Buhlmann and RGBM

[Zept]

Quick question: is RGBM a development of the Buhlmann algorithm or was it developed independently? Or to put it slightly differently, are there fundamental differences between the two models?

Thanks for any enlightenment you can provide,

Zept

 

[Dr Deco]

Dear Zept:

Buhlmann

The decompression techniques of Professor Buhlmann were developed first of all to allow deep diving in the altitude lakes of Switzerland. This was for purposes of military defense from an invasion of his country.

Second, the system was developed to allow for mixed gas diving, that is, the use of helium and nitrogen. Since this gases enter and exit the body differently because eof their solubilities, the decompression characteristics differ. In its conceptual basis, it is a single-phase, Haldane type model.

RGBM

The Reduced Gradient Bubble Model (RGBM) has as its purpose, the control of both dissolved and gaseous nitrogen and helium. It is an algorithm that (mathematically at least) tracks the number of tissue microbubbles and their size, and modifies the stop depths to give the tissues the most favorable decompression characteristics. That is, it attempts to give the greatest gradient for dissolved inert gas while keeps microbubbles small at the same time. This is not something that can be physically measured in the body (at the current time) but is determined from analysis of diving data. This data allows one to create the model (algorithm) for the decompression table (or algorithm in the deco meter).

As algorithms are developed over the years, bits and pieces will be added together. Ideas can be borrowed from one and added to another. Sometimes it is truly difficult to trace the “pedigree.” In this case, however, RGBM is different from the original Buhlmann concepts.

Dr Deco (on vacation this week)
:mean:

 

[Zept]

...that's very clear and helps a lot. Enjoy your holiday!

 

[BRW]

Guys,

Let me also point out that models are one thing, but
actual diving and testing are something else. And that
is where RGBM shines -- it's been validated and tested
for the past 5 yrs or so. Tables, meters, and software
with RGBM benefit from all the testing -- I have an article
to be published on just this. So RGBM works and has
been validated -- and it's a complete model with no
ad hoc juxtapostioning of diving regimens on top of each
other. AND it's the only dual phase model with such
credentials. This is important -- and why it's licensed.

And I will post it here afterward -- if OK with Mike.

BTW, also see my other thread post on RGBM tables.

Bruce Wienke

Program Manager Computational Physics
Counterterror And Countermeasures Dive Team Ldr

 

[Dr Deco]

Bruce:

You are most welcome to post material on dive table calculations and their models, for example, RGBM. I do not do this type of work and therefore do not have a deep background in that topic area.

I am sure that the readers would be interested- - - I also!

Dr Deco
-- on vacation this week :mean: