Nitrogen Narcosis: What It Is and How It Affects You - Maluku Diving

[DevonDiver]

What do you make of the reduced amount of N2 that still results in narcosis in that study?

Oxygen is more narcotic than nitrogen. However, oxygen resides in the brain at a lower partial pressure than it is respired (ambient pressure) due to metabolism.

More narcotic than nitrogen, but lower partial pressure in the brain (where it matters) - so the narcotic effect is not in-line with a simple ppO2 calculation based on ambient pressure. If you have a more narcotic gas, but at a lower partial pressure, it has a lower narcotic effect. A lower narcotic effect... on a par with nitrogen... perhaps?

The results of the study on narcosis impairment and nitrox found no discernible difference between air and nitrox.

For the diver, who has to limit respired ppO2, the greater narcotic potential of oxygen, offset by it's decreased partial pressure in the brain... presented no identifiable difference from breathing a lower O2, higher N2 mix. In short, it balances thereabout and there's no practical narcosis difference as far as the diver is concerned.

Some agencies state that nitrox is less narcotic than air. Other agencies state there is no difference in narcotic effect between air and nitrox. It depends whether the agency concerned based their belief on 'pure Meyer-Overton' theory, or whether their belief was influenced by practical studies.

 

[Vicko]

Anybody who claims they don't get narced should try to work a puzzle at 20 meters with multiple pieces and film themselves,
I know of people who do 100 meter dives on air for sponge and corals, they work at that depth because they can FOCUS on a simple task, not becaus they are imune to narcosis. I never did something like that but I dive to 50-55 regularly and I thought that it does not effect me mentally. I lost all illusions of my tolerance to being narced after I watched a video of that dive and figured out that I can't remember at least 50% of the things I was looking at, including a swim trough of the wreck that took about a minute.
Light trimix is not so expensive that I'm willing to compromise the enjoyment of my dives.

 

[reefrat]

There are some highly experienced air divers who routinely dive past 150 ft and get away with it, but the majority of divers I have heard say that they don't get affected by narcosis are not those people- in fact IMO they wouldn't know poop from clay when it comes to deep diving and related physiology or safe techniques.
I did my share of deeper air dives when I was younger and even more stupid, these days I stick to my personal fun dive limit of 100 ft unless there is a very good reason to go deeper. From experience I can detect subtle symptoms of my own narcosis and in warm clear water they seem to appear bang-on at 100 ft as though someone flicked a switch.
So narcosis, and the effects of dynamic airway compression/ impaired ventilation (search for Dr. Simon Mitchell), decreasing scrubber effectiveness, increased gas usage (OC) and shorter NDL on air have convinced me that despite all the amazing advancements in dive gear and techniques the immersed human body does not like to go much deeper than 100 ft!

 

[oldschoolto]

Failing to understand that every person is effected differently , is the biggest problem of these threads...

I don't know any two people that are effected the same way... Close, But not the same...

To use drinking and driving as a reference. Some people can't drive at .05 to .08 others it's .10 and then we have people that live there life at .25 and you'd never know it... Lawyers, Doctor and Airline pilots...

I'm wanting to bring a brain puzzle down to 150' to do and video tape it.. But, I'm sure some will say.. Well he knew it before hand, or it's a mental task he is focused on.. But, But... Are we not supposed to be focused on our diving ??? Or, does the new divers stand on the boat yelling Yahoo as they jump in because they have a Buddy and a computer....

Jim..

And, Just to stir the pot a little bit more.. I dove without a computer till last year.. I wear it on my left arm and very rarely look at it.. I have my Bottom timer / Depth gauge and watch on my right arm and running my NDL and/or Deco times in my head.. You know those outdated tables that will take you passed 200' on Air..

 

[Dan]

I dove deeper than 130' twice. First one was at 132' just for curiosity as a newbie on my dive #15 in Son of Rock Monster in Cayman Brac. 2nd one was at 144' to get a closer look at Mola Mola while being cleaned by Emperor anglefish (see my avatar) in Crystal Bay, Nusa Penida, Bali. Both times were under the watch of DMs above me and were in calm & 100+' visibility. The dives were so relaxing & peaceful. Everything seemed to happen in slow motion. I guess that would be the feeling when I'm narced.

 

[longtimer]

What I find is I become narced from CO2 poisoning regardless of the depth and mix if I over exert myself or exceed my known pp(x) tolerances. What I can do today or tomorrow differs and bears monitoring. Personal experience AND situational awareness governs my limitations. Pushing the envelope is no longer part of the equation.

 

[Subcooled]

First of all there is the effect of submersion. Things tend to become more complicated under water than they are under air. The density of water versus air might be a cause for this as well as the need to breathe from a mouth piece (not very natural). The submersion effect is a fact. Another thing is the "gloves-narcosis" (there is research about both - check Rubicon foundation archive). You all know that bare hands is more convenient than wet gloves, wet three finger gloves, dry gloves or dry mittens. Then there is anxiety that affects capabilities. Dense gasses also seep into the body and apparently slow down certain functions of the nervous system: I can recall my contingency plans at depth, but memorizing what happened five seconds ago is difficult. So storing and recalling are differently affected. As short term memory fails, all reasoning fails. Commanding fingers to operate requires more work too. There is a delay, stiff fingers. Vision and perception of time are affected too. All of this is clearly noticeable at -47m (enough to be noticed down there). A certain slowness can be detected at -30m already, but problems become more pronounced with depth - and the deeper you are the faster they grow. Some people find nitrogen narcosis relaxing - a bit like alcohol - but others realize the dangers and get scared.

The worst possible "narcosis" happens when you dive in a drysuit (no pee valve), and you need to pee, and you cannot Hypothermia is not much easier. But... at -40m+/-120ft+ without helium the brain is severely incapacitated.

 

[Subcooled]

Best attempt at 6ATA (-50m), dry chamber. Please pay attention to the challenging calculations and the task to connect, in this order, A-1-B-2. Literally, apparently (the choice to do it literally was a difficult one and required a lot of thinking).

 

[wildbill9]

Ahhh...."studies" showed this to be true....makes me remember that 87.43% of all statistics are made up on the spot. I feel same was about studies, give me the data and I can prove most any postulate I wish. My wife is ow certified and I am aow, we both have been diving since late 70's and have a great many dives under our belts. She has never been arrested from the diving police for exceeding 60 feet. I am no more safer and she is no more unsafe just because she doesn't have aow certification or me because I do. I am no expert and don't have memorized all that data on "rapture of the deep" but from actual experience I must disagree with the op that it is unsafe to dive below 60 feet. This thread has been very entertaining but I truly hope new divers don't put to much credence in the fear factor that he seems to promote. Yes I believe in safety first but I must wonder why he even started this thread?

 

[The Chairman]

Narcosis is the process of acquiring the mental aptitude of a cow. Just as the most dangerous cow is the one who believes it's not a cow, the most dangerous diver is the one who believes they don't get narced. When you put on Scuba gear, you lose about 10 points off your IQ. You lose another 10 when you splash and again for each additional atmosphere. The deeper you go, the more your bovine quotient approaches "1".

What? You don't feel stupid at depth? Imagine that? You're too stupid to feel stupid. That's the problem of narcosis.