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<john.r.strohm@bi*.co*> writes: > One of his slides showed their standard treatment profile. A patient > typically does 10 treatments. > > 45 fsw. 30 min on 100%O2, 5 min air break, 30 min on 100%O2, 5 min air > break. O2 is given in a mask or in a hood. > > He even had the number on another chart: 2.4 ata ppO2 .... > This may or may not have any relevance to diving in water as opposed to in > a dry chamber. It's not entirely relevant. When you have to keep your mouth closed around a mouthpiece in order to keep breathing air/nx/gas and not water, a seizure has a nasty way of becoming a fatal event. Seize in a chamber and they just switch you to air until you calm down. Some divers will use full-face masks or dry bells, especially on deco, in order to be able to survive a seizure if one were to occur. Patients will be laying down and relaxed; you can tolerate a much higher ppO2 without seizing than if you're working (swimming, etc.). Back in the bad old days, a friend of mine took the "oxygen tolerance test" given to commercial divers. They'd all be sitting in a chamber on greatly elevated ppO2s, and one would be randomly selected to drop and give ten on the floor of the chamber. Nobody ever made it to their tenth pushup without doing the funky chicken, but the other guys would generally be fine. On the bottom, especially way back in a cave or under heavy deco obligation, you need a low ppO2 for near-zero tox risk even at a heavy workload. The general standard is 1.4 max on moderately short dives (under an hour), dropping to a lower value for longer bottom times. On moderately short deco, people will do 1.5 on a given gas's deepest stop, but if you're going to push your ppO2s you want your face in a dry environment, and probably need support divers too (if you and your buddy did the same profile and he seizes on deco, guess what happens when you get excited about it). -- Anthony DeBoer <adb@on*.ca*> -- Send mail for the `techdiver' mailing list to `techdiver@aquanaut.com'. Send subscribe/unsubscribe requests to `techdiver-request@aquanaut.com'.
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