Pathophysiology of decompression sickness. In: Bove AA Ed. The pathophysiology of decompression sickness. London, Harcourt Publishers, , Second, I put a lot of effort into unselectively presenting the peer reviewed and published evidence of relevance to the topic in these discussions.
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My first post on this thread is an account of ALL the human studies of relevance to deep stops in decompression diving, including those published in peer reviewed journals. Ross wants peer-reviewed evidence: I have provided it. Third, Ross appears to demand a level of evidence from me that he never provides himself. He seems oblivious to the fact that he is not able to cite any evidence from scientific investigations that supports his position.
In contrast, my opinion on this subject is entirely shaped by the available evidence. I once supported the concept of deep stops prescribed by bubble models, but that is no longer the case because the overwhelming weight of evidence that has emerged suggests that this approach to decompression is not optimal. The discussion centres on whether increased tissue blood flow has a significant influence on tissue gas uptake or elimination. Here are a couple of quotes. Instead we appear to be limited by tissue absorption rates, exactly as the models are designed and operate. Models and their internal gas tracking, are not designed as perfusion limited.
The basic sequence of mono-exponential gas kinetic formula, uses the partial pressure of gas versus the tissue absorption rate. This rate is represented with a half time value. Thus, his position appears to be that its not blood flow perfusion that matters, its the "absorption rate" or "half time". This is like saying that "its not oxygen that keeps us alive, its the air we breathe".
Oh no, there's been an error
It is matter of some concern to me that someone who offers to provide authoritative answers to decompression questions does not understand one of the field's most basic concepts; that the primary determinant of a tissue's gas exchange half time is its blood flow. Caveat emptor. Simon M. This paper sets out best practice for use of Doppler for studies of decompression. Thank you Iain. The fact that Ross is incorrectly citing this paper has been pointed out to him on many occasions when he has used the same argument, but here we are on the end of it yet again.
It is a good illustration of how all of Ross's claims must be viewed with a great deal of suspicion; even those that he words in the strongest possible terms. Rossh, I have a genuine question.
Tech Divers, Deep Stops, and the Coming Apocalypse
You've probably already said your answer, but I am not a scientist and probably didn't understand. What do you think of Buhlman M-values as an upper limit for tissue loading? I also realise that VPMB doesn't do much on tissue loading and is mostly about bubble size, but under buhlman the tissues include the blood which when super saturated with gas would cause bubbles if my understanding is correct, which it very well could not be. Yes I understand that using proper profiles and proper DCS as an end point, is not allowed in test review. The problem with using VGE as an endpoint, is that they are harmless in the broader population.
So what are you really measuring? There is better indicators available through bio chem changes and markers David Doolette tried to connect the nedu test result with VGE using the method of that paper That was Simon's paramount piece of evidence that used real DCS as an end point, and it can't be connected either. Venous gas emboli detected by two-dimensional echocardiography are an imperfect surrogate endpoint for decompression sickness. Doolette DJ. Ross claims I am "outside the peer process", but the responsibility my peers have given me in representing our field in major reference works tells a different story.
This is the internet.. On the internet you have done all the nasty things I described above.
No one peer review's you here, and anyone who dares call you out on these matters, is attacked ad homiem, or chased off as fast as possible. Stop trying to hide behind your credentials, and face up to reality. Second, I put a lot of effort into unselectively presenting the peer reviewed and published evidence of relevance to the topic in these discussions.
Its your invalid and false interpretations of the science, and your use of out of context meanings and relevance to all these pieces. Many of the connections you claim, do not exist, or are not relevant, but you claim them as supporting evidence regardless, thereby creating a false premise. Your the one making new claims: its up to you to show valid evidence. I only need show how your argument is defective, using existing science.
Simon M You are making up false straw man arguments about me again. You didn't get the argument you wanted over there, so you make one up over here You are desperate Rossh: However, if exercise level and therefore increased perfusion was a real issue, then it would be the leading cause of injury, and figure heavily in the case reports.
Where is the identifiable trend line in case reports, with a common exercise component? It does not seem to exist. Simon: We see cases of DCS in divers who have worked hard on the bottom all the time.
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I'm glad you wrote that, because "what is barn-door obvious", from that above, is you finally admit that most DCS are from dive environmental conditions, and not from model problems. But it raises a math question Last month you had 40 cases running around your vivid imagination I'll let you do the math. Summary: Doolette D. For safer decompression, try to avoid being cold during and following decompression and heavy exercise at any time immediately before, during, or soon after diving.
Scuba Diving: Decompression Illness & Other Dive-Related Injuries
In addition DCS risk will be greatest on the first day of diving and after a break of about a week. Conversely, decompression safety might be increased by keeping cool on the bottom and using active warming during decompression, limiting exertion on the bottom, for instance, by using a scooter instead of swimming, and exercising gently during decompression. As I said. Models are correct to ignore this effect, as its just not big enough to make a difference. You are making up false straw man arguments about me again. There is nothing false or straw man about it Ross.
It is absolutely clear from your "its not blood flow - it is half times that determine gas uptake" comments that you had no idea that blood flow is the key determinant of a tissue half time. Yet here you are portraying yourself as expert and offering to answer questions on decompression theory. This is a great example of your tendency to concrete thinking. Of course there are many risk factors that can influence decompression risk, and any one of them could become the predominant influence in any particular case.
The thing that defines a risk factor is that if you keep everything else constant and vary only the risk factor, then it changes the risk of the dive.
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As for quoting David, why don't you quote his post from the SB thread where he told you that you were simply wrong about exercise as a risk factor for DCS? Furthermore, if you think a few minutes makes a meaningful difference over and above the general noise in decompression success good luck. On some dives I'd agree with your last paragraph. On others, the difference is pretty huge.
I just don't logically see how that works. And which studies show reduced inflammatory markers using bubble models compared to pure dissolved gas models? The conclusion is: VGE can be used for comparisons of decompression procedures in samples of subjects but must be interpreted cautiously. If you find a difference, there is likely a difference in the risk of getting bent. I think Fake News is more apt tbh. How on earth did this thread end up in "Contact an Admin"? Given it's here, I think we should nominate a representative Admin and get them to decide the facts and make a definitive ruling.
Like Judge Judy, only different. Sorry, I am travelling so am posting between flights.
It is a bit disjointed.
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