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--Boundary_(ID_SRDhFsbKZVwn8Iq+i2y+Yg) Content-type: text/plain; charset=us-ascii Content-transfer-encoding: 7bit Hi Bill, Your analysis, once again, assumes you are using pure O2 during the entire deco phase. It is natural for oxygen to be a more efficient at effecting decompression, that is the entire basis for using hyperoxic gasses, there is nothing new in your post. Concentration gradients are precisely what using hyperoxic gasses have been about from the start, there is no added magic in your analysis. Again Bill, it's hard to not see this holy grail of yours as just marketing, the oxygen window, as you state it below offers nothing new, and the analysis again neglects taking oxygen breaks in the comparison with the 36/80 deco. You folks live in a dream world, you take breaks from oxygen, but do not account for them. When presented with a blatant oversight such as this, you sink into denial. Oxygen window is a good repackaging job for what hyperoxic gasses were all about in the first place, I should have thought that it was yet another (re)invention from the WKPP. Next, they will (re)invent saturation diving. And I thought this was going to be interesting. Bill Wolk wrote: > On 8/29/00 1:29 AM, ScottBonis@ao*.co* wrote: > > >Let me try to ask my question in a slightly different way. If I weren't > >worried about oxygen toxicity (this is just a fictious example here), then I > >get the impression that the theory is that deco'ing on 100% O2 at 30 feet or > >forty feet would be more efficient at offgassing nitrogen than deco'ing on > >100% O2 at 20 feet. Is this correct, or am I all screwed up again? > > Scott - > > The short answer is yes, you're absolutely correct. The textbook > definition of an "oxygen window" is "the difference between total gas > pressures in arterial and venous blood; exists because oxygen is partly > metabolized by the tissues, so venous oxygen pressure is lower than > arterial oxygen pressure." > > But we use the term a little differently when we talk about > decompression. We essentially use "oxygen window" to represent the > difference between the concentration of inert gas dissolved in tissue vs. > the concentration of oxygen and inert gas in arterial blood. > > If you'll excuse a bit of an oversimplication, I think I can make the > concept (and deco) a whole lot clearer: Remember the concept of osmosis > from biology? If you have a high concentration of a substance on one side > of a cell membrane and a low concentration on the other, the substance > will cross the membrane until the concentration on both sides is equal. > The more of the substance on one side and the less on the other, the > higher the osmotic pressure > -- literally the force that the substance on > the high concentration side exerts as it tries to push through the > membrane. And usually, the higher the osmotic pressure, the faster the > substance moves towards equalization. Like lots of people pushing > through a turnstyle. This is the key. > > In deco, you have tissues that are oversaturated (highly concentrated) > with inert gas -- on one side of the cell membranes. If you breathe 100% > oxygen, your arterial blood carries large amounts of O2 in both > hemoglobin and plasma. When it reaches the saturated tissues at the > capillary level (where arterial blood gives off its oxygen and thereby > becomes venous blood), the high osmotic pressure (lots of inert gas in > the tissue and none in the blood) forces the N2 and He from your tissue > in the bloodstream --> decompression. At the same time the high osmotic > pressure on the other side (lots of 02 in the blood, less in the tissue) > forces O2 into the surrounding tissue, which has the effect of > oxygenating tissue and reducing swelling and clotting -- essentially, > healing the cellular damage caused by deco diving. > > The more oxygen in your blood, the larger the osmotic pressure > differential or "window" forcing inert gas out of the surrounding tissue > and therefore the more efficient (and faster) the deco. Now, at this > point it sounds like F02 and not P02 is what matters since hemoglobin > only binds a set number of 02 molecules, but here's another key: higher > pressures force more oxygen to dissolve in plasma where it's carried > without hemoglobin. So the higher the P02, the more oxygen is carried > over all in the blood and therefore the greater the oxygen window where > gas is exchanged at the tissue level. > Now you can easily see why 80/20 is a poor choice of deco gas compared > with 100% 02 -- 80/20 reduces the oxygen window because the blood is not > only carrying dissolved oxygen, it's also carrying nitrogren -- so > there's lower osmotic pressure and therefore less inert gas moving from > tissue to blood (and therefore slower, less efficient deco) and there's > also less oxygen moving from blood to tissue (resulting in more residual > cellular damage). It's less efficient all around. > > In putting this post together, I ran across a couple of websites that are > worth bookmarking [Cobber -- add these to your links page]: > http://www.oxytank.com/quanda.htm > is a terrific resource on hyperbaric oxygen therapy and physiology that > clears up a lot of concepts and misconceptions about O2 and deco. The > other link is a hyperbaric medicine glossary -- > http://www.gulftel.com/~scubadoc/glssry.html -- which is where I found > the definition of oxygen window. > > Best - > > Bill Wolk > > On8/29/00 1:29 AM, ScottBonis@ao*.co* wrote: > > >And finally my basic question, the one I tried clumsily to ask previously, > >remains exactly what is the relationship between this level of dissolved > >oxygen in blood plasma (if that's what the "window" is), or the PP(O2) in > >the > >deco gas that gives rise to it (if that's what the "window" is), and the > >rate > >of off gassing of nitrogen. I'm just having a lot of difficulty following > >the concept. > > > > Best regards -- > > Bill > > -- > Send mail for the `techdiver' mailing list to `techdiver@aquanaut.com'. > Send subscribe/unsubscribe requests to `techdiver-request@aquanaut.com'. -- Guy --Boundary_(ID_SRDhFsbKZVwn8Iq+i2y+Yg) Content-type: text/html; charset=us-ascii Content-transfer-encoding: 7bit <!doctype html public "-//w3c//dtd html 4.0 transitional//en"> <html> Hi Bill, <p>Your analysis, once again, assumes you are using <br>pure O2 during the entire deco phase. It is natural <br>for oxygen to be a more efficient at effecting decompression, <br>that is the entire basis for using hyperoxic gasses, there <br>is nothing new in your post. <p>Concentration gradients are precisely what using hyperoxic <br>gasses have been about from the start, there is no added magic <br>in your analysis. <p>Again Bill, it's hard to not see this holy grail of yours as <br>just marketing, the oxygen window, as you state it below <br>offers nothing new, and the analysis again neglects taking <br>oxygen breaks in the comparison with the 36/80 deco. <p>You folks live in a dream world, you take breaks from oxygen, <br>but do not account for them. When presented with a blatant <br>oversight such as this, you sink into denial. <p>Oxygen window is a good repackaging job for what hyperoxic <br>gasses were all about in the first place, I should have thought <br>that it was yet another (re)invention from the WKPP. Next, <br>they will (re)invent saturation diving. <p>And I thought this was going to be interesting. <br> <p>Bill Wolk wrote: <blockquote TYPE=CITE>On 8/29/00 1:29 AM, ScottBonis@ao*.co* wrote: <p>>Let me try to ask my question in a slightly different way. If I weren't <br>>worried about oxygen toxicity (this is just a fictious example here), then I <br>>get the impression that the theory is that deco'ing on 100% O2 at 30 feet or <br>>forty feet would be more efficient at offgassing nitrogen than deco'ing on <br>>100% O2 at 20 feet. Is this correct, or am I all screwed up again? <p>Scott - <p>The short answer is yes, you're absolutely correct. The textbook <br>definition of an "oxygen window" is "the difference between total gas <br>pressures in arterial and venous blood; exists because oxygen is partly <br>metabolized by the tissues, so venous oxygen pressure is lower than <br>arterial oxygen pressure." <p>But we use the term a little differently when we talk about <br>decompression. We essentially use "oxygen window" to represent the <br>difference between the concentration of inert gas dissolved in tissue vs. <br>the concentration of oxygen and inert gas in arterial blood. <p>If you'll excuse a bit of an oversimplication, I think I can make the <br>concept (and deco) a whole lot clearer: Remember the concept of osmosis <br>from biology? If you have a high concentration of a substance on one side <br>of a cell membrane and a low concentration on the other, the substance <br>will cross the membrane until the concentration on both sides is equal. <br>The more of the substance on one side and the less on the other, the <br>higher the osmotic pressure <br>-- literally the force that the substance on <br>the high concentration side exerts as it tries to push through the <br>membrane. And usually, the higher the osmotic pressure, the faster the <br>substance moves towards equalization. Like lots of people pushing <br>through a turnstyle. This is the key. <p>In deco, you have tissues that are oversaturated (highly concentrated) <br>with inert gas -- on one side of the cell membranes. If you breathe 100% <br>oxygen, your arterial blood carries large amounts of O2 in both <br>hemoglobin and plasma. When it reaches the saturated tissues at the <br>capillary level (where arterial blood gives off its oxygen and thereby <br>becomes venous blood), the high osmotic pressure (lots of inert gas in <br>the tissue and none in the blood) forces the N2 and He from your tissue <br>in the bloodstream --> decompression. At the same time the high osmotic <br>pressure on the other side (lots of 02 in the blood, less in the tissue) <br>forces O2 into the surrounding tissue, which has the effect of <br>oxygenating tissue and reducing swelling and clotting -- essentially, <br>healing the cellular damage caused by deco diving. <p>The more oxygen in your blood, the larger the osmotic pressure <br>differential or "window" forcing inert gas out of the surrounding tissue <br>and therefore the more efficient (and faster) the deco. Now, at this <br>point it sounds like F02 and not P02 is what matters since hemoglobin <br>only binds a set number of 02 molecules, but here's another key: higher <br>pressures force more oxygen to dissolve in plasma where it's carried <br>without hemoglobin. So the higher the P02, the more oxygen is carried</blockquote> <blockquote TYPE=CITE>over all in the blood and therefore the greater the oxygen window where <br>gas is exchanged at the tissue level.</blockquote> <blockquote TYPE=CITE>Now you can easily see why 80/20 is a poor choice of deco gas compared <br>with 100% 02 -- 80/20 reduces the oxygen window because the blood is not <br>only carrying dissolved oxygen, it's also carrying nitrogren -- so <br>there's lower osmotic pressure and therefore less inert gas moving from <br>tissue to blood (and therefore slower, less efficient deco) and there's <br>also less oxygen moving from blood to tissue (resulting in more residual <br>cellular damage). It's less efficient all around. <p>In putting this post together, I ran across a couple of websites that are <br>worth bookmarking [Cobber -- add these to your links page]: <br><a href="http://www.oxytank.com/quanda.htm">http://www.oxytank.com/quanda.htm</a > <br>is a terrific resource on hyperbaric oxygen therapy and physiology that <br>clears up a lot of concepts and misconceptions about O2 and deco. The <br>other link is a hyperbaric medicine glossary -- <br><a href="http://www.gulftel.com/~scubadoc/glssry.html">http://www.gulftel.com/~scub adoc/glssry.html</a> -- which is where I found <br>the definition of oxygen window. <p>Best - <p>Bill Wolk <p>On8/29/00 1:29 AM, ScottBonis@ao*.co* wrote: <p>>And finally my basic question, the one I tried clumsily to ask previously, <br>>remains exactly what is the relationship between this level of dissolved <br>>oxygen in blood plasma (if that's what the "window" is), or the PP(O2) in <br>>the <br>>deco gas that gives rise to it (if that's what the "window" is), and the <br>>rate <br>>of off gassing of nitrogen. I'm just having a lot of difficulty following <br>>the concept. <br>> <p>Best regards -- <p>Bill <p>-- <br>Send mail for the `techdiver' mailing list to `techdiver@aquanaut.com'. <br>Send subscribe/unsubscribe requests to `techdiver-request@aquanaut.com'.</blockquote> <pre>-- Guy</pre> <p> </html> --Boundary_(ID_SRDhFsbKZVwn8Iq+i2y+Yg)-- -- Send mail for the `techdiver' mailing list to `techdiver@aquanaut.com'. Send subscribe/unsubscribe requests to `techdiver-request@aquanaut.com'.
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