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Nitrox instead of air for lower DCS risk?

Discussion in 'Ask Dr. Decompression' started by BigTuna, Mar 7, 2006.

  1. diverdown78

    diverdown78 Angel Fish

    # of Dives: 25 - 49
    Location: ohio
    36
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    yes...if you still dive on air tables
     
  2. Rolodive

    Rolodive Dive Shop

    # of Dives: 100 - 199
    Location: St. Croix in the US Virgin Islands
    8
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    The situation which people seem to ignore is the fact that dive times are often not limited by no-stop times nor available gas in the cylinder. In many tourist spots, most notably in my mind a recent trip to dive Hawaii, dive time has more to do with the desire of the divemaster to get back to shore and on with his/her social life. Here in laid back St. Croix they tend to shoot for 40-50 minute dives, but in Hawaii we found we were getting hustled back to the boat after just 25-30 minute dives. The recently pubescent boat crews and dive staff are underpaid, overworked, and seldom have their heart in being under water yet again for the 28th time this week. In that scenario, you are way better off with nitrox cause when you dive with this kind of operator, you're going to dive the same amount of time and same depths no matter what you're breathing, so you will in fact decrease your nitrogen loading with nitrox.
     
  3. Screwbag

    Screwbag Guest

    # of Dives: 50 - 99
    Location: Sweden
    22
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    0
    Just to toss in my 2 cents here...
    Several of the Commercial diving companies around scandinavia are switching to nitrox for their daily gas use...as it increases their insurance safety profile...at least thats what they tell me...
     
  4. TropicRat

    TropicRat Instructor, Scuba

    38
    4
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    BT:

    Been around the track a time of two myself.

    It's a no-need to engage brain before shifting into drive. Do it before your next dive!!

    For older divers Nitrox is the ticket. In your case go by the old saw and treat it like
    it was air.

    Reduced DCS and the increase of O2 on old things is highly beneficial.
     
  5. DevonDiver

    DevonDiver N/A

    # of Dives: 5,000 - ∞
    Location: Subic Bay, Philippines
    15,396
    8,150
    113
    The easiest way to to comprehend the potential benefits of nitrox, is by considering it in terms of the EAD (equivalent air depth) of the dive profile.

    Nitrox allows you to conduct a dive to depth X, whilst only absorbing nitrogen as if you were at depth Y.

    This means that for two identical dives, the nitrox user will have less nitrogen saturated into their tissues. Less saturated nitrogen equals lower risk of DCI.

    However, if the nitrox user took advantage of the shallower EAD, as tool for increasing their bottom time, compared to an air diver at the same depth, then they would lose that safety benefit.

    They would absorb nitrogen slower, but would do so for a longer time....so the end result would be the same.
     
  6. Wayan

    Wayan Instructor, Scuba

    # of Dives: I'm a Fish!
    Location: Indonesia - Bali
    327
    3
    0
    You need to do more than to just change to nitrox to reduce the risk
    Use air tables instead of Nitrox tables
    change dive profiles
    reduce bottom times (considerably)
    Do not dive as deep
    increase surface interval times (it appears most people us the 1-1 1/2 hour )
    hydrate hydrate some more

    Combining these together these MAY reduce the risk (but not necessarily substantially) but as with anything in life there is no guarantees. Have seen people with what seems to be perfectly sound profiles (air / and or EANX)
    end up with DCS / DCI.
     
  7. PhatD1ver

    PhatD1ver ScubaBoard Supporter ScubaBoard Supporter

    # of Dives: 200 - 499
    Location: Shanghai, China
    334
    141
    43
    so, as a newby, who is going to get nitrox trained end of the month on my dive trip... let me ask this... in April I did a trip and we did three days of three dives a day... by end of day three, I was bonked, a little light headed, and minor headache, and splotchy red/hivey stuff on my arms (but not chest)... clearly showing some signs of that 'subclinical signs of DCS' and cancelled my morning dives for Day 4 that would have still left me 24 hours before I flew back the next day (Day 5) ...

    The dive computer was tracking all this, I was fully loaded with nitrogen when I left the water on dive #9, in theory I'd burn plenty off in 16 hours, but since I'm older, Phatter, and haven't got much experience under my belt yet, I also figured I might just off-gas a little slower than some....

    Finally, here is the question... last day, all dives were to 20 meters or less, if I had switched to Nitrox all day on Day 3, theoretically, with the same dive plans and bottomtime, I should have had less nitrogen in my system... YES?

    I'm thinking of following the common thought here and just going to 100% nitrox going forward when I have multidive days. Boat diving, it's a pain for the operator to prep three tanks for me.. TOUGH.
     
  8. DocVikingo

    DocVikingo Senior Member

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    Yes, but whether the reduction in nitrogen would be enough at this point to meaningfully reduce the risk of DCS is questionable.

    And speaking of questionable, the development of mild light headedness, minor headache & and splotchy red/hivey rash on the arms is by no means definitive of DCS--mechanisms other than breathing compressed air could have caused these.

    Finally, as a matter of proper terminology, if these were in fact signs/symptoms of DCS, they wouldn't be "subclinical"--after all, they are evident/showing/manifest, aren't they? : )

    I'm not sure you'd want to do that as breathing "100% nitrox" [which means 100% oxygen/0% nitrogen] would very likely send you into convulsions before you descended very far down into the water column.

    You'll learn all about this in your nitrox training class scheduled for end of this month.

    BTW, you're going to adore Anilao.

    Have a dive circus.

    Cheers,

    DocVikingo
     
  9. Compressor

    Compressor ScubaBoard Supporter Staff Member ScubaBoard Supporter

    # of Dives: 1,000 - 2,499
    Location: NYS
    2,854
    1,322
    113
    A great discussion with top notch advice given in this thread. I'll look for similar thread on trimix.
     

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