Posted by Kendall Raine on November 09, 2001 at 13:46:00:
In Reply to: Re: deco on air worthless? posted by Jason on November 08, 2001 at 17:45:04:
Jason;
Chris is right that deco on air is generally better than no deco at all. That's obvious.
Mike's right that decoing on air doesn't give a very beneficial inert gas gradient. With 100% O2, there is no inert gas to absorb, so the elimination of inert gas is maximized for any depth. Using 100% at 20 fsw puts the partial pressure of O2 at it's "safe" maximum of 1.6 ata and so constitutes the optimal frontier of maximizing the oxygen window and keeping the risk of CNS toxicity low. It's a compromise. You would actually be much more deco efficient running the PO2 higher-closer to 3.0 ata-but you would then run a high risk of having a seizure underwater and dying. While decoing once you're dead becomes moot, it's definitely not "efficient." For example, on a Table 6 recompression treatment such as what Marta did last weekend, they ran her at 2.8 ata for close to 3 hours. That maximized the oxygen window. CNS toxicity seizures in a dry chamber are pretty harmless.