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125 feet air dive DCS risk?

Discussion in 'Ask Dr. Decompression' started by Into the Water, Feb 8, 2017.

  1. Into the Water

    Into the Water DIR Practitioner

    # of Dives: 100 - 199
    Location: Sweden, Värmland
    25
    11
    3
    Hi
    Would really appreciate if some body with good deco theory experience and deep air diving help me to analyze few dives. And write some arguments.
    How safe would be to dive same dives in warmer water in term of DCS? What was main mistake on diving that kind of profiles? Could be DCS be avoided with diving same profile in warm water or with longer deep stop 80%, 50% and shallow stop 20 feet and 10 feet?

    Diver maid two dives:

    Water temp 39-40 degr, surface interval between dives 1:42, Gas 21%

    1st dive: Depth - 124 feet, Avd - 66 feet, Dive time - 33min, dive profile below.
    1st dive.jpg

    2nd dive: Depth - 119 feet, Avd - 63 feet, Dive time - 34min, dive profile below.
    2nd dive.jpg


    Second dive was finished 5:15pm, about 8:30 pm diver started to feel DCS symptoms: joint pain in left arm shoulder and elbow, numbness in fingers, overall weakness and fatigue. Early in the morning he was delivered to hospital. Report from doctor: DCS type 2, Table B6:a 5h

    0 - 18 m
    21% O2 10 min

    18 m, 70 min:
    100% O2 20 min x 3
    21% O2 5 min x 2

    18 - 9 m
    100% O2 15 min

    9 m, 210 min:
    100% O2 60 min x 2
    21% O2 15 min x 2

    9 - 0 m
    100% O2 30 min

    VAS 4 - 0.

    Not allowed to dive for 3 month

    same evening symptoms came back but much less

    next day again treatment 2h

    Max depth till 14 m

    100% O2.
    21% O2 5 min.

    Stopp på 9 m 10 min.
    Stopp på 3 m 3 min.

    VAS 3-0.

    T Diklofenak 50 mg x 1 and later one more time

    1-1,5 month later, sometimes still feeling joint pain in left arm elbow and shoulder.

    Please avoid useless speculations. I need only arguments and maybe it is still possible for me to change few ego sick divers from future mistakes.
    My own opinion don't dive below 100 feet on air it's 2017 already.
     
    Last edited: Feb 8, 2017
  2. tbone1004

    tbone1004 Technical Instructor ScubaBoard Supporter

    # of Dives: I'm a Fish!
    Location: Greenville, South Carolina, United States
    16,176
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    disclaimer, not a physician, so this is just my opinion.

    warm water is both better and worse for DCS. Ideal temp profiles for your body are cool at the bottom and warm on the ascent. Cool at the bottom slows nitrogen coming in, and warm on ascent helps to get rid of what was absorbed. If diving wet, this somewhat naturally occurs due to the compression, however you also have cumulative heat loss, so I don't know at what depth/temperatures those balance out.

    125ft on air is too deep for me personally due to narcosis. I get narc'd easily, and I don't like being narc'd. I can function much deeper than that on air, and have, but really don't like diving much below about 90ft if I am doing any sort of work.

    Questions I have
    Wetsuit or drysuit?
    Diving day before or no?
    History of DCS?
    Which algorithm was the computer running?
     
  3. Into the Water

    Into the Water DIR Practitioner

    # of Dives: 100 - 199
    Location: Sweden, Värmland
    25
    11
    3
    Dry suit :) in Sweden we not used for wet suits :); about 20 days since last dive; no previous experience with DCS; I think RGBM algorithm, as a standard on most rec dive computers, conservatism lvl wass on 1 from 0 to 2.
     
    Last edited: Feb 8, 2017
  4. offfi

    offfi Nassau Grouper

    # of Dives: 100 - 199
    Location: Austria
    102
    43
    28
    I just had had a qick look at those profiles and did no calculations.
    They seem pretty normal to me, to be honest.
    Relatively quick descent to the maximum depth (~36m), staying there for about 5 minutes, afterwards slowly riding up until the safety stop.
    The safety stop is not a perfectly straight line, but it is noticeable.

    Nothing “ego sick" in my opinion.

    I would rather suggest a medical examination of the diver, particularly searching for a PFO.
     
  5. Into the Water

    Into the Water DIR Practitioner

    # of Dives: 100 - 199
    Location: Sweden, Värmland
    25
    11
    3
    That could be a reason, didn't thought about that. But more or less it's bounce dive?
     
  6. offfi

    offfi Nassau Grouper

    # of Dives: 100 - 199
    Location: Austria
    102
    43
    28
    Oh, I just saw the temperature!
    40°F, so around 4°C?
    Might make a difference, but that is beyond my experience...
     
  7. tbone1004

    tbone1004 Technical Instructor ScubaBoard Supporter

    # of Dives: I'm a Fish!
    Location: Greenville, South Carolina, United States
    16,176
    7,568
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    I'd argue the algorithm was probably too aggressive and too biased to deep stops for that profile. I don't have planning software on this computer and don't have my Petrel with me, but I would be willing to bet that an extra 5 minutes at the 10-20ft stop would have likely prevented it, especially considering the temperature. When I'm diving in cold water like that I always extend the final stop by a few minutes, or dive a more conservative algorithm. Will drop my GF's from 85 to 70 or 75, or at least extend the final stop by 3-5 minutes, just in case. Will then take it very easy at the surface to prevent joint bends
     
  8. Into the Water

    Into the Water DIR Practitioner

    # of Dives: 100 - 199
    Location: Sweden, Värmland
    25
    11
    3
    Yes, on the surface around 3-4°C and on bottom 4-5°C
     
  9. Duke Dive Medicine

    Duke Dive Medicine Medical Moderator Staff Member

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    Being cold during decompression is one of the known risk factors for decompression sickness. In theory, the same profile in warmer water would carry less risk of decompression sickness, but there are other factors like level of exercise under water that make it impossible to determine this for sure.

    There may not have been a mistake at all. No decompression algorithm is perfect. Any dive to that depth carries a certain probability of decompression sickness. In general the probability of DCS increases with both increasing depth and longer bottom time. If the computer never went into alarm, this could be considered an "unexplained" DCS hit.

    Being cold during decompression is a known risk factor for DCS. In theory, making the exact same dive in warmer water would carry less risk of decompression sickness. I would exercise extreme caution in inserting deep stops that are not specifically called for in the decompression profile. It's possible to on-gas at a deep stop that is inappropriately inserted, which would increase the risk for decompression sickness. Longer shallow stops on hyperoxic mixtures would speed the elimination of inert gas and may decrease the probability of DCS, but temperature and gas supply becomes a concern there.

    Switching to helium below 100 feet would not necessarily influence the probability of DCS. It would, as already pointed out, eliminate nitrogen narcosis though.

    Hope this helps.

    Best regards,
    DDM
     
  10. offfi

    offfi Nassau Grouper

    # of Dives: 100 - 199
    Location: Austria
    102
    43
    28
    I wouldn't call that a bounce dive.
    If I remember correctly, we did almost all dives of a 2 week diving trip in the Philippines with profiles like this. (Will have a look when I'm home)
     

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