I would. Aloha, Rich
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