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Thread: What is your max depth tolerance to Narcosis?

  1. #61
    Darlene Starr - DIY Diva Scuba_Vixen has a brilliant future Scuba_Vixen has a brilliant future Scuba_Vixen has a brilliant future Scuba_Vixen has a brilliant future Scuba_Vixen has a brilliant future Scuba_Vixen has a brilliant future Scuba_Vixen has a brilliant future Scuba_Vixen has a brilliant future Scuba_Vixen has a brilliant future Scuba_Vixen has a brilliant future Scuba_Vixen has a brilliant future Scuba_Vixen's Avatar
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    Re: What is your max depth tolerance to Narcosis?

    For those who might be interested in what must be the mother of all "deep air" threads, started back when helium was first being really accepted into the mainstream of deeper technical diving, and the one that was quite an eye opener for me, (provided the greatest impetus to build my blending station) have a look here:

    The Deco Stop


    Darlene

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    Re: What is your max depth tolerance to Narcosis?

    As stated in the other currently active link at this time..
    A friend of mine who is an MD in anaestesia and a technical diver as well has just again recently confirmed me that there is NO Sufficient modell existing for what is happening at N2 narcosis!
    He as an expert as narcosis is day to day business for him should know well..

    When the word Meyer-Overton Theory is raised he gets completely mad as it seems such hypothesis has no finding what so ever to be used in diving and high gas partial pressure related issues..
    The connections and conclusions out of that are purely constructed..

    Don't ask me to repeat the reasoning.. Here I was out following for not being an MD myself

    Just to share that, if it helps at all

  3. #63
    RBW Member MatV is a jewel in the rough MatV is a jewel in the rough MatV is a jewel in the rough MatV is a jewel in the rough MatV is a jewel in the rough MatV is a jewel in the rough MatV is a jewel in the rough MatV's Avatar
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    Re: What is your max depth tolerance to Narcosis?

    On a ship I used to dive OC on air from frequently (SS Florette) in the Eolien Archipelago we as a group of 14 divers more or less always did the same dives. Median deepest depth was about 54m. Since the water is clear there, you could pretty good watch each other. Giving us some ease was the fact of an absolutely professional boat crew and captain.
    Incidences attributed to narcosis were:
    -Following to a depth of 72 m, during ascent a girl seemed somehow absent minded until she met ca. 25m. On request she stated just that feeling.
    - At 68m, my buddy was slow returning the ok sign, and he told me afterwards he knew he was. This slowlyness went away in subsequent dives.
    -A girl proceeded after a down drop to 60m into just the wrong direction, I managed to redirect her so we could see the amazing dropoff at 72m.
    -a guy shot up from 55m because he was thinking he'd be short of air because his computer showed bullshit decompression times, instead of communicating and reassuring.
    -I was going down once to 65m, and immediatley knew this was not my business there and than, went up to 55m and felt absolutely ok.

    Other facts: -2 guys were extracting a black coral together with the rock it stuck to at 70m, and planting it down to the same depth at another site.
    -I was doing drawings of critters at 50m, and writing notes, with no change in handwriting.

    On similar boat tours a friend of mine, who is a doctor, dopplered us after specific dives, and only once fond an echo which was just beginning to sound like a Spencer 1 grade (done deep stops and everything).
    Once I was somehow fading after having lifted a 30 kg anchor from 42m to 40m, recovered at 35m.
    A friend had been at 80m, during his ascent, at 55m, he entered a small cave. When he was turning back out, the opening closed before his eyes not darkness, he said he waited a minute, and it opened up again.....
    In a cold quarry (4°C) at 33m I was thinking my buddy was singing (can't translate "jodeln", a strange rite they do in the Alp mountains)... In reality it was the switch sound when my mechanical reserve closed my left bottle...
    Other observations with less accomplished divers: A girl lost memory of everything she had seen at a depth of 34m, but knew what she had been doing at 30m.
    A guy, after a fiesta night, was heavily narced at 26m, and not telling it because he liked it.

    Conclusion:
    manifestions of narceddom vary considerably between and within people.
    The turn on of effects seems to be the shallower the higher the metabolism is (cold, physical and mental effort,) the higher the degree of the "unknown" is (divesite, buddy).

    There may be effects related to blood pressure indicating a higher BP to be somewhat beneficial, but I cannot be more precise at the moment.

    People vary probably as much in their sensitivity as they vary in general.
    There are people I would dive with no matter how.
    There are people I would dive deep only on mix.
    There are people I would not dive with no matter how.

    IMHO one is pretty safe up to -30m. Most can become accustomed to depths between 30m and 45m, provided reasonably good conditions, deeper, down to 55-65m, much relies on experience and personal factors, it is not for everyone. Deeper than that rescuing a buddy will be very, very difficult. The dangers of CO2 become very prominent.
    Getting used to narcotic effects is reality at least for some. That is my personal feeling, and is backed by the qualified opinion of an Anaesthesist who has a profound scientific background.
    Getting used to narcotic effects of narcotics is a reality he is daily verifying.
    French studies (Rostain e.a.) state the fact of getting accustomed. They state as well the errors made in studies where N2O is used to replace Nitrogen, because of a different interaction with different GABA receptors (apart from study design).

    Mattthias
    Last edited by MatV; 29th July 2010 at 16:16.

  4. #64
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    Re: What is your max depth tolerance to Narcosis?

    Quote Originally Posted by tlegner  View Original Post
    What are your personal max narcotic depth tolerances to narcosis? I know one OC diver that says he is narked at 120ft while two deep oc tech divers routinely go to 210ft on air with no effects of narcosis.

    What are your experiences with Narcosis?

    Do you think divers built up a tolerance to narcosis?

    What are your thoughts on air dil and narcosis?

    Thanks, Troy
    thats imposible determine with any degree of accuracy:

    Diet, Hydration, Dive history and frequency, Fitness level, etc. play a major role.

    As far as people saying that they have a "tolerance", thats complete nonsense. What people really mean is that they are "use to" feeling impaired but they are still none the less impaired.

    I good example of that would be a drunk, comfortable being drunk or not you are still drunk.

    Narcosis is a very sly and cunning adversary when diving part of the reason is because it doesn't get much attention anymore and it gives us a false sense of security as so many of these posts have clearly demonstrated.

    Jon

  5. #65
    RBW Member bobdiver is an unknown quantity at this point bobdiver's Avatar
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    Re: What is your max depth tolerance to Narcosis?

    i think there is a build up to depth tolerence within reason and for me im comfy at 40meter on air,,i regularly push into the 60m range but deep down i no im impaired,as an x military diver deep air was the norm as there was no joys of mix gas,,so narcosis became a way of diving and was taken for granted,,anyway thatsjust my own personal opinion for the subject,happy diving

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