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Thread: Air breaks

  1. #1
    RBW Member vincnt moore will become famous soon enough vincnt moore will become famous soon enough vincnt moore will become famous soon enough vincnt moore's Avatar
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    HAMMERHEAD

    Air breaks

    Doing a poll/survay on how air break are incorporated into your deco on

    long dives

    ( over 160 min). And when CNS approaches 75 percent. Time duration on the

    brake how many minutes off before going back on. Any additional thoughts or

    practices would be interesting to hear, especially when your clock is running

    out. Lung irritation clearing increases gas exchange after break increasing

    gas exchange thoughts.

  2. #2
    Randy Thornton Mixaddict has much to be proud of Mixaddict has much to be proud of Mixaddict has much to be proud of Mixaddict has much to be proud of Mixaddict has much to be proud of Mixaddict has much to be proud of Mixaddict has much to be proud of Mixaddict has much to be proud of Mixaddict has much to be proud of Mixaddict has much to be proud of Mixaddict has much to be proud of Mixaddict's Avatar
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    Re: Air breaks

    Quote Originally Posted by vincnt moore  View Original Post
    Doing a poll/survay on how air break are incorporated into your deco on

    long dives

    ( over 160 min). And when CNS approaches 75 percent. Time duration on the

    brake how many minutes off before going back on. Any additional thoughts or

    practices would be interesting to hear, especially when your clock is running

    out. Lung irritation clearing increases gas exchange after break increasing

    gas exchange thoughts.
    When diving CCR, I don't do air breaks, as I am rarely breathing 100% O2. At deco, I rarely go much above 1.4 PO2 except for short intervals. Consequently, personally I see little need for an "air break".

    Regards,
    Randy

  3. #3
    RBW Member joesympatico is an unknown quantity at this point joesympatico's Avatar
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    Re: Air breaks

    Quote Originally Posted by vincnt moore  View Original Post
    Doing a poll/survay on how air break are incorporated into your deco on

    long dives

    ( over 160 min). And when CNS approaches 75 percent. Time duration on the

    brake how many minutes off before going back on. Any additional thoughts or

    practices would be interesting to hear, especially when your clock is running

    out. Lung irritation clearing increases gas exchange after break increasing

    gas exchange thoughts.


    So you want to come off the loop to deco? why?

  4. #4
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    Re: Air breaks

    Quote Originally Posted by joesympatico  View Original Post
    So you want to come off the loop to deco? why?
    Why do you think it would be necessary to come of the loop to accomplish an air break.

    Whats wrong with the basic skill of a dil flush and lower set point.....i guess going to OC on the BOV might be considered coming off the loop.

    Also, the OP might be looking at dive planning should he need to go to OC bailout for his deco.

    John
    Last edited by jkaterenchuk; 4th February 2009 at 18:51.

  5. #5
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    Re: Air breaks

    I do air breaks at 125% CNS as indicated on my intigrated computer. Ill flush with diluient and run 0.7ish for 5mins then go back on 02 for 10mins

    Intigrated computer sorts out the added deco. If on tables i dont count the time on the air break.


    ATB

    Mark

  6. #6
    RBW Member vincnt moore will become famous soon enough vincnt moore will become famous soon enough vincnt moore will become famous soon enough vincnt moore's Avatar
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    HAMMERHEAD

    Re: Air breaks

    A Mini-Forum on air breaks and O2 toxicity in clinical HBO2 therapy.
    Since last year’s publication of Hampson and Atik’s paper on risk of CNS O2 toxicity in patients receiving HBO2 therapy (1), the journal has received an interesting letter exchange that is printed in this issue in our mini-forum format. Because different air break schedules are in use (e.g. 5, 10 or 15 minutes) that vary with HBO2 pressure and exposure time, and some uncertainty exists within the hyperbaric community about the origins and rationale for use of routine air breaks in HBO2 therapy, we thought it would also be useful to provide some additional background on the subject from two scientists who have been personally involved in the development of clinical HBO2 treatment tables, Dr. Paul Sheffield and Dr. Jim Clark. Both experts have provided useful historical perspectives on the theoretical and practical rationale behind the development of air breaks to prevent both pulmonary and CNS O2 toxicity during the administration of HBO2 treatments at pressures above 2 ATA. Because the O2 toxicity risk plot of time versus dose is a steep rectangular hyperbola, air breaks are not usually necessary for routine treatments at pressures of 2 ATA or less and durations of 2 hours or less, unless the individual patient is known to be at risk for convulsions. It is particularly noteworthy that after almost 50 years of work, optimal HBO2 to air break durations are still not fully agreed upon. Fortunately, however, the treatment tables used most commonly today have a very low incidence of convulsions. Nonetheless, any O2 convulsion is highly undesirable, and though the old saw claims the O2 seizure is benign, this axiom may not stand the test of time as tools with better discrimination are brought to bear on the effects of O2 toxicity on the brain, especially in elderly and injured patients. Also included is a paper by Richard Smerz, "Incidence of oxygen toxicity events during the treatment of dysbarism" which was originally presented at the UHMS Annual Scientific Meeting’s Oxygen 2002 Workshop, La Jolla, California, July 1-2, 2002. The paper included here provides some additional new data on the risk of O2 toxicity in the treatment of DCS using deep tables.
    Claude A. Piantadosi, MD
    Duke University Medical Center
    Editor-in-Chief, UHM
    REFERENCE
    1. Hampson N, Atik D. Central nervous system oxygen toxicity during routine hyperbaric oxygen therapy. Undersea Hyperb Med 2003; 30:147-153.
    Copyright ©


    Yes this would be off the loop, reason so you dont have to drive the loop po2 back up when going back on. Also using lowest o2 gas for break.
    Last edited by vincnt moore; 6th February 2009 at 00:45.

  7. #7
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    Re: Air breaks

    Quote Originally Posted by vincnt moore  View Original Post
    Yes this would be off the loop, reason so you dont have to drive the loop po2 back up when going back on. Also using lowest o2 gas for break.

    That would not be totally true as your lungs have an oxygen poor gas in it.. even if you try and expell all teh gas, it will take a few breaths to mix and flush and you have to flush the loop now anyway (unless you can take a few breaths off oc oxygen)
    Joe Radomski
    CCR Trimix Instructor Trainer
    ANDI Instructor Trainer Director #10

    All posts are personal opinions and DO NOT reflect any affiliated agency unless specifically stated.

  8. #8
    So many CCR So little etc Mark Chase has a reputation beyond repute Mark Chase has a reputation beyond repute Mark Chase has a reputation beyond repute Mark Chase has a reputation beyond repute Mark Chase has a reputation beyond repute Mark Chase has a reputation beyond repute Mark Chase has a reputation beyond repute Mark Chase has a reputation beyond repute Mark Chase has a reputation beyond repute Mark Chase has a reputation beyond repute Mark Chase has a reputation beyond repute Mark Chase's Avatar
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    Re: Air breaks

    Quote Originally Posted by jradomski  View Original Post
    That would not be totally true as your lungs have an oxygen poor gas in it.. even if you try and expell all teh gas, it will take a few breaths to mix and flush and you have to flush the loop now anyway (unless you can take a few breaths off oc oxygen)

    Damed dodgy trying to expel all the gas before going back on loop. The loop might not be breathable then you'd be in a world of trouble.


    I find that until I have off gassed all the helium the loop PP02 gets diluted anyway. So much so that one of the primary indicators for me that i have cleared the helium deco is a stable loop PP02.

    Id triple flush anyway to clear helium from the loop so triple flushing after an air break works for me as id be doing this every 15mins of deco anyway even if I were not doing air breaks.


    As an aside I am more concerned with preventing mucus build up on the lungs and promoting better off gassing that I am with preventing 02 tox. I dont think I have ever gone past 200CNS so I dont consider the risk of 02 tox to be significant anyway.

    Looking back over some notes I think 187cns was my worst and that was a nearly four hour dive.


    ATB

    Mark

  9. #9
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    Re: Air breaks

    Well, in my limited experience, going OC for the air breaks is a GOOD thing to do. Firstly setting set point to 0.7 isn't really a good air break gas. Officially need to get less than 0.5 PO2, and that's much easier to do with simple o/c air, if the idea is to truly 'rest' the lungs. Also, flushing to lower PO2, then trying to raise the PO2 back up, especially using weak diluents e.g. Tx5/70 means wasting a LOT of gas/potential buoyancy issues, and I DON'T want that risk if the deco's big enought to require air breaks! In short you can do air breaks on the loop, but its not the most practical way to do it. Yes, i know the gas in my lungs will be different/will dilute the high PO2 loop gass when I go back onto the loop, BUT in practice, never found this to be a significant issue. The inspiration will quickly /easily attain/hold high set point on going back on the loop again. I've tried both on the loop and off loop air breaks, and its a no brainer for me. Try it and see. YMMV

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