Mailing List Archive Mailing List Archive
> And you can believe that it is extremely critical in the > dives that I'm doing. I could care less about the > accuracy of the deco table. Its the tox that's a > bitch to recover from. - George I didn't realize your phisiology was so predictable that you know exactly how much oxygen is the maximum limit your body can withstand. When do you convulse? At a PO2 of 1.6ATA, or 1.62ATA? Or is it 1.58ATA? Would that be at 15 minutes into the dive, or 17 minutes? 31 and a half minutes? People have convulsed at 1.2ATA oxygen. People have also functioned completely normally at 7+ATA oxygen (yes, that's pure oxygen at SEVEN atmospheres). Many people have done many strenuous dives at 1.6ATA without any problems at all. Most prefer to limit their maximum exposure to 1.4ATA. But of course, it's not just the PO2, it's a function of both PO2 and time....and exertion....and temperature...and individual variation...etc, etc etc...we don't even know what all factors are involved. We probably understand less than half of them. As far as I'm concerned, any inspired PO2 between about 1.2ATA and 1.8ATA is a crap-shoot. Tend towards lower PO2 on stressful dives, and higher PO2 on long deep mellow dives, but otherwise probability of a convulsion on any given individual on any given dive is pretty-much unpredictable in this PO2 range. Obviously, an O2-induced convulsion is much nastier underwater (and less recoverable) than mild DCI or even serious DCI. But if you think that knowing the O2 content of your breathing mixture within a few percent margin of error is going to help you determine your chances of being nailed by an O2-induced convulsion...then dream on. The only reason I'm making such a big fuss about this is that one of the aspect of "technical diving" that concerns me is this "number-worship" that's going on all over the place. People keep drawing crisp lines for limits of PO2, and OTUs, and time, and a whole bunch of other factors, much like Skin Diver mag has done with the "go below 130 feet and you instantly die" depth limit. But they forget these are, at BEST, totally rough estimations. The bottom line is that we all want to increase the probability that our bodies continue to function reasonably normally before, during, and after our dives. To do this, we take into account all sorts of stuff that someone at sometime or another suggested has some sort of impact on our bodies when we expose our bodies to increased ambient pressure. Unfortunately, our bodies are very dynamic and chaotic systems. Assuming that excessive precision in measuring things like inspired PO2 will somehow increase our chances of survival is delusional. O.K., climbing down off my soapbox... Aloha, Rich Richard Pyle deepreef@bi*.bi*.ha*.or* ******************************************************************* "WHATEVER happens to you when you willingly go underwater is COMPLETELY and ENTIRELY your own responsibility! If you cannot accept this responsibility, stay out of the water!" *******************************************************************
Navigate by Author:
[Previous]
[Next]
[Author Search Index]
Navigate by Subject:
[Previous]
[Next]
[Subject Search Index]
[Send Reply] [Send Message with New Topic]
[Search Selection] [Mailing List Home] [Home]