On Tuesday, July 10, 2001 10:17 AM, Chuck wrote:


Mike wrote:
> > Adding He to the mix will reduce the narcosis level, which
> > presumably would allow the diver to remain more alert and be able to
> > respond to the stimuli in a fashion significantly different from than if
> > they were "under the influence" so to speak.

> IF we assume that the narcotic gas is N2 and not O2.

I don't think that there's any doubt that higher than normal PPN2's induce
narcosis.  If that weren't the case then deep heliox dives would not have
been as successful as they are and have been.  What's often forgotten,
however, is that - as far as I'm aware - other gasses when breathed at high
partial pressures have an effect on our physiology, and hence our subjective
perceptions.  CO2, for example, is often quoted as 'boosting' the effects of
nitrogen narcosis.

Chuck!  While I don't doubt your suggestion that oxygen plays a role in
narcosis factors - mainly 'cause, although I've heard this mentioned before,
I don't know the mechanics of it! <BWG> - I'm not altogether sure how a
person would remedy the situation in open-circuit diving! :-)

At a personal level - and somewhere between being hyperoxic and hypoxic - my
brain needs all the oxygen it can get!  :-)