While there is some gas phase in the blood at start, tissues still are
modeled in bubble models.  Abyss (RGBM) has compartments with
1,2,5,10,20,40,80,120,240,480 and 720 min tissue half-times.  

I was stating my feeling that somehow the models seem to get more
unpredictable at the middle tissues. As I get closer to the filling of
the middle tissues, I seem to get more fatigue.  However, I may not have
enough experience to make a significant statistical universe.  While gas
phase is cause of the DCS symptoms, how the tissues add gas phase as
they supersaturate still controls the number of bubble seeds.  

>----------
>From: 	Richard Pyle[SMTP:deepreef@bi*.bi*.Ha*.Or*]
>Sent: 	Thursday, May 09, 1996 1:31 PM
>To: 	David Norton (Excell Data)
>Cc: 	'David Wilkins'; 'techdiver@terra.net'
>Subject: 	RE: TWO trimix dives a day ?
>
>
>> Tom Mount posted a while back about a study that was done where deco on
>> air for 100 ft dives > 60 mins caused symptomatic bubbling.  Better deco
>> gases solved the problems, but I still wonder what's wrong with model
>> that we didn't predict the bubbles better.
>
>The general problem with all the models is that none of them are based
>on 
>a solid understanding of what's actually going on in our bodies during 
>comprerssion and decompression.  The tissue-compartment-based models
>are 
>the most popular, but are probably farther from reality than the 
>bubble-based models (which, by comparison to the tissue-compartment 
>models, are largely untested).  The compartment models assume no gas 
>phase in the blood, and bubbles start to *form* if the difference
>between 
>the dissolved gas tension and the ambient pressure gets too great. The 
>bubble models assume the gas-phase bubbles are already there 
>("micronuclei"), and these bubbles grow or shrink depending on the
>ratio 
>of gas partial pressure inside the bubble, and the dissolved partial 
>pressure in the surrounding blood and tissues.  The partial pressure in
>
>the blood & tissues is a function of what we are breathing, what the 
>profile was, diffusion characteristics of the particular gas, perfusion
>
>characteristics of the particular diver's circulatory system, etc.  
>Partial pressure inside the bubble depends on a variety of things, 
>including ambient pressure, the diver's blood pressure (over ambient 
>pressure), the size of the bubble (smaller bubbles have higher internal
>
>pressures due to proportionally larger effects of skin tension), etc.
>We 
>get "bent" when the bubbles grow to a sufficient size or cause
>sufficient 
>secondary effects that symptoms occur.
>
>From all I know, the real-world data (e.g., doppler studies, my
>personal 
>dive history, dive histories of other experienced divers, etc.) tend to
>
>suggest the bubble models are a more accurate reflection of what is 
>really going on.
>
>Aloha,
>Rich
>

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