Slow tissue on gas from stops

[PfcAJ]

That is true the overwhelming majority of the time, but not always.

There are cases, as was true in this case, when the students are employees of the shop that is offering the instruction, and that instruction is only offered through a specific agency. Any such employee choosing to get their instruction through a competing agency would be fired. When I decided to cross over to TDI after a couple years of UTD instruction, I did so knowing it would end my employment, and it did. (I was considering leaving for other reasons, which helped with my decision.)

You need to take responsibility for yourself at all times.

Every post is about what someone else would or would not allow you to do.

 

[boulderjohn]

You need to take responsibility for yourself at all times.

Every post is about what someone else would or would not allow you to do.

Try to follow this.

When I was with UTD, I was a student 100% of the time. I had to do what I was told.
If I left UTD, I would lose my job.
When it got to be too much, I left UTD, and I lost my job.

If that makes me a worthless, spineless piece of scum in your book, then so be it.

 

[UWSojourner]

As I have said before there is reason to believe thaat UTD-RD would have looked worse in comparison to another GF profile with less emphasis on deep stops than 30/-.

Simon M

I think that's fairly certain. Consider the chart below.

The chart shows the exposure to supersaturation ("integral supersaturation, ISS") for the divers in the UTD-RD study. It's easy to see why, having been provided the advantage of 44% more decompression time, the UTD-RD profile may have still performed more poorly than the GF30/85 profile. Despite the considerable justifications provided for all the UTD-RD tweaks (see Video 1 and Video 2), the net result was to cause the overall supersaturation levels of the UTD-RD profile to exceed that of the GF 30/85 profile. In other words, the UTD-RD profile took the 44% time advantage and completely squandered it in terms of lowering the overall levels of decompression stress (as was found in the study). In any case, the simple ISS metric would have provided a signal that perhaps UTD-RD was losing sight of the exposures their profiles were creating.

But look at the GF50/54 profile. This profile has the same runtime as the UTD-RD profile. Once the diver surfaces, the UTD-RD diver is exposed to 62% more supersaturation than the GF50/54 profile. For what??? What benefit is being gained for the 62% increase? Based on all the evidence the most likely answer is "None".

 

[Dr Simon Mitchell]

Hello Dan,

...the apparent logic then goes that any bubble model, RD and almost all GFs save one - and we don't know which one, mind you - are all "defective".

You are, perhaps a little disingenuously, playing on the fact that we don't know what optimal decompression is and we probably never will. And yes there can be only one truly optimal decompression regimen for a particular dive. But there are reasonable grounds (as elegantly demonstrated by UWSojourner above) for believing that UTD-RD as it stood in the trial was sub-optimal in comparison to a range of GF approaches that would have prescribed a decompression of same or even shorter length. So, some people might choose to call it defective on that basis.

My point with Dr. Brambilla's remark (which I posted in response to a remark about Andrew Georgitsis' confidence in a video linked to previously), is that if experts in hyperbaric medicine would assume high emphasis on deep stops for safety - yes, presumably to accomodate the Declaration of Helsinki - and express this in a video; surely, it's fair game if a diver participating in the study also expresses confidence in deep stop emphasis in a video about the trial in question?

Is that not precisely heeding the words of scientists, as opposed to dismissing them?

No, the scientists were not predicting the trial outcome when they made the comment you refer to. Indeed, if they had cause to be sure of a positive outcome for the deeper stop approach they would not be doing the trial, because it would have been considered unethical (you need a degree of equipoise to justify a trial). Given there was enough uncertainty to justify a trial, then the sort of carry-on we saw from Georgitsis is ALWAYS inappropriate and I hope he feels suitably embarrassed.

On another note entirely, and I only mean this to be food for thought, I believe Spisni is only around a year or so since publication at this time, and Ratio Deco 2.0 has already been on the streets for quite a while. Doesn't exactly sound like the workings of an adamant zealot incapable of change...

I suspect Georgitsis knew the results of the Spisni trial long before it was finally published. And as for the implications of the changes he made, I don't think he had much choice under the circumstances.

Simon

 

[Dan_P]

When I was with UTD, I was a student 100% of the time. I had to do what I was told.
If I left UTD, I would lose my job.
When it got to be too much, I left UTD, and I lost my job.

I wasn't going to touch this further, but the above is really zeroed in on UTD;
Maybe take your grudge up with the dive shop that employed you and trained the people you've mentioned.
This is all pre-me so I don't know, but weren't it booted from the organization anyway??

Seems like a genuine misdirection of gall, to me.

 

[Diver0001]

I wasn't going to touch this further, but the above is really zeroed in on UTD;
Maybe take your grudge up with the dive shop that employed you and trained the people you've mentioned.
This is all pre-me so I don't know, but weren't it booted from the organization anyway??

Seems like a genuine misdirection of gall, to me.

I'm triggering on the word "grudge" here.

I know John very well and he's one of those people to whom I believe others should listen carefully EXACTLY because he's not the kind of person to hold a grudge. He is one of those people who points to the facts even if the facts are not convenient.

UTD put itself in the market with a message that they had a monopoly on wisdom and knowledge, kicking off the heals of the DIR wars when all things DIR were considered good and sacrosanct.

These days... and yes, we are a decade or more further... diving has progressed, deco theory has progressed but UTD has not progressed. AG hasn't been keeping his knowledge up to date and it's starting to show. I guess maybe he thinks he is and some of his disciples do too (I do not use the word disciple randomly here) but the reality is that the rest of us have to deal with facts.

John has done here what he has done many times, which is to point out that the emperor has no clothes. Everyone who knew as much about technical diving in this day and age already knew it but John is the one among us with the clarity of observation to point it out.

R..

 

[Dan_P]

Hi Simon,

I don't think it's passing along anything for more than it is if I say that using "defective" for "imperfect" is misleading.

You are, perhaps a little disingenuously, playing on the fact that we don't know what optimal decompression is and we probably never will. And yes there can be only one truly optimal decompression regimen for a particular dive. But there are reasonable grounds (as elegantly demonstrated by UWSojourner above) for believing that UTD-RD as it stood in the trial was sub-optimal in comparison to a range of GF approaches that would have prescribed a decompression of same or even shorter length. So, some people might choose to call it defective on that basis.

Mr. Journer's presentation was very lovely indeed, and I shall hope to see it involved in a comparative study at some point, that we may advance our knowledge further still. I should be thrilled to participate in such trials as a watery dummy, and in either case, am famished for fresh reports to gorge upon.
However.
The point is that if "some people" choose to pass "suboptimal" for "defective", they're shoehorning into it much more than RD, and too much. I would invite you to correct me in that view, or clarify where the line in the sand goes.

I.e. there are many gradient factors that may well seem to probably bring about nearer-to-perfect physiological ("better") results than, say, 30/80, so 30/80 is "defective"?. What of 40/70, then? And 50/60? 54/56?

We've done this enough times by now that I'm sure we agree that the universal language is well in excess; I feel "defective" misses the mark. That's my sole point, regarding "defective".

No, the scientists were not predicting the trial outcome when they made the comment you refer to. Indeed, if they had cause to be sure of a positive outcome for the deeper stop approach they would not be doing the trial, because it would have been considered unethical (you need a degree of equipoise to justify a trial). Given there was enough uncertainty to justify a trial, then the sort of carry-on we saw from Georgitsis is ALWAYS inappropriate and I hope he feels suitably embarrassed.

I understand that there should be some level of balance in things, but at the same time, that doesn't explain the use of the the word "safety" for choosing a GF which also has relatively heavy emphasis on deep stops.
My point is that the remark seemed to imply that a relatively great reduction in emphasis on deep stops compared to RD1.0, was deemed unsafe by the experts who set up the trial. One could be forgiven for extrapolating on that to imply that more deep stop emphasis is good, surely?
That said, I hear what you're saying about the carry-on.

I suspect Georgitsis knew the results of the Spisni trial long before it was finally published. And as for the implications of the changes he made, I don't think he had much choice under the circumstances.

Even if he did, it'd still have to be short terms in a context of procedural change in the world of scuba. I mean, buddy breathing was a thing till around 2007...

 

[Dan_P]

I'm triggering on the word "grudge" here.

I know John very well and he's one of those people to whom I believe others should listen carefully EXACTLY because he's not the kind of person to hold a grudge. He is one of those people who points to the facts even if the facts are not convenient.

UTD put itself in the market with a message that they had a monopoly on wisdom and knowledge, kicking off the heals of the DIR wars when all things DIR were considered good and sacrosanct.

These days... and yes, we are a decade or more further... diving has progressed, deco theory has progressed but UTD has not progressed. AG hasn't been keeping his knowledge up to date and it's starting to show. I guess maybe he thinks he is and some of his disciples do too (I do not use the word disciple randomly here) but the reality is that the rest of us have to deal with facts.

John has done here what he has done many times, which is to point out that the emperor has no clothes. Everyone who knew as much about technical diving in this day and age already knew it but John is the one among us with the clarity of observation to point it out.

R..

I don't know the guy, I'm sure he's a good guy.
It's nothing personal like that - I say that with all honesty.
The thing is this anti-UTD crusade is getting really old - and paradoxally, obsolete.

Besides, UTD was heavily involved in setting up a relatively large-scale, in-water, human trial, and changed RD on the basis of it, and you come out with the above, saying the organization hasn't progressed?
Out of order, sir.

Further, if someone says, "hey, I know RD is not perfect but I find it practical for this and that reason", surely, your condescending play to religion is amiss entirely.

 

[Diver0001]

I don't know the guy, I'm sure he's a good guy.

At least we can agree about that. This is progress.

surely, your condescending play to religion is amiss entirely.

I certainly don't want to go back to where we were 15 or 20 years ago. I can certainly understand you wanting to move beyond that, as do I. I'm not entirely convinced, however, that AG doesn't see himself as a bit of a messiah in diving circles. The RD "research" to which you refer can not be described as research in the scientific sense. AG literally announced the conclusions of the trial before it had begun.

To me this almost drew out the "emperor has no clothes" comment due to the asinine manner in which the study was performed.

I'm hearing you say that you like and respect AG. I'm sure you're not the only one. I'm also sure, however, that others like myself tend to respect actual scientists even more when it comes to these kinds of debates. In years/decades past divers were brow beaten into believing what the DIR "generals" were saying even though little of it was verified. These days they need to debate that with actual scientists doing actual science.... and that can be a little harder for the hard-core to accept.

R..

 

[Dan_P]

I certainly don't want to go back to where we were 15 or 20 years ago. I can certainly understand you wanting to move beyond that, as do I. I'm not entirely convinced, however, that AG doesn't see himself as a bit of a messiah in diving circles.

I personally don't think so, but that doesn't matter - and if he does, that doesn't effect any of the choices you or I have to make.

The RD "research" to which you refer can not be described as research in the scientific sense. AG literally announced the conclusions of the trial before it had begun.

To me this almost drew out the "emperor has no clothes" comment due to the asinine manner in which the study was performed.

I don't know what you mean with that; are you saying the Spisni study wasn't a scientific study?
It was very much supported by UTD - logistics and divers, etc. - and UTD adjusted practices with the findings from it.
I don't understand why you're saying the Spisni study was unscientific and asinine...?

I'm hearing you say that you like and respect AG. I'm sure you're not the only one. I'm also sure, however, that others like myself tend to respect actual scientists even more when it comes to these kinds of debates.

I'm saying it doesn't matter what I think of AG, or JJ, or Sheck, or Simon, or John, or anyone else for that matter.

Maybe I respect Simon, but argue with him anyway,
or maybe I think Simon is an evil mastermind, but acknowledge solid points anyway.

It doesn't matter what I think of him. It has nothing to do with that.
Except it does look personal in some cases, which is why I said something about it.

In years/decades past divers were brow beaten into believing what the DIR "generals" were saying even though little of it was verified. These days they need to debate that with actual scientists doing actual science.... and that can be a little harder for the hard-core to accept.

I'm not saying that I don't understand the impact history can have. But I wasn't around for the DIR wars, so probably there is some legacy there still haunting that I'm not being sensitive to.

But this thread is mostly riddled with conversation and argumentation that is rooted in scientific observations, deductions and well-conceived ideas.

I like to try and keep it that way...
Or, I could spend my time ranting and raving over when with DSAT/PADI I was taught to use VPM on my computer for technical dives.