When diving underwater, oxygen is typically considered toxic at a partial pressure of 1.4. However, hyperbaric chamber treatment tables regularly require taking patients up to 60fsw on 100% O2, which translates to a partial pressure of 2.81. Why is the same amount of oxygen more toxic underwater than in the chamber, if the pressure exerted on both the body and the gas are the same in both scenarios? What variable when we’re “dry” allows us to tolerate more than double the amount of oxygen than when we’re “wet”?
In: Biology
I think you have a units error here somewhere. 60fsw is about 1.8 atm. If it’s pure oxygen then the oxygen partial pressure is also 1.8 atm, not 2.8. Which is actually pretty close to the 1.4 used for the dive tables. The Navy allows 1.7 for four hours.
But also think about *why* you’re treating in the hyperbaric chamber…its not that you want 100% O2, it’s that you want 0% of whatever the thing it is we’re trying to get out of you (nitrogen if it’s a diver). And the only gas we can give you at 100% without killing you is oxygen, so that’s what we do.
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