Will http://www.ncbi.nlm.nih.gov/pubmed/25525213 change deco procedures?

[tomfcrist]

I have been following this thread with great interest.

It appears to me that the contention is centered on one side attempting to keep the whole idea of deep stops alive while the other side is saying that the statistics of DCS just don’t indicate this. Somebody is mostly wrong and somebody is mostly right.

I think there are three separate arguments.

1. Bubble models suck. Dissolved gas models are better.
2. Bubble models are fine, so are dissolved gas models.
3. Deep stops are not properly scheduled via bubble models or dissolved gas models, and Deep stops have not and will not in the near future be scientifically tested in such a way that makes demonizing them valid.


Let's be clear...no model out there is bends proof. Some models work better for some people than others.

 

[lowviz]

... 3. Deep stops are not properly scheduled via bubble models or dissolved gas models...

Yep, the models don't use them. But ever since Pyle, there seems to be something worth investigating there.

What is it?

... Deep stops have not and will not in the near future be scientifically tested in such a way that makes demonizing them valid.

I, for one, would just love to see them tested in an unbiased manner. Demonizing comes later.

Let's be clear...no model out there is bends proof. Some models work better for some people than others.

Indeed.

And the only intelligent reply to that statement is: "Why?"

 

[Kevrumbo]

. .. Hypocrites, the lot of you. .. .

Hmm.. So ratio deco (RD) was the failure - not VPM-B.

Ratio deco - a simplistic depth averaging math method, with an aggressive ascent pattern, a known shortage of last stop time for its procedures, and backed by some questionable classroom theory.

You had an issue on day 4 and 8, in a daily series of many dives.

Ratio deco was the problem.....


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

Can we now please start pointing fingers at the failing ad hoc method designs (RD), and leave the real models (VPM-B) to continue doing planning properly.

No Ross . . . Hypocrisy has nothing to do with it. Simply put, what used to work for me (RD method and its applied dissolved & free phase basis ) is not effective anymore unless I pad it with a lot of extended O2 deco profile time. To be fair, I never said anything negative about your VPM /V-Planner or even Kee's RGBM/GAP product (and I used to have them both loaded on an old Pocket PC).

Andrew Ainslie here in offshore SoCal was having very serious DCS problems while using VPM/V-planner live on a Liquivision X1 dive computer in good faith over many deep CCR dive trials. . .and you're implying he's a hypocrite???

Shame on you Ross. Have you any decency?

---------- Post added December 28th, 2015 at 04:55 AM ----------

I think there are three separate arguments.

1. Bubble models suck. Dissolved gas models are better.
2. Bubble models are fine, so are dissolved gas models.
3. Deep stops are not properly scheduled via bubble models or dissolved gas models, and Deep stops have not and will not in the near future be scientifically tested in such a way that makes demonizing them valid.


Let's be clear...no model out there is bends proof. Some models work better for some people than others.

A more inductive argument:

"A tissue compartment washing inert gas out quickly might be less prone to bubble formation and growth than a tissue with slower inert gas kinetics where the supersaturation persists for longer" (Simon Mitchell).

What is the physiological basis to explain this apparent unexpected result of the NEDU studies?

 

[shoredivr]

I have been following this thread with great interest.

It appears to me that the contention is centered on one side attempting to keep the whole idea of deep stops alive while the other side is saying that the statistics of DCS just don’t indicate this. Somebody is mostly wrong and somebody is mostly right.

I also understand how researchers can become overly involved with their own approach, to the point of compromising the science that backs it up.

This particular realm of diving appears to be pertinent for only the most aggressive of technical divers, so the whole thing is completely academic for me. However, I do believe that there is something here to be learned. Physical outcomes are driven by physical laws. Lessons learned at the extremes can act as valid extrapolations of existing algorithms and thus help refine the mid-ground.

Is the “helium penalty” just another fudge that makes an imperfect ascent profile work a bit better? This is fascinating stuff.

As I read it, the research community is unwilling to invest in a fundamental study that would speak directly to this issue as the scientific gains are perceived to be weak and the study would be expensive. This issue has gone begging for years. There is no lack of researchers, but this problem just doesn’t have the face value and “wow factor” that funds grants.

Let’s assume that a proper study was designed and executed to put this entire “deep stops / helium penalty” issue to rest once and for all. Would that not provide fundamental information that applies to EVERY decompression model now in use?

Question for the probabilistic modelers: What sample size of properly designed dives would you estimate to be needed to provide sufficient power to reject the null hypothesis in a binary trial of the two approaches?

Statistics, after all, is what keeps science progressing. If it were not for the universal acceptance of the statistics part of the scientific method, we would still be arguing every single blessed concept.

somebody set set up a crowd source fund for research on technical dive profiles.

 

[ajduplessis]

The industry cant even agree on OW depths, good luck with the crowdfunding. It would be great thou, if by some miracle it does happen......

 

[fsardone]

Money is only one of the elements:
-you need a team of scientists willing to design the testing protocol;
-need divers to be the test subjects;
-need a pressure pot with instrumentation;
-need physicians and a chamber for incidents.

If you want to pay for all of that you need a Government budget and a good driver for spinning such a research. We are unfortunately dependent on the fall out of military research, which is why I really appreciate Dr Doolette and Dr Mitchell efforts to share these findings.

Even if we find a team working pro-bono the equipment usage fee will be huge (you can rent from government but prices are not on the cheap side and only spare capacity can be used).

Unfortunately Return of Investment on these studies would be low ... due to the limited numbers of us technical divers.

Cheers

Fabio

 

[PfcAJ]

2/ Are you familiar with the expression, "if some is good, then more must be better" ? I think it applies to deco too.

That +7 is too far off scale to considered realistic. We don't offer it for that very reason.

¯\_(&#12484_/¯

 

[Divetech99]

Money is only one of the elements:
-you need a team of scientists willing to design the testing protocol;
-need divers to be the test subjects;
-need a pressure pot with instrumentation;
-need physicians and a chamber for incidents.

If you want to pay for all of that you need a Government budget and a good driver for spinning such a research. We are unfortunately dependent on the fall out of military research, which is why I really appreciate Dr Doolette and Dr Mitchell efforts to share these findings.

Even if we find a team working pro-bono the equipment usage fee will be huge (you can rent from government but prices are not on the cheap side and only spare capacity can be used).

Unfortunately Return of Investment on these studies would be low ... due to the limited numbers of us technical divers.

Cheers

Fabio

Instead of crowd funding, which will never happen given the small population of Tec divers, why not something along the lines of "crowd testing". Meaning, hundred of Tec dives happen everyday around the world. If there is a way that we can all band together and give our individual and dive profile data to a team of scientists, perhaps they could study it and reach some conclusion.

Yes, many have tried this form of data collection, including DAN, but somehow, we don't hear anything coming out of it. Maybe it's the lack of resources to do the analysis? If so, why not just make the raw data available to the public, and have a "crowd analysis" in forum discussions like this thread.

Can someone please provide the leadership and create a movement to make this happen?

 

[tomfcrist]

Instead of crowd funding, which will never happen given the small population of Tec divers, why not something along the lines of "crowd testing". Meaning, hundred of Tec dives happen everyday around the world. If there is a way that we can all band together and give our individual and dive profile data to a team of scientists, perhaps they could study it and reach some conclusion.

Yes, many have tried this form of data collection, including DAN, but somehow, we don't hear anything coming out of it. Maybe it's the lack of resources to do the analysis? If so, why not just make the raw data available to the public, and have a "crowd analysis" in forum discussions like this thread.

Can someone please provide the leadership and create a movement to make this happen?

Haven't you heard? We are just a bunch of dumb sheep...we don't actually know if we are bent or not.

 

[rossh]

No Ross . . . Hypocrisy has nothing to do with it. Simply put, what used to work for me (RD method and its applied dissolved & free phase basis ) is not effective anymore unless I pad it with a lot of extended O2 deco profile time. To be fair, I never said anything negative about your VPM /V-Planner or even Kee's RGBM/GAP product (and I used to have them both loaded on an old Pocket PC).

Andrew Ainslie here in offshore SoCal was having very serious DCS problems while using VPM/V-planner live on a Liquivision X1 dive computer in good faith over many deep CCR dive trials. . .and you're implying he's a hypocrite???

Shame on you Ross. Have you any decency?

Hi Kev,

You combined two post answers into one, and drew the wrong conclusion. Many of the people being critical of VPM-B, are often replacing it with a GF version of almost the same thing. That is hypocrisy.


I met with Andrew in about 2009. He was happy then. Andrew was our X-Link tester for the X1 and the code base for that. I talked to him many times up to about 2012 - long after all his X1's died (he had 7 units over time), and he was a great public supporter of our products. He never said a word about injuries. And then one day in 2013, he suddenly changed. Hmmm.... ?? I wonder.


Tell us Kev, in your RD dives in the 9 days straight, did you add or do anything extra for the fact it was 9 days in a row with out a break? Do you account for accumulated effects of multiple days diving?

What is the physiological basis to explain this apparent unexpected result of the NEDU studies?

See anything there?

4 major influences on DCS: Exercise, Thermal, Dive profile, Predisposition.


Deco models control just one piece of that overall stress map.


(diagram courtesy of unknown [I forget] SB poster - thank you)