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Am I to understand that U have abandoned the view that
divers build up a resistance to narcosis?
Safe bubbles
Esat Atikkan
> --- "Michael J. Black" <mjblackmd@ya*.co*> wrote:
> > --- PVanscoik@ao*.co* wrote:
> > > Dr. Black,
> > > i would love to see some real data - repeat
> > hyperbaric chamber dives
> > > on the same cohort & test scores. are we
> debating
> > facts or opinions?
> > 
> > Peter,
> > 
> > Here's some real data, albeit a small study, from
> > the Journal of
> > Undersea and Hyperbaric Medicine 1995
> Mar;22(1):41-9
> > Dissociation of
> > the Behavioral and Subjective Components of
> Nitrogen
> > Narcosis and Diver
> > Adaptation, by Hamilton K, Laliberte MF, Fowler B
> > (DCIEM):  Abstract:
> > 
> > We investigated adaptation to nitrogen narcosis by
> > compressing 11 highly
> > experienced divers in a hyperbaric chamber to the
> > equivalent of 54.6
> > meters of seawater once a day for 5 consecutive
> > days.  The behavioral
> > component of narcosis was assessed with a serial
> > choice-reaction time
> > (RT) task, and the subjective component with a
> > global magnitude estimate.
> > Supplementary magnitude estimates were obtained
> with
> > adjectives describing
> > work effectiveness and body sensations.  The
> results
> > showed that there
> > was no adaptation on the RT task, although
> learning
> > was evident.  In
> > contrast, the global estimate dissociated from RT
> > and showed clear adap-
> > tation by Day 3.  The work effectiveness
> adjectives
> > followed RT and did
> > not show adaptation.  Some body sensation
> adjectives
> > showed clear
> > adaptation, but others did not.  These results
> lead
> > to the conclusion
> > that the anecdotal reports of adaptation by divers
> > can probably be
> > attributed to the subjective rather than the
> > behavioral component of
> > narcosis.  Dissociation of these components
> suggests
> > mediation by different
> > brain mechanisms, and it is speculated that the
> > gamma-aminobutyric acidA/
> > benzodiazepine receptor complex, which has been
> > implicated in both the
> > anesthetic and anxiolytic properties of agents
> such
> > as nitrous oxide,
> > may be involved. (end)
> > 
> > In other words, there is some degree of adaptation
> > to nitrogen narcosis.
> > Divers think they're better after repeated
> exposures
> > but that's about it.
> > 
> > 
> >
>
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> 
>
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