Handling Narcosis

[texdiveguy]

I am glad you remember that post. I hope you also remember the secret training offer you made to me four years ago. You wanted to give me a tech diving course at 200 ft dives when I had only 7 dives. You thought other instructors and tech-divers would rip you apart on the boards so you sent me this course offer in private. This is the exact PM you sent me (I still have the message saved after 4 yrs):-

"I am not going to post this publicly but I don't think going to 200ft is that difficult. These guys are making it sound like a moon landing. If you are comfortable in the water I could get you safely down there and back with about 2 weeks training.
I think there are some who don't want people to know just how easy it is.

cheers,
Dave..."

If I had taken this "secret tech-instruction offer" of yours then yes I may have known the answer to my own question on handling narcossis. Since I did not / could not, my question about how deep divers handle narcossis is justified.

.......... dang why does it many times come to this.

 

[wedivebc]

I am glad you remember that post. I hope you also remember the secret training offer you made to me four years ago. You wanted to give me a tech diving course at 200 ft dives when I had only 7 dives. You thought other instructors and tech-divers would rip you apart on the boards so you sent me this course offer in private. This is the exact PM you sent me (I still have the message saved after 4 yrs):-

"I am not going to post this publicly but I don't think going to 200ft is that difficult. These guys are making it sound like a moon landing. If you are comfortable in the water I could get you safely down there and back with about 2 weeks training.
I think there are some who don't want people to know just how easy it is.

cheers,
Dave..."

If I had taken this "secret tech-instruction offer" of yours then yes I may have known the answer to my own question on handling narcossis. Since I did not / could not, my question about how deep divers handle narcossis is justified.

Deep diving is not rocket science and one can be trained if they are not a moron.

 

[Kevrumbo]

Report from Benthic on The Deco Stop Board, about the DAN Technical Diving Conference, this past 18-19 January '08:

Peter Bennett presented on Narcosis. It is clear that the medical community is doubtful that anyone can 'handle' narcosis. They seem to be of the opinion that 'acclimatization' is little more than your ability to know what to expect.

2008 DAN Technical Diving Conference

EDIT:
The above was already posted earlier in the thread, and I find it somewhat to be true in light of my experiences in Truk Lagoon (180' on Air Mix, 50% and O2 Deco).

The insidious narrowing of perception and situational awareness is a secondary condition directly related to Nitrogen Narcosis, and IMO can be caused by over-concentration on the task at hand to compensate for the cognitive impairment as well --concentrating hard, methodically & meticulously tying in a penetration line for example-- but oblivious to other potential cause & effect scenarios --i.g. while meticulously tying in that penetration line, you've unwittingly managed to entangle your SPG in loose line AND silt-out the passage behind you. In other words, you can be a very well trained and skilled diver, and able to react to a particular contigency despite cognitive impairment: but you can still be overwhelmed by multiple contigencies/problems/failures, especially where time and breathing gas supply become factors.

In sum: Goal oriented, task loading missions on deep air, and especially while solo, are very dangerous endeavors . . .(ask yourself: Can you truly expect to handle all possible contingencies in such an impaired state at depth on Deep Air?)

 

[dkatchalov]

To the OP - I just started reading Shadow Divers and the author's depictions of narcosis @ 200ft are extremely vivid. Whilst I cannot vouch for their accuracy given I have not been below 105ft, they are based on testimonies of many respected deep wreck divers.

So if you want to know what it's like, read that book to get some idea.

 

[Phreatic Fanatic]

.......... dang why does it many times come to this.

I don't know, but ethical journalists usually refuse to reveal sources. :mooner:

 

[DA Aquamaster]

In sum: Goal oriented, task loading missions on deep air, and especially while solo, are very dangerous endeavors . . .(ask yourself: Can you truly expect to handle all possible contingencies in such an impaired state at depth on Deep Air?)

I agree with you completely. But that is not to say that I agree that all dives should have an END of 100' or less or that a extended range dive to 130'-150' on air is always a bad idea - and the statement you are quoting is not saying that either.

One of the first question that always comes to mind when I hear a diver state that they ALWAYS do their dives with END's of 100 ft or less (and you even see them quoting ENDS as low as 80') is "how many dives per year do you actually do?"

One of the things I have noted with some techncial divers is that once these divers get wreck or cave as well as trimix trained they seem to dive less. Trimix is expensive and shallow (above 150') dives or, heaven forbid, quarry dives are just not much fun, so they don't do them very often or at all. Which leaves them making perhaps a half dozen dives in the 200' range per year and very few other dives of any type.

To digress for a moment. I am very proud of my abilities as a pilot and I have successfully made some very challenging flights, but the thing I am perhaps proudest of is having the judgment to stop flying when I realized I was not flying enough to keep my skills sharp enough to meet the demands of those same very challenging flights. I have known several pilots who have crashed and in a couple cases died because despite their high level of trianing, they just did not fly enough to maintain an adequate level of currency.

As an instrument rated pilot I enjoy having an autopilot and a flight director or HSI on an instrument landing to minimums in crappy, turbulent, gusty and icy conditions as a coupled approach is much easier to fly and greatly reduces the task loading and mental gymnastics required. However I also realize that I need to have the skills to make that same approach to miniums in the same crappy conditions with needle ball and airspeed with a VOR, ILS, or NDB because it does not take much in terms of systems failures to reduce you to that point and pilots die because they do not maintain their skills at that level - regardless of their training and remote past experience.

The same thing applies to technical diving. Being cave wreck and trimix trained does not mean much if you only do a handful of dives per year as you are then not diving enough to keep the myriad of skills rerquired current and your ability in the water, even in the best of circumstances is not what it should be.

Trimix is expensive and on an average $150 per day boat dive, using trimix in the 130'-150' range will complicate your logistics and at least double your diving costs. If you have the money and can deal with the logistics and still make as many dives as you would otherwise (and at a minimum enough to stay fully current on all the required skills and maintain peak performance in the water) knock yourself out and use trimix. But if using trimix in the 100-150' range means a diver is diving less and staying less current and less proficient, then his or her reliance on trimix is probably not adding the level of safety that the diver believes.

There is also something to be said for knowing your limits and knowing under what circumstances you can perform well at END's of 100'-150' as it adds confidence when you are a lot deeper on trimix.

Now, per the original statement I agreed to - absolutely, I do not want to be off the main line in a cave or deep inside a wreck at an END substantially more than 100' but I also do not want to limit the number of dives I make in the 100'-150' foot range due to the high cost and logistics of trimix solely because I am diving below 100' when the other factors and conditions are such that I am not going to be excessively task loaded. In short, deep air makes sense when the conditions are such that trimix is not required and that is a complex decision based on several factors, not just an agency policy that dictates a maximum END based on worst case assumptions.

 

[SeaHound]

To the OP - I just started reading Shadow Divers and the author's depictions of narcosis @ 200ft are extremely vivid. Whilst I cannot vouch for their accuracy given I have not been below 105ft, they are based on testimonies of many respected deep wreck divers.

So if you want to know what it's like, read that book to get some idea.

Very good reference. I just ordered the book. Thanks!

 

[dkatchalov]

Very good reference. I just ordered the book. Thanks!

Good stuff, enjoy it.

 

[scubastudy.org]

Hi SB,

I'm carrying out research into narcosis in the UK with a scuba charity and have a couple of queries for you all.

The following is my own opinion gathered from talking with many UK divers: I have found that as divers we seem to be afraid to admit to experiencing narcosis, it often reminds me of people who claim not be drunk after vast amounts of alcohol. "narcosis doesn't affect me!" (So if you feel you want to reply to this via Private Message then do so). However I have seen from my own research that divers can experience the effects of narcosis whilst being unaware of.

I'd like to know if there are members here who have been in dive chambers to a 'depth' greater than 99ft (30m) and what their experience was compared to the equivalent depth in the water. It would be interesting to know what the dive profile was in a chamber (max. depth/ total time at depth/ total dive time excluding safety or deco stops.) compared with what you experience in the water.

My reason for asking this is that I have carried out chamber dives on a number of qualified divers, and have asked for their views on their in-water narcosis experiences and have found that when asking them in a group, the general consensus is that "narcosis doesn't affect me". Unfortunately I am unable to replicate my study in the water, so I thought I'd attempt to get some answers from divers.

So have you been narced in a chamber? Was it deeper or shallower than in the water? What affect did it have on your performance/memory?

Any views or opinions would be appreciated,

Cheers

Graham

 

[Kevrumbo]

I'll let you know . . .as an intern member of the Volunteer Crew of the Catalina Hyperbaric Chamber, part of our non-treatment duties involve taking visitors for an orientation dive to 60'/18m; and doing an annual functional check of the fire control sprinkler system while pressurized to 165'/50m (I've heard it gets silly in there as the narc'd Crew clad in wetsuits starts dousing each other with the fire hose)

The nightmare scenario however, is taking a victim in full cardio-respiratory arrest with a suspected Arterial Gas Embolism, performing CPR on this patient while the Chamber is being pressurized to 165'/50m --the heat of compression is well over 95deg F/35deg C (imagine being inside your Scuba tank during a fast fill!)-- you're narc'd out-of-your-mind and laboring to near exhaustion in the heat trying to save this person's life. . .