UWSojourner
Active Member
Reasonable speculation.
Nice of Don to share the experience. Its good to be reminded of the risk and the limitations of our best laid plans. Best wishes for a full recovery.
My DCS Hit
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Nice of Don to share the experience. Its good to be reminded of the risk and the limitations of our best laid plans. Best wishes for a full recovery.
Are you being paid to say anything to prop up the Nedu test nonsense? It sure seems like it, because the stuff you wrote here and above, and below, using the nedu test as some justification,... is so laughably bad and contradictory.. You're a smart guy when it comes to understanding supersaturation and modelling. So why these evasive and silly argumentative points?
You talk of "spiked" supersaturation as meaningful in the nedu test, but don't like the "peak" supersaturation as shown in proper supersaturation graphs. You claim your ISS is better because of the supersaturation and time combination, but then dismiss that same combination of parameters when used to look at the ascent in this dive.
All that flip-flopping and double speak..... just to prop up an invalid assumption and widely reported fallacy of the nedu test.
*****
There are records of successful trips to 600ft and more, and they all employ the use of deeper stops. That includes either the proper selections of GF, or bubble models. This dive reported here, is the first deep and direct test of the Dr. Simon Mitchell endorsed "new, more efficient" deco, and it failed half way through the deco ascent. It failed because it ignored the basics of physics and bubble growth. This error has been done before by pioneer divers, and the corrective action was deeper stops.
Sadly, there will be more like this dive report to come.... and the blame will lay squarely with those promoting this defective "new, more efficient" deco.
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UWSojourner
Active Member
Ross, it’s not so much that you know nothing; more that you know so many things that are just not true.
This deco on this dive clearly was insufficient. Was it the profile as you claim you KNOW? Maybe. Was it the twice normally recommended ascent rate? Perhaps. Was the exertion at depth? Probably contributed. Was there impairment as exhibited by pain breathing at depth? Don’t know.
One thing it wasn’t: it was not recommended by Dr Mitchell. 40/70 is not 60/90 and nowhere in any thread was 600ft in the discussion.
As much as you’d like to promote this as a rebuttal to the clear evidence that deep stops were oversold, there’s just nothing there.
This deco on this dive clearly was insufficient. Was it the profile as you claim you KNOW? Maybe. Was it the twice normally recommended ascent rate? Perhaps. Was the exertion at depth? Probably contributed. Was there impairment as exhibited by pain breathing at depth? Don’t know.
One thing it wasn’t: it was not recommended by Dr Mitchell. 40/70 is not 60/90 and nowhere in any thread was 600ft in the discussion.
As much as you’d like to promote this as a rebuttal to the clear evidence that deep stops were oversold, there’s just nothing there.
Simon Mitchell
Well-Known Member
Ross,
It is extremely naive to take a single case of DCS and conclude by extrapolation that the approach to decompression employed must be wrong for the entire community. You have no idea what would happen if you took 100 divers and decompressed them the way Don decompressed, and another 100 divers and decompressed them over the same decompression time but distributed the decompression time deeper. In every study of that nature performed to date the profiles emphasising deeper stops have performed less well. That is a fascinating fact to ponder because the logic for adoption of deep stops back in the early 2000s was EXACTLY the sort of individual case "got sick so obviously the stops should have been deeper" notion that Ross is spruiking here.
Individual cases are a poor basis for refining decompression strategies because there are so many things that can profoundly affect an individuals risk on a given day. The risk is greater and far less predictable for very deep dives. Virtually all the dives performed during the early 2000s fad for creating depth records were performed using bubble models and deeper stops, and every single one of those divers got sick, often multiple times. I have never made an issue of this because it would be scientifically invalid to do so, but now we have a dive that had fewer deep stops than you think are necessary and the diver got sick, so you are trying to claim that this proves more deeper stops are good. Its ridiculous, and the bottom line is that you could be making a massive attribution error here.
I just want to pick up on a few of your other points.
It is so unfortunate that the readers of this forum cannot be present during conversations among the true experts in this field to learn for themselves how you repetitively make these confident authoritative statements that are fundamentally wrong. I spoke with David about this just a month ago at the ONR Grant Review meeting in Washington. He made it clear that their intergral supersaturation calculations take account of all relevant tissues that might become significantly supersaturated during a decompression, and that this equates with all the 16 Buhlmann compartments; they just don't call it 16 compartments. They divide them into 3 categories (eg fast, medium, slow) but they are all there. It is not 3 widely spaced "non overlapping" cells as you imply. David sees nothing wrong at all with UWSojourner's analyses, which are, in fact, effectively identical to what NEDU does.
Actually Ross, you initiated this "campaign" with misinformed criticism of seminal scientific studies published in my field of expertise; an area about which you know very little, but in which you like to appear expert. You are not an expert, and yet you trade on your software writer's association with a decompression model to pretend you are. Earlier this year on another board you were vehemently arguing that tissue perfusion did not affect decompression, but rather (you claimed) it was tissue half times that determine tissue gas exchange; an argument tantamount to insisting that it is not oxygen that keeps us alive, but rather the air that we breathe. This lack of understanding of one of the most fundamental aspects of gas exchange physiology illustrates how much (or little) credibility divers should attribute to you in these discussions.
My only "campaign" has been to defend some seminal science in my field of expertise against your poorly informed attacks.
I suspect you do yourself no favours in being so cynical. For a start, I have never specifically endorsed 60/90 with a rapid ascent between stops. I have always said that we should back away from deep stops cautiously, and that I did not know where the sweet spot lies. But more to the point, there have been many divers bent using VPM. Do we blame you for all of those?
Simon M
It is extremely naive to take a single case of DCS and conclude by extrapolation that the approach to decompression employed must be wrong for the entire community. You have no idea what would happen if you took 100 divers and decompressed them the way Don decompressed, and another 100 divers and decompressed them over the same decompression time but distributed the decompression time deeper. In every study of that nature performed to date the profiles emphasising deeper stops have performed less well. That is a fascinating fact to ponder because the logic for adoption of deep stops back in the early 2000s was EXACTLY the sort of individual case "got sick so obviously the stops should have been deeper" notion that Ross is spruiking here.
Individual cases are a poor basis for refining decompression strategies because there are so many things that can profoundly affect an individuals risk on a given day. The risk is greater and far less predictable for very deep dives. Virtually all the dives performed during the early 2000s fad for creating depth records were performed using bubble models and deeper stops, and every single one of those divers got sick, often multiple times. I have never made an issue of this because it would be scientifically invalid to do so, but now we have a dive that had fewer deep stops than you think are necessary and the diver got sick, so you are trying to claim that this proves more deeper stops are good. Its ridiculous, and the bottom line is that you could be making a massive attribution error here.
I just want to pick up on a few of your other points.
It is so unfortunate that the readers of this forum cannot be present during conversations among the true experts in this field to learn for themselves how you repetitively make these confident authoritative statements that are fundamentally wrong. I spoke with David about this just a month ago at the ONR Grant Review meeting in Washington. He made it clear that their intergral supersaturation calculations take account of all relevant tissues that might become significantly supersaturated during a decompression, and that this equates with all the 16 Buhlmann compartments; they just don't call it 16 compartments. They divide them into 3 categories (eg fast, medium, slow) but they are all there. It is not 3 widely spaced "non overlapping" cells as you imply. David sees nothing wrong at all with UWSojourner's analyses, which are, in fact, effectively identical to what NEDU does.
Actually Ross, you initiated this "campaign" with misinformed criticism of seminal scientific studies published in my field of expertise; an area about which you know very little, but in which you like to appear expert. You are not an expert, and yet you trade on your software writer's association with a decompression model to pretend you are. Earlier this year on another board you were vehemently arguing that tissue perfusion did not affect decompression, but rather (you claimed) it was tissue half times that determine tissue gas exchange; an argument tantamount to insisting that it is not oxygen that keeps us alive, but rather the air that we breathe. This lack of understanding of one of the most fundamental aspects of gas exchange physiology illustrates how much (or little) credibility divers should attribute to you in these discussions.
My only "campaign" has been to defend some seminal science in my field of expertise against your poorly informed attacks.
I suspect you do yourself no favours in being so cynical. For a start, I have never specifically endorsed 60/90 with a rapid ascent between stops. I have always said that we should back away from deep stops cautiously, and that I did not know where the sweet spot lies. But more to the point, there have been many divers bent using VPM. Do we blame you for all of those?
Simon M
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Simon Mitchell
Well-Known Member
Yes, that's pretty funny. Ross is introducing an argument David made about what he (Ross) was doing, and is trying to use it as a stick to beat you for something you have never done!
Fantastic.
Simon
Simon Mitchell
Well-Known Member
Hello Bobjr,
I can totally see why you might say this, but while it seems logical and may be true, I would not agree that you "can say" it for sure.
Ross talks as though he knows what is going on out there in the diving world, but i am not sure why he believes he would. He is not a physician. He does not see cases. People do not call him for advice when they get sick. All these things happen to me in my role as a specialist diving physician, and I get to see and hear many stories. We see some bizarre stuff in relation to these very deep dives. For example, I dealt with a technical diver relatively recently who did a 150m bounce dive and got sick within about 20m of leaving the bottom! His problem behaved like saturation diving DCS. Using the logic implicit in your statement, you could argue that a saturation decompression (sort of the ultimate deep stop approach) could have prevented it, but clearly this is impossible on a deep bounce dive, and moreover, his colleagues performed decompressions with GF decos starting at 40-50 Lo without incident over multiple dives. It is as though some people are just going to get sick no matter what they do because of some unknown issue at least partly independent of the decompression profile. Don could have been one of these on his day.
Simon M
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Throughout this anti-deeper stop campaign of yours, you have a track record of distorting the science interpretations, to suit your own purpose. You have quoted science out of context, and obfuscated some medical aspects, all to manipulate the public into your biased views... that is what we argue about..... Your efforts to make change, based on invalid or false information. It's gets worse, because you encourage non science people like Kevin Watts, to make up junk science supporting noise. You get away with this because the public does not appreciate the specifics, and you achieve a fait accompli. There are no peers of yours that will challenge this in public, because it's the wrong forum.
Most of your justification points along this path, have been proven invalid by sound and reasonable science.... but that truth just interferes with your agenda.
************
I have just been reading the papers in the latest major court battle over a diving death, and I see the divers were using 90/90.
See what your irresponsible comments and public coercion has done... This new trend you started, is a step backwards. You have fixed nothing, and re-introduced old reinvented problems.
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Nitrogenius
oppinionated ;)
Bullshit Bingo again!
There is no anti deep stop campaign..
The only one "campaigning" against anything Simon says is you!
Ironically exactly in the way that you claim Simon is allegedly doing:
"You have quoted science out of context, and obfuscated some medical aspects, all to manipulate the public into your biased views... that is what we argue about..... Your efforts to make change, based on invalid or false information."
Did you look in the mirror when you typed this?? What a kafka-esk persiflage this is..
Nitrogenius
oppinionated ;)
I don't see how you can say that..
Too many factors involved.. David already pointed to it, there is no way anyone could predict that the outcome would have been different with a deeper distribution of stops..
Well did I say no one can predict that..
oops.. sorry, of course there is the all-knowing, all-mighty ross that can point it to the one single isolated cause of this unfortunate outcome of the dive!
P.S: Ross, are you maybe related to a certain Daniel Razorista? Definitely lots of similarity in style..
Maybe I missed it, but where did Ross ever point out anything stating it was the single cause of the DCS hit?? I recall he pointed out "a cause", ie a factor in it, but not that it was the only thing. I also doubt that even Ross would ever say had VPM been followed, Don wouldn't have gotten bent. Its such an unknown dive with so many variables, no one can say what the factors involved were.
What I've taken from this is that following VPM would have lessened the saturation, which arguably is "a" factor in the DCS hit. But most likely one of many other factors.
What I've taken from this is that following VPM would have lessened the saturation, which arguably is "a" factor in the DCS hit. But most likely one of many other factors.
silent running
Member
Wow. Ross, you know what's irresponsible?
-Assuming you know exactly why someone decided to dive 90/90 and then blaming someone else, anybody else for it.
-Asserting that scientists and MDs who have devoted their lives to studying dive physiology and hyperbaric medicine would manipulate data and whole tests for some sorts of bizarre personal motives.
-Asserting that there are "peers" waiting in the shadows to dispute the obvious statistical conclusions of the NEDU study, if only the "right" forum were held.
These are not the words of someone who has the facts on their side, it's really outrageous and divisive stuff you're slinging, again, and which prevents reasoned discussion, which is the best way to learn.
Simon Mitchell
Well-Known Member
Sorry Ross, this fails the plausibility test.
One could choose your version:
Rogue scientist indulges in repetitive scientific malfeasance to mislead the diving community and promote dangerous practices while his peers say absolutely nothing. With the addendum for important context: Indeed, to reward his malfeasance his peers appoint him Editor in Chief of the world's top ranked diving medicine journal from 2019 onwards.
Or one could choose the more likely reality (as much as it pains me to stoop to your level):
Delusional commercially-conflicted nut job concocts a classical conspiracy theory to explain why the scientific community ignores him and rejects his ideas.
If you can point to where your sound and reasonable science has been published then i will give due consideration. I looked on Medline and could not find your name anywhere.
Simon M
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I can’t say what factors caused this but whatever the cause (or solution) it cannot be attributable to decompression shallower (future event) and must be due to previous and therefore deeper decompression. This is purely a review of what happened on this dive and is a single data point - only a fool would draw any further conclusion and if I gave that impression I apologise I was just giving commentary on this dive.
Simon uses the The Argument From Authority - the claim that the speaker is an expert, and so should be trusted.
Apparently, no-one is allowed to have a different opinion.
***
Lets have a little check of the disgraceful and dishonest things that you Dr. Simon Mitchell, has twisted and manipulated onto the public, in the execution of your agenda.
1/ Grossly misinterpretation the nedu test, numerous times, with continued deception through word game play,
2/ Five failed attempts by you explain some science connection from nedu test to deep stop models. You want me to post the links....
3/ encouraged others to fabricate and promote fake model and phony profile data.
4/ Grossly represented VGE and its meaning and origins, and ignored the peer consensus position.
5/ Make sham video's with the errors above, and added phony deco models, and reported conditions that are impossible or don't exist.
6/ help create or promote junk science graphs and measures that prop up your agenda.
7/ and more..
Here is an example of this, from just 9 months ago... Mitchell's distorted world of self serving science interpretations.
****
At the end of the day... you fixed nothing, and made matters worse by increasing dive stress, which is what happened to Don's dive here.
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UWSojourner
Active Member
He actually doesn't use that argument. But even it he did, it would beat The Argument Out of Left Field -- the claim that you should be trusted because all the known decompression academics in the world know nothing about decompression and are conspiring against you.
Thanks for that link. I hadn't seen Dr. Mitchell's nice summary of the available research.
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I remind the group, the one and only time this Nedu test was put in a peer review forum, was 2008 when it was first shown at the UHMS Deep stop workshop (abstracts or complete book). The reception was neutral, and the summary consensus position at the end was neutral too. see here and here, or the full discussion. Simon of course, took on a one sided view of this. It's his central argument, and it does not relate to tech diving, leaving Simon with a problem - so he embellishes the meaning and interpretations, and bullies any one who does not accept his version.
Simon does not have the peer support on the nedu test that he wants you to think. He is doing this on his own without the backing of others, and in the public forum only. Only his friend David - the junior scientist on the test, and the guy who wrote the "made for public" version of the report, backs Simon on the nedu test. The two seniors on the test, have remained silent on the topic ever since.
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Simon Mitchell
Well-Known Member
Public forum only?? Doing it on his own?? This paper...
Doolette DJ, Mitchell SJ. Recreational technical diving part 2. Decompression from deep technical dives. Diving Hyperb Med 43, 96-104, 2013
...which articulates many of the perspectives you object to, was peer reviewed and published in the world's first ranked diving medicine journal without any subsequent adverse commentary from colleagues. And didn't Neal Pollock also tell you to "stop the hand waving and respect the data"?
The version you refers to on which Dr Doolette was lead author was actually the official NEDU Technical Report. Here is the reference.
Doolette DJ, Gerth WA, Gault KA. Redistribution of decompression stop time from shallow to deep stops increases the incidence of decompression sickness in air decompression dives. NEDU Technical Report 11-06, July 2011.
Plain and simple, obvious to anyone (except you).
Once again you confidently state something completely the wrong way around and demonstrate yourself as being incapable of objectively discerning the truth of even simple matters like this. You just decide what you want to be true, and present it as the truth; whether it is or not.
Simon M
The version you refers to on which Dr Doolette was lead author was actually the official NEDU Technical Report. Here is the reference.
Doolette DJ, Gerth WA, Gault KA. Redistribution of decompression stop time from shallow to deep stops increases the incidence of decompression sickness in air decompression dives. NEDU Technical Report 11-06, July 2011.
Plain and simple, obvious to anyone (except you).
Once again you confidently state something completely the wrong way around and demonstrate yourself as being incapable of objectively discerning the truth of even simple matters like this. You just decide what you want to be true, and present it as the truth; whether it is or not.
The two other authors said all they want to say in the report (the exact same things David says and which I defend against your attacks), and (wisely) can't be bothered arguing on the internet.
Simon M
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Simon highlights my point perfectly.....
The lead scientist was Wayne Gerth, who presented his version at UHMS and DAN conferences in 2008. By that time, the test had served its purpose within the USN. The new USN dive manual version 6 (2008) was updated to a new set of model and tables, and it was all over.
Then 3 years later, David produced the 2011 re-formatted public report version, complete with his extras added, and more. I suspect you had been scheming for this since the whole thing was a non starter flop in front of your peers at the 2008 UHMS/DAN conferences, and failed to get any traction in the public. So you needed to do the "direct to public" approach, which is what you have been doing ever since.
In any case, you have interpreted and used the nedu test, way outside the consensus position of your peers in 2008.
Interesting.... you lot cannot defend your position in the nedu test and the false interpretations / claims you make: that it is has a link to tech diving, bubble models, or VPM.... You got nothing valid. All you got is more bluster and bully and authoritarian intimidation.... You don't have the science on your side for this one.
To defend and deflect, is your little posse of fanboys, trying to trick us all with psycho-babble.
*****
But what has any of this to do with Don's dive ??? Its yet another distraction away from the reality that he was injured following a dive plan that uses your approved "new, more efficient" deco method.
Yes it's one dive only, but it's a very big serious and significant test, and these really deep dives put a deco approach to the test and quickly find the faults. You better get used to this Simon and cross your fingers, because you pushed the world into this new direction based on your personal preference, and without a valid science reason behind it.
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Is it just me, or is this thread taking a turn for the surreal?!! I find my self reading some of these posts and feeling like I'm about to be told the world is flat and NASA ESA etc are all out to fool us so the UN-run world wide theocracy can seize control with greater ease!
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