Physiology and Computer algorithms

[Scuba]

Interesting observations, Scuba
I've heard that contary to what one might naturally think, the incidence of DCS has on the whole been influenced upwards with computer use. I did not personally see the literature on this, but an instructor I know said he did.

Apparenly, the gist of the finding was that computers are naturally less convervative that pure table use on the whole, so computers bring people closer to their limits and thus suffer more hits on average.

JAG

I believe this study has been discussed here before. I don't know the particulars of it. Someone familiar with it may want to comment. Here are some issues regarding it.

Computer use has greatly increased over the last few years.
Let's say 70% of DCS cases where suffered by computer users last year. If 75% of divers use computers we now have a whole different perspective. Furthermore, where these divers diving closer to or at the deco model limit than divers without computers? Just because someone gets DCS, doesn't automatically translate into the deco model, or computing tool or method, being the causal factor.

 

[padiscubapro]

The lawsuit you site, wasn't about a "faulty alg" per se.. but it appears it did have a fault.. From what I know the UNDERWATER calculations are all correct, the problem appears to be that IF the person did a nitrox dive, whatever gas they were using was used for surface interval credit instead of Air..

unless they were diving very high o2 mixtures and were runing everything to the edge normal safety stops and conservative profiles should have prevented problems..

the divers who are suing are experienced divers and should have known better.

 

[jagfish]

"Just because someone gets DCS, doesn't automatically translate into the deco model, or computing tool or method, being the causal factor."

True, but it would be interesting to sort those DCS cases into what algorithms they were diving...
JAG

 

[Dr Deco]

Hello Readers:

Models

All models must first be physical or physiological and then be translated into some solvable mathematical form. In all cases, it is necessary to make assumptions. Usually these are simplifying assumptions. When you actually see the models, you are well aware that they will fit some circumstances and not others.

What assumptions are made will depend to some extent on the prevailing concepts that are prevalent at the time. Currently we are seeing an interest in “bubble models.” The idea has been around in at least one form for sixty years, but it was not necessarily in a useable form. The Haldane “critical supersaturation model” was the “thought for the day,” and all modifications were made around it.

There has always been a shortage of physical scientists in barophysiology and some models were simply less popular. It really depends mostly on trends that change slowly. In the past several decades, biochemical theories of DCS were all the rage. Today they are not covered at all in the new Bennett and Elliott book.

In addition, a model will often assume a life of its own. That is, the model will begin to believe that nature is following the model rather than the other way around. This is not to cast aspersions at anyone – it is common occurrence.

Different scientists will also approach a problem in a different way. It is possible that certain aspects of physiology or physics are omitted because it is difficult to introduce them into the model. Or one does not wish to introduce them because that changes the model so much that it now no longer the original modelers idea.

They Work

All of these models (meters or tables) work because they are very conservative. That is why they can have such different times for decompression and still be successful. Think about it. :06:

Dr Deco :doctor: