Oxygen narcotic?

[Eric Sedletzky]

Yes, AFAIK O2 is narcotic.
I don’t like it either, I’d rather get narced on air, but I avoid narc in the first place if I can help it. Higher percentages of O2 affects me in a strange way and makes me very paranoid. I can experience some very uncomfortable psychoactive affects even well below the MOD’s of whatever mix I’m using. If I push it up to 1.5 or 1.6 it get’s really bad.

 

[RyanT]

At the end of the day, no one really understands why gases become narcotic or how the process of narcosis (or anesthetic) actually works.

At least one contributor to gas narcosis seems to be the pressure exerted by the gas on neural tissue. Given that O2 is a heavier gas than nitrogen, it is logical to think that O2 is going to be narcotic. My own experience with nitrox bears this out. Likewise, as a substantially lighter gas, it also explains why helium provides such a narcosis benefit.

Ken is right though, the phenomenon of narcosis/anesthesia is probably more complex than just this.

 

[Tassi Devil Diver]

For my gas planning I don't treat O2 as narcotic, O2 is metabolised where as N2 is not, from what I understand the narcotic potential is thus greatly reduced.

 

[helodriver87]

For my gas planning I don't treat O2 as narcotic, O2 is metabolised where as N2 is not, from what I understand the narcotic potential is thus greatly reduced.

You only metabolize 4-5% of the oxygen you inhale in a typical breath. That's a pretty big assumption about the remaining 95%

 

[RayfromTX]

Objective vs. Subjective Evaluation of Cognitive Performance During 0.4-MPa Dives Breathing Air or Nitrox. - PubMed - NCBI
This link is from this rather great thread from 2017 on the same topic. At least the first 10-12 pages are enlightening.
Nitrox: Narcosis myth?
Dr. Simon Mitchell weighs in starting in post #68

 

[uncfnp]

Objective vs. Subjective Evaluation of Cognitive Performance During 0.4-MPa Dives Breathing Air or Nitrox. - PubMed - NCBI
This link is from this rather great thread from 2017 on the same topic. At least the first 10-12 pages are enlightening.
Nitrox: Narcosis myth?
Dr. Simon Mitchell weighs in starting in post #68

Hey Ray. See my post #3 in this thread. Same linked study and Dr Mitchell’s quote. If you clink the quote it will take the reader directly to post #68 in that thread.

I find it entertaining to read individual posts that persist in ignoring this study and Dr Mitchell’s opinion.

 

[RayfromTX]

I was trying to find a study that Simon pointed me to offline that indicated a more rapid recovery from narcosis on ascent when diving nitrox but this was the best I was able to find quickly. My narcosis at 1ATA made me fail to notice your post #3. Reading that old thread hurt me again. I miss Cameron every day.

 

[Protondecay123]

If you leave Helium out of the mix, it seems that indeed oxygen is less narcotic under the conditions (partial pressures) encountered while diving.

Objective vs. Subjective Evaluation of Cognitive Performance During 0.4-MPa Dives Breathing Air or Nitrox. - PubMed - NCBI

Well, the subjects of this study weren't even scuba diving were they? Weren't they just taken down to pressure in a hyperbaric chamber? I'll quote Dr. Mitchell here.

These were dry dives in a hyperbaric chamber without concomitant task loading, and without provoking any tendency to retain CO2 at the same time. It is difficult to fathom what it all means for diving in the real world.

 

[VE7DAC]

Sorry to wake this thread up again, but how does the idea of oxygen narcosis get along with rebreather use?

If you accept 1.4-1.6 PPO2 as a safe CNS limit, but also think it causes narcosis at that level, shouldn't rebreather divers be constantly narced?

What about deco stops on 100%? If oxygen is narcotic, I'd expect to feel those effects at a 6M stop.

Or am I missing something here?

 

[Doby45]

Sorry to wake this thread up again, but how does the idea of oxygen narcosis get along with rebreather use?

If you accept 1.4-1.6 PPO2 as a safe CNS limit, but also think it causes narcosis at that level, shouldn't rebreather divers be constantly narced?

What about deco stops on 100%? If oxygen is narcotic, I'd expect to feel those effects at a 6M stop.

Or am I missing something here?

I normally fly my breather at a 1.0 setpoint..