Breathing rate, air integrated computers and DCI correlation

[lmorin]

I believe this article points out the correlation of increased workload & DCS. This article is in the Dive Alert Network ( DAN ) medical info ( I have selected pertinent paragraphs ):

Decompression Illness: What Is It and What Is The Treatment?

By Dr. E.D. Thalmann, DAN Assistant Medical Director

Who Gets DCI? Decompression illness affects scuba divers, aviators, astronauts and compressed-air workers. It occurs in approximately 1,000 U.S. scuba divers each year. Moreover, DCI hits randomly. The main risk factor for DCI is a reduction in ambient pressure, but there are other risk factors that will increase the chance of DCI occurring. These known risk factors are deep / long dives, cold water, hard exercise at depth, and rapid ascents.

Prevention of DCS
Recreational divers should dive conservatively, whether they are using dive tables or computers. Experienced divers often select a table depth (versus actual depth) of 10 feet (3 meters) deeper than called for by standard procedure. This practice is highly recommended for all divers, especially when diving in cold water or when diving under strenuous conditions. Computer divers should be cautious in approaching no-decompression limits, especially when diving deeper than 100 feet (30 meters). Avoiding the risk factors noted above (deep / long dives, exercise at depth or after a dive) will decrease the chance of DCS occurring.

I think you are reading too much into the above. Even if it is correct, it refers to "hard exercise at depth" and "diving under strenuous conditions." These are circumstances much like diving on air to beyond 130 ft--i.e., not recreational diving. Hence, it is a non-issue for recreational divers, as far as I am concerned.

 

[Nykka]

After her "hit", she was able to correct her breathing by using an air integrated dive computer. She always uses 32% EAN or higher. She has not had any further incidents.

Relatively newer diver here... I have a question re: the above statement. Isn't it more likely that the switch from 21% O2 (or Air) to 32% EAN would result in not having further incidents? I'm struggling to see how it was from switching the type of computer...

 

[Jim Lapenta]

It made things easier for her as she did not have as much money weighing her down and forcing her to work harder under water. I can train my students to plan conservative profiles, not over exert, use good judgement when deciding if a dive is safe to do, and get the same safer results. And they don't have to shell out over a grand for one item that may or may not help.

 

[HIGHwing]

Don't you want the most conservative option based on your activity?

To answer your question, no I don't. I want a computer from a manufacturer that is using a published model that I can learn about, understand, and interpret the manipulations I choose to make based on the parameters of the dive. I can then experiment, log the outcomes, and make meaningful changes to the model I'm following based on my plan. You're advocating making unknown changes to the model as if science has proof-positive identified the mechanisms involved in decompression stress/injury. It's necessary for you to consider the magical dive computer you're using is filling buckets with numbers, not lab results. I retract my position if there is a probe running through your wetsuit, but otherwise, stop shamlessly trying to convince people adding pulse and SAC rate solves the mysteries of decompression. If it was only that simple.

 

[beaverdivers]

Relatively newer diver here... I have a question re: the above statement. Isn't it more likely that the switch from 21% O2 (or Air) to 32% EAN would result in not having further incidents? I'm struggling to see how it was from switching the type of computer...

If the diver has significant workload, then the " No Stop" time will be reduced regardless of the mix.

 

[HIGHwing]

If the diver has significant workload, then the " No Stop" time will be reduced regardless of the mix.

Sadly, you didn't even bother to read his question. But, I've become very curious about how you might answer it.

 

[WB2GLP]

BD, you never did give us the specifics of the dive profiles from the 90s that earned her a chamber ride. We take a big leap from no specifics to "no more problems" with so many other factors in the middle. Blaming it solely on breathing patterns is illogical.

Ever since I moved to West Orange, NJ, I have not been involved in a car accident. Therefore, moving to West Orange, NJ prevents car accidents. No, It has nothing to do with the fact that I'm 10 years older, drive a little slower, take the train to work in NYC, and that I still remember the last time I was hit while diving (sorry, driving) aggressively. ;-)

 

[scubadivingsteve]

To clarify, your position is that by monitoring respiration and modifying as indicated with a air integrated computer the risk of DCS/DCI is reduced. Sorry I forgot but this question is for beaver.

 

[Nykka]

If the diver has significant workload, then the " No Stop" time will be reduced regardless of the mix.

I'm sorry, but I am still needing some clarification.
In your original post you said there was an older lady who got "hit" while diving in Cozumel. You then say that after 6 months she dived again using both an AI and a non-AI computer (and also switched from breathing air to EAN 32). You state that "she was able to correct her breathing" using the AI computer and has had no further incidents.
Now, if I remember my stats class correctly, you have stated two possible causes (type of computer & switching gas) of the effect (no more "hits").
When I questioned how it's the computer you assign to the cause and not the gas, you replied by saying the above.
So, my questions to you are:
1) Isn't it still more likely that gas switching is the cause of the effect?
or
2) Are you saying that this older diver has (since the "hit") always had an increased workload, thereby, rendering the choice of gas immaterial?
As I stated before, I am still struggling to see how the AI computer is the cause of not getting bent.

 

[ianr33]

If the diver has significant workload, then the " No Stop" time will be reduced regardless of the mix.

How much is the No Stop time reduced? How do you know how much to reduce it by? Where can I find this information? How can I incorporate this into my dive planning?
Where is the published science behind your algorithm? Or do you just take a WAG at it and incorporate this as a "feature" in your marketing material??