Son of Deep Stops *or* Waiting to be merged with the mother thread...

[Dr Simon Mitchell]

Some quick comments on various statements before the thread gets closed:

Don't try to turn the attention to VPM-B. VPM-B is still the most current, the most accurate, and the most reliable planning model we have.

There are no data whatsoever that support this statement, and indeed, there is a body of emerging data that suggest it is wrong.

In VPM-B anything past +5 is equally garbage. That's why VPM-B stops at +5 ,and even that has gotten to the end of useful range. There is no such thing a VPM-B +7. You cannot buy a +7, you cannot make a +7, there is no planning program that allows us to view a +7. It does not exist. And yet by magic, it turns up in someones pretty colored, devoid of dimension, biased to shallow side, comparison chart. I wonder why they cooked up a non-existent data point to compare?

As has been pointed out to you many times, +7 involves a critical radius well within the original VPM model parameters and adopting it should simply make the model more conservative. There is no basis for saying it does not exist. It is there in the original literature. In that regard, you have argued many times in the past that VPM is internally consistent, but now you seem to be saying that VPM works on low conservatism but not high conservatism. Good luck with that. And now Kevin has demonstrated that VPM-B/E+5 (which you sanction) produces a profile almost indistinguishable from VPM-B+7 (which you call a fake). See here:

Son of Deep Stops *or* Waiting to be merged with the mother thread...

You can't have it both ways Ross.

VGE is not indicated of DCS... this is the current peer position here

Dealt with in the previous thread. There is not a single diving physician or scientist in the world who agrees with your VGE narrative.

There are no flaws in its VPM theory. ... Its based on first principles of science, its peer reviewed and published in Bennett Elliot, which is the bible of deco theory.

It is mentioned in a chapter in B&E. That in no way means it has been “peer reviewed”.

We have a very successful decade of dives on this approach, and records show this. More than half the world followed this approach in some format. VPM-B has been to great depths and used as is in many different dives successfully.

A totally unsupportable statement. There is no prospectively gathered database of dives using VPM of known outcome. You have no data whatsoever.

Further more, every existing dive computer uses the same formula for on gassing as desktop planning tools and models. Thats millions of dives that have been done successfully on all brands of dive and deco computers, that rely on these same formula.

This is an incredibly naïve statement. All deco models involve (presumptive) tracking of inert gas tensions using similar equations, but how bubble and gas content models subsequently interpret and “act on” those measurements are completely different.

+7 does not exist. You cannot buy it, or make a plan with it anywhere. Only Kevin has it, because Kevin "made it up" the +7. Kevin fabricated this made up +7 data point, because he had no other way to make a connection or comparison to the nedu profile. And if you take away this artificially simulated +7 VPM profiles, there is nothing left to connect VPM to the nedu test.

That’s the problem isn’t it Ross. VPM+7 (and VPM B/E+5) do unequivocally link VPM to the NEDU study, despite your efforts to obfuscate this fact.

There is an interesting back story to that. In 2004 it was going to be as Bruce said, and it was going to be good - a real model comparison. At least that's how he explained it. And then..... look what the nedu did instead. Two obscure shallow test models...

Dealt with by David and UWSojourner. All I can do is shake my head.

The nedu finally tested two shallow stop navy design models. What ever they discussed and promised in 2004, would seem to have been adjusted. You could take it for granted that Bruce, with his fingers in RGBM, is not going to get excited about a pair of shallow stop nedu test models.

Except that he did. Even called them “RGBM-like”. And I have little doubt that if the result had been different both he (and you for that matter) would be hailing it as confirmation that your bubble approaches represent optimal decompression.

For a while there a few years ago, Simon and friends tried to show us an RGBM profile that they said matched. But when we pointed out that they had added the times up the wrong way, they withdrew it … and, I don't have a bone in this fight either way. Don't care. But I know you guys tried to put a (not real) RGBM profile into the public domain, only to discover you did not add the runtime correctly.

We never withdrew anything. As David pointed out the profile is still sitting there in the Deep Stops proceedings document as provided by Bruce himself (Table 10 in his paper).

But take a look at this. Why did they quit the shallow stop test half way?? Answer: Because it was about to fail its rejection criteria test, and invalidate the whole effort

Dealt with by David.

The Nedu divers got injured from the cold (deliberate extra thermal stress) not the profile time.

Extensively discussed in the RBW threads. Complete rubbish. If divers becoming cold are selectively disadvantaged by doing deeper stops then we should be thankful to the NEDU study for demonstrating that to us.

So to your question - There is plenty of basis to be stating the nedu test was far too long by ordinary deco standards. Every deco model has less than half the deco time of the test.

If you would like me to organise for you to complete an NEDU profile with the same work and thermal conditions as the NEDU study with less than half the deco I would be happy to organise that for you.

Also it shows that thermal stress can ruin any kind of otherwise safe dive : see this: TR 2007 06

The thermal stress was identical for both profiles. If a deep stops profile is selectively disadvantaged by a diver getting cold then that is valuable information to come out of the NEDU study.

Controlling your thermal status is Your responsibility. You better take it seriously too - see this: TR 2007 06 (+ Neal Pollock’s slide)

Same comment re temperature. Neal’s slide risks becoming the most misrepresented educational slide in the history of diving. Nowhere on it does it ascribe any quantitative contribution of the various factors to risk. I would point out that without a dive profile the rest of the factors become immaterial.

But today, all we have is one person trying to side step the proper process and coerce the public directly - not acceptable.

"One person" and virtually the entire scientific community. What is "not acceptable" is that someone selling a deeps stops algorithm.......



Simon M

 

[rossh]

Some quick comments on various statements before the thread gets closed:



There are no data whatsoever that support this statement, and indeed, a body of emerging data that suggest it is wrong.



As has been pointed out to you many times, +7 involves a critical radius well within the original VPM model parameters and adopting it should simply make the model more conservative. There is no basis for saying it does not exist. It is there in the original literature. In that regard, you have argued many times in the past that VPM is internally consistent, but now you seem to be saying that VPM works on low conservatism but not high conservatism. Good luck with that. And now Kevin has demonstrated that VPM-B/E+5 (which you sanction) produces a profile almost indistinguishable from VPM-B+7 (which you call a fake). See here:

Son of Deep Stops *or* Waiting to be merged with the mother thread...

You can't have it both ways Ross.



Dealt with in the previous thread. There is not a single diving physician or scientist in the world who agrees with your VGE narrative.


It is mentioned in a chapter in B&E. That in no way means it has been “peer reviewed” in that context.



A totally unsupportable statement. There is no prospectively gathered database of dives using VPM of known outcome. You have no data whatsoever.



This is an incredibly naïve statement. All deco models involve (presumptive) tracking inert gas tensions using similar equations, but how they subsequently interpret and “act on” those measurements are completely different.



That’s the problem isn’t it Ross. VPM+7 (and VPM B/E+5) do unequivocally link VPM to the NEDU study, despite your efforts to obfuscate this fact.



Dealt with by David and UWSojourner. All I can do is shake my head.



Except that he did. Even called them “RGBM-like”. And I have little doubt that if the result had been different both he (and you for that matter) would be hailing it as confirmation that your bubble approaches represent optimal decompression.



We never withdrew anything. As David pointed out the profile is still sitting there in the Deep Stops proceedings document as provided by Bruce himself (Table 10 in his paper).



Dealt with by David.



Extensively discuss in the RBW threads. Complete rubbish. If divers becoming cold are selectively disadvantaged by doing deeper stops then we should be thankful to the NEDU study for demonstrating that to us.



If you would like me to organise for you to complete an NEDU profile with the same work and thermal conditions as the NEDU study with less than half the deco I would be happy to organise that for you.



The thermal stress was identical for both profiles. If a deep stops profile is selectively disadvantaged by a diver getting cold then that is valuable information to come out of the NEDU study.



Same comment re temperature. Neal’s slide risks becoming the most misrepresented educational slide in the history of diving. Nowhere on it does it ascribe any quantitative contribution of the various factors to risk. I would point out that without a dive profile the rest of the factors become immaterial.



"One person" and virtually the entire scientific community. What is "not acceptable" is that someone selling a deeps stops algorithm.......



Simon M

Ah yes.. .the mythical "body of emerging data". this would be the same one that got reviewed back in 2008. Your peers did not support or agree with this strongly one sided position you have taken Simon.


There is no such thing as +7 Simon - its all wishful thinking (and Kevin's house), but no where else. You hang onto this fictitious data point, because its the ONLY way that it can make to VPM and Nedu connection. And its all made up......

If we take away the made up +7 nonsense, then the whole argument falls apart.


No one has agreed with your narrative of VGE Simon... There is not a single document that you have pointed too, or shown us to support your position on extra vascular micro-bubbles becoming VGE.

All we have is tests where they blew up rabbits or skipped hours of deco time.. Not quite what we need to solve everyday deco. The literature is clear - its undecided, but that does not give anyone free license to make stuff up.

The latest Consensus Development Conference (procedures on proper use of VGE), is getting further away from the DCS correlation that some try to hang onto. It's now no more than an association: http://www.dhmjournal.com/files/Mollerlokken_ConsDevelopmentConference.pdf


Your comments are still trying to imagine the nedu test did things it never tested. It hasn't grown a deep stop yet. It still is not related to tech diving. These profiles are still low profile stress, and still do not protect fast tissues.

And when its all over, the on/off gassing formula is already in every dive computer and desktop planning tool, and works just fine.... so this trying to isolate deep stops as some how deficient....... its a nonsense argument.


Would you like to see some more supersaturation graphs, built to the same spec as the TR 11 06 report, with the reviewed and approved formula, that clearly show how your previous "plausible explanations" are not correct?


All that posturing over RGBM and squabbling with the LANL, ...... about who made the biggest mistakes first... Deco scientist's ....


#####


What about pointing the finger at the real culprit of bad tech practices ?? Its the DIR classroom, when they get a bit too attached to their theories, with things like the 'we make no bubbles' and 'cut the last stops out' ,and super slow ascents and more. None of that is from VPM-B, but you blame VPM-B for all this anyway. Why?

Take a fresh look at the people who reported issues - It Kev R with RD at truk. It's several other posters here who report things like 'slow ascents"

Now if you want to advance extra safe deco practices, and extra long deco times, then go right ahead. Tell the world.

But please stop with the "sky is falling" arguments ... VPM-B is just fine without your help - it has a decade of excellent service records, and it doesn't need you 'fixing" it.

.

 

[leadduck]

Don't you see a major difference between your standard profiles for rec/tech divers that you have in your chart vs. the testing procedure the NEDU adopted?

The divers in the NEDU study were WORKING during the bottom phase of the dive.

If you exert yourself during the entire bottom time of a dive and stick with your standard tech decompression schedules you're at high risk for getting bent. That's been known by tech divers forever. Pyle said that if he exerted himself on the bottom he could never get enough deco.

I've heard rules of thumb that exertion during the bottom phase of a dive is equivalent to 50-100% more bottom time. That's huge. Even if you take something in the lower range of that estimate VPM-B+3 gives you run times very close to the NEDU times when you adjust for the work factor.

Well that's maybe an approach that's easier than arguing about VPM-B +7: Calculating with a factor 2x on bottom time to consider strong on-gassing by workload.

So let's have a look at VPM-B +0 (critical radius N2 = 0.55) for 60min bottom time at 170fsw, and compare the schedule to the NEDU schedules:

 

[cerich]

I asked Neal Pollock about some this at TekUSA just the other month. This thermal stress stuff and other deco stress causes and measures, are somthing he was presenting about.

I'd love to be able to say, "... add x minutes for this or that.." But as he pointed out, it can't be done. We don't have dimensions to calibrate too.

How cold is a little bit cold? Whats that worth?

*****************


When you go diving, its YOUR responsibility to be prepared, equipped and capable. You must possess the right knowledge and training for the task. You must use the right procedures, and have sufficient knowledge to deal with contingencies. Anything that needs extra deco to compensate, is for you to decide.


Deco modeal make basic plans, per a basic decompression requirement - anything extra is your responsibility.


Examine this... look at all the contributing factors... Deco models have control on just two of these - the rest is up to YOU.

OK, so this is basically an assertion by you that your deco software is not much use outside of non defined narrow band regarding temp and the other factors you grabbed from Neal's slide. Do you really think that the divers using your software universally have the knowledge and ability to start factoring in all of that? Aren't they buying what is presented as a solution?

Your lack of addressing thermals, while pointing to them as a MAJOR concern that could present in unacceptable DCS % with deco times TWICE what your software would recommend blows my mind. Hell, I could see a case being made for a recall under the CPSC (http://www.cpsc.gov//PageFiles/106141/8002.pdf), don't say that lightly by the way. Simply put, since introduction there has been enough evidence that even you can't define a safe use operating envelope for the software.

 

[Storker]

We have a very successful decade of dives on this approach, and records show this.

Ah, so you have data! Great! Wonderful! That's just what roughly a dozen people have been asking for, repeatedly and for a rather long time.

I suggest you submit those data for publication ASAP, in a proper peer-reviewed journal on decompression science. That way, the scientific community and the diving community can evaluate those data and try to reconcile them with those data that have been previously published. Last time I checked, that's how science progresses. I'm pretty certain that if the methodology is sound, you won't have many problems getting your paper past the reviewers. After all, new data which properly challenge established concepts are pretty exciting to true scientists.

Acknowledgements: Thanks to @Simon Mitchell for pointing out this little gem which I overlooked in the steadily growing word salad that this thread - also! - has turned into.

 

[David Doolette]

The latest Consensus Development Conference (procedures on proper use of VGE), is getting further away from the DCS correlation you try to hang onto. It's now no more than an association: http://www.dhmjournal.com/files/Mollerlokken_ConsDevelopmentConference.pdf

That would be the document that reads on its first page, column 1, last three lines: "However, the bubble load detected in large systemic veins, and in particular, in the mixed venous blood is considered to be correlated with the probability of DCS."

 

[Storker]

Neal’s slide risks becoming the most misrepresented educational slide in the history of diving.

Only for those who have no relation whatsoever to the concept of "most significant factor determining..." and "least significant factor determining..."

Last time I checked, the dive profile was the most significant factor for DCS, by a pretty large margin. IIRC, they teach that - albeit indirectly - even in OW class.

 

[rossh]

That would be the document that reads on its first page, column 1, last three lines: "However, the bubble load detected in large systemic veins, and in particular, in the mixed venous blood is considered to be correlated with the probability of DCS."

Your cherry picking David...... Its referencing to conditions like Pulmonary DCS, which is certainly life threatening. However its unlikely to a problem for normal everyday diving procedures.


From the sentence prior... which is the more normal conditions.... "The detection of bubbles in any individual is not diagnostic for decompression sickness (DCS).

Or in more detail... not correlated in way Simon hopes. Recommendation 11.

 

[rossh]

.

 

[rossh]

Well that's maybe an approach that's easier than arguing about VPM-B +7: Calculating with a factor 2x on bottom time to consider strong on-gassing by workload.

So let's have a look at VPM-B +0 (critical radius N2 = 0.55) for 60min bottom time at 170fsw, and compare the schedule to the NEDU schedules:

Yet another made up non existent profile? Because it cannot make any real connection to the nedu profiles? So it all has to be invented.... pathetic.


.