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George: On Mon, 22 Jul 1996 gmiiii@in*.co* wrote: > Pete, a simple echocardiogram will do the trick for most PFO's. I don't blame you for not reading to the end of my post. It was too long. Here's my point: Every test has to be judged by its specificity and its sensitivity. i.e., the true positive and false negative rate. I don't doubt that if you *find* a PFO with any of these tests, one exists. So it's specific. But, I also don't think that the test is very sensitive; I suspect that maybe *everyone* can "lift the seat" if they try hard enough. So why tell the 30% of folk who actually get the test that they cannot dive (I think PFO is usually considered an absolute contraindication to diving), when maybe almost everyone is at risk under the right (or wrong) circumstances? > Well, when somebody gets a mysterious CNS hit, and DAN calls > it "unearned" is this not a little bit suspicious to you? So if the test is not sensitive enough to pick these cases up, then would these events have been prevented? I think not. > Come on Pete, tell these guys to get checked before they check out. How many photographers hold their breath to control their buoyancy while shooting? How many shooting on a surging reef, pop up 10-15 fsw while doing this? I see it happen all the time - the guy (or woman) surges up and no bubbles (no rebreather either). Concentrate on diving better, not on the false assurance some test in a doctor's office gives you. I do not discourage anyone from getting any test that their pocketbook, insurance and "medical provider" can dream up. I'd be drummed out of the guild if I said otherwise. That's the American way - the right to consult with any medical specialist you can afford. I know that comes right after pursuit of happiness. But it's also American to ask what exactly are you getting for your money? If the test doesn't reasonably exclude a PFO, it's worthless. Are you going to pay me to test your tanks by tapping on the outside and telling you what's on the inside? If so, I have this bridge.... > So which is it Pete? Get an aids test which <1% of the > population has, or get a PFO test which 30% have? If a 100% of folks had either condition you wouldn't need to do any test. I have this $15 test to detect if you are alive: I tell you that your co-payment on this visit will be $1000 and watch your reaction. Paradoxically, the higher the true frequency of the condition the less accurate the test can afford to be, and still hit the mark.I think if you are going to do deco diving, particularly where if you take a hit you may endanger your buddies, it is not unreasonable to be checked for PFO. But I would sure like a better (more sensitive) test and I would really like to know what the *in water* dynamics of this are. Maybe the extra pressure on your chest from the water keeps the PFO closed 99.999% of the time, even in people who have one. And George, get tested. We'll all feel safer ;-) > Talk your way out of this one For an Irishman? No sweat, Georgie. -peter heseltine "Safer diving through wiser physiology"
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