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<html> Hi George,<br><br> If my understanding is correct, the purpose of "bubbling" is to reduce the total in water decompression time.<br> And I can see that it will give great advantages for the long cavedives you do with hours of decompression;<br> but I was wondering if this is also practiced upon when doing those relatively short open water (bounce) dives.<br> Let�s say 30mins at 60m. (200ft.)<br> Doesn't the increased risk of bubbles outweigh the gained benefit in time for "recreational technical divers" on those dives?<br> As you know all the training agencies from recreational to technical say that bubbles are evil,<br> and I have a hard time accepting the fact to intentionally bubble at the shallow stops.<br> as I think the slightest error will make the shit hit the fan<br> Isn't it safer to just hang a little longer and keep the gas into solution as much as you can on dives where it is feasible?<br><br> And second: Bubbling in the bloodstream may be OK, but if you are bubbling here; aren't you also bubbling in the tissues as well, because pressure is equal everywhere; and so causing damage?<br><br> Please correct me where I'm wrong<br><br> Best,<br> David<br><br> <br> At 09:07 AM 2/6/02 -0500, you wrote:<br> <blockquote type=cite class=cite cite><font face="arial" size=2>* If somebody wants to put that post on here, go ahead*</font><font face="Times New Roman, Times"> </font><br> <br> <font size=2>Here it is,</font><br> <br> <font face="arial" size=2>WHY WE DO NOT BOUNCE DIVE AFTER DIVING IN THE WKPP</font><br> <br> <font face="arial" size=2>It is ok to offgas from the tissues into the blood stream in bubble form in</font><br> <font face="arial" size=2>the later steps of decompression as it is a more efficient, faster way of</font><br> <font face="arial" size=2>getting rid of the remaining gas ( by reduced pressure ) than by elevated</font><br> <font face="arial" size=2>oxygen alone ( which starts taking exponentially more time with greater</font><br> <font face="arial" size=2>risk) . However, this depends on having a good lung filter and no shunts.</font><br> <font face="arial" size=2>All of you have been PFO tested if you are diving with us.</font><br> <br> <font face="arial" size=2>The correct way to ascend from the last stop is one foot per minute for the</font><br> <font face="arial" size=2>bigger dives.</font><br> <br> <font face="arial" size=2>The greatest potential for offgassing in bubble form is when the pressure is</font><br> <font face="arial" size=2>totally removed back to one ATA out of the water. Now you get a real shower</font><br> <font face="arial" size=2>of bubbles , relative to what was happening in the water. A good , clean</font><br> <font face="arial" size=2>deco with the foot per minute ascent reduces this dramatically .</font><br> <font face="arial" size=2>In MOST people, the greatest bubbling occurs out of the water and continues</font><br> <font face="arial" size=2>for up to four hours, not even peaking for a couple of hours. In a well</font><br> <font face="arial" size=2>vascularized, fit person like me, it is over with in 30 minutes. Don't bet</font><br> <font face="arial" size=2>on that with most of you.</font><br> <br> <font face="arial" size=2>In ALL people, the bubbles continue to grow in size after the pressure is</font><br> <font face="arial" size=2>off. They accumulate like gas into themselves from the surrounding blood or</font><br> <font face="arial" size=2>tissues ( if there are bubbles in the tissues or injury sites ) and they</font><br> <font face="arial" size=2>grow bigger. This is why you feel pain later rather than earlier if the</font><br> <font face="arial" size=2>bubbles are in joints or tissues - they get bigger before they begin to</font><br> <font face="arial" size=2>shrink. This is why what starts out as micro bubbles can get by the lungs</font><br> <font face="arial" size=2>and grow and get lodged downstream, and you get neurological symptoms later.</font><br> <font face="arial" size=2>Now here is the important part. If you understand everything I have said</font><br> <font face="arial" size=2>above, then you know that bouncing to 20 feet or whatever to pick up a</font><br> <font face="arial" size=2>bottle and immediately returning to the surface is the like giving yourself</font><br> <font face="arial" size=2>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</font><br> <font face="arial" size=2>places , the spine and brain blood supplies. You do not want this.</font><br> <br> <font face="arial" size=2>If you dive after dive, stay down and let everything reset. Get the bubbles</font><br> <font face="arial" size=2>all compressed, and then deco out and ascend accordingly.</font><br> <font face="arial" size=2>I do not want support divers diving support within four hours of doing a</font><br> <font face="arial" size=2>real dive or deep support. This works out fine, since we have support</font><br> <font face="arial" size=2>activities lasting up to 18 to 24 hours and need to rotate everyone.</font><br> <font face="arial" size=2>Let me assure you that we have found this out the hard way in the past.</font><br> <br> <font face="arial" size=2>Parker used to get hot as hell when it would happen. In those days we had</font><br> <font face="arial" size=2>"volunteers", and they would all get bent diving to 20 feet to pick up</font><br> <font face="arial" size=2>bottles. We have also seen some severe cases of this where dives were done</font><br> <font face="arial" size=2>away from the project with no support, and the players went back for bottles</font><br> <font face="arial" size=2>later and got hammered.</font><br> <br> <font face="arial" size=2>Don't do it. Also, obviously, do not freedive after a dive. When you want to</font><br> <font face="arial" size=2>freedive, do that first and then go scuba diving.</font><br> <br> <dl> <dd>----- Original Message ----- <dd>From:</b> <a href="mailto:girvine@be*.ne*">George Irvine</a> <dd>To:</b> <a href="mailto:Techdiver@Aquanaut.Com">Techdiver@Aquanaut.Com</a> <dd>Cc:</b> <a href="mailto:Cavers@Ca*.Co*">Cavers@Cavers.Com</a> <dd>Sent:</b> Wednesday, February 06, 2002 6:13 AM <dd>Subject:</b> deco posts , repets, etc. start with this<br><br> <dd> <font face="tahoma" size=2> <dd>-----Original Message----- <dd>From:</b> George_Irvine@</font><br><br> <font size=2> <dd>Mike, I will put out my repet post and the others in sequence, but first let me mention something here that is being missed.</font> <br><br> <font size=2> <dd>Gas does not transfer from tissues into arteries or veins, it does so into capillaries. The artilleries coming from the heart are huge, thick, elastic , pulsing conduits that get smaller as they branch out until they become capillaries, and then the return to the heart is through veins which are also thick and get larger as they combine to return blood to the right side of the heart.</font> <br><br> <font size=2> <dd>That blood is then sent to the lungs, where the massive network of tiny capillary beds located in about 45,000 square feet of surface area, act as a "filter" for bubbles. The "filtered" and now oxygenated blood which has passed its co2 and other excess gasses to the lung space, goes back to the heart to be pumper through the system again. The whole trip takes about two minutes to happen.</font> <br><br> <font size=2> <dd>You do not bubble into the arteries. If bubbles get into the arteries it is because they passed the filter or were "shunted" over through a PFO in the arterial walls, or because they were momentarily compressed enough momentarily to get past the lungs and then reexpanded as the pressure dropped prior to reaching the capillaries, in which case they lodge in the smaller and smaller vessels and block them. This occurs in bounce diving, as in doing a dive and then bouncing back down to retrieve something, like a deco bottle. This is why we do not allow bouncing in the WKPP, and why we require our support divers to stay out for 4 hours before diving shallow for support.</font> <br><br> <font size=2> <dd>* If somebody wants to put that post on here, go ahead*</font> <br><br> <font size=2> <dd>Most people get the greatest rush of bubbles from the tissues into the blood stream upon surfacing from 20 feet or so. This is why we do that differently, post to follow. Most people tend to bubble for hours after a dive. Most bubbles tend to grow from the surrounding supply of gas before they get smaller and disappear.</font> <br><br> <font size=2> <dd>If the bubbles are in the tissues, yo have pain. The way to prevent bubbles in the tissues is to properly decompress starting deep and at a rate that allows the bubbles to escape to the blood stream. Deep this needs to be done carefully and in solution, shallow you can press the gradient and allow offgassing in bubble form into the blood stream. The difference is that if you screw up shallow, you can go back a little and fix it. If it occurs deep, that makes it impractical and a huge waste of time for nothing. For people wight cardiac or pulmonary shunts, offgassing in bubble form is super dangerous. For those without, it is far more efficient. For those with PFO's, the risk is greatest AFTER they get out of the water for the reasons stated above ( growth of bubbles and continuation of bubble offgassing)</font> <br><br> <font size=2> <dd>I think you can see where I am going to tell you that you need to do your shallowest dives first, do your drills before yo do your dives, and why you can basically ignore repetitive dives using the correct deco. You can NOT ignore them with respect to oxygen exposure.</font> <font size=2> <dd>This post is long enough , basic enough and preliminary enough. Now we can go on to the whole bit.</font> </blockquote> </dl><font face="Comic Sans MS"><br> </font></html> -- Send mail for the `techdiver' mailing list to `techdiver@aquanaut.com'. Send subscribe/unsubscribe requests to `techdiver-request@aquanaut.com'.
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