Posted by BillP on May 12, 2001 at 21:01:26:
In Reply to: Re: That's a fascinating read, John! posted by John Walker on May 12, 2001 at 17:06:27:
Thanks for your reply, John. I hope that you're still around or can drop by an Internet cafe on your trip, but I'm afraid that I might have missed you.
Yes, I'm aware that medical science is full of theories. But I'm also aware that the world is full of medical quackery and people who spend WAY too much time and effort thinking of elaborate explanations to justify their conclusions and recommendations (usually because they have a personal agenda to support), and way too little time and effort trying to determine if their conclusions are true and their recommendations valid. I've learned to not be too gullible when faced with a medical claim. The generally accepted process to evaluate a new idea is to form a hypothesis, search the literature for information to support or refute the hypotheis, devise a well designed study to TEST the hypothesis, if the study results support the hypothesis (or refute it in a significant way) submit the study findings for peer review and publication, and once the hypothesis has been adequately tested and supported make recommendations based on the conclusions you've drawn from the data. A few of those steps between interesting idea and conclusions/recommendations appear to have been skipped in the nitrogen, helium, and cell rigidity issue.
Bill Mee (http://www.aquanaut.com/bin/mlist/aquanaut/techdiver/display?24193,from), George Irvine (http://www.aquanaut.com/bin/mlist/aquanaut/techdiver/display?22881,from), MHK (http://www.scubadiving.com/talk/read.php?f=1&i=57809&t=57765) and Jarrod Jablonski (according to MHK- I've not talked to him) seem to have an interesting idea about nitrogen, helium, and cell rigidity. They put it differently and all seem to add their own twists, but if I have synthesized their ideas properly they seem to be saying:
1) Diving causes red blood cells to become rigid.
2) That rigidity is caused by increased partial pressure of nitrogen.
3) The rigidity is NOT caused by increased partial pressure of helium or oxygen.
4) The rigidity of the red blood cells is of enough clinical significance to recreational divers that those divers should alter their behavior (dive trimix in the recreational range) so as to limit the untoward effects of nitrogen.
I have found where Bill Mee has cited one peer reviewed published study (http://www.aquanaut.com/bin/mlist/aquanaut/techdiver/display?35308,from) to support his claim.
You seem to think that I have an agenda to "discredit whoever I can on this issue." Such is not the case. I only want to get at the facts in the matter. I have made certain assertions in this issue:
1) The above claims are EXTRAORDINARY and are not found in the dive medicine/physiology texts or medical literature that I am aware of. (I freely admit that I'm not aware of everything. That's why I'm ASKING QUESTIONS.)
2) The "burden of proof" for extraordinary claims lies with those making the claims, not with those who ask for supporting evidence to back up the claims.
3) If the claims are true, they would be VERY important to the diving community at large and worthy of the claimants' time and attention to support.
4) The study that Bill Mee cited does not support the above claims.
5) I have seen no other sound evidence (other than George Irvine, Bill Mee, MHK, and JJ "say it's so") that supports the claims. And by sound evidence I don't mean emails on the techdiver list, secret studies that cannot be released, articles on websites or in magazines, or discussions on Internet forums. I mean well designed and preferably peer reviewed studies that actually look at the stated cause and claimed effect. If the effect is so profound, it should be pretty easy to demonstrate. There should be "many studies" showing the effect. But the "many" and "several" studies that are said to show the effect never seem to appear. (You referred to "several studies" in your post above. Can we have them for review please?) But so far when I ask for the studies the person making the claim is too busy, or someone else has the information, or I'm operating in bad faith so I'm not worthy of receiving the information and I'm soundly abused for daring to ask.
You also seem to think that I have been constantly changing the questions every time I'm answered in order to discredit the answer. That is not the case either. I have asked the same question again and again and it just hasn't been answered yet. I'll ask it again now.
Can you provide any sound evidence (not conjecture) that shows that increased partial pressures of nitrogen causes rigidity of red blood cells in the recreational diving range, that the effect is clinically significant to recreational divers (has an important effect on their lives and health), and that the red cell rigidity is not caused by increased partial pressure of helium or oxygen? If so, what is this evidence? Where are these studies to be found?
Your posts above have some interesting information and some intriguing speculation, but I don't see where you've tested your hypotheses. It looks like you've only formulated them. So, can you or anyone else answer the same questions that I've been asking over and over? I really don't mind hearing about it if you do have the information. Again, I have no other agenda here except to get at the facts.
Have a good trip,
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