Ever narked? Never!

[Steve S]

In my younger days I was in the 'I don't get narced camp' then I realised I was but wasn't aware of it, AFAIC that is the most insidious one, if you feel anxious or euphoric you know there is a problem and hopefully you can take steps to remedy this, but if you are mired in a gentle fog if something goes wrong you may not be able to react to it.

I'm also in the continually checking camp but hand on heart I don't feel that much difference on mix than on weak nitrox, but then I am woolly and befuddled on the surface

It is a personal thing and we all react differently and also at varying depths but I have found descending very slowly helps me, as does a long and slow exhale and avoiding exertion.

Safe diving,
Steve

[al kennedy]

oh yes....

10m on the Pins wreck in Strangford, appalling vis, pitch black. i'd arranged with my buddy beforehand to do gas-sharing drills, making a random unarranged signal during the dive. she got in first, and signalled she was OOG, i stared at her for several seconds thinking wtf does that signal mean, i've never seen it before... then it all clicked into place...

on the Laurentic i went after a lovely porcelain 'pull' from an old cludgy, the sort with a cistern at head-height, i spotted it between the beams squeezed down to get it. i was so chuffed. when i pulled it out of my pocket on the surface it had transformed into a lead fishing weight...

fast descends (CO2) and dark conditions/poor viz really gets me going.

[principia]

Can some explain the thinking or science behind the fast descents and C02 that people keep mentioning?

I tend to descend pretty quick and the last dive I did out of Brid I got really bad narcosis but put that down to the previous 40 dives being in warm clear water.

J.

[ardhill]

I feel some sort of cognitive change every time I am diving, no matter what depth.

Sure there are some factors which produce greater narcosis - depth, darkness, speed of descent, mindset just before descending, hard work just before descending.

Me narked - Yep every time, it's just the degree of narcosis that varies.

[SoggyFox]

Originally Posted by principia

Can some explain the thinking or science behind the fast descents and C02 that people keep mentioning?

i'm sure someone will be along with the full version but i believe it to be a result of quickly increasing PPCO2 in your body.

[Mal Bridgeman]

Originally Posted by principia

Can some explain the thinking or science behind the fast descents and C02 that people keep mentioning?

I tend to descend pretty quick and the last dive I did out of Brid I got really bad narcosis but put that down to the previous 40 dives being in warm clear water.

J.

I shall attempt a layman's description ... but if Mr Hobbs is reading I am sure he can do a much better job.

I think it's to do with increasing partial pressures of the gases acting upon tissues (synapses) in the brain and causing them to constrict and process info more slowly. The amount of constriction seems to vary with the speed at which you increase the partial pressure so the faster you descend the quicker the pp changes and the more befuddled you get. Adding Helium to the breathing mix, which is a very "thin" gas, has the effect of "relaxing "those tissues and reducing the narcotic effect.

CO2 is a much more dense gas than nitrogen so when the ppCO2 starts to become significant then it's impact on the tissues is much greater. Rather than causing a befuddled forgetful effect of nitrogen, though, it causes the fear dread and panic feelings described.

HTH
Mal

[principia]

Cheers Mal, I hadn't really thought or known about this before. I just thought that I'm one of those people that gets narced in anything deeper than a bath.

I think I will try descending a bit slower and see if it feels any better. Failing that I guess I am going to have to get a squirt of helium into the mix.

J.

[Jules]

At 30m i dont feel narked but my camera controls get more difficult to use... so i think that's caused by narcosis, it's the camera that narked not me.

By 45m on air I am pretty well off my head with my heart pounding in my ears and I spend the whole time checking my contents gauge and computer without really registering what either is telling me, I can also feel a voice in my head screaming "get me out of here", as i go shallower say back to 35m I feel fine and I wonder what all the fuss was about, by 20m i feel great and I can even work my camera.

Jules

[Ahmed Adly]

Narcosis is a VERY slippery customer because, just like Anesthesia, it's mechanics are a total mystery. In both cases we do have a ball park figure for amount and effect though.

Yesterday, I completed a Deco Procedures course with some exceptional students. We polished off the course with a nice 20 minute drift dive at 45 meters and visited the good old Giftun Tunnle.
They did claim to feel effected by narcosis a bit but each had brief and unique descriptions about their symptoms as it seemed of lesser priority than the huge groupers we saw and the nice color of the cave walls.

I do suspect that reaction times under narcosis are slow as well.

[SilvaFish]

Originally Posted by ardhill

I feel some sort of cognitive change every time I am diving, no matter what depth.

Sure there are some factors which produce greater narcosis - depth, darkness, speed of descent, mindset just before descending, hard work just before descending.

Me narked - Yep every time, it's just the degree of narcosis that varies.

Yep, agreed with this one. It depends with me; I start to FEEL narked at around 27m. I am aware of a slow down below 10m, but not enough to really notice. Personally, I think I get narked pretty easily and tell my buddies this (err on the side of caution). There are a small handful of people who won't dive with me because I get narcosis (maybe they think it's bad that I mention this to them before hand?) but these are the same people who do not admit to ever getting narcosis or getting problems; so what attitude makes a safer diver? Anyway, no love lost with them!

Back to the question though, slower descents also mean less narcosis for me, and Nitrox doesn't make a jot of difference apart from post dive.

Cheers,
Lou