Nitrox Not Helping With Narcosis... It's not making sense.

[antattack]

The term "Nitrogen Narcosis" is misleading. What divers experience is "Gas Narcosis", and Oxygen enriched gas is more narcotic than air.

As Rhone points out, our understanding of the effect is not perfect, but what we do know is that our nervous systems are affected by changes the properties of gases in solution at depth. All gasses have a narcotic effect, changing your blend is merely a method of managing narcosis. We rate gases by their narcotic effects relative to nitrogen. It turns out that Oxygen is 1.7 times as narcotic as Nitrogen, so Nitrox should make narcosis worse. Helium is only .6x as narcotic, so it's a little better.

The wikipedia page is a good start, I also recommend reading "Recreational Trimix Diving" by Kevin Evans and Richard Johnson. I'm not a tech diver yet, but found it to be accessible and very interesting!

 

[boulderjohn]

My reading indicates that the magic number for N2 narcosis seems to be ppN2 of 3.4 or thereabouts. What is it for O2 narcosis? It has been said that a diver would suffer a grand mal seizure before feeling O2 narced. Is that correct?

When people speak of a PPN2 of 3.4 as being narcotic, it is first of all a rough estimate that varies both by individual and by the specific incident. More importantly, we never breathe nitrogen by itself-- a PPN2 of 3.4 is always accompanied by some PPO2. It would be more accurate to say that a certain PPN2 + the accompanying PPO2 created the narcotic effect. If (as many people believe) the two are approximately the same in their narcotic potential, then reducing the nitrogen in the nitrox mix will have no effect because there is a corresponding increase in the amount of O2.

It is also very hard to measure the effects of narcosis. I have never felt any kind of euphoria or any kind of recognizable sense of being narked, but I know darn well I have been narked. I would only know the degree to which I was narked by my abilities in handling a situation. In the two most clear cases in which I know I was narked because of my performance, I was using nitrox, and I was not seriously deep.

EDIT: I also did much of my cave diving training in depths of about 90-100 feet, and I used nitrox 32 for those dives. I truly think that my worst moments in that training were related to narcosis.

 

[Dive-aholic]

The term "Nitrogen Narcosis" is misleading. What divers experience is "Gas Narcosis", and Oxygen enriched gas is more narcotic than air.

As Rhone points out, our understanding of the effect is not perfect, but what we do know is that our nervous systems are affected by changes the properties of gases in solution at depth. All gasses have a narcotic effect, changing your blend is merely a method of managing narcosis. We rate gases by their narcotic effects relative to nitrogen. It turns out that Oxygen is 1.7 times as narcotic as Nitrogen, so Nitrox should make narcosis worse. Helium is only .6x as narcotic, so it's a little better.

The wikipedia page is a good start, I also recommend reading "Recreational Trimix Diving" by Kevin Evans and Richard Johnson. I'm not a tech diver yet, but found it to be accessible and very interesting!

Wikipedia is a poor source because it lacks the documentation needed to support the information presented there. Where did you get your numbers from?

---------- Post Merged at 04:25 AM ---------- Previous Post was at 04:18 AM ----------

I don't think that weight is the correct measure of narcotic potency.

Neon is even less narcotic than Helium, despite being heavier. And CO2 is thought to be about twenty times as narcotic as N2 even though it is almost identical in weight.

True, weight in itself, is not a good indicator, but it's a start. Also, CO2 isn't and element, it's a compound. While Neon may be less narcotic, that is based on much more limited testing. Besides, as I said earlier, the awarenessdive of narcosis is subjective.

 

[nimoh]

Wikipedia is a poor source because it lacks the documentation needed to support the information presented there. Where did you get your numbers from?

---------- Post Merged at 04:25 AM ---------- Previous Post was at 04:18 AM ----------



True, weight in itself, is not a good indicator, but it's a start. Also, CO2 isn't and element, it's a compound. While Neon may be less narcotic, that is based on much more limited testing. Besides, as I said earlier, the awarenessdive of narcosis is subjective.

I am not aware of any evidence that suggests weight is a good indicator, so I will agree until someone changes my mind.

N2 and O2 are compounds as well, how is that relevant?

 

[debajo agua]

When people speak of a PPN2 of 3.4 as being narcotic, it is first of all a rough estimate that varies both by individual and by the specific incident. More importantly, we never breathe nitrogen by itself-- a PPN2 of 3.4 is always accompanied by some PPO2. It would be more accurate to say that a certain PPN2 + the accompanying PPO2 created the narcotic effect. If (as many people believe) the two are approximately the same in their narcotic potential, then reducing the nitrogen in the nitrox mix will have no effect because there is a corresponding increase in the amount of O2.

It is also very hard to measure the effects of narcosis. I have never felt any kind of euphoria or any kind of recognizable sense of being narked, but I know darn well I have been narked. I would only know the degree to which I was narked by my abilities in handling a situation. In the two most clear cases in which I know I was narked because of my performance, I was using nitrox, and I was not seriously deep.

EDIT: I also did much of my cave diving training in depths of about 90-100 feet, and I used nitrox 32 for those dives. I truly think that my worst moments in that training were related to narcosis.

From my internet research, there seems to be some debate about the Narcotic effects of O2. I stumbled across a rebreather forum where the subject seem to stirred up quite-a-bit of controversy. I find myself wondering, does O2 under pressure works as some sort of catalysis to induce N2 Narcosis at a lower ppN2 (just an idea)? To-date, I haven't had the fortune of experiencing any perceivable N2 narcosis while diving. I'm very curious about how I, and the divers I dive with, will react as we're exploring greater depths. I bought some equipment from a seasoned diver and asked him about his own experiences with N2 narcosis, he said had an urge to bolt to the surface, even though nothing was wrong and he knew better... he describe it as a unreasonable urge.

What I don't understand at this point is the narcotic effects of O2. I know that hyperbaric chambers can bring patients on O2 to ppO2 of 3.0. I'm curious as to what symptoms do these patients experience that are narcosis like? Are they getting high while in the chamber at these pressures? If so, I've never heard of such a thing. I like to think that I know something about people, and if this were the case, I can't help but think people would be stealing Oxygen and building hyperbaric chambers in there backyards to get high (it would probably be a lot safer than making and smoking meth).

Anyhow, I'm left with a lot of unanswered questions; mainly, what do we know for sure about the narcotic effect of O2? In my Nitrox class there was no mention of the narcotic effects of O2, other than it didn't prevent narcosis for this very reason (it's a narcotic too). Why then, were there no warnings about possibly getting O2 narced, which I thought was strange. If O2 is a narcotic at depth, and we're using increased amounts while diving, shouldn't there be some kind of warning about getting narced on Nitrox?

 

[boulderjohn]

Anyhow, I'm left with a lot of unanswered questions; mainly, what do we know for sure about the narcotic effect of O2? In my Nitrox class there was no mention of the narcotic effects of O2, other than it didn't prevent narcosis for this very reason (it's a narcotic too). Why then, were there no warnings about possibly getting O2 narced, which I thought was strange. If O2 is a narcotic at depth, and we're using increased amounts while diving, shouldn't there be some kind of warning about getting narced on Nitrox?

You answered your own question in your post. Nitrox is believed to have the same narcotic potential as air, so you are warned that it doesn't prevent narcosis. They don't warn you that nitrox is more narcotic because that is not what is believed to be true.

 

[debajo agua]

I think I see the point.

Let's take EAN32 as an example: EAN32 MOD 112' or 4.40 Ata...

EAN32 At 4.40 the ppN2 of 2.95 and ppO2 of 1.4 ...

Air at 4.40 the ppN2 of 3.43 and a ppO2 of .93 ...

A difference of only ppN2 of .48 ... that may, or may not, be negligible but it's certainly not a huge difference between the two.

Is that the point that's being made?


P.S. For those of you who question my math, I didn't include 1% other atmospheric gases into my calculations for partial pressure.

 

[nimoh]

I think I see the point.

Let's take EAN32 as an example: EAN32 MOD 112' or 4.40 Ata...

EAN32 At 4.40 the ppN2 of 2.95 and ppO2 of 1.4 ...

Air at 4.40 the ppN2 of 3.43 and a ppO2 of .93 ...

A difference of only ppN2 of .48 ... that may, or may not, be negligible but it's certainly not a huge difference between the two.

Is that the point that's being made?

I think you are missing the point, the narcotic effect of O2 and N2 are assumed to be the same.

So, EAN32 and EAN36 have the same potential for narcosis. In other words, with respect to narcosis, it doesn't matter if you replace some N2 with O2 in the mix, the potential for narcosis remains the same. However, if you add helium, you can reduce it.

The MOD for EANx really has nothing to do with narcosis, and is based on the danger of oxygen toxicity.

 

[boulderjohn]

I want to make an analogy that has nothing to do with scuba to see if this helps.

Let's say I have two bags that each have two kinds of soil in it. Both kinds of soil weigh exactly the same. One bag is comprised of 80% soil A and 20% soil B. The other bag has 20% soil A and 80% soil B. Both bags will weigh the same, even though they have different mixtures.

We believe that both N2 and O2 have roughly the same narcotic potential. It therefore does not matter what percentage of each is in the mix. The final mix should have the same narcotic potential.

 

[debajo agua]

I think you are missing the point, the narcotic effect of O2 and N2 are assumed to be the same.

So, EAN32 and EAN36 have the same potential for narcosis. In other words, with respect to narcosis, it doesn't matter if you replace some N2 with O2 in the mix, the potential for narcosis remains the same. However, if you add helium, you can reduce it.

The MOD for EANx really has nothing to do with narcosis, and is based on the danger of oxygen toxicity.

I see, so if both O2 and N2 have the same narcotic potential (I believe both are currently assigned 1.0), then by logic, a diver should feel the narcotic effects of 100% O2 at least between 2.0 ata or 3.0 ata. I know it sounds if I'm being difficult, but I'm really trying to understand how it was arrived at the conclusion, that O2 is equal to N2 in it's narcotic effects on the human body. They're two different elements with two different mass, and both have different characteristics. I understand that ppO2 levels have an effect on the CNS and can cause a person to have seizures if exposed to high levels... That's fine and I'm not contesting that; obviously, it effects the CNS but to what degree? I think I might be having a problem with the word "narcotic". To me it means something specific, mainly, a state of euphoria or irrationally behavior e.g. I wouldn't consider aspirin a narcotic, to me it's a CNS suppressor but its effects are mild. Maybe that's because I take it in small doses, idk.

I do know of a story where a diver made a mistake with switching his deco gas and seized underwater. He survived and said that he felt something was off when he switched gases, so it's still a mystery as to whether he experienced some sort of narcosis, or just a common pre-ictal state before he seized. He said everything happen very rapidly, within a few breaths. Did he suffer from O2 narcosis before he seized? Again, Idk

I called a Dr. in the field of hyperbaric medicine today, and I'm awaiting a call back. Hopefully, he won't be too annoyed with me asking questions. I'll relay back, what he has to says about O2 narcosis.