EaNX and PPO2 of 1.6

[Charlie99]

Here's a case of pulmonary oxtox. An unusual case, by an unusual guy, Richard Pyle, the guy that first popularized deep stops.

http://www.deepcaves.net/diving/confessions_II.html

The oxtox stuff is about 2/3rd in. 3 days of multiple rebreather dives at constant 1.4ata ppO2 setting, with lots of surface O2 in between. He got bent while in some remote NW Hawaiian islands and went onto a 2 hours on, 30 minutes off O2 treatment cycle while the boat headed back towards civilization. He started having some pretty severe symptoms after 8 hours on O2 (following many hours in the previous 3 days at 1.4ata and 1.0ata O2).

 

[jim2386]

Hey guys,

Sorry for causing all this craziness. It really wasn't my intention to get everyone worked up. Just wanted clarification is all. I apologize.

Btw, we talked to H20 Below and for those of you wondering, the new requirement is if you're going to touch the deck, you must show proof of an advanced technical diving card. This would be like advanced nitrox or tri mix. In the words of H20, if you don't have these and go below 137', you sit out the next dive. It doesn't really bother me either way. Trust me, I try my best to be very safe when I dive and don't push things. I just wanted to know what the ramifications of passing 1.6 for a minimal amount of time would be just for peace of mind.

Anyway, looks like my trip to the oriskany is on for next weekend (Sept 18th-21st) and I'll have a trip report when I get back and of course underwater pictures and movies as always

-Jim

 

[nereas]

Hey guys,

Sorry for causing all this craziness. It really wasn't my intention to get everyone worked up. Just wanted clarification is all. I apologize.

Btw, we talked to H20 Below and for those of you wondering, the new requirement is if you're going to touch the deck, you must show proof of an advanced technical diving card. This would be like advanced nitrox or tri mix. In the words of H20, if you don't have these and go below 137', you sit out the next dive. It doesn't really bother me either way. Trust me, I try my best to be very safe when I dive and don't push things. I just wanted to know what the ramifications of passing 1.6 for a minimal amount of time would be just for peace of mind.

Anyway, looks like my trip to the oriskany is on for next weekend (Sept 18th-21st) and I'll have a trip report when I get back and of course underwater pictures and movies as always

-Jim

Jim,

Advanced nitrox (EAN 50 thru 100% O2) is normally taught together with Decompresion Diving.

The other advanced tech courses are:

Deep Air (to 185 ft)

Basic Trimix (also to 185 ft)

Advanced Trimix (beyond 185 ft)

CCR

Anytime you dive deeper than 130 ft, your NDL time is so short (5 mins USN) that you are basically going into deco. And all of these advanced tech courses presume deco.

 

[HowardE]

Hey guys,

Sorry for causing all this craziness. It really wasn't my intention to get everyone worked up. Just wanted clarification is all. I apologize.

Jim...

Don't be sorry. It's a polite informative discussion here... That's what ScubaBoard is all about

 

[DA Aquamaster]

Pulmonary toxicity is the result of above normal PPO2's over time not just pressure. If you are in the hospital long enough on 100% O2 you run the risk of pulmonary issues even at 1 atm.

I agree that a PPo2 of 1.6 is not going to mean bad things for a particular diver on a particular dive, but statistically it does increase the risk and mileage varies from diver to diver. Being stressed, working hard, retaining CO2 could all increase the potential for ox tox. While it is not likely to be an issue in a brief exposre, I'd question the wisdom of an instructor diving to the deck on the oriskany and incurring a PPO2 of 1.6 just to say you went there.

If its important to go there, do it with a mix that stays under a PPO2 of 1.4 and accept the reduced NDL for the dive overall.

I'm middle of the road on Trimix. An END of 135-145' in good viz under good conditions with no penetration for a diver who has experience working down to that depth over several recent dives is not that big an issue, but if any one of the above is missing, it gets potentially much more serious if something goes wrong. I also tend to discourage anyone from going below 130' period on a single tank because the gas margin is tight and the NDL's are short and both severely limit the time you have to resolve a problem regardless fo the gas used.

 

[ianr33]

Jim,

The other advanced tech courses are:

Deep Air (to 185 ft)

Basic Trimix (also to 185 ft)

Advanced Trimix (beyond 185 ft)

"Deep Air" is actually called Extended Range and is good for 180 feet (not 185) This is rapidly falling out of favor as not many divers want to use air at that depth

Basic (Intro Trimix) goes to 200 feet

Advanced Trimix has a limit of 330 feet (At least for TDI)

 

[jviehe]

Hey guys,

Sorry for causing all this craziness. It really wasn't my intention to get everyone worked up. Just wanted clarification is all. I apologize.

Btw, we talked to H20 Below and for those of you wondering, the new requirement is if you're going to touch the deck, you must show proof of an advanced technical diving card. This would be like advanced nitrox or tri mix. In the words of H20, if you don't have these and go below 137', you sit out the next dive. It doesn't really bother me either way. Trust me, I try my best to be very safe when I dive and don't push things. I just wanted to know what the ramifications of passing 1.6 for a minimal amount of time would be just for peace of mind.

Anyway, looks like my trip to the oriskany is on for next weekend (Sept 18th-21st) and I'll have a trip report when I get back and of course underwater pictures and movies as always

-Jim

Well, your original question was whether youd instantly tox if you go below 1.6 pp02 and how does this relate to exposure over time. The answer, if i understand correctly now, is that, basically, we dont know. PADI reccomends that recreational divers stay below a pp02 of 1.4, and that the risk of tox above that is high, and above 1.6 is unnaceptable. The time, according to the single exposure table would be be 45mins at 1.6, iirc. Since on nitrogen limits you cant spend more than a few mins at that depth, its moot. So, the ramifications could be fatal if you are going to push the limits, or could be negigible. Unless you are properly trained, equiped, and experienced, you should not be diving dangerously, in any case. There is nothing on the deck worth dying for, nothing beyond your abilites worth dying for.

 

[ucfdiver]

The other advanced tech courses are:

Deep Air (to 185 ft)

This class is still being taught?

 

[HowardE]

This class is still being taught?

As a matter of fact... I just did that class under advisement from my instructor: John Chatterton.

Here's my trip report: http://www.scubaboard.com/forums/te...training-pirates-cove-dive-center-samana.html

 

[bleeb]

Well, your original question was whether youd instantly tox if you go below 1.6 pp02 and how does this relate to exposure over time. The answer, if i understand correctly now, is that, basically, we dont know.

I'm not sure if you just phrased that poorly or you really meant exactly what you just said. Some militaries used to (still?) set their PO2 limits as high as 2.0 and IIRC some posters in this thread have alluded to regularly going above 1.6, even during 'working' portions of dives. So the literal answer to the literal question "do you (always) instantly tox if you go below 1.6 ppO2" is "no" and not "we dont know". Some people will tox fairly quickly, especially if the other factors mentioned previously are in play, but some will take longer.

If that's not exactly what you meant, maybe try restating it before the gasoline you dripped restarts the fire.