My first ever oh sh*t moment. (CO2 hit?)

[UofMI_Divegeek]

I have never heard the term "dark narcosis."
But,
A feeling of dread, discomfort, unease, and lack of confidence is quite common in cold, low visibility waters. My first experience with this phenomena is at

Being Stalked

Remember that CO2 is known to precipitate narcosis (and other bad things) and EANx has been demonstrated to enhance CO2 retention. This CO2 retention was so robust that the Israeli military was considering CO2 tolerance testing of its combat swimmers (and recreational divers) using oxygen enriched air mixtures.

A table of relative narcotic potency is attached

So, while the described symptoms may have a narcosis component, it is highly likely that CO2 buildup was a significant factor in this experience.

 

[steinbil]

After speaking with several divers more experienced than myself, as well as the feedback in this thread, I'm leaning towards gas narcosis. The cold, dark water, and my slight discomfort/inexperience might have turned it into a "dark narc" or an anxious/paranoid effect rather than a careless buzz. I'm still wondering if, given the higher narcotic effect of CO2, that a slightly elevated level of CO2 might influence the type/strength of narcotic effect. And in that case, if poor ventilation, due to being uncomfortable and with a very tight weight belt, could have lead to a very slight elevation in CO2 to add to the gas narcosis I was already experiencing. So I'm quite sure it was not a "CO2 hit", but it might have been a factor.

I've since been back to the same depths in the same area, in similar conditions, without anything more than a slight buzz.

 

[berndo]

... it is highly likely that CO2 buildup was a significant factor in this experience.

Based on what?

Can you specify, what part of the story makes you think CO2 could have been a significant factor or any factor really?
I read the report you linked to. Wouldn't you agree with me when I say you're really just guessing? Feeling uneasy will increase the effect of narcosis. It's a very run or the mill case of narcosis.

I have been very hammered form narcosis but only twice I got scared from it. Different circumstances than the OPs but pretty close to the 'I don't wanna die here' type feeling and quite severe. I didn't exert myself in either case.

In other cases I exerted myself, like in my example and I felt no narcosis whatsoever. How is this possible when a little CO2 allegedly causes severe narcosis in other people.

 

[UofMI_Divegeek]

Of course, most post-dive (Monday morning quarterbacking) analysis is speculation.

But, DCS, narcosis, etc are all subject to your body chemistry on the day you dive. So, it is not unusual for different symptoms to be observed on the "same dive" on different days.

 

[berndo]

The cold, dark water, and my slight discomfort/inexperience might have turned it into a "dark narc" or an anxious/paranoid effect rather than a careless buzz.

This passes the duck test.

I wouldn't try to read too much into it, unless there is some actual evidence, which at least I can't find in your story.
The only thing that kind of points towards CO2 is the headache but that can easily be cause by stress and being tense.
When people breath too little and try to save gas (which we used to call instructor breathing), the headache usually lingers for a while after the dive.

 

[berndo]

But, DCS, narcosis, etc are all subject to your body chemistry on the day you dive.

Yes, of course, I agree.
Having said that, I find it quite a stretch to say '... it is highly likely that CO2 buildup was a significant factor in this experience.'