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--Boundary_(ID_DfqqBg7CY0dFOTqYxX3jvA) Content-type: text/plain; charset=us-ascii Content-transfer-encoding: 7bit How do you know? <g> THOMAS Hi Thomas, Should I not be asking that question? Alleviating reduced alveoli membrane gas permeability perhaps? Gas permeability, ring a bell? Breaks from O2 is a preventative measure against many pulmonary ailments, of which gas permeability is a component. It is not meant to increase pulmonary efficiency, but to prevent, or reduce it's degradation. Therefore, when we say that gas breaks increase pulmonary efficiency, we are in fact saying that we are increasing it from the diminished state induced by breathing pure O2. We mistakenly believe that it is increased, an unfortunate consequence of not being accurate in our descriptions. It is not to say that I lay claim to having any knowledge on the subject beyond what is taught in scuba classes, but the characterization that our pulmonary efficiency is somehow magically increased is a pretty easy one to debunk, especially given that exposure to pure oxygen has been know for years to have deleterious effects on the lungs. If you, or the WKPP, have found some way to "turbo charge" the lungs, there is big money out there for you, but you would probably be required to publish your findings first for others to examine. What is pertinent, however, is that off-gassing is a function of the concentration of inert gasses in the gasses we breathe. Given that we switch off from breathing O2, we are, during those moments, not benefiting from the increased off-gassing afforded by using hyperoxic gasses, or pure O2. This is the essence of my reasoning, we assume in our modeling that we breathe O2 for the entire duration of the shallow stops, yet we breath gasses that don't provide us with the benefit of the concentration gradient of O2, and for a substantial portion of that decompression. This is essentially much like not doing decompression according to the schedule we calculated, for the respective duration and gas exposures. Wouldn't any diver be "concerned" by that realization? Naturally, I can only speculate how we got to this unfortunate impasse. My guess is that this stems from the first uses of hyperoxic gases for decompression where we used standard air tables, or computers, and simply used the hyperoxic gasses as a safety measure, or to add conservatism to the decompression regime. Then, we realized that this affected our lung efficiency, so we compensated for that by taking breaks. Breaks became part of the operational aspect of diving, but never made it into the accounting. What is sad is that this oversight is now penalizing us in the estimation of our decompression requirements, because now, we generate schedules that assume we use those gasses for exacting amounts of time. We are therefore assuming greater risk of DCS as a result. This doesn't mean we'll surely get bent, but it means that it's another fudge factor that isn't on the books, and could affect "statistics". Do you not think this is food for thought? -- Guy --Boundary_(ID_DfqqBg7CY0dFOTqYxX3jvA) Content-type: text/html; charset=us-ascii Content-transfer-encoding: 7bit <!doctype html public "-//w3c//dtd html 4.0 transitional//en"> <html> How do you know? <g> <p>THOMAS <br> <p>Hi Thomas, <p>Should I not be asking that question? <p>Alleviating reduced alveoli membrane gas permeability perhaps? Gas <br>permeability, ring a bell? <p>Breaks from O2 is a preventative measure against many <br>pulmonary ailments, of which gas permeability is a component. <br>It is not meant to increase pulmonary efficiency, but to prevent, <br>or reduce it's degradation. <p>Therefore, when we say that gas breaks increase pulmonary efficiency, <br>we are in fact saying that we are increasing it from the diminished state <br>induced by breathing pure O2. We mistakenly believe that it is increased, <br>an unfortunate consequence of not being accurate in our descriptions. <p>It is not to say that I lay claim to having any knowledge on the subject <br>beyond what is taught in scuba classes, but the characterization <br>that our pulmonary efficiency is somehow magically increased is a pretty <br>easy one to debunk, especially given that exposure to pure oxygen <br>has been know for years to have deleterious effects on the lungs. <p>If you, or the WKPP, have found some way to "turbo charge" the <br>lungs, there is big money out there for you, but you would probably <br>be required to publish your findings first for others to examine. <p>What is pertinent, however, is that off-gassing is a function of the <br>concentration of inert gasses in the gasses we breathe. Given that <br>we switch off from breathing O2, we are, during those moments, <br>not benefiting from the increased off-gassing afforded by using <br>hyperoxic gasses, or pure O2. This is the essence of my reasoning, <br>we assume in our modeling that we breathe O2 for the entire duration <br>of the shallow stops, yet we breath gasses that don't provide us <br>with the benefit of the concentration gradient of O2, and for a substantial <br>portion of that decompression. This is essentially much like not <br>doing decompression according to the schedule we calculated, <br>for the respective duration and gas exposures. Wouldn't any diver <br>be "concerned" by that realization? <p>Naturally, I can only speculate how we got to this unfortunate impasse. <br>My guess is that this stems from the first uses of hyperoxic gases <br>for decompression where we used standard air tables, or computers, <br>and simply used the hyperoxic gasses as a safety measure, or to <br>add conservatism to the decompression regime. Then, we realized <br>that this affected our lung efficiency, so we compensated for that <br>by taking breaks. Breaks became part of the operational aspect of <br>diving, but never made it into the accounting. What is sad is <br>that this oversight is now penalizing us in the estimation of our <br>decompression requirements, because now, we generate schedules <br>that assume we use those gasses for exacting amounts of time. <br>We are therefore assuming greater risk of DCS as a result. This <br>doesn't mean we'll surely get bent, but it means that it's another <br>fudge factor that isn't on the books, and could affect "statistics". <p>Do you not think this is food for thought? <pre>-- Guy</pre> </html> --Boundary_(ID_DfqqBg7CY0dFOTqYxX3jvA)-- -- Send mail for the `techdiver' mailing list to `techdiver@aquanaut.com'. Send subscribe/unsubscribe requests to `techdiver-request@aquanaut.com'.
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