Narcosis-does nitrox make a difference? Does experience make a difference?

[TSandM]

fdog, I really like your story about the Benchmark run!

When I started diving, I would get furious with myself for screwing simple stuff up underwater . . . I'm talking about going through a list of things we were going to do, and then getting underwater and messing up the order or the details in a way that I simply wouldn't do on land. I'm a pretty smart woman when my head isn't wet . . . but underwater, it seemed as though I was just stupid in amazing ways. And we are talking dives in the 30 to 40 foot range here!

I have yet to have ANY dive I have done give me a discernible "drunk" feeling. What I have learned to recognize is a, "Huh?" response to new information (at least I hope I've learned to recognize it -- I clearly REMEMBER it later) that tells me I am just not functioning well at all.

I personally do not think there is a tolerance effect to narcosis. But I think that, as you become a more experienced diver, routine diving tasks require less processing (so they go better when you're impaired), and you relax and breathe more efficiently, so you reduce the CO2 component of narcosis at any given depth. I do not think Nitrox makes a difference. Helium DEFINITELY does.

 

[nimoh]

I think that, as you become a more experienced diver, routine diving tasks require less processing (so they go better when you're impaired)

I think that is commonly misinterpreted as building a tolerance to narcosis

 

[DevonDiver]

I think that is commonly misinterpreted as building a tolerance to narcosis

I agree. What's ingrained, stays ingrained. The diver retains whatever skill-set has been embedded in muscle memory and can deal with problems that they are familiar with resolving. They are also more cognizant of their decreased mental performance and can compensate for that through increased mental focus, deliberacy of action - cutting through the fog. The 'fog', however, remains an issue. The Nascar becomes a rusty tractor... but moves forwards regardless. Problems only arise when a sharp bend appears suddenly..

 

[Dr. Lecter]

I think that is commonly misinterpreted as building a tolerance to narcosis

Muscle memory is part of tolerance of/adaptation to narcosis, especially when you're talking about the degree of narc that comes with air well past 130', but I have found that experience with personal symptoms is also a large part of it. I can rely on muscle memory to perform any number of tasks while narced, but you have to recognize a problem before you can respond to it regardless of whether the response is conditioned or conscious. And then you have to adapt your response to your narced condition.

That's where experience with being narced and just how impaired you are comes into play. The deeper you go, the more you have to work at keeping alert to what you're doing, what's going on around you, and what you need to be monitoring. Thinking itself becomes an additional task. And when you encounter a problem you have to respond (when you finally do respond) bearing in mind that you've been delayed and have degraded fine motor skills: slow is smooth, smooth is fast, try to get it right the first time and don't fluster yourself/create new problems. The more experience you have being narced, the better you will understand and adapt to the impairment.

The 'fog', however, remains an issue. The Nascar becomes a rusty tractor... but moves forwards regardless. Problems only arise when a sharp bend appears suddenly..

Which is why you shouldn't be driving at full speed when you're deep on air; sudden problems are more easily handled when narced if one has consciously aknowledged the impairment and tempered their reactions while amping up their self-awareness. Even then you're not as good as you would be less narced, but it beats the Hell out of kicking along mindlessly enjoying the pretty fishes/obsessing about the dark and scary lack of viz.