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Thread: Undeserved hits / Is it possible to make sure we dont get em?

  1. #1
    RBW Founder schford has a reputation beyond repute schford has a reputation beyond repute schford has a reputation beyond repute schford has a reputation beyond repute schford has a reputation beyond repute schford has a reputation beyond repute schford has a reputation beyond repute schford has a reputation beyond repute schford has a reputation beyond repute schford has a reputation beyond repute schford has a reputation beyond repute schford's Avatar
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    Undeserved hits / Is it possible to make sure we dont get em?

    So I was reading some stuff from DAN who were saying that 57 off percent of all hits are 'undeserved' and it got me thinking had I and my dive buddies just been lucky?

    I got to wondering what they meant by that - did they mean that the profile of the dive meant that the person should not have got bent or did they do some real analysis? Did they think about work rate, temperature, Hydration, alcohol consumption, rate of ascent etc etc or is just one of those throw away lines.

    Oh he was only at 40m for 10mins he shoudl not have got bent that is undeserved!

    The fact that he went up like a rocket ran up the beach and wolfed a few beers would not enter into it

    So that got me thinking then outside of following the computer what should we be doing? I have my own little routine but I wondered how to imprive on it and learn form you all....

    To share I will start

    1 - I always make sure I am hydrated before a dive and for a big one will take some of those squeezy iso balanced drinks to drink on the boring deco stops.

    2 - I always ascend real slow with plenty of deep stops to hopefully stop bubbles forming (following RGBM).

    3 - Plenty of shallow stops following GF to get rid of the bubbles in case they formed.

    4 - Gentle finning around on the stops to encourage off gassing...

    5 - Very regular flushes of my counter lungs to get rid of the nasty He I am off gassing and make sure I am breathing lovely O2.

    6 - Pass my kit up use a lift and sit breathing my breather on O2 for at least 10 mins still doing counter lung flushes with O2 to make sure I am not breathing He.

    7 - Not much beer in the night and none for at least 4 hours...

    Kind of an aside but I always run the dives in GAP before hand to check out RGBM and GF deco schedules and to make sure I have enough bailout but also to have in the back of my mind how much padding to do if I get an oopsy like a dry suit flood whch would lower my temp so make me much mroe likely to get a hit...

    Well thats mine......anyone else?

  2. #2
    An independent diver. bletso is just really nice bletso is just really nice bletso is just really nice bletso is just really nice bletso is just really nice bletso is just really nice bletso is just really nice bletso is just really nice bletso is just really nice bletso's Avatar
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    Re: Undeserved hits / Is it possible to make sure we dont get em?

    I think there are few undeserved hits. If you read the case histories from DAN, there usually seems to be some predisposing pathology. That said, there is always a statistical chance to get bent on some of the most simple of dive profiles.

    There is an infinite number of things which can alter the circulatory system. Any of them can contribute. I like to point out to students the long list of contributory factors for bends and them ask what is the common thread. It doesn't matter, age, sleep, sick, previous injury, hydration,.... They never guess it. ALL affect the body's ability to move disolved gases through the circulatory system and out the lungs.

    Dale

  3. #3
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    Re: Undeserved hits / Is it possible to make sure we dont get em?

    It's been said before. The only way to absolutely avoid a 'hit' is to not dive (or fly for that matter, since explosive loss of cabin pressure at altitude could also cause DCS)

    That being said. Aside from padding tables, and staying hydrated (again, there is no good objective evidence to support dehydration as a risk factor, but it seems reasonable to suppose it is) I think slowing ascent rate is probobly the major preventive thing people can do to reduce their risk.

    Another thing to think about is limiting any constricting bands that might cause a change in venous of capillary blood flow. I have seen DCS as a result of watch/computer straps tightened at depth, that became too tight on ascent. Also think about drysuit seals, weightbelts, harnesses.

    My .02$

  4. #4

    Re: Undeserved hits / Is it possible to make sure we dont get em?

    Well,
    On deep dives I won't drink the whole week before other then a glass of wine on 2 to 3 of the day's out of 7 as I believe in the moderation thing. As it can help your digestion and also your ability to disolve Saturated fats. The french have drank wine with meals for a long time and have one of the lowest incidents of heart disease.

    But for down to 110 feet I've drank lots the night before and dove that afternoon. Done that a lot. And drank a beer on the boat within an hour of getting out of the water from the last dive.

    That was pretty normal.

    I will say with a hangover you get Narced very shallow. So if you have one it's best not to dive. I've done it were I could feel it tunnel my vision as shallow as 45ft. I don't know, it probably isn't narced and I was probably still drunk.

    This was back in my party till I puked day's. Drink all night till 3am, go home with a girl, get to sleep by 6am and up at 7:30am and diving by 8:30am. And Repeat the next day. Repeat the diving and drive home the next day. I did take naps during the diving and during the afternoon. If said girlfriend would let me. She didn't dive so she got to nap during the time I dove.

    Never had a hit. I'm in pretty good shape though.

    I always wondered about the hits since a lot of people that want to set Depth records are around 50. I would think that isn't the age to be setting records. I had an opinion of divers who died while diving rebreathers was Mostly older divers. Not trying to point fingers but no matter what shape you think your in, at 50 your body is still 50. At 70 and 80 minor shocks to the system could trigger a heart attack. And a couple of the divers have been those ages.

    Past 120 feet all bets are off. Since if you're past 120 you're usually around 240 or more. Don't hear a lot about in between that.
    Last edited by mverick; 31st March 2007 at 20:43.

  5. #5
    Sebastian Chander Deep Smeg is a jewel in the rough Deep Smeg is a jewel in the rough Deep Smeg is a jewel in the rough Deep Smeg is a jewel in the rough Deep Smeg is a jewel in the rough Deep Smeg is a jewel in the rough Deep Smeg is a jewel in the rough Deep Smeg's Avatar
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    Re: Undeserved hits / Is it possible to make sure we dont get em?

    Quote Originally Posted by bletso  View Original Post
    I think there are few undeserved hits. If you read the case histories from DAN, there usually seems to be some predisposing pathology. That said, there is always a statistical chance to get bent on some of the most simple of dive profiles.

    There is an infinite number of things which can alter the circulatory system. Any of them can contribute. I like to point out to students the long list of contributory factors for bends and them ask what is the common thread. It doesn't matter, age, sleep, sick, previous injury, hydration,.... They never guess it. ALL affect the body's ability to move disolved gases through the circulatory system and out the lungs.

    Dale

    Following on from Dale, i think that given everyday we seem to be finding more and more factors involved in DCI, making it infinetely more complicated, than we would like, that the term 'undeserved' should be replaced with 'unexpected' or 'not quite understood yet' hits. This would also help to lift the stigma that a lot of divers attach to those of us who have suffered from DCI, and perhaps this may encourage those with early symptoms to report them and get treated without fear of being branded a crappy diver.

    It should come as little surprise that while current practises allow the greater majority of divers to avoid DCI hits, there will always be those that still get hit despite reasonable prudence.

    Furthermore those of us pushing deeper and longer and using newer technology will have to accept they are throwing more and more variables at an already overly complicated equation and therefore are increasing their chances of incurring an 'unexpected/not quite understood yet' hit.

    Overall I believe that Stuarts 'Routine' represents a lot of common sense based on what we do know, but He, Sarah, Chris B. and I all did a similar dive in Grand Cayman a few years back and despite all best practises I ended up with my first ever doppler scores. Nobody else did and I had made a simlar dive 7 days earlier.

    I have my suspicions as to what contributed to this, but again it's just something unexpected, and we will never be able to avoid these incidents as long as we choose to dive.

    Cheers

    Seb
    Last edited by Deep Smeg; 31st March 2007 at 20:53.

  6. #6
    Decodiver
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    Re: Undeserved hits / Is it possible to make sure we dont get em?

    I get out of the water and get shedded..............

    Must be just me then...........

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    Thumbs up Re: Undeserved hits / Is it possible to make sure we dont get em?

    If you drink don't dive....

  8. #8
    Sebastian Chander Deep Smeg is a jewel in the rough Deep Smeg is a jewel in the rough Deep Smeg is a jewel in the rough Deep Smeg is a jewel in the rough Deep Smeg is a jewel in the rough Deep Smeg is a jewel in the rough Deep Smeg is a jewel in the rough Deep Smeg's Avatar
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    Re: Undeserved hits / Is it possible to make sure we dont get em?

    Quote Originally Posted by Decodiver  View Original Post
    I get out of the water and get shedded..............

    Must be just me then...........
    B**tard! I wish I could do that!

  9. #9
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    Re: Undeserved hits / Is it possible to make sure we dont get em?

    Next year it will be a full hundred years since Dr. John Scott Haldane published his investigations into deco theory in 'The Prevention of Compressed-Air Illness'. It's amazing how little the theory has advanced since then, compared with the explosive growth in almost every other area of science. For all the imposing differential equations in deco theory, it doesn't work well deep and it has no idea how to to allow for percentage body fat, physical fitness, age, breathing efficiency, dehydration, work rate or a host of other vital factors. It reminds me of Naismith's Rule I use for hiking: I input the horizontal distance I am going to walk and the vertical climb and it tells me whether I risk getting caught still up on a high mountain plateau as the sun goes down. By trial and error, you get an idea of what adjustments work for your shape and fitness. With deco, however, I can't afford an error, so I have no idea how close to the line I really am. Given the thousands of hours people spend around the world diving every day, it beggars belief that we don't have a model for deco that allows us to input a few vital statistics - height, weight, % bodyfat, VO2 max/kg - and get a personalised deco schedule.

    There must be a business model in exploiting all the free data from well-wishing divers with computers, which give good data on profiles. You need to match that up with physical data on the divers, and you need anonymity to reduce the risk of lying to boast of how deep they've been, or hide how fat they've got. The internet allows divers to easily upload their dive profiles and any information about chamber visits. How about RBW teams up with a computer manufacturer and runs a Deco Wiki? The dive computer maker crunches the data, and RBW provides the infrastructure to accumulate test subjects and PM them with follow-up questions. It could provide modest income for RBW, and for divers it would give them their best hope for a model that works for longer deeper dives done by rebreather divers. No computer manufacturer could afford such extensive, risky tests done in any other way. Moreover, rebreather divers are physically rather different from the subjects used in US Navy tests. If you want to do a thing right you've got to do it yourself: we aren't going to get a model that really works for longer-for-deeper divers unless we do it ourselves.

    Rant over. Time I went diving!

  10. #10
    RBW Member RonMicjan has a reputation beyond repute RonMicjan has a reputation beyond repute RonMicjan has a reputation beyond repute RonMicjan has a reputation beyond repute RonMicjan has a reputation beyond repute RonMicjan has a reputation beyond repute RonMicjan has a reputation beyond repute RonMicjan has a reputation beyond repute RonMicjan has a reputation beyond repute RonMicjan has a reputation beyond repute RonMicjan has a reputation beyond repute RonMicjan's Avatar
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    Re: Undeserved hits / Is it possible to make sure we dont get em?

    Excellent thread stuart, funny thing, Simon Mitchell did a seminar at oztek with just about the same idea, he talked about hydration, drugs, predispositions and PFO's, I will take a look at my notes and try and post some of the conclusions. better yet...Paging Dr Mitchell...Paging Dr Mitchell...

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