Can Narcosis be managed?

[jlcdvr]

I thought you were on vacation. Step away from the keyboard. Joel

[Draker]

I thought you were on vacation. Step away from the keyboard. Joel

Everyday is a vacation!


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[SUB ZERO]

This is a cave diving forum, let's ask "can narcosis be managed in a cave environment".

In the context of cave diving, back in 1996 I was the accident analysis committee chair for the NACD and someone asked about the number of deep air cave diving fatalities. The records that I had indicated that between the 1960s and 1994, approximately 55 people that had some level of cave training died while deep air diving. This happened to align with what I was taught by my cave instructor, deep diving was the #1 cause of fatalities of trained cave divers.

Of those, 2/3rd of them died on dives at depths between 150-180'. This result surprised me, I was personally expecting most of the fatalities to have been at much deeper deaths (over 200'), 150' on air didn't seem that extreme of a depth to me at the time.

Best I could figure at the time is that the likely chain of events for many of these, which I still believe as the most likely scenario today, was:

1. Primary light dies - remember the period we're talking about was when halogen bulbs and wet cell nicads were common, primary lights were not nearly as reliable as they are today
2. In the process of deploying a backup light, something happened (silt out, turned around, or off the line)
3. Stress caused increased gas consumption
4. Between being at 6ATA and increased gas consumption from stress as well as the delayed reaction time from slight narcosis impairment, there was a reduced amount of time for problem solving - diver runs out of air at some point near the exit.

Life has risks, driving along US27 to Peacock Springs on a foggy morning can be one of the most hair raising experiences a person can ever have. Some risks can be managed, some can't. When figuring out a personal risk / reward tolerance for deep air cave diving, I would hope the person contemplating it would also consider the impact to the community in the event something goes wrong. In the last five years we've lost access to several amazing sites, I'd hate to be the one to cause other places to get shut down simply because I didn't want to buy some helium.

In an overhead environment, the answer would be NO! I am not a cave diver yet but dipping below 100 without mix should be totally off limits IMHO.

[OFG-1]

Back in the 70's I taught at a commercial diving school. The thinking in the community at the time was that commercial divers should be qualified to dive 190 feet on air. Every student got a 190' chamber ride, I probably ran 80 students a year through it. Reactions varied from nothing, to pissing and drooling on yourself. We asked them to write their name on a slate, again varied from not bad to a couple of scratches. Some could solve a basic addition problem, most could not. Most laughed like idiots. Some could not form words.

This was 10 minutes at 190 in a warm controlled environment.

[Jim Wyatt]

In 1982 the US Navy thought divers should be qualified to 190 feet on air and ran us to that depth in a chamber just like OFG-1 discusses above with pretty much the same results as he discussed. In 1988 or so my wife and I did some incrementally deep dives off the wall at Grand Cayman and ended up at 240 feet one day. I saw a purple panther about 50 feet long crawling up the wall during that dive. I realized that had a problem happened there was little likelihood that we could have solved it because we were narced the max.

The OP has asked "Can Narcosis be managed". My answer is and always has been "can driving drunk be managed"?

After we did some dives at Eagles' Nest on air I confirmed the fact that in the event of a failure, especially a cascading set of failures there was little likelihood that we could solved the problems while narced.

Once we had access to helium we never looked back, once I had access to a designated driver I never looked back.

All in all its a bad idea to try and manage narcosis in open water or a cave. There is no need to...

[Sludge]

Reactions varied from nothing, to pissing and drooling on yourself. We asked them to write their name on a slate, again varied from not bad to a couple of scratches. Some could solve a basic addition problem, most could not. Most laughed like idiots. Some could not form words.

Sounds like my first date with my wife.

[FW]

Like alcohol, you build up a tolerance to nitrogen. BUT... also like alcohol, building up your tolerance to high partial pressure nitrogen usually results in addiction to diving.

Is that supposed to be a bad thing??

[RGU]

Is that supposed to be a bad thing??

I confess to enjoying the dream world of deep air. In the early days of using trimix, we reserved helium for dives below 200 feet.

[kensuf]

Ken, I read through this very carefully, and my best take away is that since my primary light is much better now vs then, I?m ok to dive deep air and save the cash by not wasting it on helium. Thanks for this!!!

We need to plan a return visit to the bottom of the Black Abyss as soon as conditions allow.
Merry Christmas!


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Speaking of sites that are currently closed....

[kensuf]

In an overhead environment, the answer would be NO! I am not a cave diver yet but dipping below 100 without mix should be totally off limits IMHO.

I'm pretty firmly entrenched in the "use helium" camp myself even though I have done my fair share of stupid stuff on deep air dives, but if you didn't want to discuss it in an overhead environment, then why did you post on cave divers forum?

I think the statistics pretty clearly back up that even at "shallow" depths, the narcosis of diving air at 150' in a cave can reduce problem solving abilities to the point that someone couldn't overcome a problem in time, and I suspect if you look at 120' you'd probably see the same. A firm 100' END in a cave makes a lot of sense, but an overhead environment with significant penetration, navigation, silt, etc is completely different than a wall dive in a warm tropical environment; diving air to 120' or even 130' in the ocean may not be the end of the world.

FWIW, regarding part of your opening statement, the cost of helium. In North Florida helium prices aren't going to leave you broke, last time I checked 18/45 was roughly $0.60 a cubic foot. And even when traveling abroad, while more expensive than the states, the cost isn't that insane. I'm sitting in the dutch antilles contemplating a 220' dive that's supposed to be a pretty hot ticket, the fills for the appropriate gases (including rental of deco bottles) will be less than $300 -- I'll spend more on covid tests for my wife and I to come back to Florida. That's OC costs, for diving mix to depths that 25 years ago I wouldn't have blinked at diving on air (we used to switch off trimix to air at 190'-200' all the time). There's really no place for diving those depths on air.