Narcosis

[xjeslesx]

Lucky this incident did not result in a dive accident.
I was recently on vacation in the Florida Keys. We diving the wreck of the Duane approx 135' max depth. As I decended I dropped past the superstructure, past the main deck, and stopped my decent along the hull of the ship. I was on the lee side so current was not an issue. I was at approx 120' breathing 28%. I've done other dives under these (comfortable) conditions, warm water, unlimited viz.
I looked along the hull and saw a 150lb+ grouper charging at me, which caught me very off guard considering goalith grouper are usually pretty shy. The fish charged me and about 1' or less from me changed course and swam over my head and onto the main deck of the ship.
This sudden shock possibly coupled with narcosis I was unaware of sent me threw a loop. I suddenly felt very narced and therefore uncomfortable at that depth. I promptly ascended to 90', I collected my thoughts and continued the dive, which wound up being a fun/enjoyable dive.

Has anyone else experienced this sudden 'Narc'?

 

[Bubbletrubble]

You may have been experiencing CO2 retention +/- narcosis. The charging grouper probably elicited a stress response (sympathetic nervous system) which caused you to breathe more quickly and with shallower breaths. FWIW, it is thought that CO2 retention may either lower the threshold for narcosis or amplify narcosis symptomatology.

Perhaps this thread should be moved to the "Near Misses and Lessons Learned" sub-forum?

 

[Duke Dive Medicine]

Narcosis is a strange phenomenon. It affects different people in different ways, and it has different effects on the same person. Many people think that euphoria is the only side of narcosis, but it can also induce fright. This may be what happened when you saw that giant set of lips charging at you - you had likely been experiencing the symptoms of narcosis that you've become accustomed to dealing with, then something changed.

 

[RogerAGrimes]

BTW, the Goliath grouper was probably not "charging" you, if you meant he was intending to be threatening. Maybe so, but probably not. The Goliath groups in Key Largo are apparently hand fed often. The last couple of years, I've had them go between my legs, swim beside me, stare at me, "chase" me...but when they figure out that I'm not going to feed them, they lose interest. The barracuda are getting the same way on most of the wreck dives. Instead of being shy, they are literally pests...although it does make for great photo ops and video. Still, I'd rather humans not hand feed face. Not natural. Nothing good can come of it.

 

[DCBC]

...Has anyone else experienced this sudden 'Narc'?

Narcosis isn't sudden; you were most likely experiencing symptoms from 50 feet but just didn't realize it. The affect varies and it depends upon your experience and will change (as has been mentioned) from day-to-day. Deep diving on air can be safe, but it takes acclimatization. One analogy might be breathing atmospheric air at a high altitude; you can adapt to a degree, but it takes patience and repetitive exposure.

 

[PfcAJ]

Narcosis isn't sudden. Its always there, but sometimes you don't notice it. The affect varies from day to day, but narcosis is always present. CO2 makes things much worse. Diving deep on air really isn't safe, and acclimatization is really just "getting used to the affects", and does nothing for anything besides repetitive tasks. This is unlike breathing air at high altitude, as there is a physiological change at altitude over time.

 

[LeadTurn_SD]

1+ to the above comments.

I do think there is a lot of variation in narcosis, but I also don't believe it just "hits". It may just not be noticed until the effects are obvious.

My personal experience is that narcosis really is in many ways like the old "Martini's Law" we learned. And for me, I may not feel particularly impared until something completely unexpected happens... then I do notice that I'm mentally "slower" or "fuzzy". Although not quite like being drunk, for me there are similarities, and if I pay really close attention I can start to feel slight differences beginning at maybe 50-60 feet, increasing to (for me) noticeable narcosis at about 150' mark.

So, yes, I've had times where I suddenly "felt" how much narcosis I was experiencing, but not that I was suddenly "narc'ed".

Oh, and to the OP (xjeslesx): Good job on recognizing that you were having a problem and correctly responding by ascending.

Best wishes.

 

[Chris Brown Tech]

Did you drop quite fast? Was it a free descent?

That will get you narked for sure, especially as you went past the main deck at 100'ish.

Was it leisurely or a "woohooo!!" kind of descent?

Anyway, you had the smarts to ascend and get your ducks in a row, therefore a good learning experience.

The Duane is awesome isnt it?

 

[DevonDiver]

+1 for the comments reflecting pre-existing, but un-noticed narcosis.

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.

 

[Duke Dive Medicine]

You Brits and your spelling of "anesthesia". Always with the extra letters. Thanks for elaborating, Devon.
One small note for all: while it's true that increased CO2 levels will exacerbate nitrogen narcosis, it's very unlikely that this is what happened in the case of this diver. If a diver is hyperpneic (breathing rapidly), it would take very small, dead-space only ventilations to cause an elevation in blood pCO2. Think of a panting poodle. Most probably, the rapid breathing that the OP experienced from his unexpected encounter would have dropped his CO2 level, not increased it.