NItrigen Narcosiss

[STOGEY]

Being a new diver I have a question regarding nitrogen narcosiss.

My question is tht I've been taught that everybody is affected neurologically by nitrogen. Some people are affected deeper then others. If a person lets say is affected at 80 ft, and on subsequent dives goes to 80 feet. Will he/she still be affected by nitrogen narcosiss, or will he/she build up a tolerance?

 

[wedivebc]

Being a new diver I have a question regarding nitrogen narcosiss.

My question is tht I've been taught that everybody is affected neurologically by nitrogen. Some people are affected deeper then others. If a person lets say is affected at 80 ft, and on subsequent dives goes to 80 feet. Will he/she still be affected by nitrogen narcosiss, or will he/she build up a tolerance?

There are some who believe that is true, including the president of a very well known technical training organization however there is no accurate way to quantify narcosis. It's like does a drunk actually drive better or has he just adapted to the impairment?
Most people believe narcosis is going to affect everyone below about 80ft but the degree to which it does is very subjective. It also affects people differently on different days.
One of the first symtoms of narcosis is denial. I have a friend who has done some obscenely deep dives on air and swears he's never been narced.

 

[Spectre]

Think of nitrogen narcosis exactly like drinking. Sometimes you get hammered after 3 beers, sometimes 5, sometimes on an empty stomach you feel something after your first beer. It varies based on all sorts of different things, most notably stress and comfort [you'll probably feel much more narced in frigid new england water than at similar depths in the florida keys].

And like drinking... some people learn to cope with the intoxication over time. It doesn't mean you are any less impaired, just that it's not as debilitating.

Now if you can cope with it to a point where you are safe under that impairment... that's a big 'ol can of worms that will be more painful then trying to explain a similiar concept to a police officer on your way home from your local watering hole.

 

[mempilot]

I'll give an example using alcohol and piloting. A while back, a flying magazine and two of their very senior columnists with buttloads of experience decided to do an experiment.

These two very skillful pilots would fly an approach in a corporate jet simulator, while being recorded for adhearance to the profile and standard opperating procedure. This would be considered a complex operation. Then they would do a shot of whiskey or whatever. 15 minutes or so later, they would repeat the exercise, and they would be recorded again under the influence. This went on until approach after approach, shot after shot, until they couldn't go on anymore due to severe impairment.

The magazine decided not to publish the results, because they thought it might lead to all pilots thinking they could do as well.

Here's the catch. These guys were well trained, well experienced, and well equipped to fly the approach in this aircraft type's simulator. While they were impaired, at points in the experiment, severly, they did quite well. Now take a couple of pilot's with less experience under their belts, and they probably would have crashed the plane at some point far sooner than these two. Would they be any more or less drunk? No. They just wouldn't be able to overcome the effects as easily as the two experienced guys.

Moral of the story. Everyone is affected by Nitrogen Narcosis. The more experience you have, the better you are equipped to deal with it. You'd probably not complain of the effects as quickly as someone else, even though they are there. Some is mind over matter, concentration, and being preprogrammed to cope. Being comfortable and in control prior to the onset of NN is a big must.

Repetative dives don't reduce NN, they just give you more experience to cope with the effects.

Hope that helps.

 

[opiniongirl]

There are physiological reasons that contribute to the depth at which divers experience the effects - generally, bigger folks tend to feel it deeper - whereas I get narced at 80 feet on the nose.

There are other factors such as speed of descent that come into play.

As for building up a tolerance, you do somewhat if diving over several days progressively deeper, but all is lost after a period of inactivity.

 

[Kennedydive]

It can all depend on the individual and on that particular day. I've often dove to a wreck at 150fsw in very cold water where Narcosis should have consumed me and felt fine with no ill effects. Was I Narced? For sure. No ifs, and, or buts. My worse case of being narced was at a shallower depth of 120fsw. That day I dove after work, hungry, tired from being up late the night before, and dehydrated from drinking coffee all day. That day I felt narced. After you enter the water you become narced. Same as if you were to take a sip of alcohol. Above 80 it has no real effect on most people the same as most people have no effects after drinking one beer. IMHO you can not build up a tolerance to it and instead should take steps to minimize it.
JK

 

[MikeFerrara]

the most interesting studies that I've seen suggest that while we don't build up a tolerance we can to some extent learn to compensate when doing certain types of tasks. We can certainly become used to the feeling so that we feel less effected.

The studies show that we can train ourselves to compensate doing rote tasks by trading speed for accuracy, for instance, or concentrating harder on the task at hand. Of course that requires us to concentrate less on something else...could be bad. Kind of like learning to find your keys and unlock your front door while drunk. The first time it's pretty hard but a practiced drunk can let himself in the house without even having to think about it...or remembering that he did it. It would be fun though to change the lock while he was out drinking, put the new key someplace in the yard, and leave writen directions explaining how to find the key and oporate the new lock. you just might find him in the morning rolled up under a bush using the writen directions to keep the dew off his face. LOL

What the studies show that we can't do is learn to think better. Studies show no improvement in reasoning ability (solving new problems) with repeated exposures even though the diver "feels" less narced.

Check out the IANTD technical diver encyclopedia for a summery of a bunch of studies.

So does training and practice help? In a way but it can also fool you.

 

[Diver0001]

the most interesting studies that I've seen suggest that while we don't build up a tolerance we can to some extent learn to compensate when doing certain types of tasks. We can certainly become used to the feeling so that we feel less effected..

I read something (maybe the same thing) showing evidence that divers do begin to perform better over time if they make many deep dives on a continuous basis. You might call this learning to compensate but you might also call it building up a tolerance. It's hard to distinguish the difference but I think it was a sort of tolerance because the effect was found to be temporary and after a few weeks out of the water the divers studied were right back to where they started. If it was compensating (a learned response) then they would have retained some of what they had learned.....

R..

 

[TwoTanks]

It can all depend on the individual and on that particular day. I've often dove to a wreck at 150fsw in very cold water where Narcosis should have consumed me and felt fine with no ill effects. Was I Narced? For sure. No ifs, and, or buts. My worse case of being narced was at a shallower depth of 120fsw. That day I dove after work, hungry, tired from being up late the night before, and dehydrated from drinking coffee all day. That day I felt narced. After you enter the water you become narced. Same as if you were to take a sip of alcohol. Above 80 it has no real effect on most people the same as most people have no effects after drinking one beer. IMHO you can not build up a tolerance to it and instead should take steps to minimize it.
JK

I had a similar experience, I've been to 140' many times in the Caribbean, and while I was no doubt narced, I didn't really feel it. I have also been to a hundred plus feet many times in Boston without feeling narced. But one day I did a dive as part of a deco. class to 115' and I was severely narced. The wreck was spinning, someone was palming my head and I was looking through toilet paper tubes. Had it not been a training dive, I would have aborted the dive immediately. However I did all of my drills flawlessly and in great time. The instructor couldn't even tell I was narced (I talked to him about it after the dive). I think that the ease with which I did the skills was due to the recent repetition of those skills. I don't think I would have responded very well to an unexpected situation or problem. An hour later I did a second dive to the same site and felt very little narcosis.

I think that you can learn to perform skills while narced, but I don't think you can train your brain to think better when narced. I also know that there is more to narcosis than just depth.

 

[Bobby]

I'll give an example using alcohol and piloting. A while back, a flying magazine and two of their very senior columnists with buttloads of experience decided to do an experiment.

These two very skillful pilots would fly an approach in a corporate jet simulator, while being recorded for adhearance to the profile and standard opperating procedure. This would be considered a complex operation. Then they would do a shot of whiskey or whatever. 15 minutes or so later, they would repeat the exercise, and they would be recorded again under the influence. This went on until approach after approach, shot after shot, until they couldn't go on anymore due to severe impairment.

The magazine decided not to publish the results, because they thought it might lead to all pilots thinking they could do as well.

Here's the catch. These guys were well trained, well experienced, and well equipped to fly the approach in this aircraft type's simulator. While they were impaired, at points in the experiment, severly, they did quite well. Now take a couple of pilot's with less experience under their belts, and they probably would have crashed the plane at some point far sooner than these two. Would they be any more or less drunk? No. They just wouldn't be able to overcome the effects as easily as the two experienced guys.

Moral of the story. Everyone is affected by Nitrogen Narcosis. The more experience you have, the better you are equipped to deal with it. You'd probably not complain of the effects as quickly as someone else, even though they are there. Some is mind over matter, concentration, and being preprogrammed to cope. Being comfortable and in control prior to the onset of NN is a big must.

Repetative dives don't reduce NN, they just give you more experience to cope with the effects.

Hope that helps.

MemPilot is correct about he stated. To add a little bit more information to this back in the 80's I raced professionally and was involved with a similar test for the DOT. On a closed circuit we fallowed a simple small course sober then added a shot at a time as well. The results were very similar as to MemPilots. One week later we performed the same test only two variables were added. One the course was altered slightly at random and two at the end of the test we had a light bar with three lights. One light meant we should stop in front of the light bar and the other two were for swerving either right or left of the light bar then stopping. With these changes the results were scary and we were incapable of performing very quickly. To relate this to Narcosis is the same thing. When Narced you may get away with many dives and not feel narced and perform the tasks needed but when things chage unexpectedly is when it can go bad fast. Narcosis, Carbon Dioxide build up, and a host of other things set in very quickly and can impare you to the point of overload.