On Sat, 27 Apr 2002 23:58:39 -0500, Crusty Russ <[log in to unmask]>
wrote:

>More than conjecture? "Lots of known theory about bubbles." ...known,
>tested, and 'proved', but none about immersion in hot water promoting
>DCS.
>
>"In this case, there were lots of observations of liveaboard divers week
>after week in hot tubs.  Yup.  SOME of them got bent."  ...and some of
>them got bent who were merely standing near the hot tub...cause?
>coincidence? Who knows?  It wasn't a study of hot water immersion and
>DCS.  Is there a link?  That's what I want to know.

Then you'll NEVER know, Crusty.  No ifs or buts about it.  Statistically,
it's damned hard to isolate the causal "factors", even if there are
millions of cases, because of "interactive" and "confounding" effects
<technical terms>  All of us will be dead long before there'll be data
(even uncontrolled ones not good for a rigorous stat study) for a
million BENT divers.  ;-)

The methods of ASSERTAINING the factors by DATA in designed experiments
are what we statisticians spend years to learn how to do ptoperly
and correctly.   That's the basis for my saying "you'll never know",


>"That were the recommendation by DAN, on the observation and
>recommendation of their Docs."  ...like I said, conjecture.  ...but
>there's nothing wrong with 'better safe than sorry.'

Exactly.  In the absence of scientific proof, that's the best you
can do, with plenty of OBSERVATIONAL evidence from which it is
impossible to isolate one factor from another.

That reminds me the La Ceiba hotel in Coz used to have a HOT POOL
next to the bar on the beach.  :-)   I even met a guy who was BENT
and hobbling around until he oculd fly home.  He said he was bent
(the hyperbaric doc said) because of the hot pool.  It could have
been some drinks, it could have been all the other contributing
factors to the bends also.

But the FACT is that La Ceiba no longer has that HOT POOL.  Call
it "better safe than sorry" if you will, but that's how ALL
the recommended prevention of DCS are.  They are ALL conjectures,
but supported by theory and observational data, but NOT established
by any "good scientific study" or "statistical study" of proof.


>Let me rephrase my statement above to make it more clear what I intended
>to communicate.
>
>"The item about hot showers and tubs was not mentioned BY THE DAN
>DOCTORS in any relationship with the other known causes of decompression
>sickness listed, but was for information to those interested."

That's not true, if you mean DAN DOCTORS in all their investigative
reports on DCS.  The ones on liveaboards to investigate the HOT TUB
as a contributing cause certainly placed their emphais on the HOT
TUB and HOT SHOWERS, to have given their caution to the boat captains
to pass on to passengers!


>They did not
>state that immersion in hot water after diving promotes DCS.  They
>provided a 'better safe than sorry' recommendation.

Who are "they"?   Given that there is no "proof", what you say they
say is no different from what they say about slow ascent, or waiting
24 hours before flying (after a repetitive liveaboard dive week),
or almost ALL of they other things "they" said.

So are all those "factors" listed in the webpage by Dr. Quack, but
those factors he listed ARE known to be contributing factors (just
not in his 62 cases) in the observational-but-not-proven sense!


>I'm not taking
>sides here, I just want to know if there is any more evidence one way or
>the other.

I know you don't mean it to be a trick question, but it's not a
proper one to ask, because DCS, by its very nature is RARE, no matter
what the cause may be.

There are thousands more times divers who take hot showers after
diving and didn't get bent than those who were bent after a hot shower
or hot tub.

The same is true for ANY other DCS-contributing factor YOU may believe.
That's why I asked WHICH one


>Searches on this question turns up little real information.

But you did come up with two of HUNDREDS of OTHER THEORETICAL
evidence to SUPPORT the observational evidence of cases of bent
divers who had used hot tubs/showers too soon.


>One study
>on one of the boards did indicate that Doppler-detectable gas bubbles
>were released into the blood stream after rewarming, but that this did
>not provoke decompression sickness. (Dr. Michael Powell, NASA
>physiologist, PhD)
>
>Dr. Richard Vann, in the chapter on Mechanisms and Risks of
>Decompression in Bove's 'Diving Medicine", p.156, under perfusion
>effects - describes warm water immersion increasing nitrogen elimination
>and decreasing DCS from 90% to 20% in oxygen breathing before altitude
>decompression. Exercise reduced the incidence from 63% to 0%. Cold water
>immersion caused an increased incidence of DCS.
>
>I believe the jury is still out on this one.

Yup.  And the jury will be out for the next 100 years -- not only on
THIS ONE, but on all the other "known" ocntributing causes, by your
definition of "jury is out".   Actually most of that jury is "out
to lunch".  :-)


>> Can you find any evidence of "good studies" on bubble theory, rapid
>> ascents, and microbubble theory, or most of the OTHER theories that
>> dive medicine doctors and physiologists recommend to divers NOT to do?
>
>At least there are 'studies' targeted at supporting the theories.  "I
>can't find any evidence in the form of *delete*good*delete* ANY studies
>that would indicate one way or the other."  I assume you can't find any
>either...proving it one way or the other.

That's precisely my point.  You don't NEED any definitive scientific
proof and you'll find a definitive one, for the paucity of data.


>> Now you've got me curious.  Do you believe in ANY of the recommendations
>> to avoid DCS?   Have you seen or scrutinized any "good scientific
>> studies" before you adopted them?
>
>Yes I 'believe' many of the recommendations to avoid DCS and have
>'faith' that that the scientists are doing 'good' work.  However,
>whenever possible, I like to question popular theories as any curious
>person would.  I don't believe in 'blind faith', I prefer faith with
>content.  That's what I base the limits that I try to stay within.

All good and well.  So, why did you pick out HOT TUB as your target
for "no evidence" and ask for "good scienric study" and not subject
your other "beliefs" to the same criterion?


>As for the whole issue with hot showers and tubs, you will never catch
>me dead or alive in a hot tub after diving or otherwise, except to rinse
>off my gear in Coz.

Not meant to wish you ill, but if ole Crusty should get bent under
a hot shower that he talked about, then it STILL wouldn't prove
anything, but it would merely add one more observational evidence to
the probable "contributing cause".

That's the way it is.

>Since I don't dive cold climate or cold water, I
>don't ever expect to experience much of a temperature differential
>anyway.

Don't be so sure.  The bent diver in hot pool in Coz I mentioned,
and the bent divers in hot tubs on liveaboards were all diving in
WARM WATER.

That boils down to one's own risk-assessment and judgment.  I love
HOT TUBS, especially my jacuzzi in "my" Cozumel penthouse.  :-)
But I couldn't jump into it immediately after any dive, and by the
time I get back there, it would have passed the 30-minute wait
recommendation anyway.  But on liveaboards, even though the urge
to jump immediately into a hot tub is most tempting, I refrain from
doing so, for the observational evidence and caution I've seen
and read, and "better safe than sorry" on those DCS theories I
belief.

What I DON'T believe, and had good supporting reasons NOT TO,
is anything the Cockroach computer says about dive safety.  <BWG>
<Obligatory tribute to Mr. Cockroach :-)) >

> As a certified ice diver, YMMV :-)

That's why I quit ice-diving.  :-)  Actually, the ice-divers DO
immediately pour HOT WATER on their bodies immediately after a dive.
But then, the ones I've seen couldn't have accumulated much bubble
at 20 ffw for 15 minutes.   I only did 10 minutes, the minimal
requirement, cuz I was wearing only a 1/4" wetsuit.  :-)))


>As far as the recommendations based on conjecture go for hot showers,
>waiting 30 minutes is an easy one for me since it usually takes at least
>that long to climb the ladder, doff the and stow the gear, dry off,
>shoot the merde with the other divers, rinse the camera and celebrate

Very true, and I've dived the CAIV02 with Crusty to know that by the
time he had his Henderson-GOLD off, I would have already eaten my
refreshments, taken a nap, and asked if anyone was ready for the
next dive.  :-)

>Do we disagree on any of this?

Not about YOUR showering habits on liveabords, but just about everything
else.   :-)


>> Changing gear ...
>
>If you like and no one else volunteers, send me the pics, you've got my
>address.  I can put them up with the CAIV2002NEDfest logo on our site
>and later move them to the trip report area.

Thanks.  Jeff is the only one (other than us) who has seen his pic
with the colorful BACK-SIDE because his mail didn't bounce.  :-)
Since I won't have time to do anything much today other than packing,
and last-minute chores (till June? <BG>).  Besides, you would be
the perfect person to put the PREVIEW of your work of art on your
webpage!

I look forward to peeking at it while I am at the internet cafe in
Cozumel.  :-)

>Jeff if you've got you ears on, I can send you an extra weight belt and
>some lead to wear around the house till you replace all that blubber.
>:-)

Jeff ears have grown back also.  :-)   BTW, he had his robe on, and I
told him he needn't take it off for the pose since the shirt is plenty
big.  Sure 'nuf.  Jeff immediately tug at the front of the shirt sfter
he slipped it on and said, "Yup, there's room left for the tank and
BC".  :-)

>How long will you and Sue be in Coz?  I assume you'll be staying in your
>usual room overlooking the pro dive pier.  If I don't talk to you
>before, have a great trip!

Till May 9, then back home on May 10 to change clothes for the next
trip starting May 11.  :-)

BTW, my RFLING address will receive but refused to SEND or REPLY
(as it happened before), so until further notice, anyone who wants
to contact me for anything the next month, please address your email
to BOTH     RFLINGclemson.edu   and   [log in to unmask]
(5 other BobLings beat me to Compuserv.  :-)  Now I know when someone
flames BobLing, it must be one of those five!!!)

I MAY be able to read/send email from the cs.com account while I am
in Coz or travelling else.  Not sure till I try.

-- Bob.