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----- Original Message ----- From: Trey <trey@ne*.co*> To: Wkpp@Ya*. Com <wkpp@ya*.co*> Sent: 22 May, 2001 07:30 Subject: bouncing - the risks > > Guys read this for once. > > WHY WE DO NOT BOUNCE DIVE AFTER DIVING IN THE WKPP > > It is ok to offgas from the tissues into the blood stream in bubble form in > the later steps of decompression as it is a more efficient, faster way of > getting rid of the remaining gas ( by reduced pressure ) than by elevated > oxygen alone ( which starts taking exponentially more time with greater > risk) . However, this depends on having a good lung filter and no shunts. > All of you have been PFO tested if you are diving with us. > > The correct way to ascend from the last stop is one foot per minute for the > bigger dives. > > The greatest potential for offgassing in bubble form is when the pressure is > totally removed back to one ATA out of the water. Now you get a real shower > of bubbles , relative to what was happening in the water. A good , clean > deco with the foot per minute ascent reduces this dramatically . > > In MOST people, the greatest bubbling occurs out of the water and continues > for up to four hours, not even peaking for a couple of hours. In a well > vascularized, fit person like me, it is over with in 30 minutes. Don't bet > on that with most of you. > > In ALL people, the bubbles continue to grow in size after the pressure is > off. They accumulate like gas into themselves from the surrounding blood or > tissues ( if there are bubbles in the tissues or injury sites ) and they > grow bigger. This is why you feel pain later rather than earlier if the > bubbles are in joints or tissues - they get bigger before they begin to > shrink. This is why what starts out as micro bubbles can get by the lungs > and grow and get lodged downstream, and you get neurological symptoms later. > > Now here is the important part. If you understand everything I have said > above, then you know that bouncing to 20 feet or whatever to pick up a > bottle and immediately returning to the surface is the like giving yourself > a home-made PFO: the bubbles in the venous side compress enough to get past > the lungs and then will reexpand on the arterial side and lodge in the worst > places , the spine and brain blood supplies. You do not want this. > > If you dive after dive, stay down and let everything reset. Get the bubbles > all compressed, and then deco out and ascend accordingly. > > I do not want support divers diving support within four hours of doing a > real dive or deep support. This works out fine, since we have support > activities lasting up to 18 to 24 hours and need to rotate everyone. > > Let me assure you that we have found this out the hard way in the past. > Parker used to get hot as hell when it would happen. In those days we had > "volunteers", and they would all get bent diving to 20 feet to pick up > bottles. We have also seen some severe cases of this where dives were done > away from the project with no support, and the players went back for bottles > later and got hammered. > > Don't do it. Also, obviously, do not freedive after a dive. When you want to > freedive, do that first and then go scuba diving. > > Any questions from WKPP guys? > > -- > Send mail for the `techdiver' mailing list to `techdiver@aquanaut.com'. > Send subscribe/unsubscribe requests to `techdiver-request@aquanaut.com'. > NetZero Platinum No Banner Ads and Unlimited Access Sign Up Today - Only $9.95 per month! http://www.netzero.net -- Send mail for the `techdiver' mailing list to `techdiver@aquanaut.com'. Send subscribe/unsubscribe requests to `techdiver-request@aquanaut.com'.
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