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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'. -- Send mail for the `techdiver' mailing list to `techdiver@aquanaut.com'. Send subscribe/unsubscribe requests to `techdiver-request@aquanaut.com'.
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