NEDU Study

[Dr Simon Mitchell]

Ross has stated in another thread that when these threads get started, "sales go up." The motive is pretty clear to me at least.

I think it would be good for this discussion if you would link the source.

R..

The Deco Stop

Simon M

 

[Patoux01]

Bottom line... this integral super saturation (ISS) measure is one big meaningless number - junk science.

Hasn't someone pointed to the math in the models that does this?

 

[UWSojourner]

Readers, be very careful about reading the graphs by UWSojourner. He uses a measure he made up called Integral Super Saturation (ISS).

This is not a recognized scientific measure. It has not been tested, validated, calibrated, or shown to be valid for this purpose. It does not appear in other place. Even worse is he sums up the data from concurrent cells into one big number, but the model structure is strictly a parallel cell design and does not function as a serial or interconnect design.

Bottom line... this integral super saturation (ISS) measure is one big meaningless number - junk science.

Like so much of what Ross asserts, this is just completely false -- and Ross knows it. It would be nice if I could take credit for ISS, but I can't.

See the links below (a small sampling) for discussion.

Doolette #1
"Controlling decompression by limiting the time integral supersaturation is a feature of U. S. Navy gas content probabilistic decompression models. This approach began in the 1980’s. Notable decompression models of this type are NMRI98 (Parker et al. J Appl Physiol 1998;84:1096-1102) which has been discussed in this thread and LEM-he8n25 (NEDU TR 02-10) which underlies MK 16 Mod1 He-O2 decompression tables in the U. S. Navy Diving Manual. In these models, the risk is a function of the time integral of superaturation, summed across all model compartments."


Doolette #2
"In probabilistic gas content models, probability of DCS is typically a function of the time-integral of supersaturation in the compartments."


Doolette #3
"The integral supersaturation is the core measure of decompression stress in successful U.S. Navy probabilistic models and man-tested decompression tables that appear in the U.S. Navy Diving Manual."


VPM's Use of Integral Supersaturation

 

[rossh]

Like so much of what Ross asserts, this is just completely false -- and Ross knows it. It would be nice if I could take credit for ISS, but I can't.

See the links below (a small sampling) for discussion.

Doolette #1
Doolette #2
Doolette #3
VPM's Use of Integral Supersaturation

Yes, there are some proper uses of variations of ISS, in navy models. Proper use means calibrated and verified outcomes, limits to prevent invalid use, constraints, constants and multipliers to keep the data valid, and sparsly spaced data streams to prevent overlapping of information.

You don't do any of that..... They do not simply add everything into one giant number like you do.

Your use of this ISS is junk science....

 

[Dr Simon Mitchell]

Readers, be very careful about reading the graphs by UWSojourner (Kevin Watts). He uses a measure he made up called Integral Super Saturation (ISS).

This is not a recognized scientific measure. It has not been tested, validated, calibrated, or shown to be valid for this purpose. It does not appear in other place. Even worse is he sums up the data from concurrent cells into one big number, but the model structure is strictly a parallel cell design and does not function as a serial or interconnect design.

Bottom line... this integral super saturation (ISS) measure is one big meaningless number - junk science

Ross, why do you persist in making claims that are so easy to prove incorrect?

Kevin did not make up integral supersaturation.

You have previously been told:

The U. S. Navy has some very successful probabilistic models in which the risk of decompression sickness (DCS) is a function of the time integral supersaturation in all compartments. (Dr David Doolette), here:

Deep stops debate (split from ascent rate thread) - Page 20

That, of itself, conveys a sense of being "tested, validated, and calibrated".

It clearly "appears in other places". US Navy probabilistic models (as above), the NEDU study report by Drs Doolette, Gerth, and Gault (see, for example, page 17 where they say)....

The DSS and sum (fast + slow compartments) integral supersaturation of the tested shallow stops and deep stops dive profiles are also indicated on Figure 7A

....and most bizarrely, it is a central component of the way VPB-M works, as illustrated here:

Deep Stops (rebreather dive charts) - Page 8

Finally, summing the data into "one big number" is clearly not inappropriate as you imply, unless you are saying Doolette, Gerth and Gault were wrong to do so in the NEDU report.

Simon

 

[rossh]

You are fond of portraying me as having an agenda that is "anti-bubble models" and "personal" and somehow unconnected from the science of diving. My only agenda is ensuring that divers do understand the current views of the diving science community. I am entirely consistent in this regard. When we generally believed in the theoretical attraction of bubble models I promoted them. If you don't believe this, then read this article I wrote circa 2001:....


Decompression Strategies: A Changing Philosophy? - www.diveoz.com.au is the biggest and most popular Australian Scuba Diving Resource!


...in which I suggest that bubble models are the coming revolution. And I am being consistent now in the light of an emerging signal in the diving medicine literature that bubble models over-emphasise deep stops. As Victor Zamora has kindly observed, I have allowed my position to be dictated by the evidence. Other scientists have done the same. Wayne Gerth spoke about "losing his religion" in regard to deep stops at the UHMS Deep Stop Workshop. I think that there is abundant evidence that the only player in this discussion with a true "agenda" that is independent of the science is you.




Ross, as stated many times previously, the only relevance of "trusted deco science formula" to this discussion is that like everyone else you use tissue gas pressure calculation methods that are common to all models. How different models apply the results of such calculations differs markedly (which is why they produce different decompression profiles). VPM places emphasis on protecting the fast tissues early in the ascent by imposing deeper stops. This results in greater loading of slower tissues with gas. The NEDU study and subsequent analysis of technical diving profiles in the light of the NEDU study findings has shown that this is almost certainly not the most efficient use of decompression time. That is the state of the evidence as of this date. If further evidence emerges that changes this interpretation, then just as I have done before (see above) I will re-evaluate my position.


Simon M

Congratulations on your new job title. Now please try not to abuse the position.


Your quote from 2004, shows you failed to the observe the difference between extra-vascular (tissue micro-bubble) and intra-vascular (VGE) formation. The article blends the two into one, and talks about them as being the same.

That is the same mistake you still keep making today, at least in these forums, which is then used to confuse people about bubble models.

********


We have shown the nedu test is not related to tech practices or VPM-B, by using the same scientific formula that the test validates its finding with....

Your welcome to dispute that, with real scientific measures, but not junk ones. The opinion based positions of the past, have been shown to be wrong.


We have shown that the opinion based theory "plausible explanations" positions, like your latest attempt #5, is not valid.

We have shown that other theories, like "similar pattern" explanations, are not correct either.

All of the above use scientifically valid formula...... the nedu test is not related to VPM-B, or other tech practices. No amount of opinion can change that.

.

 

[UWSojourner]

Proper use means calibrated and verified outcomes, limits to prevent invalid use, constraints, constants and multipliers to keep the data valid, and sparsly spaced data streams to prevent overlapping of information.

I see you found the technobabble generator.

Your use of ISS is junk science....

Yes, nothing fancy, it's just science.

 

[Dr Simon Mitchell]

Ross, this is all getting a little strange, don't you agree? In the space of a couple of posts we have gone from:

Readers, be very careful about reading the graphs by UWSojourner (Kevin Watts). He uses a measure he made up called Integral Super Saturation (ISS).

It does not appear in other place

to....

Yes, there are some proper uses of variations of ISS, in navy models.

That's a big shift from "kevin made it up" and "it doesn't appear in other places".

And as for this....

Proper use means calibrated and verified outcomes, limits to prevent invalid use, constraints, constants and multipliers to keep the data valid, and sparsly spaced data streams to prevent overlapping of information. You don't do any of that..... They do not simply add everything into one giant number like you do.

I put this in the same category as your "kevin made ISS up" claim. Dr Doolette had no problem with what Kevin was doing with ISS and neither do I.

Simon

 

[rossh]

I put this in the same category as your "kevin made ISS up" claim. Dr Doolette had no problem with what Kevin was doing with ISS and neither do I.

Simon

Of course you like it.... it's a one sided nonsense measure, that always favors the shallow profile..... junk science... which is why you let Kevin make it up and use it.... so you can avoid being blamed for it later on.


But you can't show any proper validated testing or industry accepted use of it for this purpose......

.

 

[Dr Simon Mitchell]

Your quote from 2004, shows you failed to the observe the difference between extra-vascular (tissue micro-bubble) and intra-vascular (VGE) formation. The article blends the two into one, and talks about them as being the same.

That is the same mistake you still keep making today, at least in these forums, which is then used to confuse people about bubble models.

Ross,

The purpose of linking to the article was that it unequivocally rebuts your frequent implication that I have some sort of long standing personal agenda against bubble models. It clearly demonstrates that I was supportive of bubble models before the emergence of contrary evidence.

It is typical of your approach to these debates that you completely ignore that and try to make the link to the article about something else. And in doing so, you go back to another argument (VGE vs tissue bubbles) that only you believe and which is easy to prove wrong.

Ross wants to deprecate the significance of venous gas emboli (VGE) because there are human data showing consistently high VGE grades after tech dives controlled by VPM. I have not allowed him to do that in various forum debates because there is a mass of evidence that VGE are important vectors of injury in their own right, and also evidence that VGE numbers reflect the likelihood of concomitant bubble formation in tissues. My perspective on "the difference between extra-vascular (tissue microbubble) and intra-vascular (VGE) formation" is not a "mistake" but rather, is reflected in the current version of every definitive textbook chapter and review of the pathophysiology of decompression sickness:

MITCHELL SJ. Decompression sickness pathophysiology. In: EDMONDS C, BENNETT MH, LIPPMANN J, MITCHELL SJ. Diving and Subaquatic Medicine (5th ed). Florida, USA, Taylor and Francis, 125-140, 2015

BENNETT MH, MITCHELL SJ. Hyperbaric and Diving Medicine. In: Longo DL, Fauci AS, Kasper DL, Hauser SL, Jameson JL, Loscalzo J (eds). Harrison’s Principles of Internal Medicine (19th ed). McGraw – Hill, Chapt e477: 2015

VANN RD, BUTLER FK, MITCHELL SJ, MOON RE. Decompression illness. Lancet 377, 153-164, 2011

FRANCIS TJR, MITCHELL SJ. Pathophysiology of decompression sickness. In: Bove AA (Ed). Bove and Davis’ Diving Medicine (4th ed). London, Saunders Publishing, 165-184, 2004

FRANCIS TJR, MITCHELL SJ. The pathophysiology of decompression sickness. In: Brubakk AO, Neuman TS (Eds). Bennett and Elliott’s Physiology and Medicine of Diving (5th ed). London, Harcourt Publishers, 530-556, 2003

FRANCIS TJR, MITCHELL SJ. Manifestations of decompression disorders. In: Brubakk AO, Neuman TS (Eds). Bennett and Elliott’s Physiology and Medicine of Diving (5th ed). London, Harcourt Publishers, 578-599, 2003

Ross is the only person (in the world as far as I can tell) who believes in his perspective on this and he is clearly wrong. He has been told so multiple times by my colleagues. In a recent discussion on the same subject David Doolette told him:

I doubt there is a single scientist working in the area of decompression research who does not believe that the sizes and profusions of intravascular and extravascular bubbles are proportional, and that a decompression procedure that results in many VGE also results in many extravascular bubbles.

As for the rest of your post Ross, the diagrams are impossible to interpret and don't depict what you claim they depict. You have previously avoided engaging in discussions about criticisms of them. I doubt there is much value in further debate and I am happy enough at this point to just let people decide who to believe on this subject.

Simon