N2 Narcosis or O2 Tox?

[Doc Harry]

I had a strange experience recently, wondering what y'all think. I believe that I was experiencing N2 narcosis, personally, but the pieces don't all fit together well (which is why I am asking for opinions).

I was diving on EANx32 that I had personally checked and labelled before the dive. It was the first dive of the day in 80-degree water. About 10 minutes into the dive I gently traversed a coral swim-through using the modified frog kick and briefly dipped down to MOD (about 105 feet, ppO2=1.4). Rather suddenly I felt like I was really, really drunk and dissociated. Thinking it was N2 narcosis I ascended at 30 FPM and my head cleared at depth=75 feet.

On EANx32 this gives me an EAD=85 feet. Doesn't make sense that I'd get narced at this depth, especially given that I wasn't exerting myself. I've been to 120-140 feet on air numerous times and felt narced only once. That was on a high-task night dive in poor viz and then I felt confused, almost panicky, not drunk.

Also doesn't make sense that I was experiencing mild O2 toxicity. I wasn't really working hard. And I've been to ppO2=1.4 on nitrox before without any symptoms.

I'm trying to make sense of what I experienced. I vote for N2 narcosis.

 

[Diving Doc]

Hi harry, in my opinion this is a classic symptom of narcosis. I would rather doubt that this is anything to do with O2. Symptoms of o2 tox are generally far more subtle and rather more rapid.

Sometimes you will get a narc for no specific reason, although I wonder if any of the following applied to you on this particular dive? Were you:

1. Morte nervous on this dive than other times?
2. Properly hydrated?
3. Tired?
4. Rushed?
5. Stressed for any reason?
6. Unusually cold?
7. Just feeling generally out of sorts?

All these can increase your susceptability to a narc.

As for o2 tox, that can never be completely ruled out. Were you using PP02 of 1.4? Looking at your dive profile, it looks like you did but i cant work feet out too well!

Hope this helps
Doc

 

[Diving Doc]

Whoops sorry just noticed the 1.4 thing!

 

[String]

Id say narcosis.

Depending which camp you sit in O2 can be equally or more narcotic than nitrogen so dives are meant to be planned assuming that.

So a 105ft dive on nitrox is the same END (equivalent narcotic depth), ie 105ft even though the EAD is lower.

Narcosis also isnt the same every time, some times it starts shallower, sometimes deeper, the symptoms vary so being ok on one dive doesnt mean you'll be equally as ok on another identical dive.

Any time you're below 30m/100ft or so you can expect to be impaired to some extent whether you're aware of it or not.

Remember VENTID for tox symptoms too. Not a sure fire diagnosis but what you described sounds to me exactly like narcosis and not much like O2-tox.

 

[Wildcard]

Narced, no question IMHO.

 

[HowardE]

Narced - definitely. Nitrox has no effect on narcosis. You were at 105 feet... you were narced.

 

[amascuba]

I'll go with the rest of the group and say that you were feeling narcosis with out a doubt, but I might give you a little more direction. There are some people within the industry who feel that Oxygen is about as narcotic as Nitrogen. Though there have been studies on the subject, none of them that I know of have been conclusive whether that is true or not. I personally tend to treat Oxygen like it is narcotic on my dives to be on a little more conservative side.

If you believe that Oxygen is about as narcotic as Nitrogen, then what you may have been feeling is a combination of the narcosis of Nitrogen and Oxygen.

That being said, I've been noticeably narced at 90ffw using 32% in 60 degree water with a little bit of task loading before. On one particular dive I had run a line at a dive site to do a survey and at the end of the dive I found it impossible to push my reel through the loop tied in the line to undo the line. After I shut my eyes for a couple seconds to relax I realized that what I was doing was trying like trying to push a baseball through the hole of a straw and was able to correct my situation from there.

I've also noticed symptoms of narcosis on 90-100fsw dives on 32% in 80 degree water with little to no task loading. The symptom that I usually notice in this situation is short term memory loss. For instance I will look at my pressure gauge to see what my pressure is, but for some reason I will forget what it is shortly after (we are talking seconds) I clip it back off to my hip d-ring. So I'll end up looking at it again two or three more times before I'm able to remember.

I'm sure that you've been narced on many of your other dives, but for some reason you just didn't notice that you were narced. This could be because of conditions, such as warm water and little to no task loading other than enjoying the sights that dive has to offer.

Pulmonary Oxygen Toxicity symptoms would be more along the lines of subtle lung irritation that would get increasingly intense the longer that the lungs are subjected to higher partial pressures of Oxygen. - This type of toxicity would be due to long exposure times to higher partial pressures of Oxygen and are rarely seen within the recreational limits of diving.

CNS Oxygen Toxicity symptoms would be almost certainly bring on full fledged convulsions. - This type of toxicity would be due to deeper depths with higher partial pressures of Oxygen. This is not an exact science at all, but more like a current best practice. That is why the current best practice is to not exceed a 1.4 partial pressure of Oxygen for the working portion of the dive and not to exceed a 1.6 partial pressure of Oxygen for the decompression portion of the dive. There are many technical divers who do not exceed 1.2 PPO² for the working portion of the dive to be more conservative. This does not mean that if you go beyond 1.4 PPO² for the working portion of the dive that you are going to have a Oxygen Toxicity event, but this risk gets higher and is ill advised.

Hope this helps.

 

[texdiveguy]

In all likelyhood narced by your description of events.

 

[DandyDon]

Narced. It happens different ways on different dives to the same person. I can't see your 1.4 being Oxtox at all.

 

[realdiver7]

I vote for narcosis on this one as well, based on the info you provided.