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John, Thanks for your thoughtful reply and yes, mea culpa for including the refs and not just offering them. Won't happen again. But I don't think we are so far apart: Everyone I talk to has a "gut" reaction that diving with a PFO is a "bad" thing. But when pressed, this is largely because of Moon's study, which now all agree grossly underestimated the true incidence of PFO in the normal population. Also, most MDs are aware of blood clots that have been reported (so rare, they make the literature as case studies) to pass through PFO's with really bad consequences. But the evidence that PFOs are actually involved in AGE or other DCI, just isn't there. If PFOs are all that common, why are not *more* divers getting AGE? Lord knows, is there something about being a smoking donut that *protects* against AGE or PFO? At autopsy they usually examine the heart very carefully in cases of sudden death and should find a PFO. Certainly if I made a diagnosis of AGE at autopsy, I would be very careful to look for PFO. But apparently they aren't found. On Fri, 26 Jul 1996, John W. Chluski wrote: > I believe it to be *possible* for a PFO to be a contributory factor in the > severity of a DCS case. Can't support this with hard data, it's a somewhat > religious thing. ;-) As an Irishman, I never tamper with religion ;-) > > >As Francis and Gorman summarize in Bennett & Elliots' book, "However, > >further studies will be necessary before the association between atrial > >septal defects (PFO) and decompression illness can be considered causal." I think they wrote this because they were being scientifically honest. There are simply not sufficient data to support the hypothesis. Recall that lots of things that *seem* plausible are proven wrong or found to be mostly true but not causally related. The world being flat for one. The only reason that people even considered smoking was not harmful was because the tobacco companies spent so much on advertising and they had to give up a habit as addictive as crack cocaine (That comparison is not made lightly and is based on some recent research about how the brain perceives nicotine and cocaine. The brain thinks they are equivalent.) But perhaps the issue here is not whether PFO causes you to get bent, but whether you get AGE from a PFO. I don't know the mechanics of why the bubbles form. I know the theories, not the facts. > Your prior argument is a very good point IMO. No, its not a perfect test > and it would be wrong to base assumptions of risk soley on this single test. So we agree that if you going to go to the bother of getting tested, for the price of a week's diving in Bonaire (Yes George, people really do dive in sunlight and in warm water and we all know what they are called - tourists), you might as well get a test that's worth the money. > Bottom line for me Peter, is as tremendous as medical knowledge and > procedures have developed over the last several decades, I realize its not > all infallible even though you folks are often held to what can be some > impossible standards. Variations between individuals I think is tremendous. Which is why the Medical Guild stays in business and we bullshit about the "art" of medicine. But sometimes, just sometimes, the answers are within our grasp and seizing them only requires us to open our minds, as well as our hands. > You have also forced me to finally order Bennett & Elliot's tome on diving > physiology to complement my small but growing library on the subject. They'll actually send you an autographed copy, according to the latest DAN magazine. Then we can all become DAN groupies ;-) George, stop grinding your teeth. Regards, Peter
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