In loop gas change calculation

[rossh]

No you don't agree. David does NOT agree with the position you have taken over the years which is fundamentally that IBCD can contribute to most types of DCS. You are misquoting him. I have published extensively with David on this issue, and the stance we have taken in those publications reflects our views (including his obviously).

I would draw your attention to his recent NEDU study:

Doolette DJ, Gerth WA. SAFE INNER EAR GAS TENSIONS FOR SWITCH FROM HELIUM TO AIR BREATHING DURING DECOMPRESSION. NEDU TR 12-04.

In which the conclusions read:

This study was designed to assess whether helium-nitrogen counterdiffusion after a heliox-to-air gas switch at 100 fsw during decompression causes unsafe potentiation of inner ear gas-supersaturation with undue risk of inner ear DCS. The results indicate that:
1. Dives to depths up to 220 fsw (704 kPa) with 60-minute bottom time and 651 kPa inspired helium partial pressure followed by no-stop decompression to 100 fsw (408 kPa) and switch to air breathing have low risk of inner ear DCS.
2. The LEM-h8n25 model may be used to compute decompression schedules with a heliox-to-air breathing gas switch at 100 fsw for heliox dives to depths up to 220 fsw and bottom times up to 60 minutes without special consideration of the risk of inner ear DCS. Additional man-testing is required to confirm that the model may also be used to compute schedules for such dives with longer than 60-minute bottom times and for such dives to depths up to 300 fsw with short bottom times

Why don't you plug that into you IBCD warning system and see what it says.





Simon M

You can plug it in the above test into our program, and it will come out correctly with a non-warning. David and I discussed the above test and how it fits in, and the basic injury method in the deep version. We agreed. The above test actually confirms the warning method in our programs, and works correctly with the existing program codes!


Wow ... you were not at this discussion, and I have never discussed my underlying theories on this with you. But you state I'm wrong anyway. You see Simon: you can't handle the truth!

You have already demonstrated in your youtube sham, that you have insufficient knowledge of deco theory, and that you will deliberately deceive and lie about anything to achieve the end result. So there is not much point in discussing any of this IBCD theory with you.

 

[rossh]

Hello Ken,

"Slamming yourself with nitrogen" was the subject of the study by David that I quote above. The risk has almost certainly been overhyped, AND contrary to prevalent perceptions the only tissue known to be at risk in the process when the gas change is from high helium to high nitrogen is the inner ear. Simon M

Actually.... "Slamming yourself with nitrogen" is only half of the conditions that causes deep version IBCD. The other half of the IBCD induced deep water Inner Ear DCS condition, is missing from the test. Hence the test procedure is correctly found a negative result.

...but his recent study (which I quote in my reply to Ross above) suggests that the risk of clinical consequences is low, even when the gas switches very much constitute a "slam" as you put it.

Simon M

And yet, people get injured from doing exactly that.

 

[oya]

you have insufficient knowledge of deco theory

This is why I stopped using your products and no longer recommend them to anyone.

 

[kwinter]

I'm not sure why you feel it is necessary to argue, Simon. While the risk of injury or consequence may be low, there is still a finite risk that even you acknowledge for inner ear damage. Please elaborate on what the downside is of flushing the loop with different gasses on ascent so that the loop contents becomes closer to your bailout gasses. I can not find any support for this being a dangerous practice. It might not be necessary, but if it is not harmful and can eliminate even a small risk, then why not do it?

 

[Simon Mitchell]

You can plug it in the above test into our program, and it will come out correctly with a non-warning.

Ross, if your ICD warning system allows a switch from heliox breathing (for 60 minutes) at 70m to air after a direct ascent to 30m then I have no problem with it. I think most people would find that claim surprising, but if it is true, then fine. I must say that I find some of your statements a bit self-contradicting.... you say the gas switch in David's study was fine, but then say....

And yet, people get injured from doing exactly that.

Anyway, my initial objection was to your implication that David agrees with your view of the pathophysiology of ICD. We have debated your views a number of times on various threads and they include (or at least have done so in the past) the belief that many forms of DCS are caused by ICD after helium-to-nitrogen switches. I know that David does not agree with this, hence my comment.

The other half of the IBCD induced deep water Inner Ear DCS condition, is missing from the test

Could you please explain what you mean by this? What "other half"?

Simon M

 

[Simon Mitchell]

I'm not sure why you feel it is necessary to argue, Simon. While the risk of injury or consequence may be low, there is still a finite risk that even you acknowledge for inner ear damage. Please elaborate on what the downside is of flushing the loop with different gasses on ascent so that the loop contents becomes closer to your bailout gasses. I can not find any support for this being a dangerous practice. It might not be necessary, but if it is not harmful and can eliminate even a small risk, then why not do it?

Ken,

I am pointing out the flaw in holding this belief so strongly, and I am doing so because over the years there have been examples of behaviors and practices which themselves may introduce risk, based on concerns about ICD. One example is the mixing and carriage of multiple cylinders of "intermediate trimix". Your dil gas practice is fine, but your admonishment about "slamming yourself with nitrogen" perpetuates the skewed perception of this issue. I am trying to provide a pathophysiologically accurate perspective.

Simon M

 

[rossh]

Ross, if your ICD warning system allows a switch from heliox breathing (for 60 minutes) at 70m to air after a direct ascent to 30m then I have no problem with it. I think most people would find that claim surprising, but if it is true, then fine. I must say that I find some of your statements a bit self-contradicting.... you say the gas switch in David's study was fine, but then say....

Anyway, my initial objection was to your implication that David agrees with your view of the pathophysiology of ICD. We have debated your views a number of times on various threads and they include (or at least have done so in the past) the belief that many forms of DCS are caused by ICD after helium-to-nitrogen switches. I know that David does not agree with this, hence my comment.



Could you please explain what you mean by this? What "other half"?

Simon M

No. You have demonstrated and recorded, you have little understanding or regard for actual dynamics of decompression. These basic concepts are essential to understanding the deep version of inner ear IBCD induced injury. You are not worth the waste of time on this matter.


*****


12 years ago, I saw this IBCD issue and formed a theory. I put a warning into our programs to help divers avoid the issue and plan around it. Then much later the Nedu test procedure and result agrees with the warning system in our programs. I discussed the issue and my theory the papers author, and he agreed with my view of the cause. End of story.

 

[Simon Mitchell]

No.You have demonstrated and recorded, you have little understanding or regard for actual dynamics of decompression. These basic concepts are essential to understanding the deep version of inner ear IBCD induced injury. You are not worth the waste of time on this matter.

Except the truth in the real world (as opposed to on Planet Ross) does not readily fit your demonstrably ludicrous narrative does it? Since you insist on taking this stance I will answer you this way: The current edition of every major textbook on diving medicine has a chapter written by me on the pathophysiology of decompression sickness.

12 years ago, I saw this IBCD issue and formed a theory. I put a warning into our programs to help divers avoid the issue and plan around it. Then much later the Nedu test procedure and result agrees with the warning system in our programs. I discussed the issue and my theory the papers author, and he agreed with my view of the cause. End of story.

David's view of the scope and cause of IBCD in deep technical diving scenarios is clearly articulated in our 2003 paper:

Doolette SJ, Mitchell SJ. Biophysical basis for inner ear decompression sickness. Journal of Applied Physiology 2003;94:2145-50.

...and further elaborated in our 2013 review:

Doolette DJ, Mitchell SJ. Recreational technical diving part 2: decompression from deep technical dives. Diving and Hyperbaric Medicine 2013;43:96-104.

Unless your "view of the cause" is confluent with those we express in those publications, then I interpret your claim that David believes in your theories to be a typically idiosyncratic interpretation of the conversation you had with him at Tek Dive USA.

Simon M

 

[matt]

Is there any proof that IBCD is even a relevant consideration for dives less than 100m? I thought not.

Matt.

 

[atedeschi]

What about the diver offgasing into the loop. When you flush the loop you change the content i.e. Lower He and Higher nitrogen. How does the offgasing Of the diver effect the loop content? My thought has always been as you ascend you keep upping the o2 and the HE in the loop continues to decrease until the o2 flush at 20'
I know the computer calculates and shaves off deco but what is really happening in the loop. If I start a dive with 10/50 as I start ascending and deco the helium content is decreasing, no?

 

[Simon Mitchell]

There is a very good thread on the IBCD subject here:

http://www.ccrexplorers.com/showthread.php?t=15598&page=2

Not much has changed really except that David's recent study referred to earlier has reinforced some of the suggestions I made.

Simon M

 

[Simon Mitchell]

Is there any proof that IBCD is even a relevant consideration for dives less than 100m? I thought not.

Matt.

Hello Matt,

I don't think there is anything magical about 100m but you are right, the dives in which onset of inner ear DCS has been observed to be closely related to a gas switch have typically been deep. As we reported in our first publication on inner ear DCS pathophysiology (Doolette an Mitchell 2003) this almost certainly relates to the vulnerability of the inner ear to already be supersaturated at the point the gas switch is made during decompression from a typical deep dive, and the consequent small augmentation of that pre-existing supersaturation by counter-diffusion. To be very clear, this happens in the inner ear because of its unique anatomy. The onset of other forms of DCS has never been temporally related to gas switching in the way inner ear symptoms have. Nor would you expect them to be based on predictions of the effect of switching from helium to nitrogen. These switches, if anything, should be beneficial to out-gassing in other tissues; a point made by pioneer diving physiologists ever since the phenomenon was first studied. Ross is the only person who proclaims a more generalizable adverse effect (which needs to be interpreted in the context of him selling software with a warning algorithm) but he consistently fails to provide any evidence or rational explanation for such an effect. There is much more about that in the thread I link to in the above post.

Simon M

 

[rossh]

.... I will answer you this way: The current edition of every major textbook on diving medicine has a chapter written by me on the pathophysiology of decompression sickness.

Simon M

And that's a good and worthy contribution. You make excellent pieces on pathophysiology matters, and are to be commended on these. No one disputes that.


But decompression model theory - no, not your specialty - very bad. Your puff piece of youtube demonstrates: A/ you do not know the difference between tissue pressure and supersaturation and the consequences of that to decompression, or B/ if you do know it, but choose to deliberately deceive the public on this matter to over inflate your arguments and present something that is not true. In any case.... errors and deception are the basis of your sham attacks, and you recorded it for everyone to see.

David's view of the scope and cause of IBCD in deep technical diving scenarios is clearly articulated in our 2003 paper:

Doolette SJ, Mitchell SJ. Biophysical basis for inner ear decompression sickness. Journal of Applied Physiology 2003;94:2145-50.

...and further elaborated in our 2013 review:

Doolette DJ, Mitchell SJ. Recreational technical diving part 2: decompression from deep technical dives. Diving and Hyperbaric Medicine 2013;43:96-104.

Unless your "view of the cause" is confluent with those we express in those publications, then I interpret your claim that David believes in your theories to be a typically idiosyncratic interpretation of the conversation you had with him at Tek Dive USA.

Simon M

You left out :

Pathophysiology of inner ear deco sickness potential role of PFO: SPUMS v45/2 p111 June 2015.
Isobaric Counter Diffussion: TekUSA 2106.




As I said above....

rossh: "... Then much later the Nedu test procedure and result agrees with the warning system in our programs. I discussed the issue and my theory the papers author, and he agreed with my view of the cause. End of story. "


David agreed with the my theory for injury, that is used behind the warnings the programs generate. It's all about deco pressures and changes, and its limited to the deep version of the IE DCS, and related type2 DCS.


Of course that theory, and the program do not attempt to explain the shallow water / post dive version of IE DCS. In the shallow version, it would seem to be much more physiology at play and obviously an issue for you to explore.


******


I'm sorry you can't handle the truth Simon. Your narcissism clearly requires you be the only voice on this matter. Please try to keep your deception and twisted facts and social manipulation, to a bare minimum this time.

 

[David Doolette]

rossh: "... Then much later the Nedu test procedure and result agrees with the warning system in our programs. I discussed the issue and my theory the papers author, and he agreed with my view of the cause. End of story. "


David agreed with the my theory for injury, that is used behind the warnings the programs generate. It's all about deco pressures and changes, and its limited to the deep version of the IE DCS, and related type2 DCS.

Hi Ross

My memory of the brief discussion we had after my inert gas counterdiffusion talk at TekDiveUSA2016 was that we discussed the fact that in the context of technical diving counterdiffusion phenomena are not really isobaric because a helium-to-nitrogen gas switch is typically followed relatively soon by continued decompression. You explained the utility of the IBCD warning in your software was that it prevented divers from exploiting a helium-to-nitrogen gas switch to accelerate decompression compared to that prescribed without the inert gas switch. Because good evidence is emerging that a helium-to-nitrogen gas switch does not allow accelerated decompression for typical duration technical bounce dives, I agreed that warning against such plans is probably not a bad thing.

I think you and Simon may be at cross-purposes in this discussion about inert gas counterdiffusion - but let me say that I understand Simon's thinking on this topic intimately, as we have spent many hours discussing and writing about it, but I really do not know how you believe counterdiffusion works. Simon is saying that there is no evidence that a helium-to-nitrogen breathing gas switch itself contributes to any other form of DCS except inner ear injury. You seem to be saying that decompression plans that include a helium-to-nitrogen breathing gas switch may result in DCS. Those are not the same things.

David

 

[Simon Mitchell]

I discussed the issue and my theory (about counterdiffusion) the papers author (David Doolette), and he agreed with my view of the cause. End of story.

I really do not know how you believe counterdiffusion works.

....hence my original concern about misquotation of David.

 

[rossh]

Hi Ross

My memory of the brief discussion we had after my inert gas counterdiffusion talk at TekDiveUSA2019 was that we discussed the fact that in the context of technical diving counterdiffusion phenomena are not really isobaric because a helium-to-nitrogen gas switch is typically followed relatively soon by continued decompression. You explained the utility of the IBCD warning in your software was that it prevented divers from exploiting a helium-to-nitrogen gas switch to accelerate decompression compared to that prescribed without the inert gas switch. Because good evidence is emerging that a helium-to-nitrogen gas switch does not allow accelerated decompression for typical duration technical bounce dives, I agreed that warning against such plans is probably not a bad thing.

I think you and Simon may be at cross-purposes in this discussion about inert gas counterdiffusion - but let me say that I understand Simon's thinking on this topic intimately, as we many hours discussing and writing about it, but I really do not know how you believe counterdiffusion works. Simon is saying that there is no evidence that a helium-to-nitrogen breathing gas switch itself contributes to any other form of DCS except inner ear injury. You seem to be saying that decompression plans that include a helium-to-nitrogen breathing gas switch may result in DCS. Those are not the same things.

David

Hi David,

We discussed as you mention, and more. I have in front of me the two pages of prepared diagrams from our conversation. We briefly discussed the IBCD experiment, its method and outcome, and how tech profiles differ, and the reasons behind that. Then, using copies of the diagrams from your presentation, I briefly described my thoughts on the deco mechanism behind the onset of deep water IE DCS and how it fits into your presented theories. This last part is what we agreed upon.



What's relevant to me all along, is if the our program's inbuilt warning is correct. From what you say, and further indicate is emerging, it appears our program correctly avoids the conditions of deep water IBCD induced IE DCS, and avoids the potential problems of extreme accelerated deco. As a bonus, it also correctly allows through the non harmful conditions such as the test.


It was back in late 2004 when I inserted this warning into the program, based on a few observations and a weak theory, and some military reports at the time. I found a simple mechanism to achieve this through ppInert tissue gradients limits. The program was also the first to draw profiles in the perspective of ppInert gradient changes across the whole ascent. Today it seems the science is coming in to support those decision.


For this insight some 12 years ago, I give myself a well deserved pat on the back. :yippee:

 

[Simon Mitchell]

For this insight some 12 years ago, I give myself a well deserved pat on the back. :yippee:

You get caught blatantly misrepresenting the views of one of my colleagues.

In further support of your position you allude to new science that just a year ago you were wantonly disparaging (an "anomaly" I think was how you described it) after it was pointed it out to you. By the way, I saw the line in which you emphasised how your warning system helps with avoidance of accelerated decompression before you removed it from your above post.

And you give yourself an award for this.

Now I've seen everything (well, hopefully).

Simon M

 

[rossh]

You get caught blatantly misrepresenting the views of one of my colleagues.

In further support of your position you allude to new science that just a year ago you were wantonly disparaging (an "anomaly" I think was how you described it) after it was pointed it out to you. By the way, I saw the line in which you emphasised how your warning system helps with avoidance of accelerated decompression before you removed it from your above post.

And you give yourself an award for this.

Now I've seen everything (well, hopefully).

Simon M

You can't stand that some one else will come up with a solution to problem - one that you want to claim for yourself.


Look at the lies you tell already. You deliberately changed my quote about David's conversation above, to invent a straw man argument, and then accuse me of "misquoting", but in fact you are pointing to your own fabrication. That is a deceptive and dishonest act from you. And now this post quoted here - a load of dribble and waffle - all of it to incite an argument about matters that never happened.


Simon Mitchell == deception, dishonest, spiteful, antagonist.

 

[Simon Mitchell]

You deliberately changed my quote about David's conversation above, to invent a straw man argument, and then accuse me of "misquoting", but in fact you are pointing to your own fabrication. That is a deceptive and dishonest act from you.

The only "change" was clarification about what the conversation was about and who it was with so that people would not have to go and establish those things for themselves. Are you seriously suggesting that the conversation was not about counterdiffusion or not with David Doolette????

Does this make you happier.....

I discussed the issue and my theory the papers author, and he agreed with my view of the cause. End of story.

I really do not know how you believe counterdiffusion works.

If he does not know how you believe counterdiffusion works, how can he agree with your view of the cause (of counterdiffusion related DCS). Just face up to it Ross, you have been caught misquoting / misrepresenting the views of one of my colleagues.

Simon M

 

[David Doolette]

Hi David,

We discussed as you mention, and more. I have in front of me the two pages of prepared diagrams from our conversation. We briefly discussed the IBCD experiment, its method and outcome, and how tech profiles differ, and the reasons behind that. Then, using copies of the diagrams from your presentation, I briefly described my thoughts on the deco mechanism behind the onset of deep water IE DCS and how it fits into your presented theories. This last part is what we agreed upon.

Hi Ross

I remember you had taken a couple pages of notes and we discussed a figure - one from NEDU TR 12-04 I think - but I don't remember this last part, your thoughts on the deco mechanism behind what you are calling deep water IE DCS. Perhaps you could explain them here?

David