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    CO2 production results

    I thought I would post this in hopes of getting some more info on CO2 production and the efficiencies of the scrubbers that are out there. First I will give you a little background on how this all came around. I am a Canadian Navy Diver and was able to take part in a study to help develop a Physical Test that will be given to all Navy Divers on a annual basis to ensure that a proper standard of physical fitness is maintained. I was involved in three tests which helped create a baseline for the group to use when developing the standard.

    The first test was the standard treadmill test where I was told to run on a treadmill until I was unable to run anymore. I must also explain that when doing this test I was started at a level that was well above my normal running pace! (that is why the test only lasted 9:50)

    The second and third tests were held in a pool where I was wearing O/C gear and hooked up to a pulley system that was around my waist and prevented me from swimming away. I had a reference point which I kept in front of me and as the time increased so did the weight pulling me backwards. We were told to keep the reference point in front of us until we could no longer swim against the weight. One of the tests was completed at the surface and the other was at 6’ under water.

    The main reason I put this all together is from what I have read in various posts is that the testing on the Evo scrubber is far beyond what the normal production of CO2 is for most people (2 hours @ 1.6L/min @ 6C). As you can see the results of the test I did showed a CO2 production well in excess of that. I know that the tests I was involved in were a maximal test and one would not be able to maintain that level for a extended time but the numbers are quite interesting. I have to admit that I really do not understand all of the data that is shown here but maybe someone out there does and can comment on the info. So here it is and I apologies if it is hard to read. They are posted in the following order……. Treadmill, surface swim and the 6’ underwater swim.
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    Re: CO2 production results

    Hi Rob,

    Thanks for the data. I sure the doc's and various experts around here will be able to appraise the results and answer any questions you have.

    Firstly, I can see you are a pretty fit guy from the VO2 figures!

    The second observation I would make is that the results consistently indicate that at about 3-4 mins into the test is when CO2 production starts to overtake Oxygen consumption. This would suggest that CO2 is being retained for some reason. By the end of each of the tests the VCO2 figure is around 20% greater than the VO2.

    These sort of tests have been done by the US NEDU to evaluate the Prism (and maybe other CCRS?). At least the prism results can be found by linking from SMIs website.

    I'm sure you'll generate some interest - nice post.
    Cheers
    AB
    Last edited by Underwaterbear; 20th July 2006 at 01:06.

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    Re: CO2 production results

    I'd sure like to have an interpretation (for idiots) on what each column means and what the figures represent.

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    Re: CO2 production results

    I will spout out what should be important here to us closed circuit divers: the VCO2 column which indicates the volume of CO2 produced in liters per minute.

    For most of the VCO2 columns in these exercises, Rob's CO2 production does exceed 1.6L/min. But of course, the stuff that they make Rob do are significantly above the typical physiological exertions rates encountered by an average diver on an average dive. Rob, too bad there is no heart rate column, or did I not know which one that was?

    A little thread hijack here...

    How is this: want to increase your scrubber duration up to an additional 30%? Easy. Go on a low carb diet before diving. I am not sure if I would need to worry about that with my large scrubber, but I would think that others with smaller scrubbers might find that useful.

    Metabolism of protein produces 15 percent less CO2 than carbohydrates do, and fat produces about 30% less CO2 per liter of oxygen consumed.

    Reference 1.
    Reference 2.

    In the second reference, it indicates that the metabolism of alcohol produces even less CO2 than fat. As far as scrubber time, then, a good pre-dive meal would be steak cooked in butter and a sour cream omelette chased with a nice cold glass of vodka.

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    Re: CO2 production results

    I am looking into the description of the acronyms the ones I do know are as follows........ RR=respiratory rate, BPM=Breaths per min, VCO2=volume of CO2 in L/min and the same for the VO2 as for the rest I am sure that someone out there knows and if not I will try to hunt down the answers.To answer Tecsimple's question, yes I did have my heart rate monitored but for some reason I did not get that info, I will have to inquire about it. Thanks for the input so far


    Rob

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    Re: CO2 production results

    Quote Originally Posted by diverrob
    I am looking into the description of the acronyms the ones I do know are as follows........ RR=respiratory rate, BPM=Breaths per min, VCO2=volume of CO2 in L/min and the same for the VO2 as for the rest I am sure that someone out there knows and if not I will try to hunt down the answers.To answer Tecsimple's question, yes I did have my heart rate monitored but for some reason I did not get that info, I will have to inquire about it. Thanks for the input so far
    Rob
    Rob
    Great post. This level of information deserves its own heading and not get lost in the general posing. Just to comment on the terms used. These are standard terms used to express the input gas and expired gas with water vapour but referenced to avoid differences in ambient temperature and barometric pressure. Pretty much back to basic diving teaching on Charlie Boyles laws
    STPD Standard Temperature Pressure Dry
    BTPS is Body Temperature Pressure Saturated
    RR BTM is Respiration Rate, Breath Per Minute
    METS is a metabolic rate of consumed oxygen based on 3.5 ml of 02 per kg of subject weight per minute of RR respiration rate
    VE Ventilation Rate usually described in BPM Breath Per Min referenced to BTPS. iain

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    Re: CO2 production results

    Quote Originally Posted by teksimple  View Original Post
    In the second reference, it indicates that the metabolism of alcohol produces even less CO2 than fat. As far as scrubber time, then, a good pre-dive meal would be steak cooked in butter and a sour cream omelette chased with a nice cold glass of vodka.
    OMG! Can I go diving with you sometime! We can stop for breakfast...

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