First time getting narced...Yipes!

[The Chairman]

From ANDI:

[FONT=&quot]Dear Sir,[/FONT]

[FONT=&quot]After a search of the relevant documents here is what we have in the ANDI training materials:[/FONT]

[FONT=&quot]Complete SafeAir User –[/FONT]


2.4-1 CSU CH 2 excerpted from discussion of “early mis-education”.
3. Oxygen toxicity symptoms overlap many Nitrogen narcosis symptoms and were incorrectly diagnosed. Is loss of peripheral vision caused by Nitrogen or Oxygen? Is the “euphoric high” “just” narcosis or are we experiencing the onset of CNS toxicity? Elevated PO2 may actually contribute to narcosis as its lipid solubility is two times that of Nitrogen.1 How can one decipher the real cause of the problem?

Footnote 1 references Meyer-Overton Theory



2.6-2 The primary symptoms of Oxygen toxicity and Nitrogen narcosis have several similarities. Divers breathing gases at partial pressures sufficiently high enough to cause both problems should be extremely cautious and suspect Oxygen as the culprit. This is prudent because it appears that Oxygen is less forgiving than Nitrogen. That is, symptoms may progress without warning. The limits of Oxygen toxicity should not be treated as lightly as many divers treat Nitrogen narcosis.

[FONT=&quot]From the Technical SafeAir Diver text:[/FONT]


2.2-7 There are other inert gases that produce a narcotic effect similar to Nitrogen, but with various degrees of potency. It is believed that the higher the solubility of gas within the fatty tissues, the more potent the effect of the narcosis.1

2.2-8 There has been discussion concerning the relative narcotic effect of SafeAir to Air. [FONT=&quot]ANDI[/FONT] has always stated that “SafeAir will reduce the narcotic effect caused by Nitrogen”. Some have questioned the validity of the “narcosis-reducing capability” of EAN. Only if we extend the Meyer-Overton Theory to include both Oxygen and Carbon Dioxide, may we argue for a “non-narcosis-reducing capability” of EAN. Both Oxygen and Carbon Dioxide are more soluble in fatty tissue than Nitrogen. One could then propose that as the Oxygen concentration increases in a SafeAir mixture, the narcotic effect would increase relative to Air based solely upon the solubility coefficients. It is still uncertain if this is true.

Since our upper limit dosage of Oxygen is 1.46 to 1.6 ata ( [FONT=&quot]ANDI[/FONT]’s Caution Zone ), and until a case study is performed to evaluate Oxygen’s narcotic effect at these dosages, [FONT=&quot]ANDI[/FONT] will not address Oxygen’s possible narcotic effect and continue to state that “SafeAir will reduce the narcotic effect caused by Nitrogen”.2-3

Frankenhaeusser,M; Graff-Lonnevig,V;Hesser,C.M.:Effects of psychomotor functions of different nitrogen-oxygen gas mixtures at increased ambient pressures. Acta Physiol Scand.59:400-409, 1963.

Albano, G; Criscuoli, P.M; Ciulla, C.: La sindrome neuropsichica di profondita. Lav Um 14:351-358, 1962.

Bennett P., Blenkarn GD: Arterial blood gasses in man during inert gas narcosis. Journal Applied Physiology 36:45-48, 1974.

Larrabee MG, Posternak JM: Selective action of anesthetics on synapses and axons in mammalian sympathetic ganglia. Journal Neurophysiology 15:91-114, 1952.

[FONT=&quot]I hope this is assistance.[/FONT]

[FONT=&quot]I can have the ITD Board review these statements for currency as the above was written by Ed Betts about 18 years ago[/FONT]

[FONT=&quot]Best wishes,[/FONT]

[FONT=&quot]ANDI Tech Support[/FONT]

1 Meyer-Overton Theory

1 The Meyer - Overton Theory states that as the solubility in lipid tissue increases, the narcotic potency also increases. This has been demonstrated as true for all of the biochemically inert gasses. EAB.

2 Frankenhaeusser,M; Graff-Lonnevig,V;Hesser,C.M.:Effects of psychomotor functions of different nitrogen-oxygen gas mixtures at increased ambient pressures. Acta Physiol Scand.59:400-409, 1963.

3 Albano, G; Criscuoli, P.M; Ciulla, C.: La sindrome neuropsichica di profondita. Lav Um 14:351-358, 1962.

 

[The Chairman]

I think it would be beneficial for instructors to concentrate less on the funny side when they talk about narcosis, and give some more examples of the varied warning signs and less funny things about narcosis.

You won't find me talking about such silly crap in my class. I simply discuss the differences between intoxication on the surface and at depth and how we lack a valid point of reference.

What does narcosis have to do with O2 toxicity? You are just throwing a red herring into the mix here.

Not in the least. What is attacked at depth? Our CENTRAL NERVOUS SYSTEM. What is impaired by narcosis? The brain which is the heart of our central nervous system. I simply don't believe that there is no deprecation of our nervous system until we hit a magic point where there is complete failure. In fact if you look at the early symptoms for CNS, they are surprisingly similar to Narcosis.

Visual
Ear
Nausea
Tinglies
Irritability
Disorientation

They only vary in that "tinglies" are specific to CNS Oxtox.

 

[ArcticDiver]

Thanks for a good thread.

And here I thought all those peaceful dives with all the little fishies were just relaxing. Little did I know I was stoned. Of course ealier in life "I Didn't Inhale" so I lacked a point of reference, eh

 

[CoralSeaMan]

The NOAA diving manual states: "...The result is that one should not expect a significant change in narcosis when diving nitrox as compared to air." (p15-3, 4th ed.)

 

[The Chairman]

It has been a great thread! I have to admit that I was WAY impressed with the ridiculously QUICK response from ANDI. That just rocked! I actually just pasted the thing up there and then answered piiki and wedivebc. It was good to see how they couched their answer.

As with all things diving, there is just a lot of myth out there and a lot of it is not substantiated by any thing but anecdote. But the science of barophysiology keeps moving on albeit a lot more slowly than we would like!

 

[Gombessa]

I had no idea they had a brand name for nitrox.

 

[kidspot]

Sorry, must have missed something, but why did you "learn trimix" to get an END of 140', knowing you're narced on air at 130'?

sry - I left out that it was a class where the END was set by the instructor ... I took the class so now (that class is done) I can determine my own END (probably 80) where I still enjoy the dive... I'm brand new at this (finished class earlier this month) I usually shy away from dives that go much below 80, now I won't have to

Aloha, Tim

 

[Dive-aholic]

First off, I'm a fairly new diver, with about 23 dives...because none of my close friends dive, I usually find buddies on Scubaboard, which generally turns out OK. Unfortunately, this means I'm usually diving with new-to-me diving buddies on a rather frequent basis.

I arranged to meet up with a couple of Scubaboardians (also fairly new divers) at the semi-local quarry. I'm diving with a BP/W and long hose with bungeed backup for the first time in open water. I knew that the Scubaboardians I was diving with wanted to make a fairly deep dive, and since I've been down to about 80 feet or so before, I felt it would be no problem.

All is well, until I hit 99 feet. I realized that there was once heck of a lot of water above my head...and I started to get a bit anxious. I looked for my buddies and realized that they were quite a ways ahead of me...about 20-30 feet or so. I started to get more anxious, and checked my SPG...2,000psi. I checked my computer...95 feet. I've dealt with anxiety before, and I concentrated on taking slow, deep breaths, and tried not to focus on how deep I was. Still not helping...I felt even more anxious, and for the first time ever in my diving career, I was considering bolting to the surface. Now, that thought made me realize that I needed to ascend before I started to panic, so I started making a gradual, controlled, slow ascent to the surface. I signaled to my buddies with my handy can light...(couldn't remember the signal for "this sucks, I'm getting out of here!" so I just waved it around until they looked back).

Around 75-80 feet, all anxiety completely disappeared! Then it hit me...I was narced...duh. We continued the dive for about 10 more minutes, and one of my buddies thumbed it due to being at 500psi.

This was a big learning experience for me. This was the first difficult thing I've ever had to deal with underwater, and I'm really proud I didn't panic or lose control of the situation.

On the plus side, I love my new gear setup!

Anyways, I feel I learned a lot from my experience...and I'm glad it ended the way it did...'cause I completely realize it could have ended quite differently.

Back to the OP...

A few observations...

But first, I realize with only 23 dives, and the training you received, you probably wouldn't know this.

What size tank were you diving? It's not advisable to dive to the depths you stated on an 80. My rule, and that of many, is don't dive deeper in feet than the size of your tank. That puts you at 80' max for an AL80 (77' really, but what's 3').

Also, your buddy called the dive at 500psi?!? What if something had gone wrong? Would you/your buddy have been able to get to the surface safely with a safety stop while doing a share air. You may have been able to on the air you had left, but probably not if your buddy was a hoov'. And what if you had a major gas loss? 500psi was definitely not enough air to get you to the surface safely.

I'm not criticizing you (actually your instructor for not teaching you proper gas management). It's something you may want to learn more about before doing more dives like this.

BTW, when are you coming back down to the panhandle?

 

[DIR-Atlanta]

I can't find any conclusive study either way, and my observations (as well as those of thousands of other divers) are that Nitrox reduces narcosis.

My observations are the opposite. One of my most noticeable narcs was on an 85 foot wreck dive using 36%. The water was warm and clear, and the wreck was one that I had dived many times before. However, the current picked up a little bit during the dive and I had to maneuver carefully along the wreck to avoid swimming too hard against it. I began to feel the narcosis within minutes after descending.

In theory, Oxygen should be twice narcotic as Nitrogen, and in my experience, I always notice symptoms of narcosis more when I am on Nitrox. This is especially true since I started diving helium based mixtures on a regular basis several years ago. For END calculations, I believe that it is most prudent to treat Oxygen as having a narcotic potential that is at least equivalent to that of Nitrogen.

And I am curious as to the basis of your statements that you "can't find any conclusive study either way" but that "thousands of other divers" feel the same way as you do. How did you collect the info on the "thousands of divers"? Did you interview them yourself?

 

[perdidochas]

My observations are the opposite. One of my most noticeable narcs was on an 85 foot wreck dive using 36%. The water was warm and clear, and the wreck was one that I had dived many times before. However, the current picked up a little bit during the dive and I had to maneuver carefully along the wreck to avoid swimming too hard against it. I began to feel the narcosis within minutes after descending.

In theory, Oxygen should be twice narcotic as Nitrogen, and in my experience, I always notice symptoms of narcosis more when I am on Nitrox. This is especially true since I started diving helium based mixtures on a regular basis several years ago. For END calculations, I believe that it is most prudent to treat Oxygen as having a narcotic potential that is at least equivalent to that of Nitrogen.

And I am curious as to the basis of your statements that you "can't find any conclusive study either way" but that "thousands of other divers" feel the same way as you do. How did you collect the info on the "thousands of divers"? Did you interview them yourself?

A bit of an exaggeration gotten from websites addressing the so-called myth of nitrox reducing narcosis. Most have said that there is no real proof either way, but that a lot of people claim that nitrox causes less narcosis. Anecdotally, based on diving the same site conducting the same activities a few days apart (similar dive conditions), I noticed that threading live shrimp onto a hook at 100' was much easier on nitrox than on air. I dove on nitrox to increase bottom time. I still would dive nitrox for that reason (i.e. I wouldn't specifically use nitrox for the purpose of reducing narcosis). I just view the reduced narcosis for me as a bonus.

Also, there are some arguments about oxygen's narcosis inducing potential because it is not an inert gas.