100% 02 during your SI?

[PfcAJ]

Yes, School Sink dual fatality a few years ago. You'll be able to find it.

For what its worth, he would have drowned anyways, but it was the o2 switch that did it, iirc. I remember an incident in the Wakulla2 project where a diver went off the ledge on an o2 bottle and blacked out. He lived. There are lots of o2 incidents and fatalities, its serious business.

 

[Captain12Pk]

Mr. Volker,
While I agree, breathing something (even if it's risky) is better than breathing nothing, I disagree with your premise.
First, a "good recreational diver" has no business dealing with O2 in the water. Second, a "good recreational diver" is not going to find himself going OOA solo at 100fsw. Gas losses are not instantaneous. So finding yourself OOA at depth requires that diver to have not been situationally aware, and therefore not a "good" diver. At least not in my opinion. So now we have an situationally unaware diver wanting to do an in water O2 switch and maintain his stops at 20fsw, 10 fsw, and up accordingly. Good luck. And why was this "good recreational diver" alone at 100fsw with O2 on his side? Wouldn't a bottle of EAN 32 be a much better choice? For a plethora of reasons? Such as finding himself OOA at 100 fsw with no buddy? I have (in training situations only) found myself OOA. The thought of "skip breathing" in 20 fsw intervals certainly does not sound appealing... andf that's presuming this "good recreational diver" has the discipline to maintain that breathing pattern, and from 100 fsw, some scheduled stops along the way to 20 fsw. That's an awful lot of task loading to expect a "good recreational diver" to deal with.
Of course these are just my opinions. YMMV.

 

[Thalassamania]

Yes, School Sink dual fatality a few years ago. You'll be able to find it.

For what its worth, he would have drowned anyways, but it was the o2 switch that did it, iirc. I remember an incident in the Wakulla2 project where a diver went off the ledge on an o2 bottle and blacked out. He lived. There are lots of o2 incidents and fatalities, its serious business.

I found it, but there is no reason that I could find to support the idea that the O2 switch did anything except extend his life by a few minutes. As far as the Wakulla2 project is concerned, the report reads: "... 8 minutes into the dive Richards blacked out, inverted and descended to the sand slope." That's 8 minutes after the switch. I have personally made a whole bunch of chamber dives to 60 feet on oxygen, and a whole lot of pure oxygen rebreather dives as deep as 30 feet (in the old days) with no ill effects.

I am not encouraging anyone to use pure oxygen below 18 feet, except in an emergency, but it seem that Dan's advice stands as reasonable and prudent.

 

[danvolker]

Mr. Volker,
While I agree, breathing something (even if it's risky) is better than breathing nothing, I disagree with your premise.
First, a "good recreational diver" has no business dealing with O2 in the water. Second, a "good recreational diver" is not going to find himself going OOA solo at 100fsw. Gas losses are not instantaneous. So finding yourself OOA at depth requires that diver to have not been situationally aware, and therefore not a "good" diver. At least not in my opinion. So now we have an situationally unaware diver wanting to do an in water O2 switch and maintain his stops at 20fsw, 10 fsw, and up accordingly. Good luck. And why was this "good recreational diver" alone at 100fsw with O2 on his side? Wouldn't a bottle of EAN 32 be a much better choice? For a plethora of reasons? Such as finding himself OOA at 100 fsw with no buddy? I have (in training situations only) found myself OOA. The thought of "skip breathing" in 20 fsw intervals certainly does not sound appealing... andf that's presuming this "good recreational diver" has the discipline to maintain that breathing pattern, and from 100 fsw, some scheduled stops along the way to 20 fsw. That's an awful lot of task loading to expect a "good recreational diver" to deal with.
Of course these are just my opinions. YMMV.

Please keep in mind, it was not MY contention that a good recreational diver should ever be OOA at 100 feet and need the pony for this.....This comes from all the posters that say the diver with 100 O2 is at risk, because they might run OOA.

I do believe that any good diver will have the gas management skills to prevent this, and they will have a nearby buddy as a redundant backup. So to me, there is no way a "good advanced diver" is going to have problems with having ther 100% o2.

 

[VooDooGasMan]

Ok dan its pouring down rain right now for hours. I say you are correct for a experienced diver as 100' so for the debate of trimix diving and switching gasses why not just have a inline analyzer right on the hose. also this is why even trimix diving you must be confident in solo, of course this was the instructor who was there.

Thal your post reminded me of episode seahunt where barrels rolled in lagoon, and rebreather diver helped mike when stuck and oxtox at 50'

 

[PfcAJ]

I found it, but there is no reason that I could find to support the idea that the O2 switch did anything except extend his life by a few minutes. As far as the Wakulla2 project is concerned, the report reads: "... 8 minutes into the dive Richards blacked out, inverted and descended to the sand slope." That's 8 minutes after the switch. I have personally made a whole bunch of chamber dives to 60 feet on oxygen, and a whole lot of pure oxygen rebreather dives as deep as 30 feet (in the old days) with no ill effects.

I am not encouraging anyone to use pure oxygen below 18 feet, except in an emergency, but it seem that Dan's advice stands as reasonable and prudent.

He didn't make it to the surface and that o2 bottle wasn't empty, right? I haven't looked at the report in some time, and I'm about to walk out the door, but if those things are true, then something killed him besides running out of gas.

It's been long established that high ppo2s when dry are different from high ppo2s in the water, so who cares what happens in a chamber? If you tox in a chamber, you still live.

As for Wak2, the switch wasn't a switch at all, he started the dive on o2 and didn't come off of it. It takes a few minutes just to get the the 20' ledge from the beach, so he was really only exposed to relatively high ppo2s for a couple minutes.

Bottom line is breathing o2 at depth is bad news, and trivializing the use of oxygen is unwise. It deserves the upmost respect, and lack of respect for o2 kills. An ounce of prevention is worth a pound of the cure .

 

[Thalassamania]

...

Bottom line is breathing o2 at depth is bad news, and trivializing the use of oxygen is unwise. It deserves the upmost respect, and lack of respect for o2 kills. An ounce of prevention is worth a pound of the cure .

We are not in disagreement. But when in a situation, that one should not be in in the first place, e.g., faced with no gas, then an ascent to 20 feet that might take two or three minutes at most, using a tank of pure oxygen might not be a bad decision. Me, I'd make a free ascent, but that's me, I have no concern what-so-ever of performing such an ascent comfortably.

 

[Deep South Divers]

I've got a related detail: Standard hyperbaric chamber treatment for burn victims and diabetic patients is 100% O2 at 2 ATAs... 33fsw.

These people are constantly monitored for tox issues during their standard 1-hour long chamber rides, however, and there is an air mask inside the chamber to handle potential problems.

It's a rare thing for a patient to have any issue, and the medical community feels comfortable enough with te practice that they place a patient in the chamber at those kinds of PPO2s. That said, medical assistance is always at least one minute away, since a patient must be properly decompressed before a monoplace chamber is opened.

My point is that while a diver certainly does not want to expose themselves to excessive PPO2s and thus place themselves in danger of a CNS tox, the effects are not so immediate that it should not be considered in lieu of drowning.

 

[Thalassamania]

I've got a related detail: Standard hyperbaric chamber treatment for burn victims and diabetic patients is 100% O2 at 2 ATAs... 33fsw.

These people are constantly monitored for tox issues during their standard 1-hour long chamber rides, however, and there is an air mask inside the chamber to handle potential problems.

It's a rare thing for a patient to have any issue, and the medical community feels comfortable enough with te practice that they place a patient in the chamber at those kinds of PPO2s. That said, medical assistance is always at least one minute away, since a patient must be properly decompressed before a monoplace chamber is opened.

My point is that while a diver certainly does not want to expose themselves to excessive PPO2s and thus place themselves in danger of a CNS tox, the effects are not so immediate that it should not be considered in lieu of drowning.

The also not exercising, take air breaks during treatment and at any sign of convulsions can be immediately switched to air, which will resolve the problem almost instantly.

 

[Deep South Divers]

Exactly.

Thats said, air breaks aren't common... They're not a part of the regimen.

...But you're right... They are available immediately at the first sign of tox.

My post above was in response to someone asking for "details.". Apparently that was several posts ago, and the conversation has gone further since. My apologies for bad netiquitte... I must have been reading an old post on this thread.

Forgive my response if it is untimely.