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Date: Mon, 14 Feb 2000 20:13:40 -0500
From: trey@ne*.co* (Trey)
To: gazela <gazela@ba*.ne*>, techdiver@aquanaut.com
Subject: Re: In water recompression. (FWD) (FWD) (fwd)
This should read "oxygen at 30 feet", not 300. 

Trey wrote:
> 
> Give me a break - this is total crap. 200 cubic feet? I used 100 cubic
> feet to decompress from 6 hours at 300 feet. Oxygen at 300 feet with no
> mask following an exposure with an injyre diver ? Idiot, you need to
> shut the f up. You have no experience with this, you have no idea what
> you are talking about, and Pyle is full of shit - he knows how to get
> bent, and that is about it. The Navy manual is dead wrong as well.
> 
> We do this al of the time and do it correctly and the result is
> generally no chamber at all. Get a clue. We do so much experimenting
> with deco that we have a lot of these situations.
> 
> gazela wrote:
> >
> > Being new to the list, I've been (appropriately) keeping quiet.
> > However, this is subject that I have researched rather extensively.
> > I think the original question- what do you do when you are unreasonably
> > distant from a chamber and you get symptoms- is a good one that needs a
> > simple answer.  IWR is practiced in Australia and Hawaii and they have
> > already worked out simple protocols.  Also the Navy Dive Manual has a
> > protocol for IWR in its chapter on decompression injury treatment.
> > The key to any emergency treatment is KISS.  If you give yourself too
> > many choices, or the treatment requires too much judgment, the error
> > (read worse injury) rate rises rapidly.
> > Two basic bits of background that you probably remember from your basic
> > OW course (if you managed to stay awake).  Bubbles grow exponentially-
> > the larger the bubble, the more rapidly it grows.  Commercial and
> > Military diving allows 5 minutes between surfacing and recompression in
> > a surface chamber.  Second, at 33 fsw, gas volume is half that of the
> > surface.
> > The basic rules common to IWR protocols call for two things- get back in
> > fast, and get to at least 9 meters.  They also call for using oxygen.
> > If you don't have a rebreather, you're going to need alot (Pyle suggests
> > 200 cu ft).  The principle is to get the oxygen, get to 30 feet and stay
> > there at least a half hour.  This is extended to an hour if there are
> > neurological symptoms.  If the symptoms do not go away, then stay an
> > extra half hour before beginning ascent.  If you don't have enough
> > oxygen, stay at 9 meters until it runs out, then switch to air (or
> > nitrox if you have it) and begin a slow ascent immediately.
> > The different protocols allow for different types of ascent.  The
> > simplest is to come up at 4 minutes per foot (12 minutes per meter).
> > The alternative is to come up at 1 foot per minute and make 45 minute
> > stops every 10 feet.
> > These protocols come pretty close to reproducing in water what the Navy
> > Tables do in a chamber when you look at the physics and the
> > neurophysiology.
> > There is only a minimal amount of advanced preparation required for this
> > type of IWR, but it should be thought out ahead of time to avoid panic,
> > confusion, and danger.
> > If you're using air, the recommendation is to go 10 feet below the depth
> > where symptoms are relieved, or 165 feet max then start a staged
> > ascent.  The last 9 meters should be on oxygen if you can get any.
> > Even if you're within reach of a chamber, if you have the support
> > available, I would agree with the concept of going back in to 30 feet on
> > oxygen until the air ambulance is there to get you.
> > Also, if you are going someplace remote, if you don't have medical
> > personnel going along, then check with your friendly neighborhood diving
> > doc for some anti inflammatory meds to take with.  They can make a big
> > difference in the recovery.
> > Now I'll slip into my asbestos suit and await the flaming.
> > Wendell Grogan
> >
> > > Date: Sun, 13 Feb 2000 10:50:11 GMT
> > > From: Edward Watson <ted.watson@ze*.co*.uk*>
> > > To: Steve Schultz <se2schul@un*.ma*.uw*.ca*>
> > > Subject: Re: In water recompression. (FWD) (FWD)
> > >
> > > <snip legalities bit, not interested in that>
> > >
> > > >     The first assumption is that the worst thing the "omitter" has
> > > > effectively done is move up the last 20 feet and out of the water too
> > > > fast.  By this I mean that if any of us do this at any point in any deco
> > > > proper or improper, we are foaming out that last pressure gradient that
> > > > NO amount of deco will remove. Only a slow ascent to the surface will
> > > > allow that last bit of gas to come out in solution. Jumping up 20 feet
> > > > will bring it out in bubble form, no matter what.
> > >
> > > >     So now the guy is out and foaming, but only the doppler knows this -
> > > > he is asymptomatic. We know from our doppler experience and endless
> > > > studies that this bubbling will actually INCREASE with time after the
> > > > diver is out of the ater, and will peak some 20 minutes to an hour
> > > > later, and hold at that level for up to hours.
> > > So assuming ommitted deco, the idea that the first 30 minutes or so
> > > post dive is effectively a surface deco stop is incorrect, it should
> > > be much longer?
> > >
> > > >     Now, we have two choices - do nothing ( which includes breathing
> > > > oxygen on the surface ), or tell him to go back and do some deco , and
> > > > then ascend slowly.
> > >
> > > What do you mean 'some deco'?- just repeat what was omitted  exactly,
> > > or go a bit deeper and start again, or add in extra time at the
> > > ommitted stops/faster ascent
> > >
> > > >     Now we have to look at the profile - how deep , how long, how
> > > > serious could this omission be? How deep do we have to get this guy to
> > > > reduce the bubbles to where we can get them into solution or at least
> > > > managable enough to offgas through the lungs or get small enough to pass
> > > > by way of the circulatory system to the lungs where we can work on them
> > > > with oxygen.
> > >
> > > >     Generally, if you can keep the guy alive, and stay on him, and that
> > > > goes for a may-be-nothing situation to a real blowout, getting him down
> > > > and getting him on oxygen ( or the correct max PPO2 gas for the depth)
> > > > are both a must if he is going to not be brain damaged.
> > >
> > > >     The general best bet in the three situations you describe are to
> > > > take your chances by going back in, finding the starting point that is
> > > > reaonable and will not take to long to ascend from, and redoing that
> > > > part of the deco, with special emphasis on taking the last 30 to 20 feet
> > > > very slowly all the way up.
> > >
> > > How do you decide what starting point is reasonable in a given
> > > situation, or is just a best guess thing
> > >
> > > >     Pain hits are not so big of a deal as an annoyance and a dive trip
> > > > ruiner as they  are not going to go away completely. For one, the bubble
> > > > traped most likely seeded much deeper , and only grew to pain size
> > > > later. You can tell the depth at which it shrinks when the pain goes
> > > > away, and do the math to figure how deep it reasonably cound have seeded
> > > > at. It is a waste of time to go back to that depth since the damage is
> > > > done and you will feel the pain of the damage long after the bubble has
> > > > been reabsorbed. The better bet is to reduce it somewhat and give it a
> > > > chance to diminish ( they generaly grow first, but you have
> > > > receompressed it somewhat) and then try to overcome it with oxygen in
> > > > the slow ascent.
> > >
> > > realistically a pain hit is going to be much easier to sort out in
> > > the field than one involving paralysis etc. What we need to know is
> > > how best to deal with it if there's going to be a reasonable delay in
> > > evacuation to a chamber. Obviously it's always going to be a balance
> > > with hypothermia, gas volumes possibly sea-sickness  all being
considerations.
> > >
> > >
> > >
> > > --
> > > Send mail for the `techdiver' mailing list to `techdiver@aquanaut.com'.
> > > Send subscribe/unsubscribe requests to `techdiver-request@aquanaut.com'.
> >
> > --
> > When I die, I want to go peacefully, in my sleep, like my grandfather.
> > Not screaming, like the passengers in his car.
> > -- Jack Handey [Saturday Night Live persona]
> > --
> > Send mail for the `techdiver' mailing list to `techdiver@aquanaut.com'.
> > Send subscribe/unsubscribe requests to `techdiver-request@aquanaut.com'.
> 
> --
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