Mailing List Archive Mailing List Archive
On 29 Jun 1994, HeimannJ wrote: > Having read Tim Olsen's msg, I'd like to repeat a claim about narcosis that > makes sense to me. I have often heard the claim that narcosis can be > overcome by repeated exposure to depth, and I have found this true. I felt > strongly narced the first time I went past 170 (in cold water), but now can > function reasonably well at this depth, at least in open water - I don't > _feel_ very narced. > > Now for the claim - this effect is not due to any reduction in narcosis, but > rather is adaptation to it. [etc...] This is an extremely interesting point which I've wrestled with for quite some time. In my experience, I would have to say that I completely agree with you. My discussions with other deep divers led many of us to conclude that narcosis "adaptation" is simply an acquired ability to deal with an impaired brain, rather than a true physiological adaptation. But now I'm not so sure. The last conversation I had with Sheck Exley was on this very topic. We had agreed that there seemed to be a "long-term" component and a "short-term" component to narcosis "adaptation". The long-term component is why I never feel any strong narcosis sysmptoms shallower than 165' or so any more, even after a year of no deep diving, and even though I was hammered during my first few dives to 130' way back when. The short-term component has to do with the fact that, over the course of a week or so of diving past 200 feet every day, I become progressively more "sober" at depth with each successive dive. It is fairly well documented that nitorgen, which is a depressant, can counter-act the effects of helium (HPNS), which is excitiatory. Sheck told me that his HPNS symptoms on his ultra-deep dives were WORSE after he had acquired the short-term narcosis adaptation through deep-air work-up dives, than they were when he had not acquired the short-term aclimation. He told me that Bill Hamiton had proposed an explanation which involved true cellular-level aclimation to account for Sheck's observations. I had intended to follow-up on it with Sheck to understand it better, but, of course, we'll never have that chance. Not to drift too far from the topic at hand, but I'm compelled to underscore the tragic fact that when we lost Sheck, we lost not only a great explorer and role-model, but we also lost a walking encyclopedia of real-world experiences that will not likely be equalled by anyone in the near future, if ever (with the possible exception of Jim Bowden). Incidently, there is a nice, short piece on Sheck in the latest Ocean Realm. Well, I guess i've said enough. Aloha, Rich
Navigate by Author:
[Previous]
[Next]
[Author Search Index]
Navigate by Subject:
[Previous]
[Next]
[Subject Search Index]
[Send Reply] [Send Message with New Topic]
[Search Selection] [Mailing List Home] [Home]