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This is a multi-part message in MIME format. ------=_NextPart_000_0046_01C1B1FC.1931BED0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit The bubbles thing I covered in one of the other recent posts, but we can go back to that separately . The other thing you are asking here is a very important topic. First, what is the real risk? It is not DCS, it is CNS toxicity. The risk of pulmonary toxicity is also an issue more so than DCS. Repetitive diving needs to be done with this in mind. You do not want to run high ppo2s over and over, and you certainly do not want to do multiday diving on high ppo2s. So the first thing we need to do is back off the working ppo2, and plan the decompressions such that we are not accumulating an excess exposure. If you do you decompression the way I outlined it in the other posts, including the way I ascend to the surface, you will greatly reduce the heavy bubble-form offgasing that generally occurs post-dive. If you are basically clean, you can dive again without penalty. If you are using the correct gas, the "residual" effect is greatly reduced. This effect is more designed to explain accumulation of gases in tissues which are not well perfused and as such tend to trap gas which becomes a battery for supplying gas to formed bubbles later on, so repetitive diving with a gut, or battery which holds gas, could contribute to making any bubbles on the next dive worse and contribute to them growing well after the dive. This does not apply to most of us. If you do the decompression for the subsequent dives correctly, there is no reason to belabor the issue. From a logistical standpoint in the ocean, it is far safer to do a couple of back to backs than one long dive which requires a long mandatory decompression. From a decompression point of view, we have seen that repetitive diving makes no difference, so we ignore the first dive in calculating the second. The only trick is that the second dive should be deeper than or equal to the first, and you can not bounce dive after a dive of any kind. We have done back to back 300's with 60 minute bottom times with no change of deco schedule . In the WKPP we have discontinued that practice due to the oxygen exposure risk, however. -----Original Message----- From: TheLostYooper@cs*.co* [mailto:TheLostYooper@cs*.co*] Sent: Monday, February 04, 2002 9:30 PM To: techdiver@aquanaut.com Subject: Decompression DIR style Hey George, I really liked the repetitive diving discussion you were having on Quest a few weeks ago. I know a lot of people were confused about the specifics of how you went about doing repetitive dives. Ignoring the previous dives is so much against the grain of normal diving practices, I think many find the idea very intriguing. Maybe you could shed some more light on repetitive nitrox dives and relatively basic trimix dives (less than 250' 40mins type of dives). I am particularly interested in repetitive nitrox dives in the 60'-100' area (both deco and no deco dives). I would also like to see a discussion regarding what you mean by decompressing with bubbles in the blood versus bubbles in tissues and solution and how all this relates to relatively basic dives and "average" divers. You do this on purpose, and I'd like to know more about why and how. I just want to get this started and let others jump in and take over with follow up questions and such. George is a fountain of knowledge, and I think it's sad to see him wasting his time with insignificant and irrelevant posts that so frequently occur here. Thank goodness for Quest! Thanks George. Mike ------=_NextPart_000_0046_01C1B1FC.1931BED0 Content-Type: text/html; charset="US-ASCII" Content-Transfer-Encoding: quoted-printable <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"> <HTML><HEAD> <META http-equiv=3DContent-Type content=3D"text/html; = charset=3Dus-ascii"> <META content=3D"MSHTML 5.50.4522.1800" name=3DGENERATOR></HEAD> <BODY> <DIV><SPAN class=3D337241611-10022002><FONT face=3DArial color=3D#0000ff = size=3D2>The=20 bubbles thing I covered in one of the other recent posts, but we can go = back to=20 that separately . The other thing you are asking here is a very = important=20 topic.</FONT></SPAN></DIV> <DIV><SPAN class=3D337241611-10022002><FONT face=3DArial color=3D#0000ff = size=3D2></FONT></SPAN> </DIV> <DIV><SPAN class=3D337241611-10022002><FONT face=3DArial color=3D#0000ff = size=3D2>First,=20 what is the real risk? It is not DCS, it is CNS toxicity. The risk of = pulmonary=20 toxicity is also an issue more so than DCS.</FONT></SPAN></DIV> <DIV><SPAN class=3D337241611-10022002><FONT face=3DArial color=3D#0000ff = size=3D2></FONT></SPAN> </DIV> <DIV><SPAN class=3D337241611-10022002><FONT face=3DArial color=3D#0000ff = size=3D2>Repetitive diving needs to be done with this in mind. You do = not want to=20 run high ppo2s over and over, and you certainly do not want to do = multiday=20 diving on high ppo2s. So the first thing we need to do is back off the = working=20 ppo2, and plan the decompressions such that we are not accumulating an = excess=20 exposure.</FONT></SPAN></DIV> <DIV><SPAN class=3D337241611-10022002><FONT face=3DArial color=3D#0000ff = size=3D2></FONT></SPAN> </DIV> <DIV><SPAN class=3D337241611-10022002><FONT face=3DArial color=3D#0000ff = size=3D2>If you=20 do you decompression the way I outlined it in the other posts, including = the way=20 I ascend to the surface, you will greatly reduce the heavy bubble-form = offgasing=20 that generally occurs post-dive. If you are basically clean, you can = dive again=20 without penalty. If you are using the correct gas, the "residual" effect = is=20 greatly reduced. This effect is more designed to explain accumulation of = gases=20 in tissues which are not well perfused and as such tend to trap gas = which=20 becomes a battery for supplying gas to formed bubbles later on, so = repetitive=20 diving with a gut, or battery which holds gas, could contribute to = making any=20 bubbles on the next dive worse and contribute to them growing well after = the=20 dive.</FONT></SPAN></DIV> <DIV><SPAN class=3D337241611-10022002><FONT face=3DArial color=3D#0000ff = size=3D2></FONT></SPAN> </DIV> <DIV><SPAN class=3D337241611-10022002><FONT face=3DArial color=3D#0000ff = size=3D2>This=20 does not apply to most of us.</FONT></SPAN></DIV> <DIV><SPAN class=3D337241611-10022002><FONT face=3DArial color=3D#0000ff = size=3D2></FONT></SPAN> </DIV> <DIV><SPAN class=3D337241611-10022002><FONT face=3DArial color=3D#0000ff = size=3D2>If you=20 do the decompression for the subsequent dives correctly, there is no = reason to=20 belabor the issue.</FONT></SPAN></DIV> <DIV><SPAN class=3D337241611-10022002><FONT face=3DArial color=3D#0000ff = size=3D2></FONT></SPAN> </DIV> <DIV><SPAN class=3D337241611-10022002><FONT face=3DArial color=3D#0000ff = size=3D2>From a logistical standpoint in the ocean, it is far safer = to do a=20 couple of back to backs than one long dive which requires a long = mandatory=20 decompression.</FONT></SPAN></DIV> <DIV><SPAN class=3D337241611-10022002><FONT face=3DArial color=3D#0000ff = size=3D2></FONT></SPAN> </DIV> <DIV><SPAN class=3D337241611-10022002><FONT face=3DArial color=3D#0000ff = size=3D2>From a=20 decompression point of view, we have seen that repetitive diving makes = no=20 difference, so we ignore the first dive in calculating the second. The = only=20 trick is that the second dive should be deeper than or equal to the = first, and=20 you can not bounce dive after a dive of any kind. We have done back to = back=20 300's with 60 minute bottom times with no change of deco schedule . In = the WKPP=20 we have discontinued that practice due to the oxygen exposure risk, = however.=20 </FONT></SPAN></DIV> <BLOCKQUOTE> <DIV class=3DOutlookMessageHeader dir=3Dltr align=3Dleft><FONT = face=3DTahoma=20 size=3D2>-----Original Message-----<BR><B>From:</B> = TheLostYooper@cs*.co*=20 [mailto:TheLostYooper@cs*.co*]<BR><B>Sent:</B> Monday, February 04, = 2002 9:30=20 PM<BR><B>To:</B> techdiver@aquanaut.com<BR><B>Subject:</B> = Decompression DIR=20 style<BR><BR></FONT></DIV><FONT face=3Darial,helvetica><FONT = size=3D2>Hey George,=20 <BR><BR>I really liked the repetitive diving discussion you were = having on=20 Quest a few weeks ago. I know a lot of people were confused = about the=20 specifics of how you went about doing repetitive dives. Ignoring = the=20 previous dives is so much against the grain of normal diving = practices, I=20 think many find the idea very intriguing. Maybe you could shed = some more=20 light on repetitive nitrox dives and relatively basic trimix dives = (less than=20 250' 40mins type of dives). I am particularly interested in = repetitive=20 nitrox dives in the 60'-100' area (both deco and no deco dives). = =20 <BR><BR>I would also like to see a discussion regarding what you mean = by=20 decompressing with bubbles in the blood versus bubbles in tissues and = solution=20 and how all this relates to relatively basic dives and "average" = divers.=20 You do this on purpose, and I'd like to know more about why and = how.=20 <BR><BR>I just want to get this started and let others jump in and = take over=20 with follow up questions and such. George is a fountain of = knowledge,=20 and I think it's sad to see him wasting his time with insignificant = and=20 irrelevant posts that so frequently occur here. Thank goodness = for=20 Quest! <BR><BR>Thanks George. <BR><BR>Mike</FONT>=20 </FONT></BLOCKQUOTE></BODY></HTML> ------=_NextPart_000_0046_01C1B1FC.1931BED0-- -- Send mail for the `techdiver' mailing list to `techdiver@aquanaut.com'. Send subscribe/unsubscribe requests to `techdiver-request@aquanaut.com'.
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