What is the amount of inert gas removed during offgassing

ianfirmin

Does anyone out there have any numbers on the amount of inert gas removed from a body during decompression? If this was (has been?) measured it may give an indication of the accuracy of the compartment model.

Lets say a body (human, goat whatever) was (in the terms of the decompression model) taken from one saturation state to another and the amount of inert gas exhaled was measured then....if you could estimate the ratio of body mass in various tissue compartments and the amount of gas expected to be excreted you may be able to validate the model.

I'm also interested if the amount of inert gas expired would significantly effect the existing fractions of gas in the loop.

Any info on this??

Kind regards
Ian

sensor330

Its not an exact science. I've done some experiment diving at DRDC in Toronto and it was uncommon for two individuals had the same bubble score, a number they give you to represent the amount of dissolved gas in your blood. As well your individual bubble score varied on a day to day basis. When the DCIEM table were developed there was a number of people who did get bent. Can't remember the number but from what I remember I was fairly surprised at the percentage of DCS occurance while diving within the prescribed table.

Scott

mempilot

How long do you want to stay underwater? There is an acceptable amount of residual inert gas that can remain, which will work it's way out over a surface interval. You can look at M-values and percentages, which is not an exact science, to get an idea of how 'clean' you will be. But, everyone is different in there tissure composition, so go luck finding an exact value.

So to give you an answer: Some of it, most of it, all of it, it depends.

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Dsix36

Doesn't get more definite than that!!!



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jaap

If you want to dig into it, do some searches on Rubicon, Rubicon Research Repository: Home

Then you will find many related things, such as this report:

http://archive.rubicon-foundation.or.../ADA277395.pdf

If a very simple and rough estimate is of any help one can approximate that a normal adult at the surface holds about 1 litre of dissolved nitrogen (can dig out a reference later). For saturation air diving it seems that Henrys law is fairly valid. This gives that a returning saturated air diver will need to eliminate something like one litre per atm of diving depth in order to eliminate all excess nitrogen. Of course this reasoning is way oversimplified.

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ianfirmin

Thanks for the Rubicon link. Excellent.

Cheers
Ian