Nitrogen narcosis

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No, and what does this nave to do with me not memorizing all my dives in excruciatingly clear detail?


If you can't remember where you parked your car I wouldn't expect you to remember your dives, tbh, or what happened on them. I was throwing it out there for people that do remember stuff longer than an hour and may have seen similar behavior underwater.
 
I stopped a fellow from continuing to follow imaginary fish down at 172ft in Kosrae. In his defense, it was so clear I could actually see the captain looking over the side of the boat down at us. Dude was pretty combative at depth and I almost let him go find Poseidon. Topside he very freaked out by the incident and I doubt he will ever go beyond 60' again.

In Rangiroa at 155', I watched a lady whip out an iPhone in a plastic bag case and start taking selfies. She was fixing her hair and on the verge of pulling off her mask when a guide grabbed her and took her up. It was seriously bizarre. She had almost no memory of the events.

OTOH, I filmed and dove with a bunch of fish collectors on air working at 215' in Micronesia and they didn't have an issue with it at all. They had some terrifying stories about people that did though.

If anyone ever does a comprehensive study on the effects of nitrogen narcosis I would most certainly want to participate.

BTW: I think I jabbed myself in the back with that same pipe in Truk Jan/20!! No one displayed any signs of narcosis on any of the dives I did there or in Palau.

This is one more case of anecdotal evidence that some people can, and some people can't, handle narcosis.

It also supports the idea that people who dive deep on air with any frequency, are a self-selecting sub-set of divers.

In other words, those that don't do so well at depth (hopefully) find out early enough and shallow enough to avoid progressing further. Those that extend their deep dives in a more progressive and incremental basis and who don't exhibit gross signs of significant impairment are more likely to eventually be able to function better at depth than a randomly selected diver.

Everyone is impaired at significant depth, but there is a vast disparity in their ability to function effectively when deep.

Things like progressive exposure, the level of expertise they have with the essential diving skills, exertion level, fitness level and also the ability to regulate their breathing to a slow deep pattern (with more complete exhalations) are all relevant and controllable to some extent.
 
If you can't remember where you parked your car I wouldn't expect you to remember your dives, tbh, or what happened on them. I was throwing it out there for people that do remember stuff longer than an hour and may have seen similar behavior underwater.

I get it actually, I was just trying to point out that "don't remember the dive" as a blanket statement is neither here nor there. Unlike a lady not remembering doing selfies on her iPhone -- that's a whole 'nother thing with pix to prove it happened.
 
This is one more case of anecdotal evidence that some people can, and some people can't, handle narcosis.

It also supports the idea that people who dive deep on air with any frequency, are a self-selecting sub-set of divers.

In other words, those that don't do so well at depth (hopefully) find out early enough and shallow enough to avoid progressing further. Those that extend their deep dives in a more progressive and incremental basis and who don't exhibit gross signs of significant impairment are more likely to eventually be able to function better at depth than a randomly selected diver.

Everyone is impaired at significant depth, but there is a vast discrepancy in their ability to function effectively when deep.

Things like progressive exposure, the level of expertise they have with the essential diving skills, exertion level, fitness level and also the ability to regulate their breathing to a slow deep pattern (with more complete exhalations) are all relevant and controllable to some extent.


I agree with this for the most part. I accept that there must be some degree of impairment at significant depth even though I have never noticed it personally. I see nitrogen while deep as any other mind altering substance. Everyone will have a different experience with it and thankfully I am not a lightweight!

I have been thinking of creating a simple Raspberry PI based reaction time measuring device and trying to put it in a housing for some IRL tests.

All I can say is that it can't be overstated that these guys were absolutely amazing at 200ft+ on air and demonstrated skills for me I doubt many people could accomplish on dry land, all while catching and containing the tropical fish way down there!! They also did nearly 3 hrs on a single 80cu tank!

 
I get it actually, I was just trying to point out that "don't remember the dive" as a blanket statement is neither here nor there. Unlike a lady not remembering doing selfies on her iPhone -- that's a whole 'nother thing with pix to prove it happened.

I have the lady on video!! It is hilarious. It is mixed in somewhere with 14 days of 3 tank a day dives and I am having trouble finding it at the moment since it was a while ago and I guess I actually don't remember all of my dives in the detail I thought I did :wink:

Amazingly her iPhone completely survived but she didn't have any pics from the dive on it. I think the touch screen didn't work through that bag thing.
 
@Kay Dee Your supposition about a focused task is interesting. I have had numerous dives 40-55m and a few to 60m on air while spearfishing. Typically starting around 45m I noticed the buzz but have vivid memories of deeper events. Successful hunts suggest I wasn't completely debilitated. No mention of issues by my buddy (or visible impairment on their part that I observed).

I also wonder about many of the points @johndiver999 made. Numerous repetitions and extreme familiarity with the task at hand, certainly. Seems very reasonable to me that someone could be reasonably functional in some aspects.

I'm a little curious to see how a deeper dive would feel now that it's for fun and without the repetitive base. (I have to fly to dive sites these days.) I doubt I'll find out, mainly because there are other options these days.

I will also be venturing into a completely unfamiliar environment soon: poor visibility & cold instead of 100m visibility in the tropics (where all my diving to date has occurred). My understanding is those can be contributing factors. Will be interesting to see how things go, even within rec limits...
 
Everyone is impaired at significant depth, but there is a vast disparity in their ability to function effectively when deep.

Things like progressive exposure, the level of expertise they have with the essential diving skills, exertion level, fitness level and also the ability to regulate their breathing to a slow deep pattern (with more complete exhalations) are all relevant and controllable to some extent.

Could not have said it better myself, and especially relevant is the "breathing part"!

On another note, and make of it what you will, this from a 'test' Tom Mount and some associates performed back in tbe 80's with new divers from, IIRC, a unniversity dive club / courses in Miami. They used two separate groupings over a period of time and set them test to do during the dive/s. They found in the cases where the instructor told the group they would get severly narced at 30m / 100ft, the majority did and on the whole pergormed the test poorly. Of the other group that was told there would be some effect from narcossis but as long as they were aware of such they could ' handle' it, the majority did 'handle' it, and the majority could perform the tasks set. However, in the end, the standout best 'performer' was a person from the first group, so again goes to show one shoe does not fit all.

So a take-away from all that is never overlook the power of suggestion, especially those divers that are just repeating ancedotes of what they have heard, or expect will happen to them, at depth. But dont get me wrong, narcosis cerainly does exist, and has proven a killer, but if you read some of the preceeding posts, and the above quote, you should realise that there were plenty of exceptions to the 'rule'.

But if I had my choice between air and gas (trimix), well it would be gas every time of course

Oh, and to the videographer I 'offended' :stirpot: a few pages back, your are right, there is more to shooting u/w video than just press and play. I, personally, just found it less demanding than u/w still photgraphy is all.
 
I would be interested to know how many folks here who have said they have experinced significant or noticiable narcosis in say the 30m to 40m / 100ft to 130ft range where just diving with no task at hand but to just "have a look around" / regular dive so to speak.

I always found that having a task to perform, specifically still photograpy - while not quite as much with video is it is more often just point, press the 'go' button, and shoot - helped 'focus the mind'.

I always start feeling VERY anxious at depth around 35m, and my perception of time become weird, no matter the environmental conditions and my tasks.

When I have a task to do, although I manage to focus on it, I tend to lose situational awareness (or at least, this is how I feel... maybe it's just the anxiety).

That said, I still can manage those dives. But, frankly speaking, I do not like them.
 
I use the same routine religiously when going deep, Was back mount now side mount two 12ltr steel @250bar and a 7 of 50% O2. Drop the shot in the wreck and get it tight as possible up and down. Hang my tanks over the side and drop in harnessed and my suit dump open 5 clicks and enough air in the bladder to float me head up. Clip the left tank and breath from it. Hang the right tank and clip off the reg. hang the deco tank. Drop head under with no mask til my breathing has slowed down completely, put on and clear my mask and move to the shot. My right hand is on the shot depth gauge visible. Open the suit valve fully and dump all the air from the bladder. I squint my eyes to get used to the dark and drop fast with the rope sliding through my fist. As the temp drops and the light fades I’ll give short squirts of air to the suit. An odd glance at the gauge and I’ll pump the bc to slow the drop as I approach the bottom, I’ll only have taken a few breaths and dropped over 60 metres. I’ll check all my gear and do a reg swap and move the shot where it won’t foul when I need to haul it. Clip my strobe and reel if the vis is bad and head off. A fast drop can be very disorienting in cold and dirty water. I dropped 73 metres to a wreck in very poor conditions and when I landed on the upturned steel hull it felt soft and fluffy like cotton wool but this passed after a minute
 
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