Northwest Dive Club

The dreaded "surface narc." (thats the one Helium can't help you with.)

When I've been narked and aware of it, I would not describe my sensation in terms of numbers of beers. My best description of how I feel is like the "dazed and stunned" feeling I got as a kid after I fell off the monkey bars and hit the ground too hard. I associate the paranoid or "dark nark" with exertion, stress and rapid breathing. My opinion is that discussions of narcosis are all too often about nitrogen and not nearly enough about CO2, which is far more narcotic and more variable and less predictable. Also, I've noticed that some medications that are known to amplify the effects of alcohol seem to make me more susceptible to narcosis while diving as well. I don't think there's a magic depth because there are so many variables, but I start expecting to notice it below 60 feet on air. It wasn't until I tried Helium that I was convinced I had no business diving air below 100 feet. But that's just me: your mileage will vary.

Joshua Smith wrote:

airsix wrote:I'm of the belief that being narked is not a "feeling", it's a physiological state brought on by specific conditions and when you're narked you're narked whether you feel it or not. "I'm not narked at 100ft" just means you have not been made AWARE that you are narked (IMHO). How many times have we heard an intoxicated person lecture us about how drunk they aren't? How many times have we all seen an intoxicated person THINK they are doing something flawlessly when in reality they are a train wreck? Same thing. An elevated blood alcohol level creates impairment whether you feel it and acknowledge it or not. It's a physiological reality and while our conscience may affect how we react to it, it does not have the power to simply mitigate the cognitive impairment with will-power or self-confidence. Well, that's what I think anyway.

Ben

I think this is basically true, in that one can feel "fine", but, in reality, be impaired. But I know that at least for me, there's a huge variability in how that impairment might manifest. And that variability is independant from depth.

This is so true... and the worst part is if you don't realize you're impaired.

For me everything "slows down" and gets very calm and comfy feeling. Kinda like "this feels kinda nice, now what's the big deal about being below 100fsw?" Yeah... not good.

Guess Tom and I are lucky to get the Dr. Feelgood Narc...and not the Dark Narc !! Nice to see such a response regarding this topic, shows responsible divers all over the Sound !! because............Drumroll Please .................... Knowing is half the Battle

I've had both kinds. But not for a long time. Since I dive a 'breather, I can't remember the last time I used air for dil.

Want a recent demo of being "narked"? Go back to the hypoxia thread and watch the video. Not exactly the same biology but close enough for our purposes. Watch the subject's responses and expressions on his face.

Yum.. Narked.. Uh starts at about 85 to 95 .. Really good times at 125 feet.. I dive air

dwashbur wrote:
For my money, there's a lot more to see in terms of life at the 40-50' level anyway...

+1.

I've yet to have anything I have had too much urge to see past 60-70fsw around where my local dive spots are... some wrecks around the PNW.. now, that's a different story =P

I feel the effects of narcosis ~85fsw on air and it intensifies from there, but I have never felt the effects on EaNX. I always get too close to my MOD before I get the chance to feel it on ean32. I never really realize that I feel it if I'm looking for it, but always note that I did something strange after I've started my ascent (like reaching for my octo thinking its my PDC). I am usually always diving EAN32 and when I am, I always stay about 20' above my MOD simply because I feel that I am personally effected by "symptoms" that others feel with depth in shallower waters. Why risk oxygen toxicity? If I'm ~85fsw and I know my MOD is ~110 feet, I feel comfort in knowing that I'm not going to just randomly african american out and die.

I relate being narcd like I do with smoking pot. some people have an awesome time with it and others completely panic and sketch out. If you know that your chemical makeup isn't fond of being narcd and it triggers your parasympathetic nervous system, I say that risking it is foolish.


Have someone who you dive with who knows what you had experienced before and who understands your fears go down with you while you dive eanx and set a goal for 70fsw, then the next dive, add 10fsw and keep progressing until you know where your limit is before you start feeling anxiety then the guessing game is over and you dont have to worry about it anymore ;-)

Mr. Owl, how many fsw does it take to get to the center of a panic attack?

Early on, I got CO2 narked at 80 feet, which wasn't particularly fun, but it did teach me to breathe slowly and deeply from then on.

I start feeling it pretty consistently at about 100 feet. When I'm in tropical waters, colors start becoming more brilliant, and up here, it's too dark to notice.

I hope I'm not opening a can of worms with this comment. I've seen at least two people in this thread comment that Enriched Levels of O2 have helped them curb the effects of Nitrogen Narcosis, and I wanted to throw out that I do not.

To be honest I believe I am more susceptible to Narcosis when I do dive Nitrox. However, I may be willing to concede that there is a predisposition because I am at a depth where I would be Narc'd on air but I begin to dwell on the following information on top of the normal stressors (simply making me more aware of my narcosis).

O2 has a higher Narcotic Potency than does N2. Almost double really (1.0:1.7). And while it is true that we metabolize oxygen we ultimately transport O2 in two ways, 1.) Hemoglobin transport, and 2.) Dissolved gas in blood (just like N2). Because the hemoglobin transport is nearly 97% saturated at the surface, and has a defined capacity that does not increase with pressure, we are really doing very little to promote additional metabolic processing of O2.

In the end scientist don't really know if O2 contributes to the human perception of narcosis or not. Some agencies do not use the O2 portions of a mixture to calculate Equivalent Narcotic Depth, some do. Personally I do, but I get narc'd easily and I heart He.

My worst cases of Narcosis as others have stated were caused by heavy work load, and CO2.

To go with my statements earlier CO2 has 20 times the Narcotic Potency that N2 does, and while it too is capable of being carried by the hemoglobin transport, it's only a small percentage of the C02.

But the Simple answer for the OP is 80-90 feet.

kitsapdiver wrote:I hope I'm not opening a can of worms with this comment. ... O2 has a higher Narcotic Potency than does N2. Almost double really (1.0:1.7).

The worms are packed in trimix, so open the can slowly...

I hadn't heard that O2 has a relatively higher narcotic potency than N2. Can you cite your source? What I've read indicates that O2 is usually regarded as about the same potency as N2.

FWIW, I don't notice any difference in narcosis between air and nitrox. Even if O2 is 1.7x the narcotic potency of N2, that equates to about a 7% potency difference between air and EAN 32 (assuming a normalized N2 potency of 1.0). My hunch is that, if there is a difference, it's overwhelmed by the effects of CO2 and daily variations in [my] physiology. YMMV.

kitsapdiver wrote:I hope I'm not opening a can of worms with this comment. I've seen at least two people in this thread comment that Enriched Levels of O2 have helped them curb the effects of Nitrogen Narcosis, and I wanted to throw out that I do not.

To be honest I believe I am more susceptible to Narcosis when I do dive Nitrox. However, I may be willing to concede that there is a predisposition because I am at a depth where I would be Narc'd on air but I begin to dwell on the following information on top of the normal stressors (simply making me more aware of my narcosis).

O2 has a higher Narcotic Potency than does N2. Almost double really (1.0:1.7). And while it is true that we metabolize oxygen we ultimately transport O2 in two ways, 1.) Hemoglobin transport, and 2.) Dissolved gas in blood (just like N2). Because the hemoglobin transport is nearly 97% saturated at the surface, and has a defined capacity that does not increase with pressure, we are really doing very little to promote additional metabolic processing of O2.

In the end scientist don't really know if O2 contributes to the human perception of narcosis or not. Some agencies do not use the O2 portions of a mixture to calculate Equivalent Narcotic Depth, some do. Personally I do, but I get narc'd easily and I heart He.

My worst cases of Narcosis as others have stated were caused by heavy work load, and CO2.

To go with my statements earlier CO2 has 20 times the Narcotic Potency that N2 does, and while it too is capable of being carried by the hemoglobin transport, it's only a small percentage of the C02.

But the Simple answer for the OP is 80-90 feet.

+1 Very well put!

When I get narked, I get sleepy/groggy. Easy first sign for me when its hitting.

60south wrote:

kitsapdiver wrote:I hope I'm not opening a can of worms with this comment. ... O2 has a higher Narcotic Potency than does N2. Almost double really (1.0:1.7).

The worms are packed in trimix, so open the can slowly...

I hadn't heard that O2 has a relatively higher narcotic potency than N2. Can you cite your source? What I've read indicates that O2 is usually regarded as about the same potency as N2.

FWIW, I don't notice any difference in narcosis between air and nitrox. Even if O2 is 1.7x the narcotic potency of N2, that equates to about a 7% potency difference between air and EAN 32 (assuming a normalized N2 potency of 1.0). My hunch is that, if there is a difference, it's overwhelmed by the effects of CO2 and daily variations in [my] physiology. YMMV.

When you called me out I spent a time looking for my copy of DECO for divers, but couldn't find it. So I'm going to cite a source less popular,

DOING IT RIGHT: The Fundamentals of Better Diving, Jarrad Jablonski, Global Underwater Explorers, 2000
Table 5.1

Which more specifically states that the anesthetic potency of a gas is inversely proportional to that gases solubility in lipids. Table 5.1 is solubility coefficient for gasses in Olive Oil.

The coefficient for N2 is 0.052 and for O2 is 0.110 so really my statement of 1:1.7 is incorrect it's more like 1: 2.1

Like I said the discussion in Deco for Divers was a better discussion wish I could find it right now.

kitsapdiver wrote:I hope I'm not opening a can of worms with this comment. I've seen at least two people in this thread comment that Enriched Levels of O2 have helped them curb the effects of Nitrogen Narcosis, and I wanted to throw out that I do not.

To be honest I believe I am more susceptible to Narcosis when I do dive Nitrox. However, I may be willing to concede that there is a predisposition because I am at a depth where I would be Narc'd on air but I begin to dwell on the following information on top of the normal stressors (simply making me more aware of my narcosis).

O2 has a higher Narcotic Potency than does N2. Almost double really (1.0:1.7). And while it is true that we metabolize oxygen we ultimately transport O2 in two ways, 1.) Hemoglobin transport, and 2.) Dissolved gas in blood (just like N2). Because the hemoglobin transport is nearly 97% saturated at the surface, and has a defined capacity that does not increase with pressure, we are really doing very little to promote additional metabolic processing of O2.

In the end scientist don't really know if O2 contributes to the human perception of narcosis or not. Some agencies do not use the O2 portions of a mixture to calculate Equivalent Narcotic Depth, some do. Personally I do, but I get narc'd easily and I heart He.

My worst cases of Narcosis as others have stated were caused by heavy work load, and CO2.

To go with my statements earlier CO2 has 20 times the Narcotic Potency that N2 does, and while it too is capable of being carried by the hemoglobin transport, it's only a small percentage of the C02.

But the Simple answer for the OP is 80-90 feet.

I've heard for years that 02 could be narcotic, but I really don't understand wth that means. I do whole 2 hour dives at a pp of 1.3 on a fairly regular basis. Never even felt a twinge of narc on my Meg....of course, that's almost exclusively with plenty of helium in the mix, but....I'm getting off topic, I think. My understanding is that science doesn't have a very good explanation for why nitrogen can be narcotic, but we all know that it can be. How is 02 narcotic? The solubility stuff doesn't mean anything to me. So what? And is this a controversial topic, somehow? I notice that vplanner gives you the option to select whether to call it narcotic or not, and I always select "not," but its never a big deal for me to increase the helium in my mix. Maybe this is more of a concern for open circuit?

*HEADEXPLODE*

... I just really like diving ^_^ it's nice.

Joshua Smith wrote:

kitsapdiver wrote:I hope I'm not opening a can of worms with this comment. I've seen at least two people in this thread comment that Enriched Levels of O2 have helped them curb the effects of Nitrogen Narcosis, and I wanted to throw out that I do not.

To be honest I believe I am more susceptible to Narcosis when I do dive Nitrox. However, I may be willing to concede that there is a predisposition because I am at a depth where I would be Narc'd on air but I begin to dwell on the following information on top of the normal stressors (simply making me more aware of my narcosis).

O2 has a higher Narcotic Potency than does N2. Almost double really (1.0:1.7). And while it is true that we metabolize oxygen we ultimately transport O2 in two ways, 1.) Hemoglobin transport, and 2.) Dissolved gas in blood (just like N2). Because the hemoglobin transport is nearly 97% saturated at the surface, and has a defined capacity that does not increase with pressure, we are really doing very little to promote additional metabolic processing of O2.

In the end scientist don't really know if O2 contributes to the human perception of narcosis or not. Some agencies do not use the O2 portions of a mixture to calculate Equivalent Narcotic Depth, some do. Personally I do, but I get narc'd easily and I heart He.

My worst cases of Narcosis as others have stated were caused by heavy work load, and CO2.

To go with my statements earlier CO2 has 20 times the Narcotic Potency that N2 does, and while it too is capable of being carried by the hemoglobin transport, it's only a small percentage of the C02.

But the Simple answer for the OP is 80-90 feet.

I've heard for years that 02 could be narcotic, but I really don't understand wth that means. I do whole 2 hour dives at a pp of 1.3 on a fairly regular basis. Never even felt a twinge of narc on my Meg....of course, that's almost exclusively with plenty of helium in the mix, but....I'm getting off topic, I think. My understanding is that science doesn't have a very good explanation for why nitrogen can be narcotic, but we all know that it can be. How is 02 narcotic? The solubility stuff doesn't mean anything to me. So what? And is this a controversial topic, somehow? I notice that vplanner gives you the option to select whether to call it narcotic or not, and I always select "not," but its never a big deal for me to increase the helium in my mix. Maybe this is more of a concern for open circuit?

WoW!
Wayyyy too much info here!!
But still, an interesting thread.
Me?
I seems to depend on, how fast I descend and most of the time, I just keep checking my computer more often.
But My last Narc, just a few Thursdays ago, I was diving 32% and felt an incredible, euphoric, narc @ 90+ feet.
Other divers on the same dive were diving air, and felt narked too.
We dropped in @ about 40 feet and went directly down to 100+ feet and then worked our way back up.
I specifically remember thinking, "This is Nice!" "I could stay right here for the entire dive! " (Then, after looking at my computer) "Or, I could just stay here for 12 minutes "

Other times, I've been much deeper (115 to 130) and did not feel a euphoric narc, but by having to keep checking my computer, I know there must have been some sort of narcosis going on.

Joshua Smith wrote:

kitsapdiver wrote:I hope I'm not opening a can of worms with this comment. I've seen at least two people in this thread comment that Enriched Levels of O2 have helped them curb the effects of Nitrogen Narcosis, and I wanted to throw out that I do not.

To be honest I believe I am more susceptible to Narcosis when I do dive Nitrox. However, I may be willing to concede that there is a predisposition because I am at a depth where I would be Narc'd on air but I begin to dwell on the following information on top of the normal stressors (simply making me more aware of my narcosis).

O2 has a higher Narcotic Potency than does N2. Almost double really (1.0:1.7). And while it is true that we metabolize oxygen we ultimately transport O2 in two ways, 1.) Hemoglobin transport, and 2.) Dissolved gas in blood (just like N2). Because the hemoglobin transport is nearly 97% saturated at the surface, and has a defined capacity that does not increase with pressure, we are really doing very little to promote additional metabolic processing of O2.

In the end scientist don't really know if O2 contributes to the human perception of narcosis or not. Some agencies do not use the O2 portions of a mixture to calculate Equivalent Narcotic Depth, some do. Personally I do, but I get narc'd easily and I heart He.

My worst cases of Narcosis as others have stated were caused by heavy work load, and CO2.

To go with my statements earlier CO2 has 20 times the Narcotic Potency that N2 does, and while it too is capable of being carried by the hemoglobin transport, it's only a small percentage of the C02.

But the Simple answer for the OP is 80-90 feet.

I've heard for years that 02 could be narcotic, but I really don't understand wth that means. I do whole 2 hour dives at a pp of 1.3 on a fairly regular basis. Never even felt a twinge of narc on my Meg....of course, that's almost exclusively with plenty of helium in the mix, but....I'm getting off topic, I think. My understanding is that science doesn't have a very good explanation for why nitrogen can be narcotic, but we all know that it can be. How is 02 narcotic? The solubility stuff doesn't mean anything to me. So what? And is this a controversial topic, somehow? I notice that vplanner gives you the option to select whether to call it narcotic or not, and I always select "not," but its never a big deal for me to increase the helium in my mix. Maybe this is more of a concern for open circuit?

It's a concern for OC because Helium is *expensive*!

Joshua Smith wrote:I've heard for years that 02 could be narcotic, but I really don't understand wth that means. I do whole 2 hour dives at a pp of 1.3 on a fairly regular basis. Never even felt a twinge of narc on my Meg....of course, that's almost exclusively with plenty of helium in the mix, but....I'm getting off topic, I think. My understanding is that science doesn't have a very good explanation for why nitrogen can be narcotic, but we all know that it can be. How is 02 narcotic? The solubility stuff doesn't mean anything to me. So what? And is this a controversial topic, somehow? I notice that vplanner gives you the option to select whether to call it narcotic or not, and I always select "not," but its never a big deal for me to increase the helium in my mix. Maybe this is more of a concern for open circuit?

What he's getting at is that "narcosis" can be estimated by the PPO2 + PPN2 or by just PPN2. People have been taught both ways over the years although I'm pretty sure I'm not a whole lot snappier in the synapse department at 100ft on 32% than I am on air. And I know I'm not suddenly a genius on 50% at 70ft.

Where do you feel it? That's quite a different question than how you estimate the martini factor. There are enough differences between OC and RB that I'm not sure the math tools and guesstimates work quite the same anyway.

CaptnJack wrote:

Joshua Smith wrote:I've heard for years that 02 could be narcotic, but I really don't understand wth that means. I do whole 2 hour dives at a pp of 1.3 on a fairly regular basis. Never even felt a twinge of narc on my Meg....of course, that's almost exclusively with plenty of helium in the mix, but....I'm getting off topic, I think. My understanding is that science doesn't have a very good explanation for why nitrogen can be narcotic, but we all know that it can be. How is 02 narcotic? The solubility stuff doesn't mean anything to me. So what? And is this a controversial topic, somehow? I notice that vplanner gives you the option to select whether to call it narcotic or not, and I always select "not," but its never a big deal for me to increase the helium in my mix. Maybe this is more of a concern for open circuit?

What he's getting at is that "narcosis" can be estimated by the PPO2 + PPN2 or by just PPN2. People have been taught both ways over the years although I'm pretty sure I'm not a whole lot snappier in the synapse department at 100ft on 32% than I am on air. And I know I'm not suddenly a genius on 50% at 70ft.

Where do you feel it? That's quite a different question than how you estimate the martini factor. There are enough differences between OC and RB that I'm not sure the math tools and guesstimates work quite the same anyway.

Ok, that makes more sense than anything I'd heard before.

Joshua Smith wrote:

CaptnJack wrote:

Joshua Smith wrote:I've heard for years that 02 could be narcotic, but I really don't understand wth that means. I do whole 2 hour dives at a pp of 1.3 on a fairly regular basis. Never even felt a twinge of narc on my Meg....of course, that's almost exclusively with plenty of helium in the mix, but....I'm getting off topic, I think. My understanding is that science doesn't have a very good explanation for why nitrogen can be narcotic, but we all know that it can be. How is 02 narcotic? The solubility stuff doesn't mean anything to me. So what? And is this a controversial topic, somehow? I notice that vplanner gives you the option to select whether to call it narcotic or not, and I always select "not," but its never a big deal for me to increase the helium in my mix. Maybe this is more of a concern for open circuit?

What he's getting at is that "narcosis" can be estimated by the PPO2 + PPN2 or by just PPN2. People have been taught both ways over the years although I'm pretty sure I'm not a whole lot snappier in the synapse department at 100ft on 32% than I am on air. And I know I'm not suddenly a genius on 50% at 70ft.

Where do you feel it? That's quite a different question than how you estimate the martini factor. There are enough differences between OC and RB that I'm not sure the math tools and guesstimates work quite the same anyway.

Ok, that makes more sense than anything I'd heard before.

I personally use PPO2 + PPN2 because in reality, we don't really know to what degree oxygen contributes to narcosis. So, if we don't know if or how narcotic it is, I assume it is.

BDub wrote: I personally use PPO2 + PPN2 because in reality, we don't really know to what degree oxygen contributes to narcosis. So, if we don't know if or how narcotic it is, I assume it is.

Ditto although in my case I am not upping the O2 content in an attempt to lessen narcosis. I just add helium. I am pretty sure that the reduction in narcosis from helium is disproprotionate to the actual amount added. I.e. a little helium helps alot more than the fHe would suggest because it reduces gas density enough that overall work of breathing is reduced and its easier to blow off Co2. At least on OC.

Interesting. I just plugged a 300' dive using 10/70 into vplanner. EAD with 02 was 110', without was 95'. I guess that's enough of a difference to worry about, but 15' isn't really that big of a deal to me.

kitsapdiver wrote: DOING IT RIGHT: The Fundamentals of Better Diving, Jarrad Jablonski, Global Underwater Explorers, 2000
Table 5.1

Which more specifically states that the anesthetic potency of a gas is inversely proportional to that gases solubility in lipids. Table 5.1 is solubility coefficient for gasses in Olive Oil.

The coefficient for N2 is 0.052 and for O2 is 0.110 so really my statement of 1:1.7 is incorrect it's more like 1: 2.1

There is a discussion of this topic in my copy of "The Physiology and Medicine of Diving" too. It mentions the relationship of lipid solubility to narcotic potency as a correlation - and I think it's important to recognize that as different from "inversely proportional".

CaptnJack wrote: Where do you feel it? That's quite a different question than how you estimate the martini factor.

That's the key consideration I feel. A value in a table of narcotic potency is just a number - two narcotics with similar potency can have very different observable symptoms.

Joshua Smith wrote:I notice that vplanner gives you the option to select whether to call it narcotic or not, and I always select "not,"

That option doesn't really seem to make any difference in my planning.

Joshua Smith wrote:Interesting. I just plugged a 300' dive using 10/70 into vplanner. EAD with 02 was 110', without was 95'. I guess that's enough of a difference to worry about, but 15' isn't really that big of a deal to me.

Yeah 15ft is well within the day to day fudge factor anyway. At least it is for me, so I don't really worry about it either.