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Steve, the term "unearned" or "undeserved" is a terible disservice to divers provided by the dive industry marionettes at DAN. If DAN were ever to tell the truth about anything in diving, it would cost the "industry" a fortune. Getting past that issue, if you have a shunt and get hit, it is hardly "unearned". Anything that allows the venous blood to get past the lungs' giant bubble filter into the arterial side is a "shunt". The more common ones are either in the cappilary beds of the lungs themselves and are as such hard to detect other than by empiricle evidence , ie you get hammered, or are in the heart itself in the form of a PFO, which up to 30% of the population has, or as some other form of atrial septal or other defect. The catch 22 is that to open a shunt or to operate as a shunt, you need to generate sufficient bubbles to alter the pressure either between the two atria of the heart, or between any two areas representing the two sides of the vascular system. This is usually done , in my humble and well informed opinion, by the last phase of decompression - the 1 ATA stop where you get out of the water and the last of the gas rushes out in bubble form. As bubbles then grow and become more impressive in their ability to block the filter, the chances of a blowby or pressure differential that will open a PFO are greatly increased. This is why the hits appeear to be "paradoxical" as they call them, PCAGE, or PAGE as opposed to CAGE or AGE. Steve, all of the strokes and bullshitters will argue this to their death, because to test everyone properly would be the death of dive instruction and the dive business, but the fact is it is like every other thing in life - if you are armed with the information, you don't "take in the snake", and as such you don't get bitten by it. The dive industry and DAN are the antitithsis of good information, and that is a fact. See that last peice of abject stupity out of DAN on deep air - Bill Mee spotted it and put a post on here about it. The fact that you are asking this question tells us all the the dive industry is grossly negligent in not informing students of these risks up front, and hopefully will lose every last lawsuit that involves this kind of intentional screwing over of people who put their trust in the agencies. No information is just as bad as bad information. Otherwise , lack of fat slobbery is not itself a guaranteee of no bends. The perfusion of all tissues is . People who have a massive aerobic base and are well vascularized are much more able to eliminate gas quickly and effectively. Fat acts like a battery for storing gas - it comes out slowly contributing to other bubble growth, and itself gets bent. The fact is that poor physical conditioning on anyone will lead to dcs induced damage in all tissues , including muscle, in those who are not well perfused. The only way to achieve angiogenisis is to deprive the body of oxygen and nutrients repeatedly in physical exrecise, and that does not mean power walking, that mean kicking ass every day for years. Steve Schultz wrote: > > Can we go over what preconditions exist that might cause someone to take > an underserved hit, or just plain increase the risk. Which ones can you > get checked out by a doctor, which ones can you do something about. > > I know of PFO - which can you can have checked by a doctor. Nothing you > can do about this one. Some 'experts' say it's ok to dive with this, but > from what I've heard from George, he feels it's an absolute 'NO'. > > Being fat/out of shape - you can have this checked by most mirrors, and it > is fixed by running shoes/bike/gym etc > > People have mentioned 'shunts'. What are these, what can be done about > them, how serious are they etc. > > thanks, > Steve > > -- > Send mail for the `techdiver' mailing list to `techdiver@aquanaut.com'. > Send subscribe/unsubscribe requests to `techdiver-request@aquanaut.com'. -- Send mail for the `techdiver' mailing list to `techdiver@aquanaut.com'. Send subscribe/unsubscribe requests to `techdiver-request@aquanaut.com'.
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