Question Ever experienced Nitrogen Narcosis?
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In reality also Oxygen causes narcosis, possibly even worst than Nitrogen, particularly when you get close to the Oxygen toxicity limits. So replacing Nitrogen with Oxygen is of little help, if not even worst.
The only case I had where I really risked my life was a combined hit of narcosis and oxygen toxicity. It was 1977, and it was my first dive at the Montecristo Island, on the middle of the Tirrenic Sea.
I did dive with my instructor, Fabio, who is also a commercial diver. Crystal-clear water, even quite warm (no thermocline), so we had no perception of real depth. In air with twin tanks, as it was normal at the time. I had an home-made BCD (a Vespa tire bladder around my neck), Fabio had no BCD (again, as normal at the time).
We descended quickly below 65m (real depth unknown, as our depth meters did max at 65m), and after reaching the bottom I started getting tunnelled vision and I was fully "drunk". When everything blacked out, just before passing out, I did fill my bladder and started ascending. I revived at around 30m, at which time my ascent speed was conspicuous. I did remove the bladder and leave it to pop out.
But the Vespa tire did take away both my mask and my regulator. I managed to retrieve the regulator and not drown, but the mask was apparently gone.
Without BCD, I started descending again. Fabio met me around 55m, where I was quite drunk again. He did give me my mask, (which was behind my head, attached to the valve of the second reg) and we slowly ascended to our planned deco stops.
Fabio did explain the strong "drunkenness" as Nitrogen narcosis, but I had always felt it more similar to Oxygen toxicity, as we happened to experience during our training using the pure-oxygen CC rebreather (ARO). Now I think that it was a combination of the two. So in the end both Nitrogen and Oxygen can be cause of narcosis, albeit the effects are not exactly the same (oxygen is worst, at least for me).
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As others have pointed out, that is not done any more. In my experience as an instructor, students were more likely to do better at depth, probably because of the practice on the surface.
Maybe. Maybe not.
When I was a trimix student for TDI, my instructor did the first dive on air while I was on trimix, and we switched for a while. He said he could feel a big difference. I couldn't feel any difference at all.
I did the same thing with a student last fall. He said he could tell the difference. I couldn't.
Everyone is different in terms of narcosis. Here are some anecdotes:
- I absolutely do not feel anything different in a narcosis situation. When I have clearly realized I was narced, it was because I realized I was being unusually stupid while completing a task. When that would happen, I would realize I must be narced, but I would not feel any different at the time.
- As both a TDI and a PADI tech instructor, I have taken students on dives up to 160 feet without benefit of helium. We discussed the potential for narcosis each time. I have never had a student have any problems or report any unusual feelings after any of the dives.
- All the serious cases of narcosis I know of (but have never personally witnessed) have happened at very serious depths--nothing like the depth limits of normal recreational diving.
Agreed. Tunnel vision is a very common symptom but most divers don't notice it because their mask limits vison so much, compounded by other distractions in the water. It is very noticeable on a chamber dive. I also tend to feel some minor numbness in my lips, but not my fingers — in a chamber or a hot water suit and a hat. YMMV.
In my case, light headedness is more likely caused by CO2 since deep breathing makes it go away. I tend to blame CO2 for symptoms that go away with deep breathing and attribute what is left to narcosis, but is it probably more complex than that.
My AN/DP instructor related a story to me. Years back they were setting the mooring line on a wreck in Erie. One really nice feature on it is an intact crow's nest. Suiting up he mentioned wanting to go take a look at it once they had refloated the line. Well, they get down there, and he needs to fiddle with gathering up the line to send it to the surface. He does, and they end the dive. On deck, he disappointingly said that they forgot to go check out the crow's nest. His partner pauses, and said the he had been leaning against the mast next to it the whole time they were messing with the mooring line...
My predominant feeling is a tingling in my face, a sort of dark doom feeling, and almost nausea.... (interesting enough, it could also be CO2 issues)
never the silliness folks mention...
My predominant feeling is a tingling in my face, a sort of dark doom feeling, and almost nausea.... (interesting enough, it could also be CO2 issues)
never the silliness folks mention...
Do people ever get giggly in cold, murky water, or dark narc in warm clear water?
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