100m air dive & workup, PG

[Tortuga68]

They are the same. Narcosis is present, regardless of the symptoms

If the symptoms vary but the narcosis is constant, as you suggest, then clearly the symptoms and the narcosis are two different things. Anyway, semantics perhaps

I think that 'narcosis management' is a fantasy

That depends on your definition of both narcosis - which we can't seem to agree on even that - and also what you mean by management. I don't hear anyone claiming that you can eliminate narcosis, but I believe you can manage aspects of it

I disagree with any belief that 'narcosis management' can actually mitigate or reduce those risks

Again, before you disagree, one would have to define the risks that are at issue. Would one be vaguing out & losing track of time/depth & air? Because I think you can manage to reduce that

Anyway, I'm not trying to convince you of anything, I just find when people tell me you can't manage narcosis they generally aren't talking about the same thing I am

 

[DevonDiver]

I felt the same way as you do, when I first started deep air diving. Over time, I learned more.

I think you are confusing symptoms with cause.

Spraying decongestant up your nose gets rid of the sniffles, but it doesn't cure the cold. 'Narcosis management' might get rid of the obvious symptoms, but it doesn't stop the narcosis severely compromising your ability.The analogy of 'drunkeness' is used so much by inexperienced (non-deep air) divers, that many divers believe that that (rare) symptom IS narcosis. It isn't. It's just one sign of it. The 'drunkeness' analogy is a PADI AOW level understanding of the subject. It's an 'urban legend'. It's what instructors tell students, when they themselves don't understand how narcosis works.

Here's a post from TS&M in the Narcosis --insidious and subtle thread:

My whole point in posting this (which is embarrassing and distressing to me) is to point out that you don't FEEL narced when you are. By the time you feel drunk or off kilter, you are so far beyond impaired that it's frightening. The first signs are failure to perceive important pieces of data, and making bad decisions. So many people post here and say, "I've never been narced!" The manifestations are way too subtle to be recognized, a lot of the time.

Here is what I wrote in the thread 'Narcosis', which is forming the basis for a more in-depth article I am currently writing on the subject. In particular, please notice the paragraphs in blue ink...

Narcosis is always anaesthesic, but not necessarily inebriating.

Anaesthesic State: Total or partial loss of sensation, especially tactile sensibility.
Inebriated State: Exhilarated or stupefied.

Narcosis (anaesthesic) is likely to be present on any deep air/nitrox dive. The very fact that the primary and initial effect of narcosis is anaesthesic, means that the diver is less aware of any physiological changes that may effect their capabilities.

When a diver has sufficient experience that their core diving skills are instinctive, then they are unlikely to notice that narcosis. This is because narcosis primarily effects problem solving and stress reactions. If at an instinctive level, diving skills such as buoyancy, trim, navigation, buddy skills or even awareness of depth/time/gas can be easily performed even when the diver is otherwise significantly narc'd.

If you're enjoying a tranquil dive at depth, but not forced to problem solve, react to the unexpected or deal with stress, then it is possible that you wouldn't 'notice' even a relatively high degree of narcosis. It is a hidden danger.

That is what some divers mistake for 'acclimatization' to narcosis.

Divers only tend to notice if the narcosis becomes inebriating, or when they are called upon to problem solve or do other non-instinctive tasks. This can lead to a false sense of confidence in their capacity that is only exposed when an emergency or stressful event occurs (and inebriation becomes an apparent symptom).

As others have already mentioned.... CO2 retention may also cause a rise in the actual level of narcosis. Which causes a 'double-whammy' impact.... because CO2 levels tend to rise in emergency or stressful scenarios.

 

[DevonDiver]

That depends on your definition of both narcosis - which we can't seem to agree on even that - and also what you mean by management. I don't hear anyone claiming that you can eliminate narcosis, but I believe you can manage aspects of it.

Again, before you disagree, one would have to define the risks that are at issue. Would one be vaguing out & losing track of time/depth & air? Because I think you can manage to reduce that

I do agree. This is what I refer to as an 'ingrained' skill. When the skill is at a level of 'second nature, it is relatively unaffected by narcosis. 'Vaguing out' doesn't deteriorate the skills that you have locked down - it effects those that you haven't.

A sufficiently experienced and skilled deep diver should have 'second nature' buoyancy, trim, propulsion and awareness of time/depth/gas. For me, I even find that line skills, knot tying and general wreck diving procedures are unaffected by extreme narcosis/depth.

With diligent and repetative training, over a large number of dives, virtually any skill can be made 'second nature'. Shut-downs, DSMB deployment, lost line drills... you name it.

A less experienced diver, who does not have 'second nature' skills, will find themselves obviously incapacitated by narcosis at a much earlier stage. This is because those fundamental abilities will be significantly and observably deteriorated.

But, dispite all of that, a diver can be unknowingly narc'd to hell and totally incapable of responding effectively to any novel circumstances that force them to attempt to utilise skills or problem solving that is not 'second nature'.

It would be fine if every solution could be solved by a direct skill based solution. Unfortunately, they cannot. Some require problem solving, improvisation and/or the application of intelligence. When this is required, even the most experienced, narc acclimatized, deep air diver, with the best narc management, will find themselves suddenly debilitated and unable to react in the manner they expected.

 

[String]

People who go "ive never been narked" worry me more than people who admit to being narked. The latter group is aware they're impaired and adjusts their procedures accordingly. The former group is impared without realising or admitting it so makes no adjustments.

Training and repetition can hone instinctive reactions meaning they can be don't without any thought. "Practice makes perfect". When narked those instincts are probably still there. However what narcosis does to anyone is effect the concious part of the mind - the problem solving part. So while someone suffering can react find to something practiced like say a mask flood if presented with a problem they have to THINK their way through they cant and that's where it gets dangerous.
There is no physiological or biochemical evidence that shows the body makes any adaptations to the effects of narcosis at all (its been investigated and disproven) which blows the "build up and develop a tolerance to narcosis" theories out of the water. There is some evidence of short term mental adaptation in the instinctive reactions as above but that wont help with problem solving.

My main worry at 100m on air wouldn't only be the narcosis but more likely to be the Oxygen toxicity issues. You're way out on the edge of that bell curve for O2 tolerance, your WOB is incredibly high due to gas density, you're retaining CO2. Strikes me as playing roulette. Its something that IS going to get you on a dive to that depth at some point. Maybe not in 4 minutes but it still could. If you do it often enough it will hit you.

I'll dive to 55m on air abroad and yes although i feel that buzz of narcosis it isnt to me THAT bad. Using the normal "DATA" techniques and actively mentally (i concentrate by noting gas and depth on a slate every 2 mins and working out a SAC rate) and find that keeps me alert.

Below that its trimix all the way. In colder, darker UK waters i wont do 55m on air.

doing the descent feet first is the hardest part of the story for me. You gotta be alwfully heavy to sink fast in the feet first position. Just seems weird to me.

Not really, pointing the fins down as well means its pretty much the most efficient shape for a rapid descent. Ive managed 38m/min ONCE that way, 20-30 is normally what i plan for though. Once you start carrying twins and 3,4 or 5 stages you're going to sink rapidly after that first few metres. VERY rapidly.

Ive never read,heard, seen, witnessed or experienced any claimed reduction in narcosis from headup/feet down though at all. To me narcosis biggest factor is the descent rate. A fast descent i get hit far worse than a slow descent.

 

[Narced Out]

Tortuga, those dives sound awesome. I love deep diving. What did you see at 100m? was it really dark and cold? I cant wait to get back out and dive to 45m on air with my al 80.

 

[DevonDiver]

I've just thought of an analogy, that might make sense.

Ingrained and instinctive 'second nature' dive skills are like hardware.
Creative thought, improvisation and problem solving is like software.

Narcosis is like a computer virus. It affects the software, not the hardware.

You can perform a dive using the hardware, but you need the software to deal with emergencies or anything novel. To be safe, at any depth, you need a combination of both hardware and software, to deal with all eventualities.

 

[Centrals]

I remember the dives well, felt relatively clear-headed for most of them (the 90m dive was the one I felt most narc'd on) and happily I experienced no symptoms of either DCS or OT

I believe you were not doing any PSAI Narcosis Management course then.
Weren't you worried after the 90m dive as the narc might get out of hand on deeper dive and O2 toxicity(PPO2 2.31)?
Interest to break Mark Andrew's record? Plenty of experienced helping hands in PG!!

 

[Tortuga68]

No it wasn't a course dive - I did the NM course in 2009 with a max depth of 74m. I just relinked that thread in my OP here.

Naturally I was a little concerned about how dumb I felt at 90m, but it's always an option to thumb the dive, and that's what I would have done if I wasn't happy either during the descent or at the bottom for the 100m dive

OT wasn't a big concern - if I was that worried about it, I wouldn't have done the dive

I'm not interested in breaking that record, or any others for that matter. Mark was lucky to walk away from the dive. Next time I go to 100 will most likely be on trimix

 

[Centrals]

Next time I go to 100 will most likely be on trimix

Mark Andrew was indeed very lucky after reading the report on Philipppine Divers all those years ago.

The helium bill for a 100m dive will be horrendous.

 

[Tortuga68]

Not really, you could be on trimix for the bottom phase only, with a travel gas