Mailing List Archive Mailing List Archive
At 06:56 PM 9/10/2002 -0400, Capt JT wrote: >The real key is not stay on 02 any longer than 20 mins, if you are new 10 >mins. Once you have several hundred dives and have used 02 to deco at the >short time, you should be aware of what your body tells you and can stay >on it for 20 mins. JT, You still don't get it. Your body can't "tell" you anything about how you'll react to O2 on any given exposure. Nothing you feel on a dive is in the slightest way useful to predict how you'll react to O2 on any future dive. Each event is random and independent. Take a look at Bennett and Elliott fourth edition page 136, for example. A diver was exposed to a PO2 of 3.1 on 20 different days over a period of 90 days. The test was stopped when the diver began experiencing neurological symptoms or signs. On the first exposure, the diver toxed at 7 minutes. On his next dive, he went 14 minutes, next it took almost 90 minutes for him to tox, and next he took 36 minutes. The times jumped all over the scale like this throughout the 90 day experiment. The study included fourteen different experimental profiles tested on 53 divers with a total of 465 experimental dives. All efforts to correlate the data with fatigue, hydration, absolute pressure, lighting, moisture, nutrition, or even eye color ware successful. >If a diver starts to feel his muscles twitch at 14 mins >on 02 and he is done with deco at 18min, does he stay on the 02 because he >has not ever had a problem even at 20mins on 02 before........get real >Mike. Of course not, JT. My point is that you're suggesting that if a diver does 20 minute O2 deco all the time he can somehow assume that he's always going to be safe at that exposure. That's not true. You're also saying that a new diver should first limit his deco to 10 minute of O2 because he doesn't yet know how his body will react to O2. This is also not true. You can't tell how you will react to O2 on any future dive based on how you reacted on any past dive. While I certainly agree that anyone new to diving should limit the severity of their decompression, I believe they should do so to gain practical experience with decompression, not, as you suggest, to see how O2-tolerant they are. You *cannot* determine how O2-tolerant you are given the current state of knowledge. >But none of this will prevent an oxtox with no symptoms. Only a buddy >or support diver can help you then. That is why I did not like it when >you guys left me alone in the water on 02 after a 300ft dive to the >Vitric JT, that was a mistake on our part. It's been stipulated as such. We've learned from our mistakes and no longer leave anyone in the water alone. What does this have to do with the incorrect suggestion you're putting forth that people can somehow determine how O2-tolerant they are based on experience. This is like saying that you can determine how narcosis-tolerant you are based on experience. None of this is supported by the available evidence. -Mike Rodriguez <mikey@mi*.ne*> http://www.mikey.net/scuba Pn(x) = (1/(2^n)n!)[d/dx]^n(x^2 - 1)^n -- Send mail for the `techdiver' mailing list to `techdiver@aquanaut.com'. Send subscribe/unsubscribe requests to `techdiver-request@aquanaut.com'.
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]