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Thread: Voluntary Hyperbaric Chamber Dive

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    Voluntary Hyperbaric Chamber Dive

    A week ago, I had my second voluntary ďdiveĒ in a hyperbaric chamber. Here in Norway, dive shops regularly organize trips to chambers for their members and customers. The price had gone up since my last dive 10 years ago, but I still thing its worth the $150, including a one hour lecture by a medical dive doctor.

    The purpose of the whole exercise is to experience the Nitrogen Narcosis induced by diving normal air (21/79) at high pressure. I have previously made a chamber dive to 50 meters, but wasnít very affected. Now, after having spent much of my spare time reading and thinking about diving physiology and accidents (on this forum), I wanted to do it again.

    We were the second group going in the tank. Listening to the first group through the intercom made me feel like missing the party of the year. 8 people laughing their head of on high pitched Micky Mouse voices really sounded like a party in a mad house. Although they had a sobering three quarters of an hour of decompression, they were still giggly when they emerged. They had been given simple questioners to fill out at the bottom and some of the answers werenít even related to the questions asked.

    Our planned dive was the Royal Navy Table 12:
    - Straight down to 60 meters (15m/min)
    - 10 minutes bottom time
    - 18 meters for 5 minutes
    - 15 meters for 5 minutes
    - 12 meters for 5 minutes
    - 9 meters for 10 minutes at pure oxygen
    - 6 meters for 10 minutes at pure oxygen

    You may notice the pure oxygen stop at 9 meters. This was a bit surprising as it equals an Opp of 1.9 ATA, and is beyond the recommended diving limits. It turns out that the chamber divers push well beyond even this when treating carbon monoxide poisoning (more on this later).

    Going into the tank I can only imagine the working conditions for the tenders and doctors, when treating really sick patients. We were shown pictures, taken the previous day, of a patient on a stretcher with all sorts of tubing and apparatus attached. For the doctors, standing crouched over him for hours, it must be quite exhausting. Since most of these dives are deco-dives, itís normal for the doctor to stay the entire dive, even though it is possible to bring them out using the lock-chamber. But, normally they want to keep the lock free in case of an emergency.

    The decent has a short stop at 6 meters, just to make sure that everyone can equalize properly. From then on itís straight down. I have to pinch my nose to equalize on fast descends and especially on this dive, I didnít take any chances Ė messing it up for the others.

    Going down it is noisy, damp and stuffy and we are all just sitting there equalizing and looking at each other Ė to see if the others were getting drugged. Like my last tank dive, I didnít feel any distinct onset of the narcosis, but I did feel exited and happy. But when we finally reached our maximum depth and the first cartoon-person squeaks; ďI donít think I feel anythingĒ we all burst out laughing.

    I find that itís difficult to distinguish between the effect of narcosis and that of just being jolly. Anyone whoíve had access to helium knows that one can have quite a laugh, making funny voices, even when totally sober.

    One of the tasks we were given was to find the hypotenuse of a triangle, given the two other legs of a triangle. I recognized it as the Pythagoras formula and managed to take the square the two cathetuses, add them together, but failed to take the square root of the result. Thinking back, I might have made the same mistake if the guy sitting next to me had kept cheering me on Ė in his hilarious cartoon voice.

    Me and my buddy managed to solve most of the simple puzzles and even had semi-meaningful topic-related discussions. In hindsight, I realize that my reasoning was impaired, but luckily I donít go completely bonkers. I think I can tell approximately when the narcosis started affecting me, but like the last time, there is no distinct hit.

    In the preceding lecture, I was quite surprised to learn that they give patients pure O2 at 20 meters. That is an Opp of 3 ATA! I actually had to ask twice, since it sounded so wrong to me. Apparently they experience cramps very seldom and when they do, they only last for about 2 minutes, after which the subject completely recovers. The doctor actually joked about how it was much easier to take the sedative himself, instead of trying to administer it to a person having spasms.

    During the ascent we were given the oxygen masks as we reached the stop at 12 meters. The plan was to start using it from 9 meters, but I asked if I could try it for a minute at 12. I just wanted the bragging rights for having breathed a partial pressure of 2.2

    What did I learn?

    The most enlightening part of the evening was actually listening and talking to a doctor that was both a recreational dive and professional hyperbaric physician. Particularly, the fact that he personally, had manage to resituate a patient, after giving first-aid and cardiac massage for over 2 hours. That really hammered in the message of:

    learn how to do it right Ė start immediately Ė and never stop!


    What I learned from the nitrogen narcosis, mostly confirmed what I already knew; Iím not heavily affected, but itís difficult to detect both the on-set and the severity. In diving terms this translates to being aware of feeling too merry and to keeping the task loading to a minimum below 30 meters. This is generally what all the literature says, but I hope it engraves deeper in my diving consciousness having actually done the dive.

    jsevland
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    Re: Voluntary Hyperbaric Chamber Dive

    I did a chamber dive once, a few years back City College in Santa Barbara.
    It was good experience, and I agree that talking to the docs and chamber operators
    is the most yielding part of it.

    Very good post, thanks, some green for you! :D

  3. #3
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    Re: Voluntary Hyperbaric Chamber Dive

    Years ago, when I thought I was bent (turns out I wasn't), I did some chamber treatments. Knowing that I was on pure oxygen at 60 fsw was frightening!

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    Re: Voluntary Hyperbaric Chamber Dive

    Excellent write up- green your way.

    One item: The graphical read out of the dive is very nice to see, but it tripped a thought from waaaaay back in my memory re a warning in the owner's manual of a dive computer I owned long ago. The caveat was to NOT pressurize it w/ air when testing- only in a water filled test tank. Reason given was possible damage to depth sensor. Anybody else ever see such a warning, or have sensors become more robust in the last 20 years?

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    Re: Voluntary Hyperbaric Chamber Dive

    They let you take a camera in the chamber? Was that shot during the "dive" or staged afterwards? I've done a few fun rides and always get the request to take a camera in declined (maybe they're worried people will start shedding clothing once narc'd :D ). Their reasoning is always fire related.

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    Re: Voluntary Hyperbaric Chamber Dive

    I'm going on a chamber ride in about a month. I'll be sure to post my experience as well. Sounds like fun.

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    RBW Member jsevland is just really nice jsevland is just really nice jsevland is just really nice jsevland is just really nice jsevland is just really nice jsevland is just really nice jsevland is just really nice jsevland is just really nice jsevland is just really nice jsevland's Avatar
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    Re: Voluntary Hyperbaric Chamber Dive

    Thanks for the comments.

    I realize that I should have pointed out a few things - given the cleverminded audience of this forum

    1) The dive computer was in a bucket of water, since the manual clearly states that it should not be air tested (Suunto). On the other hand, the tender we had with us down wore his on his wrist ...

    2) The chamber is really strict on taking electronics into the chamber, so we basically had to empty our pockets and take off watches. I brought both a camera and a video camera into the tank, but both were inside underwater housings (that were rated at more than 60 meters)

    The last time we did the dive, my brother was allowed to take his digital camera (with out a housing) into the tank. I guess that facility was a little more sloppy, and that digital cameras were less common.

    On the way down the camera worked just fine, taking pictures and all. After surfacing we noticed that the screen had cracked. The camera was replaced, since the guys at the shop clearly could not understand what had happen to it

    My brother - not me

    jsevland

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    Re: Dive computer on Chamber Dive

    Quote Originally Posted by Skipbreather  View Original Post
    The caveat was to NOT pressurize it w/ air when testing- only in a water filled test tank. Reason given was possible damage to depth sensor. Anybody else ever see such a warning, or have sensors become more robust in the last 20 years?
    Yup, same warning from the chamber operator when I did my chamber dive, around 98 or 99.
    Dropped my Uwatec Air Console into a Big Gulp, worked well, no damage. :D

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