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Thread: Are Rebreathers Safer for DCI prone divers than OC

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    Lightbulb Are Rebreathers Safer for DCI prone divers than OC

    Gday,

    First time reader, and Poster, so please be kind.

    Just some background on why I am asking.... And seeing there is some Doctors whom I most prob have talked to over years, some history helps.

    I work in the underwater video game, as well as teach diving when I get some time off, and got introduced to RB by one of the members on RBW.

    So you can imagine my life not only revolves around diving, but I rely on it for money.

    In 2001, I had a minor Joint 'unexplained' bend in my right arm, that was looked at and treated in POW Sydney, I was upto about dive 500 at the time.

    Now in 2005 I had a second 'unexplained' bend in my left arm, this time it was not a joint but a muscel pain, I was treated on a Island in the arse end of the world for it by only 100% O2 for 1001 reasons I was not able or to get to a chamber.

    So here I am thinking what to do next, I have had the docs check the heart, and no I do not have a hole in it, and now considering the RB route.

    It got me thinking, due to the RB's ability to administer the best 02% for the depth you are diving to, at the PPO you request, wouldnt it reduce the chances of DCI when diving ?

    I am looking at the Inspiration as my next big outlay of toys, am I doing it for the right reason, is the reason correct or am I thinking totally off the beaten track and know not what I speak of ? :)

    There is a lot of other reasons a RB would help me in my work, no bubbles, silence and length of dive times, so if they are all bonus's ... then do I have the beat up my bank manager again ?

    Thanks for your time and advice ..

    Cameron.

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    Re: Are Rebreathers Safer for DCI prone divers than OC

    I'm not a dive doc, not even deco trained, and don't know if there is anything that can really help deco prone divers other than staying of the water.

    But I think between pO2 diving, warm and moist gas and the extended gas supply that you can use for more conservative profiles (read longer shallow/safety stop(s) on rich mix to pure O2) a CCR should be of some help.

    If something does happen you can be on pure O2 as of 6 meters and stay there till you get to the boat's, island's or whatever supply. With proper training, equipment, surface support and conditions permitting, even in-water reco may be a viable option at a remote location.

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    Re: Are Rebreathers Safer for DCI prone divers than OC

    I agree totally with what Caveseeker said.
    if you use the CCR and run a constant PPO2 of say 1.3 atm and set your dive computer to air, then yes it will be safer from a inert gas stand point. watch out for your CNS clock and OTU's. But if you run a constant PPO2 of say 1.3 atm and use a constant PPO2 computer or tables for a PO2 of 1.3 atm then you are no safer from a inert gas stand point.;)

  4. #4
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    Re: Are Rebreathers Safer for DCI prone divers than OC

    I would expect RBs to be better in terms of DCI risk - but only if you use them to make it so. If you use them to do longer, deeper dives and rack up similar amounts deco as you used to on OC then perhaps not. If you dive to OC air profiles with one then yes.

    You say you got the docs to check your heart and don't have a "hole". Was this a full checkout ie an echocardiogram looking specifically for a PFO, etc. Simple tests like listening with a stethoscope (and some more complex tests) may not show a PFO. I'd want some input from a cardiologist with an interest in diving medicine.

    Neil

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    Re: Are Rebreathers Safer for DCI prone divers than OC

    Hi Cameron-

    This thread echoes the discussions that flew over a decade ago when Nitrox first went mainstream, and has many of the same elements. Simply put, when you dive a Nitrox 32 but hold to air no deco tables, you have significantly increased your safety margin. If you choose to dive to the limits of a Nitrox 32 no deco table, then you would get zero safety benefit. When you dive a CCR w/ air diluent you have in every sense of the word a Nitrox mixing machine on your back and the exact same principal applies. The best part is you also get all of the other benefits mentioned in the previous posts.

    How much of the margin you choose to use will be your decision. Any decent cert course should train you in how to calculate the difference.

    Dive safe,
    Ken

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    Re: Are Rebreathers Safer for DCI prone divers than OC

    Cameron,

    G'day, mate, and welcome to Rebreather World. You have some good questions here, and as usual, our members have pitched in with solid, and thoughtful advice.

    I am a Diver Medic Technician with decompression training. We have some Docs on this Board with more training and education in this subject than most of the rest of the world combined. I'll leave the ultimate comments to them.

    I will tell you, however, that our members who have responded here are "spot on" so far!:D

    From your anecdotes, you are headed in the right direction in analyzing your diving practices to search for possible reasons or links that might be causing your DCS problems.

    The first thing to remember, and this is just a caveat, is that in reality there is no such thing as 100% certainty that you will not be a victim of DCS, even if you do everything right 100% of the time. There is ALWAYS that chance that you will be one of the "statistical out-liers" in the program. The Docs, DMT's, and CHT's will mutter, shake their heads, and say: "Hmmmmm..."!

    This is why, when we find someone who has seemingly done everything right, and still is "hit", we speak now of an "Unexpected" case, or incident, of DCS, rather than the older term "Undeserved Case". I mention this not to alarm you, but merely to keep your expectations in line with reality!:)

    Now, as I said, there are are various strategies to pursue to lower your statistical chances to the lowest possible level, and our members have suggested some already.

    As obviously know already, a PFO is condition that may lurk quietly in the heart, causing no problems until the patient is put in some kind of unusual situation, such as decompression diving. You, however, have taken steps to rule that out.

    Also, as you know, any method that reduces your intake, dose, or "fix" of inert gas is valuable. In the case of OC diving (Shudder! ), the use of Nitrox mixes will reduce the amount of nitrogen received on any dive, within limits, of course.

    Just so an eCCR will reduce your inert gas intake on any dive, again within its physical limits, of course, because it is akin to having a gas-mixing technician strapped to your back to provide the "best" possible gas fractions at any position in the water column.

    Also, as has been pointed out, the gas is warm and moist, which has benefits for the diver as well.

    We're glad you've come aboard RBW! You cannot find a better resource for information about rebreathers, and all of their related subjects than this Board.

    Stay with the discussion, and be prepared to make extensive "pro and con" lists. As you can see, our members are willing to help!:D

    Rob Davie
    RBW Admin
    Last edited by ROB DAVIE; 9th January 2006 at 15:47.

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    Re: Are Rebreathers Safer for DCI prone divers than OC

    Quote Originally Posted by ROB DAVIE
    Just so an eCCR will reduce your inert gas intake on any dive, again within its physical limits, of course, because it is akin to having a gas-mixing technician strapped to your back to provide the "best" possible gas fractions at any position in the water column.
    Much more streamlined though :D

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    Re: Are Rebreathers Safer for DCI prone divers than OC

    Quote Originally Posted by Sutty
    I would expect RBs to be better in terms of DCI risk - but only if you use them to make it so. If you use them to do longer, deeper dives and rack up similar amounts deco as you used to on OC then perhaps not. If you dive to OC air profiles with one then yes. Neil
    Good advice for the safety concious.
    Don't forget you can also do your safety stops at 1.55 -1.6 and get a tad more margin. (unless you are on Steve's Meg ;) )

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    Re: Are Rebreathers Safer for DCI prone divers than OC

    Quote Originally Posted by Sutty
    Much more streamlined though :D
    Ya got a point there, Judge! :p

    Rob

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    Re: Are Rebreathers Safer for DCI prone divers than OC

    when you say you are inherently prone to DCI, it sparks my interest in to your diving style and habits, you said both hits are in the arms "joint" elbow and muscle.

    What was the temp of the water of said hits?
    what type of exposure wear was used ?
    Do you get cold during an average dive ?
    would you say that your exposure wear is tight?

    this is just speculation on my part but I,m interested in the questions posed and have a theory formulated in my own mind about capilary restriction due to temp and exposure of the joints.

    As already stated the advantages of the higher po2 would be negated with longer exposures and I would be willing to bet the longer exposure would put you at higher risk for dcs if any correlation could be drawn of my opinion to the previous hits.



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