Narcosis-does nitrox make a difference? Does experience make a difference?

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tracydr

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[MENTION][FV]I believe that nitrox does not make a difference with nitrox. Not entirely sure as far as experience. I do know that if you build up to deeper dives, you may not "feel" the narcosis as much. However, dark narc can happen at any time. It's a fairly random occurrence. I also know that I've experienced regular narcosis many times from 100-130 feet with decreased ability to make decisions and tunneling of my ability to think. I've also had dark narc a couple of times, which is quite scary. I think both times, this was brought on by CO2 build up caused by current and exertion at depth.
Here's an old link to help promote some discussion:

http://www.scubaboard.com/forums/basic-scuba-discussions/468350-narcosis.html#post6926829
 
If you subscribe to the view that oxygen is as narcotic as nitrogen then nitrox will obviously make absolutely no difference to narcosis.

Furthermore, once you get much deeper that 100 feet the tolerable percentage oxygen in the mix drops rapidly until you end up with just 26% at 42m (130 feet) assuming a maximum ppO2 of 1.4 bar. Even if you assume oxygen is not narcotic a 5% reduction in nitrogen content would not make a significant impact on narcosis levels.

Finally, in depths where a significantly high percentage of oxygen is tolerable, you would not typically expect to see narcosis anyway.

In short, nitrox isn't going make any difference to narcosis.

As to experience making a difference; yes it will but not in the way people imagine. You cannot really build up a tolerance to narcosis. However narcosis is like being drunk in that in reduces short-term memory. The more experienced the diver the more their skills and abilities will reside in the long-term part of their memory. They will have built up a 'muscle-memory' of all significant drills and activities to the extent that they can do them without very much thought. This means they will appear to cope better with narcosis as fewer of their skills will be impaired. But, and this is the big problem, only regularly practiced routine skills will not be significantly impaired. Less well practiced skills, such as emergency ascents, are still likely to be affected just when you need them the most.
 
im going for

yes and yes.
 
If you subscribe to the view that oxygen is as narcotic as nitrogen then nitrox will obviously make absolutely no difference to narcosis.

Furthermore, once you get much deeper that 100 feet the tolerable percentage oxygen in the mix drops rapidly until you end up with just 26% at 42m (130 feet) assuming a maximum ppO2 of 1.4 bar. Even if you assume oxygen is not narcotic a 5% reduction in nitrogen content would not make a significant impact on narcosis levels.

Finally, in depths where a significantly high percentage of oxygen is tolerable, you would not typically expect to see narcosis anyway.

In short, nitrox isn't going make any difference to narcosis.

As to experience making a difference; yes it will but not in the way people imagine. You cannot really build up a tolerance to narcosis. However narcosis is like being drunk in that in reduces short-term memory. The more experienced the diver the more their skills and abilities will reside in the long-term part of their memory. They will have built up a 'muscle-memory' of all significant drills and activities to the extent that they can do them without very much thought. This means they will appear to cope better with narcosis as fewer of their skills will be impaired. But, and this is the big problem, only regularly practiced routine skills will not be significantly impaired. Less well practiced skills, such as emergency ascents, are still likely to be affected just when you need them the most.


He just said everything I was about to post
 
[MENTION][FV]I believe that nitrox does not make a difference with nitrox. Not entirely sure as far as experience. I do know that if you build up to deeper dives, you may not "feel" the narcosis as much. However, dark narc can happen at any time. It's a fairly random occurrence. I also know that I've experienced regular narcosis many times from 100-130 feet with decreased ability to make decisions and tunneling of my ability to think. I've also had dark narc a couple of times, which is quite scary. I think both times, this was brought on by CO2 build up caused by current and exertion at depth.
Here's an old link to help promote some discussion:

http://www.scubaboard.com/forums/basic-scuba-discussions/468350-narcosis.html#post6926829

Nothing I've ever tried has given me the impression that Nitrox makes any difference.

I do get the impression that exposure makes a difference but only in a similar way to drinking. The more you drink, the more you can 'act normal' even though you're under the influence. Seems to work like this with narcosis too.

R..
 
I've read that everyone is affected to some degree at about 100'. I've done a few deep dives between 100 and 130 and haven't consciously noticed much of anything. I'm certainly not one who has learned to adapt, since I deep dive so infrequently. No difference nitrox or air. Perhaps the reason is everyone is different. I am a very meticulous guy, perhaps touching on OCS. I'll be checking my SPG needlessly in 20' of water with tons of air left. I am constantly searching for shells. I don't often drink, but when I do (it's "Dos Equis"...) I seem to have a very high tolerance for it. I am never a "rowdy or noisey drunk". Maybe all this helps with narcosis?
 
People want to feel narcosis before they acknowledge it. That's a short, short sighted way of looking at it. On the surface we have two main indicators when we impaired: balance and speech. It's hard to fall down when you are neutral and we don't speak underwater so our main indicators are worthless. Getting narced is best described as becoming a cow. Cows can follow a path, but block the path and the cow has a very limited faculty for resolving the problem. In fact, the cow may waste a better part of the day just looking at the block without ever going off of the path and simply walking around it.

The only way to know that you're impaired is to look at your depth gauge. For every additional atmosphere, your bovine indicator moves 25%. By the time your Bovine Index hits one, your problem solving skills are incredibly impaired whether you feel it or not. You can complete lots of dives (follow the path) without having a single incident giving you a false sense of security. But when the Cow Dung hits the fan, you're still about as smart as a cow.

What does oxygen do to your Bovine index? Nothing, nada and squat. You might be breathing smarter, but you're still a cow.
 
The only way to know that you're impaired is to look at your depth gauge. For every additional atmosphere, your bovine indicator moves 25%. By the time your Bovine Index hits one, your problem solving skills are incredibly impaired whether you feel it or not. You can complete lots of dives (follow the path) without having a single incident giving you a false sense of security. But when the Cow Dung hits the fan, you're still about as smart as a cow.

While there's no doubt that increasing depth and the narcosis it causes affects all divers to some degree (and the same diver to different degrees on different days), trying to mix Martini's Law with Animal Farm is complete and total horse:censored:. I understand this is Basic Scuba, but what you've just said--or more precisely, the absolute nature of your statement--has no basis in fact.
 
I dont think Nitrox really helps you at those depths unless you are willing to push to 1.6 PPO2....which is not advisable.

I also believe that narcosis does different things to different people. I can tell you that when i was doing my deco class and diving 140+fsw on air i was narced even though i didnt feel that way. and when i had to solve complex scenarios at that depth, i did so with no problems......however, when asked to write my name on my slate, i couldnt do it. I believe that narcosis destroys my fine motor skills, but that doesnt change my ability to "think through" a problem such as OOA, Free flow etc.

Now when i dive air to 180+, i dont assume that anyone will be the most efficient at dealing with problem scenarios/situations....but it CAN be done.....Slowly.
 
Do not use Nitrox at any significant depth. It can kill you. Any depth involving nitrogen narcosis is too deep for nitrox mixes that are significantly different from atmospheric air. You may be ok according to the tables, but it's really dumb to get that close to passing out suddenly and fatally, and meaningless to use an oxygen % only a few points above atmospheric 21% O2. Nitrox is great for spending extended time at depths less than about 75 feet, and that it what it is designed for. When you begin to go deeper Nitrox becomes increasingly dangerous.

I agree with the comments about narcosis and experience. If you think you have the narcotic effects of depth under control you are thinking with a narcosis fogged brain. It's self deception, like those kids who think they are such masterful multi-taskers that they can text and drive.

Part of the training I did a million years ago involved descending to about 110+ feet and trying to do fairly simple tasks. It's amazing how coming back up just a few feet suddenly made you realize how narked you were only a few seconds earlier, a few feet deeper. That's the only good thing about narcosis: it goes away instantly, and now you can tie that complicated knot. Put the fear of god into me, and here I am four decades later, doing fine.
 
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