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You wrote: > >Dr.A.A Buhlmann, a medical type, in is published book, "Decompression - >Decompression Sickness," Rev.2 provides the following table in regards >to O2 at altitude. > > > 0 to 150meters 3500meters 7500meters >Ambient Pressure 1.0 Bar .68 Bar .38 Bar >Pressure of Inspired Oxygen .196 Bar .129 Bar .066 Bar >Pressure of Inspired Nitrogen .74 Bar .487 Bar .250 Bar >1 Bar = 1.01325 ATA > >The fraction of O2 can be calculated from the data provided. > 0 to 150meters 3500meters 7500meters >Fraction of Oxygen .196 .189 .173 > >If you believe Dr. Buhlmann's data then the fraction of O2 in the >atmosphere also changes as well as the partial pressure (function of >the O2 fraction anyway). There are other sources not close at hand >which can provide more extensive data on atmospheric content at >altitude. But then again as someone has already mentioned I don't think >we are planning a dive on K2. > >Mr. Carl Heinzl wrote Oct 1, 1995 to Eric Maiken: >>I appreciate your posting on this matter, however, no one has as yet >>posted any factual physiological information on why a diver would be >>hypoxic at altitude after a dive. > >On Sept.30, I wrote: >>If you were breathing normoxic air from a tank at 33 ft @ 7,000ft you >>would be breathing a partial pressure of oxygen of about .37 ATA O2 >>(.21 x 1.77), well above any hypoxia concerns. If you were breathing >>the air from the tank at the surface @ 7000 ft, you would have an O2 >>partial pressure of about .16 ATA (.21 x .77) which is where you may >>begin to experience some minor signs of hypoxia. >Presto you are hypoxic at the end of the dive! > >In this last case a Nitrox mix > 21% would keep you above the .16 ATA. >However as soon as you took the redulator out of your mouth you drop a >little below .16 ATAs O2 due to the reduced atmosphere and O2 fraction. >You would be hypoxia before you started the dive anyways. > >However I suspect you are looking for an answer to another question >rather than atmospheric O2 partial pressure requirements to sustain >proper body function. I did find an interesting bit of information from >Dr. Buhlmann. He states "The adaptation to high altitude mainly >concerns the erythropoisesis with the development of polyglobulia, with >which the circulatory system's capacity to transport oxygen is >increased. The affinity of hemoglobin for oxygen decreases somewhat, >which causes an increase in the PO2 in tissues." Go figure! >Unfortunately Dr. Buhlmann is dead and can't comment. > >Doug Chapman >-- >Send mail for the `techdiver' mailing list to `techdiver@terra.net'. >Send subscription/archive requests to `techdiver-request@terra.net'. > Doug, Are those values fraction inspired gas or the alveolar/arterial ppO2. The lungs are saturated with H20, thus @ sea level the 45 mmHg has to be added, + there is CO2 wh/ adds the equivalent amount. At altitude, the lungs continue to be saturated & CO2 is present. They then account for a proportinately higher % of inspired air, and alveolar/arterial air becomes that much deficient in O2 (and N2). Sorry don't have the excat numbers, but the vapor P can be calculated. Regards Esat Atikkan
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