Newsgroups: rec.scuba
Subject: Re: ?diuretics and diving
From: wall@hel4.brl.mil (Jeff Wall)
Date: 10 Sep 92 09:55:41 EST
 <1992Sep9.012557.21801@mailer.cc.fsu.edu> <pl30r7c@twilight.wpd.sgi.com>
Distribution: world
Organization: U.S. Army Human Engineering Lab  Aberdeen, MD

In article <pl30r7c@twilight.wpd.sgi.com> story@sgi.com (David (Duis) Story)
writes:
>In article <1992Sep9.012557.21801@mailer.cc.fsu.edu> mayne@cs.fsu.edu writes:
>>In article <pk0rt8k@twilight.wpd.sgi.com> story@sgi.com (David (Duis) Story)
writes:
>>>
>>>The reduction in tiredness after using Enriched Air is believed to be
>>>due to the reduction in asymptomatic DCS, not increased O2 (which your
>>>body can't use anyways.)
>>
>>If it is true that using Enriched Air (aka nitrox) is reducing
>>"asymptomatic DCS" and this explains why some people feel better
>>after a dive using nitrox than they would have after the same
>>dive on air, I question whether the DCS is, strictly speaking,
>>"asymptomatic." Is tiredness just an unrecognized symptom?
>
>Yes.  It's not really "asymptomatic", if you recognize the symptoms.
>But folks are really really bad at recognizing the symptoms -- or is
>it admitting that they are DCS symptoms?  As proof, witness the
>incredibly long average delay between the last dive and treatment for
>DCS, as reported by DAN.

You always hear that denial is the first reaction to DCS symptoms, and I
beleive it.  This summer while diving off the coast of North Carolina I thought
I might have been bent.  After I had climbed out of the water and was standing
on the boat I started to feel a numbness and tingling sensation on the back of
my left hand.  My first thought was "OH SH*T", then I desided to try and relax
and think this through (I hadn't said anything to anyone else on the boat at
this point).  I took off my Darlexx and noticed the cuff was tucked under my
watch band on my left hand.  I had simply lost some circulkation and my hand
was falling asleep.  But I definetly went through the denial stage trying to
think of resaons why it couldn't be DCS.  BTW my dive plan was well within the
NDL of the EDGE I was using.

>>It is truely scary to think that we are routinely suffering
>>unrecognized DCS like that.
>
>Yup.  Makes safety margins a big deal.  Also makes me wonder about the
>1/2 of the day boat passengers who are sleeping on board instead of
>making that last dive of the day....
>
>>Are there long term consequences to such "asymptomatic" DCS?
>
>Commercial divers have shown long-term consequences of routine extreme
>exposures.  No such database exists for sport divers, though a few
>post-mortem studies of folks who were bent once or more showed
>scarring in key areas, believed to be the result of the bends.
>
>>This would seem to be an extremely strong argument for nitrox.
>>But why wouldn't just backing off a couple of stops on the tables
>>give the same benefit, if the well accepted theory of equivalent
>>air depths is correct? Of course we can't back off a couple of
>>stops on no-decompression dives.
>
>Sure, backing off is a good idea.  And you CAN actually back off a
>couple of stops on a no-STOP dive by making a "safety" stop.

While in North Carolina our group was talking to one of the boat captains about
DCS (he's seen his share) and he said he had NEVER seen a person get bent who
did a "descent hang" at 15'.  Now granted there is hard evidence here but when
you run as many trips a week as this guy did, you see your share of bends
cases.   Now "decent hang" is kind of flexible but while I was down there I
would hang for 15 minutes or more.  This seemed pretty incredible to me that of
the people who got bent NONE had done a hang for some reason or another.  Makes
me want to hang.

>Remember, EVERY dive is a decompression dive!  You are decompressing
>when you surface, aren't you?  You were supersaturated, weren't you?

Jeff Wall
wall@hel4.brl.mil