Deep Air - Here we go again....

[Sloth]

Due to the inconclusive nature of the studies of the narcotic effects of oxygen some modern tech agencies play it on the conservative and conclude that oxygen is narcotic for END calculations when diving deep with trimix.

For example on the ambiguity of the subject here is a double blind study that shows no reduction in narcosis with divers breathing EAN 36 versus air at 30m. erez.heilweil.com/nitrox/Nitrox_Experiment.pdf

While another study show minimal to no reduction in reaction time when divers at 4 ata where exposed to higher and higher ppo2 with a reduction of ppn.

The obvious examples of oxygen narcosis involved extreme exposures of ppo2 resulting in unconsciousness before convulsions. These exposures were so high that it's not really relevant to tech divers.

Personally I will continue to hedge my bets and count o2 as narcotic on END calculations.

 

[Sloth]

double post

 

[nadwidny]

It's only scary to you. Basicly all my diving is self taught and I have never been bent, never gone OOA or had any dive related incident over a 50+ year diving time span.

So you got lucky. Proves nothing.

 

[LiteHedded]

Well this one started off good but has devolved into the standard silliness. I'm going to bow out until next week's deep air thread

 

[DCBC]

Have there been any significant attempts to study whether or not oxygen is narcotic since then? In Dr. Sawatsky's article, he mentions the standard lipid solubility theory (which I've never been to keen about) and dismisses many tests because they aren't consistent enough to compare, but I didn't see anything about any more recent attempts to isolate the involved gases.

Seems like it would be pretty simple, and it could even be done simultaneously with standard hyperbaric treatment.

I'm unaware of any recent studies that have focused on establishing that O2 narcosis exists. Perhaps this is a result of the PPO2 being carefully managed; it's level is always contained. Even when the PPO2 gets to the point of toxicity, there have been no reports (that I'm aware of) that a narcotic effect has ever existed. I think that this would be difficult for the hyperbaric community to accept, as we have generations of divers using mixed-gas at 4 digit depths for weeks at a time without any reported affect.

 

[LiteHedded]

I'm unaware of any recent studies that have focused on establishing that O2 narcosis exists. Perhaps this is a result of the PPO2 being carefully managed; it's level is always contained. Even when the PPO2 gets to the point of toxicity, there have been no reports (that I'm aware of) that a narcotic effect has ever existed. I think that this would be difficult for the hyperbaric community to accept, as we have generations of divers using mixed-gas at 4 digit depths for weeks at a time without any reported affect.

a quick 30 second search produced this:
Rubicon Research Repository: Item 123456789/7316
I'm sure there are more but I'm not real motivated

 

[DCBC]

a quick 30 second search produced this:
Rubicon Research Repository: Item 123456789/7316
I'm sure there are more but I'm not real motivated

I believe that this is the study that Dr. David Sawatsky referred to (see my previous posting). Obviously you're not real motivated or you would have realized this. Perhaps if your motivation changes, you might read the article.

 

[Sloth]

Even when the PPO2 gets to the point of toxicity, there have been no reports (that I'm aware of) that a narcotic effect has ever existed.

Patton WMD (1967) Experiments on the convulsant and anesthetic effects of oxygen
Showed the narcotic effect of oxygen on mice. The ppo2 were extreme but anesthetic properties were observed.

Once again the literature is sparse. Hard to prove the case of the narcotic effects of oxygen one way or the other.

 

[Rhone Man]

a quick 30 second search produced this:
Rubicon Research Repository: Item 123456789/7316
I'm sure there are more but I'm not real motivated

Gene Hobbs (from Rubicon) usually chips in a some point with a reasonably concise but highly accurate summary of the more recent scientific studies of the narcotic potency of oxygen. And then everyone will ignore Gene and get back to usually fruitless butting of heads that characterises these threads (I am still bitter about one of my threads which I tried very carefully to turn into a sensible discussion of the topic descending into the usual chaos within about 3 posts).

Gene will cut me off if I am wrong, but I believe current thinking is that oxygen is probably roughly as narcotic or slightly more narcotic than nitrogen (ie. less than its lipid solubility would suggest, but certainly more than zero). But like all scientific studies of narcosis, I think it is all pretty fuzzy (no pun intended).

 

[DCBC]

Patton WMD (1967) Experiments on the convulsant and anesthetic effects of oxygen Showed the narcotic effect of oxygen on mice. The ppo2 were extreme but anesthetic properties were observed.

Once again the literature is sparse. Hard to prove the case of the narcotic effects of oxygen one way or the other.

Yes; this is an even older study. Considering the millions of hours of logged mixed-gas diving in the industry, so called oxygen narcosis is something that needs to be proved, rather than disproved. All recent studies seem to be inconclusive, or at least nothing has come to light that the hyperbaric community has accepted.