UTD Decompression profile study results published
- Thread starter Dr Simon Mitchell
- Start date
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Timeline as I understand it:
1. AG was with GUE and left (or was asked to leave; I don't know the circumstances)
2. AG worked for NAUI tech and was eventually asked to leave; I don't know the circumstances.
3. Somewhere during the above, my original TDI instructor took classes from AG.
4. AG formed 5th Dimension (I think).
5. I started my tech training with TDI.
6. AG formed UTD and our group all crossed over with the instructor. We were immediately taught to use RD for all decompression planning.
7. Because of my concerns with some of the issues with the use of RD as the primary planning tool for decompression, I am put into contact with Jarrod Jablonski, who told me about the history of GUE's use of RD and how it was being used at the time. My primary concern was UTD's belief that RD did not have to be adjusted for altitude. JJ said it did need to be adjusted for altitude, but they had never done anything with that so he did not know how.
lv2dive
Formerly known as KatePNAtl
So, what is the actual resulting ascent plan?
I don't understand. If you're using RD, why would you have to run numbers? Isn't the whole point that you can actually be on the bottom, after 25 minutes at 170', knowing you have your standard gases, and in relatively little time, with no calculator, just spit out an ascent plan?
I know that but what AG was saying is (1) bubbles lead to an immune reaction and (2) the immune reaction is actually what causes DCS.
Personally I don't buy it, I have a hard time accepting what the DIR heavy-weights say about deco theory in general and this just seems weird and obviously wrong to me.
R..
Again, I don't understand. So, what if it's a diver certified for GUE Tech 2 and they are doing a dive to 170' for 25 minutes. Are you saying that even then that person would not use 50% and O2? They would only ever use 1 deco gas? Or they wouldn't use RD to calculate their ascent, or what?
My question was, and still is, if you are GUE Tech Infinity certified and you dive to 170' for 25 minutes, on 18/45, and you have 50% and O2, what would your GUE Ratio Deco ascent be?
If the answer is that you would still only use 1 deco gas, okay, that's good to know. But I would still like to know what the ascent plan would be, so I can see how it compares to the UTD one they actually used and the GF30/80 one.
PfcAJ
Contributor
GUE's RD purposefully mimics GF 20/85. Its not perfect, and if there's debate the default solution is back to 20/85.
@stuartv , The resulting plan would be
165ft for 25min
30fpm to 75% avg depth (130ft)
10fpm to gas switch (70')
3min stops on 50%
20min on oxygen
As for "isn't the whole point that you can actually be on the bottom, after 25 minutes at 170', knowing you have your standard gases, and in relatively little time, with no calculator, just spit out an ascent plan?", yes, that's the point. And I did that. I'd wager that its pretty close to 20/85. I'd also wager that deleting the oxygen and just staying on 50% has minor impact to the overall deco time.
RD is a guideline to help wrap your brain around the relationship between deco time and dive time+depth. Its NOT the end all be all. It will get you close if you use it within the parameters it works best.
PS, I also thing that 20/85 stops you too deep based on the latest from Doolette and friends. Whenever I do a dive where I'm using RD as a planning tool I slow the ascent more around 60% of avg depth.
@stuartv , The resulting plan would be
165ft for 25min
30fpm to 75% avg depth (130ft)
10fpm to gas switch (70')
3min stops on 50%
20min on oxygen
As for "isn't the whole point that you can actually be on the bottom, after 25 minutes at 170', knowing you have your standard gases, and in relatively little time, with no calculator, just spit out an ascent plan?", yes, that's the point. And I did that. I'd wager that its pretty close to 20/85. I'd also wager that deleting the oxygen and just staying on 50% has minor impact to the overall deco time.
RD is a guideline to help wrap your brain around the relationship between deco time and dive time+depth. Its NOT the end all be all. It will get you close if you use it within the parameters it works best.
PS, I also thing that 20/85 stops you too deep based on the latest from Doolette and friends. Whenever I do a dive where I'm using RD as a planning tool I slow the ascent more around 60% of avg depth.
Out of curiosity they say that it suppose to be a 5 year test, and they where starting in 2014.
But results were already published apparently, so did they stop or they still are doing tests ?
are divers still volunteer to sing in to try GF like 45/75 or 40/70 at 50m for 25min ?
But results were already published apparently, so did they stop or they still are doing tests ?
are divers still volunteer to sing in to try GF like 45/75 or 40/70 at 50m for 25min ?
CAPTAIN SINBAD
Contributor
Thanks so much Dr. Mitchell. I have been meaning to write to you to discuss the short comings of UTD ratio deco. I am glad you posted this. It answers a lot of questions I had in mind regarding UTD Ratio Deco. I would like to see if UTD modifies its ascents to reflect research or would they modify research to justify their ascent profiles.
OP
Hello,
Just picking up on some of the comments / questions.
I think you have worked out the answer to the first bit yourselves. The "tweaks" to Buhlmann that Andrew was referring to were the GF modifications themselves. I do not believe there were any extra "tweaks".
Unfortunately there is a 1 year embargo on papers published in DHM. This is perfectly understandable though because it is a societal journal funded entirely by the South Pacific Underwater Medicine Society and the European Underwater and Barometric Society. Expeditious journal access constitutes a substantial reason for membership and if it could be instantly downloaded by anyone, then people would not bother to be members, and there would be no journal. One solution that many of you who clearly have a strong interest in such matters could consider is joining one of the societies. SPUMS does not require you to be a doctor or medical person to join. The journal is almost always packed full of interesting stuff. Have a look at the membership section on the SPUMS website. It is not too expensive.
It is generally accepted that decompression and bubble formation initiate inflammatory responses in the body. What is less clear is the extent to which these responses are responsible for the symptoms of decompression sickness. To be clear, we don't fully understand the relative contributions of the physical effects of bubbles and harmful effects of inflammation. Related questions will define one of the controversial issues surrounding this paper: viz, what do the measured differences in inflammatory markers really mean? I think the best way to interpret it is that the inflammatory markers are a plausible measure of decompression stress and (perhaps) a poorly characterized indicator of risk of DCS.
The term aggressive decompression is difficult to define, but my sense of it would be that it refers to decompressions that carry a greater risk of DCS (in as much as we are capable of predicting that). But to some extent it is in the eye of the beholder! I am sure Andrew Georgitsis would say that the 30/85 decompression was more "aggressive" than the RD one, but in fact, based on my definition, the opposite has proved to be true (mainly because the RD one appears to be poorly designed).
This was largely my point in stating that this study does not define 30/85 as "optimal". The widespread use of a very low GF-Lo was intended to make the GF algorithm emphasise deep stops and look more like a bubble model. However, as has been extensively discussed on this board, there is mounting evidence that the theoretically attractive idea of emphasising deep stops has not lived up to expectations. In that regard it is quite possible (indeed likely) that a GF-Lo of 30 continues to over-emphasise deep stops on some profiles at least. Unfortunately, as I have discussed elsewhere, we do not have data that guide us on how far to back away from deep stops. I have discussed my personal use of GFs elsewhere.
Simon M
Just picking up on some of the comments / questions.
victorzamora:
I think you have worked out the answer to the first bit yourselves. The "tweaks" to Buhlmann that Andrew was referring to were the GF modifications themselves. I do not believe there were any extra "tweaks".
Unfortunately there is a 1 year embargo on papers published in DHM. This is perfectly understandable though because it is a societal journal funded entirely by the South Pacific Underwater Medicine Society and the European Underwater and Barometric Society. Expeditious journal access constitutes a substantial reason for membership and if it could be instantly downloaded by anyone, then people would not bother to be members, and there would be no journal. One solution that many of you who clearly have a strong interest in such matters could consider is joining one of the societies. SPUMS does not require you to be a doctor or medical person to join. The journal is almost always packed full of interesting stuff. Have a look at the membership section on the SPUMS website. It is not too expensive.
Diver0001:
It is generally accepted that decompression and bubble formation initiate inflammatory responses in the body. What is less clear is the extent to which these responses are responsible for the symptoms of decompression sickness. To be clear, we don't fully understand the relative contributions of the physical effects of bubbles and harmful effects of inflammation. Related questions will define one of the controversial issues surrounding this paper: viz, what do the measured differences in inflammatory markers really mean? I think the best way to interpret it is that the inflammatory markers are a plausible measure of decompression stress and (perhaps) a poorly characterized indicator of risk of DCS.
The Chairman:
The term aggressive decompression is difficult to define, but my sense of it would be that it refers to decompressions that carry a greater risk of DCS (in as much as we are capable of predicting that). But to some extent it is in the eye of the beholder! I am sure Andrew Georgitsis would say that the 30/85 decompression was more "aggressive" than the RD one, but in fact, based on my definition, the opposite has proved to be true (mainly because the RD one appears to be poorly designed).
stuartv:
This was largely my point in stating that this study does not define 30/85 as "optimal". The widespread use of a very low GF-Lo was intended to make the GF algorithm emphasise deep stops and look more like a bubble model. However, as has been extensively discussed on this board, there is mounting evidence that the theoretically attractive idea of emphasising deep stops has not lived up to expectations. In that regard it is quite possible (indeed likely) that a GF-Lo of 30 continues to over-emphasise deep stops on some profiles at least. Unfortunately, as I have discussed elsewhere, we do not have data that guide us on how far to back away from deep stops. I have discussed my personal use of GFs elsewhere.
Simon M
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