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Thread: CO2 tolerance

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    RBW Member lancsman is on a distinguished road lancsman is on a distinguished road lancsman's Avatar
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    CO2 tolerance

    Hi,In an other post Asked about dangerous CO2 level and was advised 0.5% SEV (thanks for answer) but this seems just too convenient to be a single number.I had always assumed that like PPO2 tolerance that PPCO2 tolerance varied by person, day fitness etc.Is the level of 0.5% SEV been set based on an aceptable level of risk and if so is it one we should review on an going basis. I know more experienced diver than myself that dived at PPO2 levels we would consider suicidal today.It looks as if we are about to see the avalablitiy of CO2 monitors, but what should we set as the alarm level?Mark

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    Re: CO2 tolerance

    Mark,

    You might find the following presentations (.mp4) interesting from a Co2 viewpoint.
    DAN Divers Alert Network
    Warkander Co2 Intoxication
    Anthony HSE Video

    DAN Divers Alert Network
    Warkander USN Testing Perspective
    Clarke Rebreather Incident investigation
    Anthony Diving rebreather Apparatus: Testing and Standards, UK/EU perspective.

    Co2 appears to also crop up in the majority of other presentations as well.

    My take on it is that the scrubber time to 0.5 is great from a duration point of view, however it is the time it takes to then rise to 1.0 that is important. If it takes (for example) ~20min, to rise that is not a major event, you get a bit of a CO2 duration buffer. If however your scrubber/unit only takes a couple of minutes to go from 0.5 to 1.0 then you may have an issue with rapid CO2 breakthrough if you push your scrubber to the limit.

    How the heck a CO2 monitor is going to be implemented by DeepLife et al, such that it gives a reliable usable display will make for interesting reading & diving.

    regards
    Brad

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    Re: CO2 tolerance

    I've asked this question in the past. I freedive a bit and quite a lot of the training techniques that freedivers use is too build a greater tolerance to elevated CO2 levels, apnea walking (which I do a fair bit of) for example. What I've wondered is this counterproductive to my rebreather diving? Surely the best thing is to have as little tolerance as possible so that when any CO2 shows up then you're on it immediately? I don't know. For me, I haven't curbed the freedive training I do but I make damn sure that my rebreather is prepped properly every time, prevention is better than cure.

    Will a CO2 monitor make a massive difference to accident stats? I have my doubts.

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    some favorites...

    Few of my favorites...

    Lambertsen, C. J. (1971). "Carbon Dioxide Tolerance and Toxicity". Environmental Biomedical Stress Data Center, Institute for Environmental Medicine, University of Pennsylvania Medical Center IFEM Report No. 2-71. RRR ID: 3861

    Knafelc, ME. (2000) Physiologic Basis for CO2 Limits Within Semiclosed and Closed-Circuit Underwater Breathing Apparatus. NEDU-TR-4-00 RRR ID: 3304

    Glatte Jr H. A., Motsay G. J., Welch B. E. (1967). "Carbon Dioxide Tolerance Studies". Brooks AFB, TX School of Aerospace Medicine Technical Report SAM-TR-67-77. RRR ID: 6045

    Since that very limit is being evaluated now there should be some new research soon and with us starting to add more from the US Naval Submarine Medical Research Lab, there will be quite a bit more available from the older work as well.
    Last edited by Gene_Hobbs; 7th September 2008 at 02:37. Reason: add...

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