Was I Narc'd?

[gcbryan]

I think that I'm like a lot of people in that I am not aware that I am having any symptoms of narcosis unless something unusual happens that makes me see that my thinking processes are not operating at full speed. If I were having a routine dive, my impulse would be to say I was not at all narced, even though I were. To refer to TS&M's martini comment, it is like the person who has had a couple of drinks but feels just fine until he has to do something that demonstrates the level of impairment that was always there.

In my most recent example, I was on a dive that was very simple except for the depth, and I was alert from the start for signs of narcosis. At one point in the dive I became aware that I was getting a very minor free flow from my regulator. I played with its adjustment, carefully moving it so that I got the easiest breathing without that slight free flow. I was actually thinking that I was being very alert and "un-narced." At that point my buddy signaled with his light. He wanted to know why I was breathing off my alternate regulator. I had no idea that I was. I looked and saw that my primary was neatly clipped off on my right D-Ring, so I must have made some sort of intentional switch, but I have no idea why. I felt perfectly fine otherwise.

A previous post referenced a 100 foot limit for DIR. I assume the reference is to the policy of using gas mixes that keep an equivalent narcotic depth of 100 feet. The poster suggested that this implies a trigger. It really doesn't--it just assumes that the effects of narcosis are normally manageable at that depth, kind of like the acceptable range for a blood alcohol level. To return to the martini law concept, if we use the 50 foot per martini rule that some people use, a 100 foot limit implies that we should be able to function with the effect of two martinis.

Maybe.

The most clear example of impaired thinking I ever had took place on air at 100 feet.

I wasn't implying a trigger at 100 fsw. I stated that of course ppn2 is elevated once underwater and only gets greater with depth.

Lynne implied that some people feel there is a threshold and she couldn't understand that. I don't believe there is a threshold however if you want to think in terms of thresholds then for DIR divers 100 fsw is a threshold beyond which it's not wise to use Nitrox.

My personal view is that narcosis is a small but growing factor as depth increases. How it effects someone has a great deal to do with how much they are worried about what they are doing or how much they are worried about narcosis, what will it be like, what if they are narced, worry, worry, worry.

I'm not in the camp that says I've never been narc'd or I was at 150 fsw and felt nothing...that's just not dealing with reality.

It is interesting however that those most concerned with narcosis are the one's who feel the greatest effects.

 

[dmoore19]

Isn't the martini rule one martini per atmosphere? (+/-30')

 

[gcbryan]

Isn't the martini rule one martini per atmosphere? (+/-30')

Since it's not a real rule there are many versions of it but I'm sure that I'm not as impaired at 100 fsw as I would be after having 3 mixed drinks in that short a period of time.

 

[Dan Ziegner]

In my most recent example, I was on a dive that was very simple except for the depth, and I was alert from the start for signs of narcosis. At one point in the dive I became aware that I was getting a very minor free flow from my regulator. I played with its adjustment, carefully moving it so that I got the easiest breathing without that slight free flow. I was actually thinking that I was being very alert and "un-narced." At that point my buddy signaled with his light. He wanted to know why I was breathing off my alternate regulator. I had no idea that I was. I looked and saw that my primary was neatly clipped off on my right D-Ring, so I must have made some sort of intentional switch, but I have no idea why. I felt perfectly fine otherwise.

The most clear example of impaired thinking I ever had took place on air at 100 feet.

(Emphases in the quote are mine.)

I surmise from the above that you still have no memory of making the 2nd stage switch, is that correct? If so, have you had other instances of memory loss of actions made when diving? It's interesting that you responded to your buddy's light with clarity of thought, but do not seem to remember moments prior. In your post dive thoughts, did you ruminate as to how long you were "blank" to your actions?

I ask because, I have made many hundreds of dives on air deeper than 100' (in the 1970-80's air is all we had), and while I was certainly "narced" to a degree, I always managed it without "going blank".

 

[DepthCharge]

Bottom line is.............everyone is narc'd at 4 ATA. How it's handled is a different matter. One day you can handle it fine, next time no so well.

 

[boulderjohn]

Lynne implied that some people feel there is a threshold and she couldn't understand that. I don't believe there is a threshold however if you want to think in terms of thresholds then for DIR divers 100 fsw is a threshold beyond which it's not wise to use Nitrox.

The limit on nitrox is based on the concern about the O2 in the mix. You introduce helium into the mix as depth increases so that you can limit both the nitrogen (for narcosis) and oxygen (O2 toxicity). I believe you are confusing this with the idea of a 100 foot equivalent narcotic depth: the mix you use on a given dive should have a nitrogen partial pressure no greater than if you were diving air at 100 feet.

Maybe I misunderstood you.

But I think problem-solving is impaired much earlier than most people think. As I sat and looked stupidly at a problem at 95 feet last week, my brain just wasn't absorbing and processing information normally. I mean, I make my LIVING in a high risk environment, where absorbing and correctly processing information is critical. If I couldn't do it, I'd get sued out of existence (or fired). But at 100 feet, I'm (as Doc Intrepid would put it) farm animal stupid. I don't feel drunk or euphoric or anxious or anything . . . I just can't think straight. And this is what the research on narcosis has said -- learned tasks are maintained, but novel situations are not handled as quickly or well under the influence of nitrogen.

At 100 feet, I watched 2 people in succession swim through a hole in the bulkhead of a wreck. As the first one went through, I noticed a finger of pipe sticking down from the upper right corner, and I thought, "It would be easy to catch your regulator hose on that." The first guy narrowly avoided that, but the second guy caught his hose, pulled it down, and went on through. When I went through, I snagged my hose and then asked two questions to myself:

• Which hose have I caught?
• Do I pull it up or down to free it?

I realized that those were really stupid questions signifying the effects of the narcosis, even though I felt perfectly fine.

Now, put these two together, and you see why I am a little concerned about the common assertion that one can safely and reliably make lots of calculations at any depth as long as you have an equivalent narcotic depth of 100 feet.

 

[boulderjohn]

(Emphases in the quote are mine.)

I surmise from the above that you still have no memory of making the 2nd stage switch, is that correct? If so, have you had other instances of memory loss of actions made when diving? It's interesting that you responded to your buddy's light with clarity of thought, but do not seem to remember moments prior. In your post dive thoughts, did you ruminate as to how long you were "blank" to your actions?

I ask because, I have made many hundreds of dives on air deeper than 100' (in the 1970-80's air is all we had), and while I was certainly "narced" to a degree, I always managed it without "going blank".

I don't believe I ever went blank. I believe I would have been able to respond to my buddy at a responsible level at any time. Here is my theory.

I had been having some problems adjusting the breathability of the alternate reg in the past, and I had recently made some adjustments to it on the surface. I was wondering at that time how it would breathe at depth. My guess is that during the dive at some point I switched to my alternate to see how it was breathing and then forgot to switch back. At some point later I had the incident and forgot that I had made the switch.

I have quite a few dives in excess of 100 feet. (The dive above was after about 20 minutes at 130 feet.) I would say the same thing as you if you asked me. I have never actually felt anything happened on any of them, and I only have actual evidence of narcosis on a few.

I have a very nice HD DVD showing the inside of the hold of the San Francisco Maru at 180 feet. It shows the contents of the hold vividly. Thank goodness. I was right next to the videographer,and I don't remember half of those things being there. But I felt great the whole time.

Loss of memory of parts of a dive is a very common symptom of narcosis, one that is often overlooked by the diver. You don't know that you forgot it until something comes along to show you.

 

[Dan Ziegner]

The loss of memory of actions made by a diver is an interesting topic in-and-of itself; but it also begs the question of whether a diver was conscious of those actions at time.

 

[boulderjohn]

The loss of memory of actions made by a diver is an interesting topic in-and-of itself; but it also begs the question of whether a diver was conscious of those actions at time.

Oh, I think that in each case I know of I was conscious of what I as doing at the time. In the video example, I remember much of that time. I know I was checking my depth and time carefully to stay within planned limits, and I did that very successfully. I remember being in the old next to the videographer. I remember some of the things we saw--just not everything.

With further thought, I am wondering what you mean by being conscious of your actions. If you perform your actions properly, you have to be pretty conscious. Perhaps I don't uderstand your definition of the term.

 

[Dan Ziegner]

With further thought, I am wondering what you mean by being conscious of your actions. If you perform your actions properly, you have to be pretty conscious. Perhaps I don't uderstand your definition of the term.

This is the problem, I'm not sure that I understand enough of "consciousness" to ask the correct questions. If a diver is aware of his actions at the time (and he has reasoned to make the action), what are the causes/mechanisms that erase the memories of it? Also, why remember only certain parts of what has passed? How would a diver ever know that he doesn't remember what passed unless pointed out by another person, or seen afterward in a visual record? Gives me the heebie-jeebies...