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Hi Rob, George This is an idea I have posted previously, but still have found few authorities to react and do any thing about it. The concept is, since gas exchange rates vary enormously between ultra fit endurance athlete types, normals, and sedentary persons, ingassing and out gassing CAN NOT BE PREDICTED ACCURATELY FOR ALL TYPES. Of specific concern, on a extreme exposure dive, the ultra fit diver with measurably high VO2 Max (which I think should be placed in a formulae and correlated with nitrogen in-gassing and out gassing rates, as it is and individual specific measure of gas exchange potential), should have absorbed MORE nitrogen after, say, 25 minutes at 150 feet, than the normal or sedentary diver. Now, offgassing rates are less tied to straight blood flow and gradient than is the ingassing rate, so this higher nitrogen saturation in the ultra-fit diver, is not necessarily offgassed at the same volume per minute ratio as would be predicted by the tables or even by the accelerated exchange rates seen on ingassing....While still more vascular, the fit diver has nitrogen saturation in tissues which will only release at a given rate, not tied as directly to fitness level. so in the first 50 foot and 40 foot stops, it would be sensible to conclude the fit diver should take longer stops than the unfit, maybe even adding a 60 foot stop not needed by the unfit diver----better gas exchange in the fit diver should allow better offgassing (relative to the unfit diver) so that somewhere in the shallower stops (30, 20 , 10) , the fit diver will catch up and then become less nitrogen saturated than the unfit divers. This same reasoning would predict that in a recreational profile, say 60ft for 55min, the unfit diver with poor gas exchange would be less at risk in a no -stop ascent to the surface, than would the more heavily saturated fit diver....But if both performed 10 minute safety stops, there is no doubt that the fit diver would surface with far less nitrogen loading than the unfit diver, and we all know EVERYONE should always do a safety stop, anyway. What are your thoughts on this Rob, and do you have any recommendations in how to implement this as a modification to the tables using VO2 max. I am copying this to George as well, and hopefully he will print it out and show it to Bill Hamilton, for his views and expertise in the physiological and statistical decompression model arena. Regards Dan Dan Volker SOUTH FLORIDA DIVE JOURNAL "The Internet magazine for Underwater Photography and mpeg Video" http://www.florida.net/scuba/dive 407-683-3592
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