Oxygen also has a narcotic effect at depth, so nitrox won't reduce narcosis for all divers. The following link describes this pretty well:
http://en.wikipedia.org/wiki/Nitrox
http://en.wikipedia.org/wiki/Nitrox
Nitrox problem, is it normal?
- Thread starter kalidor's8
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Superlim9
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Waterskier1, you are correct.. the biggest advatage to nitrox is increased time at depth with a decreased risk of getting narcosis. You will also have a reduced MOD due to the increased amount of oxygen in the mix... eanx32 is like 111 for 25 min and eanx36 is 95 for 45minutes. It "should" be less likely but there could always still be accurances of narcosis depending on the factors. By looking at the other factors of the dive especially the overexertion also leads to the possability of excessive CO2 in your lungs hence it being hard to catch a breath.... to answer your question.. I do not know why people jump to the narcosis conclusion when there can be alot of other reasons. If you read through there were alot of people giving alot of different suggestions which is why kalidor asked questions.. becasue there are alot of possible answers. Most of the arguments started when other people didnt like the fact that we are making dives to 150-165ft. When the dive is planned and you do you research...it is pefectly safe and it opens up many more dive sites... recreational tables are limited to 130-140 in order to increase a built in safety factor and to take some of the brain work out of diving like figuring in stops and planing the dive with enough air for the dive and any required stops instead of swimming around and looking at fishes until you have 5-600 psi left and then going to the surface. All in all limiting the tables opens diving up to a broader range of people. However... DO NOT start using alternate tables untill you have the apropriate training to do so safely.
~Bill
~Bill
I'm not a big fan of wikipedia, since it's written by anyone who thinks they know. I haven't heard of O2 narcosis as related to NITROX. CNS, yes, but not narcosis. I'm not an expert here, but I think the reason Helium (or other gases) are used is not because of O2 narcosis, but rather because of CNS due to the O2. It is my understanding that these two (narcosis and CNS) are completely different aflictions. Am I mistaken?
Also, since I'm still learning about this, is difficulity breathing a normal symptom of Narcosis? I have in my mind, from my prior reading, that narc'd people are doing silly/stupid things, like giving their regs to fish, etc, and that other than drowning doing these silly/stupid things, there really isn't a danger. OTOH, if one can not breathe, that is quite dangerous. When I did my deep dive, the instructor gave us problems to work on slates, to show how we might slow down, but I never got the impression that he was worried that we would not be able to breathe.
Also, since I'm still learning about this, is difficulity breathing a normal symptom of Narcosis? I have in my mind, from my prior reading, that narc'd people are doing silly/stupid things, like giving their regs to fish, etc, and that other than drowning doing these silly/stupid things, there really isn't a danger. OTOH, if one can not breathe, that is quite dangerous. When I did my deep dive, the instructor gave us problems to work on slates, to show how we might slow down, but I never got the impression that he was worried that we would not be able to breathe.
Narcosis and CNS are totally separate things.
However O2 is believed by most to be narcotic, as narcotic as nitrogen or MORE narcotic depending on which theory you follow. If you go by Meyer-Overton lipid solubility you get O2 being more narcotic than nitrogen.
Narcotic effects are generally believed to be the cumulative value of the partial pressure of the various narcotic gases in the mix. So if you assume O2 is as narcotic as nitrogen then removing nitrogen and replacing it with oxygen as you do in nitrox will have no effect at all on narcosis.
PADI and i believe GUE teach that Oxygen is narcotic. Not sure about others.
As for its effects, ive seen some divers totally paralysed by it. Just there wide eyed, big grin almost totally unresponsive. I've also seen divers attempt to remove their kit, talk to a starfish and other things. It can be very dangerous ESPECIALLY if they get what would normally be a minor problem like a mask flood or wet breath.
If you want more of a read of ENDs and the various interpretations of it see here: http://www.techdiver.ws/trimix_narcosis.shtml
However O2 is believed by most to be narcotic, as narcotic as nitrogen or MORE narcotic depending on which theory you follow. If you go by Meyer-Overton lipid solubility you get O2 being more narcotic than nitrogen.
Narcotic effects are generally believed to be the cumulative value of the partial pressure of the various narcotic gases in the mix. So if you assume O2 is as narcotic as nitrogen then removing nitrogen and replacing it with oxygen as you do in nitrox will have no effect at all on narcosis.
PADI and i believe GUE teach that Oxygen is narcotic. Not sure about others.
As for its effects, ive seen some divers totally paralysed by it. Just there wide eyed, big grin almost totally unresponsive. I've also seen divers attempt to remove their kit, talk to a starfish and other things. It can be very dangerous ESPECIALLY if they get what would normally be a minor problem like a mask flood or wet breath.
If you want more of a read of ENDs and the various interpretations of it see here: http://www.techdiver.ws/trimix_narcosis.shtml
I share you opinion of Wikipiedia, I just referenced it because it summed up what I was trying to say.
O2 toxicity is indeed a separate issue from narcosis. We discussed narcosis in my nitrox class and it was also stated there that O2 has narcotic effects very similar to nitrogen. This is not to say that O2 CNS toxicity is the same as narcosis. If you take a CNS hit you will likely convulse, lose conciosness and drown. Narcosis from O2 exposure will have symptoms similar to nitrogen narcosis.
O2 toxicity is indeed a separate issue from narcosis. We discussed narcosis in my nitrox class and it was also stated there that O2 has narcotic effects very similar to nitrogen. This is not to say that O2 CNS toxicity is the same as narcosis. If you take a CNS hit you will likely convulse, lose conciosness and drown. Narcosis from O2 exposure will have symptoms similar to nitrogen narcosis.
This is what I love about SB... you are always learning. I do not think PADI teaches O2 narcosis, at least I didn't see it in their NIROX course. Indeed, I haven't heard of it until this post. I glanced over the reference, and see that it is a possibility though. I will study this more. Thank you!
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I know that it is DIRigueur to say that oxygen is as narcotic as nitrogen but I don't think there's data to support that idea. What data there is points in the other direction in as much as hypoxic nitrogen/oxygen mixes used in habitats to slow the oxygen clock are more narctoic than air and are oft refered to as NARTOX for this reason.
Are these instructor notes/lesson guide? I didn't get any lecture, just read the study guide and watched the DVD. I could have missed it, but I thought I was pretty attentive to the differences and positive/negatives of NITROX. I will have to dig out my student guide and review it. I will admit that when I took this course, I knew nothing about gas mixes (related to breathing), and the benefits and limitations of those mixes. What I came away with was too much N2=> nitrogen narcosis and possibly the bends, too much 02=>Oxygen toxicity and CNS. I guess I missed an important part.String:
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kalidor's8
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I think that is part of the fun about boards like this. You get ppl from all over the place with so many agencies out there and so many views on diving. As long as you can understand there are a lot of different divers out there and lots of ways to do things.
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