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>Robert
>good response Can you provide me the paper reference on the cig vs
>altitude, that is excellent information.
It was quite some time ago I came across that "tidbit". I believe it was
from either the Navy's Flight Surgeon Manual or the Aerospace
Physiologist's Manual.
What it was really refering to was the increased levels of carbon
monoxide in cigarette smoke. As most of you are aware, this bonds to the
hemoglobin in red cells irreversibly tying up receptor sites (normally 4
per hemoglobin molecule). Physiologically, since you have fewer available
sites, it looks to the body as if the air is "thinner" with less O2
available going into a normal number of hemoglobin-O2 pick-up sites (what
you really have is a normal concentration of O2 with a reduced number of
pick-up sites). It's a crude approximation, but "close enough for
government work". While I've not seen the Navy's undersea medicine manual
yet (that's next on my agenda) you're still tying up the same O2
receptors when you smoke and dive as when you smoke and fly...I can't see
how that's a good thing in either case. A red cell normal survives in the
body for about
120 days, so once you start to tie up receptor sites, the effects hang
around a bit.
We haven't even gotten into the physical effects on the lungs, like the
lose of the hair cells (cilia) that clean the debris out or the changes
in the cells ("dysplasias") and other "doc-speak" that means that the
cells start to look "funny" on their way to becoming cancerous (which is
decidedly *NOT FUNNY*).
>
>Also, I like some others find it difficult to state someone is in good
>shape when they do not exercise. Having been involved in diving and
>exercising the majority of my life I discovered that to be in shape I
>had to workout.
Aerobically conditioned people have more "efficient", toned
cardiovascular systems and O2 utilization. Just as a conditioned runner
may have a resting heart rate of say 47 compared to the typical person in
the 70's. They're more relaxed, they breath slower. They have a
physiologic reserve in the event they need to respond to a crisis.
My diving experience is so minimal at this stage of training, I shouldn't
comment further, but the above state of health sure sounds like an ideal
state of affairs at depth where you're trying to get the most "bang for
the buck" from a limited, finite air supply.
>
>Drugs and diving, we have a lot of information that reflects that
>decongestants such as sudafed may contribute to diving accidents, which
>we published three years ago. correct me if I'm wrong but drugs are
>effective by producing biochemical changes in the physiology, if this
>is true they have to effect divning safety one way or another. It would
>seem that unless a drug had a proven positive side effect on diving and
>diving related disorders that the RULE SHOULD BE DO NOT DIVE WHEN ON
>DRUGS AND MAEDICATIONS PERIOD. IF YOU NEED A DRUG FOR SOME REASON STAY
>DRY.
I'm in absolute agreement. Keep in mind that I'm a pathologist and flight
surgeon, not a pharmacologist, so I can't speak to the individual
chemical reactions, but drugs react in unpredicable ways at altitude and
depth. I'm not sure whether its a change in the relative gas saturations
or what, but the fact is that an aviator at altitude or a diver at depth
is physiologically, "altered" temporarily from the same person at sea
level at one atmosphere and the usual gas partial pressures. Drug testing
usually takes place where everyone else lives (sea level in open air) not
where aviators and divers live. We give sudafed to aviators *under
supervision* since it has the least effect on motor-sensory activities at
altitude. But an aviator doesn't have to contend with the diver's N2
narcosis effects at depth (or O2 toxicity at even deeper depths). Might
there be a synergistic effect between such drugs and ppN2 narcosis? Might
be, but I wouldn't what to be the diver to personally find out! Ain't
worth it! (as a newbie "dry-behind-the-ears" diver I've heard the one
about the guy who tried to buddy breath with a grupper!)
I'm personally increasing my excercise program since I took up diving to
shed a few more pounds if only to hold on to less N2 and carry less lead!
(the additional conditioning reserve wouldn't hurt either)
Take care.
Robb Wolov
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