Mailing List Archive Mailing List Archive
>George Wentland, >I have deco'ed in the ocean many times in big swell on my boat's deco >system or a >lift bag. The swells here in CA get pretty big. I have yet to see a >significant >increase or decrease in depth due to a passing swell. Even if >hypothetically a >passing wave increased your PO2 and if you were breathing at the instant >the wave >passed overhead the momentary increase in PO2 is so slight that it won't even >effect you. I also checked my Maestro Pro Nitrox computer log for my last 50 >dives and not one deco shows an increase in PO2 due to passing swells. >100% O2 is >the way to go. I agree. Brief exposure to high PO2 does not justify not using 100% oxygen for decompression. If such brief exposure were so bad, do you think Francisco "Pipin" Fereirra would have survived his freediving record depth of 437 feet on air (21% O2 @ 437 feet = PO2 of 3.0)? How would he have survived when he got below 500 feet (still using air) by taking a breath from a spare air bottle? In the first example, actual PO2 might have been slightly lower since he obviously used some of the oxygen during the descent (so less than 21% remained) but the other example is perfectly valid since he took a breath of 21% O2 air while at depth. Oxidative stress is indeed something important to consider. Since oxygen is so vital and so damaging at the same time, many protection mechanisms exists in our bodies to prevent oxidative damage. Brief exposure to high PO2 can be dealth with. Long exposure to high PO2 will cause a depletion of the molecules involved in the protection mechanism (oxygen scavenger and other name of the sort are used to describe these molecules). Once you have depleted all your defenses, oxygen will be free to cause some damage to the tissues... but this is not likely to occur with brief exposures. But again, if you use good deco techniques, you can prevent most of the PO2 shifts. Etienne **************************************************************** *Etienne Beaule, ebeaule@gl*.ne* * **** * *B. Sc. Physiology * **** * *First aid/CPR instructor * ********** * *Search and rescue consultant * ********** * *Nitrox diver * **** * * * **** * **************************************************************** -- 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]