From: ((Steven B. Harris))
Subject: Re: "Liquid" Oxygen in the film "The Abyss"
Date: 14 Jun 1995

In <feuerDA2Mz6.ILs@netcom.com> feuer@netcom.com (Ted Feuerbach) writes:

>: It's not obvious to me why
>: these would be of use in really deep diving however.  The emboli which
>: form on ascent (bends) for spontaneously in tissues, and would not be
>: stopped by having the lungs full of fluid.
>
>:                                                   Steve Harris, M.D.
>
>The basics (figures are not exact, but close):
>
>The main issue is not so much Decompression Sickness (The Bends),
>although dissolved gasses in the body tissues are an issue.  The
>tendency of the inert components in the gas that we breathe becomming
>an anesthetic gas under high pressures is.  Nitrogen becomes an
>anesthetic at depths of greater than 100 ft (Nitrogen Narcosis),
>and causes extreme stupidity in most people in depths greater
>than 150' (6 atm).  I think the depth record for breathing
>normal air is 464 ft.  My personal limit is about 165 ft.
>
>At greater depths, Helium (or even Hydrogen) are used to replace
>the Nitrogen.  These too become an anesthetic, but only at higher
>partial pressures.  Oxygen also becomes toxic at high partial
>pressures, so as depth is increased, the O2 concentration must
>be lowered.  Pure O2 is toxic (for extended periods) at less
>than 2 atmospheres (about 30 ft).  Commercial divers in
>depths of greater than 600 ft may use as little as 0.5% O2
>in their breathing mixture.  Normal air is about 26% O2.
>Note that 1% O2 and 99% Hydrogen is *not* an explosive mixture.
>
>Another issue is compressability.  To use a gas at ambient
>pressure in the scenario in this movie (20,000 ft off the
>Cayman Wall) you would be at about 600 atm.  Therefore,
>every breath you took would be about 600 Liters of gas
>at the surface!!!
>
>An uncompressable liquid with even a small amount of O2
>dissolved in it would work at these depths.
>
>Now, as to the emboli formed.  Decompression Sickness (DCS)
>is caused by the inert gas (normally nitrogen) that becomes
>dissolved in the tissues by breathing gas mixtures at higher than
>normal pressures.  If you surface too quickly, your body does
>not have enough time to offgas and the nitrogen comes out of
>solution in your  bloodstream and tissues like a shaken soda bottle.
>Not pleasant.  If you are breathing a liquid, there is
>no inert gas (the liquid takes its place) to become dissolved
>in the tissues.  Dissolved gasses are not actually a limiting
>factor with depth, though.  One can always simply spend more
>time in a hyperbaric chamber while the outgassing takes place.
>This process sometimes takes *weeks* for commercial divers.
>
>Ted
>--
>Ted Feuerbach                                  feuer@netcom.com
>Feuerbach, Witthaus & Associates       Voice/Fax (415) 988-6814
>Disclaimer:  Well, yes, I guess I do speak for FW&A.
>


I agree with some of the things you say, not all.  True, a system with
liquid in the lungs means you inhale a LOT less "gas" per breath.  This
is not a problem for rebreather systems, however-- which is what you'd
surely be using at any great depth.  The problem with gas rebreathers,
however, is what you note: gigantic partial pressures for whatever
gas component makes up most of the gas.  Whether enough helium disolves
in the body fluids to give bends on rapid ascent, even at 600 atm, I do
not know.  I could easily believe that helium is less than 600 times as
soluable in water as nitrogen, but I don't have figures.

Disagreements: Helium is NOT an anaesthetic at any pressure.  At very
great pressures it is actually an anti-anaesthetic (epileptic), and the
really deep pressure chamber dives actually have had to add a wee bit of
nitrogen back in to compensate.  World record for these, however, is
only something like 2000 feet (60 atm), I believe.

Finally, I do know that hydrogen and oxygen have the widest range of mix
for explosive gas composition known (I've seen the range and I remember
that it is HUGE).  I've forgotten the numbers, but it would not surprise
me if 1% O2 and 99% H2 is indeed explosive (unless you have specific
ranges in front of you).  Nor would it surprise me if the critical mix
range for explosiveness is not pressure-dependent.


                                             Steve Harris

From: ((Steven B. Harris))
Subject: Re: "Liquid" Oxygen in the film "The Abyss"
Date: 14 Jun 1995

In <stephen.40.2FDE65BF@pond.com> stephen@pond.com (stephen@pond.com (OR
micromed@pond.com)) writes:

>>>In the motion picture called "The Abyss," a certain unusual
>>>technological idea was presented. Some people in the movie used a
>>>technique that, at extreme depths of water, replaces heliox (a mix of
>>>helium and oxygen) as a breathing medium. This method incorporates
>>>oxygen in suspension. I believe they referred to it as "Liquid Oxygen."
>>>--- Adam Joshua Smargon ---- recycler@vaxu.org
>
>>Yes, there are exist pure fluorocarbons (Perflubron, I believe, is the
>>tradename for the most promising one) known which carry enough oxygen in
>>them to be breathed instead of air, and which are not damaging to lungs.
>>Routine medical applications (as for treatment of hyaline membrane
>>disease) are only a couple of years off. It's not obvious to me why
>>these would be of use in really deep diving however. The emboli which
>>form on ascent (bends) for spontaneously in tissues, and would not be
>>stopped by having the lungs full of fluid.
>>
>>                                                  Steve Harris, M.D.
>
>
>Actually, the theory behind the use of the fluorocarbons in this
>application have to do with the avoidance of the collapse of the lungs
>due to pressure. There is a practical limit in which the lungs would
>collapse to a ball of tissue due to external pressure (probably the chest
>wall, too.) Filling the lungs with this fluid would create an
>incompressible hydraulic fluid.
>
>--Stephen A. Pulley, D.O., FACOEP
>Stephen A. Pulley, D.O.                       stephen@pond.com
>Kathleen C. Sardella, P.A.-C                  micromed@pond.com


No, somebody else noted (correctly) that the main reason for breathing
liquid involve lessened inert gas partial pressure, and thus less tissue
saturation with inert breather gas.

The chests of divers are already prevented from collapsing by giving
them presurized gas.  They have to be.  That's what a SCUBA regulator
does!  In no diving system can there be more than about 1 lb/square inch
or so difference in pressure between the lungs and the outside of the
chest.  Your muscles are not strong enough for anything more.  That's
why you cannot breath through a snorkle more than about 2 feet long.

                                            Steve Harris, M.D.

From: ((Steven B. Harris))
Subject: Re: "Liquid" Oxygen in the film "The Abyss"
Date: 15 Jun 1995

In <feuerDA6IMt.FD8@netcom.com> feuer@netcom.com (Ted Feuerbach) writes:

>: I could easily believe that helium is less than 600 times as
>: soluable in water as nitrogen, but I don't have figures.
>
>Some people also easily belive that the earth is flat!  ;-)

Well, if you have the figures, please provide them.  I don't see
solubility figures for helium in my CRC.  Furthermore, for anaesthesia
and bends we are talking about two different things: one relates to
solubility in oils, the other to solubility in water.

>Don't speculate.  You don't seem to comprehend hyperbaric
>physiology.  In preventing DCS (Decompression Sickness) one
>must consider not only how soluable the gas is but how fast the gas
>can pass in and out of various tissues.  Various tissues absorb
>gasses at differing rates and give them up at differing rates.
>The gasses in the lungs pass into the blood stream.  They they are
>then absorbed into the tissues.

Yes, yes, I do know all this.  There are even differences caused by how
often the bends have occured in the past, or how much barotrauma has
occured in the past.  Apparently old barotrauma causes nidi for bubbles
to form.  Old hands get the bends easier than newbies.

>Also, you mention
>rate of ascent.

No, you've got me confused with somebody else.

>Rate of ascent is less of an issue and your mention
>of it is misleading.

Ditto.

>> Disagreements: Helium is NOT an anaesthetic at any pressure. At very
>> great pressures it is actually an anti-anaesthetic (epileptic), and the
>> really deep pressure chamber dives actually have had to add a wee
>> bit of nitrogen back in to compensate.
>
>Helium *will* cause narcosis at high pressures, as will all the
>noble gasses.

Prove it.  The noble gases vary wildly in solubility.  Xenon is about as
anaesthetic as nitrous oxide, and has been used in surgery for this
purpose.  Argon is slightly more soluable in oil than N2, and should be
a bit more anaesthetic at depth.  I doubt if you can come up with any
experiment at any pressure showing anaesthetic properties from helium.

>And yes, mixtures are varied for the purpose that you
>suggest, however, this is not germain to the discussion.  Nitrogen
>is used to help prevent HPNS.  It is the *pressure* that is thought
>to cause the seizures.  There are so many variables and individual
>differences that there are no exact rules to gas mixtures/depths/
>times/decompression/etc that will work for everyone.

True.  But it is also true that nobody has seen helium narcosis.

>> World record for these, however, is
>> only something like 2000 feet (60 atm), I believe.
>
>Better check your record book!

Well, if you have a better number, let's hear it.  That's what I
remember from about 10 years ago, from the papers.

>> Finally, I do know that hydrogen and oxygen have the widest range of
>> mix for explosive gas composition known (I've seen the range and I
>> remember that it is HUGE). I've forgotten the numbers, but it would
>> not surprise me if 1% O2 and 99% H2 is indeed explosive (unless you
>> have specific ranges in front of you).
>
>This was from a commercial diving text.

I've looked it up.  You're right on this one.  Everything over 94% H2
(6% O2) is safe. Upper safety limit is 4.6% H2.  From 4.6 to 94%, look
out.

>Did you loose the MD since the last post?  My post was general
>information, not a definitive work on hyperbaric physiolgy.  For
>that I would have required a couple more pages of text.   ;-)

You'd have done better giving more specific info.  Instead you just
called me wrong but provided no better data, and had me confused with
somebody else, too.

>Stick to something you know.


When you demonstrate that you know more, you can be the teacher.  So far
I've seen mostly hot air.

                                                 Steve Harris, M.D.