How Does Narcosis Effect You?

[bl6394]

150 ffw on air - feels about like two beers. I'm functional - but reaction time slowed.

203 ffw on air: I only stayed briefly - and could only concentrate on one thing at a time - and not very well. I was significantly impaired.

Unless it's a very comfortable dive (warm, OW, non-penetration) - below 130 ffw - I dive mix.

Bjorn

 

[Yoyoguy]

The one time I was really aware of being narced was on a dark, cold dive to 100' in Lake George on the Radeau. Short term memory loss was very obvious.

I will echo this! Cold, 100ft dive in Lake George on the Radeau. This was the first time I felt Narced. I got a little anxious for a few seconds and then told myself "this is what narcosis feels like, don't panic". I then began to calm down and all was well. It hit me really hard when I hit the bottom and then as I calmed it seemed to start to go away and I really started to enjoy the dive. I have since been that deep or deeper in cold dark areas and have experienced being narced but nothing was ever like that first time. I find if I keep myself slightly task loaded, it helps...for example I make sure I am checking my dive comp more often than I normally do on shallower dives especially since if you are narc'd you might forget the readings on the comp the first time you looked at it

 

[packrat12]

I can say I have been more narc’d on helium (19/20) then on air when diving to 176’.

One of the things missing in this question, although inputted by some, is what was going on when the narcosis was experienced. When I was more narc’d on helium, I was pulling down hard in a strong current and had built up CO2. The air dive was a hot drop and easy. I was able to do complex tasks without issue. On helium, I was slower to do easier tasks. Helium is not the end-all in narcosis. A more holistic approach is needed due to the multiple factors that cause narcosis.

CO2 is 25x more soluble then Nitrogen (25x more narcotic). It definitely plays a very important role in narcosis and yet is ignored by most divers. I would be willing to bet that a significant number of divers that come up saying “wow I was narc’d” would also say that they were exerting more than normal.

Net result for me: It is not just air that needs to be taken into consideration when talking about being narc’d. We need to take into account things such as stress, physical exertion ect. I personally will never call it Nitrogen Narcosis. I use just Narc’d or Inert Gas Narcosis because it better describes the real causes of narcosis.

Great article by Johnny Brian
Carbon Dioxide, Narcosis, and Diving | Global Underwater Explorers

 

[oldschoolto]

John Chatterton did a good write up on CO2, The name of it was.. Diving with Stevie Wonder..

Diving with Stevie Wonder

Jim....

 

[Kevrumbo]

CO2 Retention/Hypercapnia and Narcosis: Deep Air with increased Gas Density & Work-of-Breathing Dyspnea; then throw in Physical Exertion or a Stress Condition, resulting in overbreathing the regulator --all leading to the Vicious Cycle of CO2 Retention and sudden Narcosis (also known as the panicky feeling "Dark Narc"). Can result in severe cognitive impairment at depth or worst case stupor and ultimately unconsciousness. . . In order to break this CO2 build-up cycle, you have to relax with a few minutes of full slow controlled inspiration breathing: --cease & desist all physical exertion that stimulates hyperventilation and abort the dive if indicated.

Taken from Undersea Biomedical Research, Vol 5, No. 4 December 1978 Hesser, Fagraeus, and Adolfson:"Studies on the narcotic action of various gases have shown that the ratio of narcotic or anesthetic potency of CO2 and N20 approximates 4:1, and that of N2O and N2 30:1. From these figures it can be calculated that CO2 has at least 120 times the narcotic potency of nitrogen. Our data would suggest that the narcotic potency of CO2 is even greater, i.e., several hundred times as great as that of nitrogen.

"

Originally Posted by TSandM
Overbreathing the regulator MEANS a CO2 hit . . . It means the increased work of breathing of using a regulator is enough, at the current demand, to prevent you from exhausting all your CO2. All regulators can deliver more gas, faster than you can use up oxygen, but the small increase in resistance involved in trigger the inlet valve and opening the exhaust valve can make the difference between being able to keep your CO2 normal under heavy work loads, and not being able to keep up.
http://www.scubaboard.com/forums/ad...8-panic-experienced-diver-20.html#post6414337
Panic in the experienced diver?

Originally Posted by TSandM
CO2 in the bloodstream is completely determined by minute ventilation, assuming the gas you are breathing does not contain additional CO2. Bailing to open circuit definitely makes it POSSIBLE to reduce the blood CO2 level, assuming you can achieve a higher minute ventilation than what's required to keep the CO2 where it is (which is in part related to level of exertion). It may not, however, be possible to reduce CO2 fast enough to clear your head and get rid of the panicky feeling, in part because the natural tendency when panicky is to breathe as fast as possible. On scuba, this means reducing the efficiency of the ventilation, because too much of it is just going to exchange gas in the trachea and large bronchi, which don't exchange gas. That's why we are taught in OW that, if we begin to "overbreathe our regulator" (meaning the diver feels short of breath despite breathing as much as he can), we are to STOP, hang onto something (reduce exertion) and breathe SLOWLY and DEEPLY. It is then possible to reduce CO2. What may not be possible is to stay rational long enough to do it.
http://www.scubaboard.com/forums/ad...8-panic-experienced-diver-16.html#post6135411
Panic in the experienced diver?

 

[certified in 1976]

Its not just based on depth. The only time I have ever been narc'd was when very foolishly diving on a cold dark 110 ft wreck in Lake Ontario with a bad hangover from a night of partying and little sleep. I had been on that same wreck twenty times previously with never a problem but that day I was completely out of it and semi panicked as it was my first experience with being narc'd.

In contrast I once (also foolishly) went down to a 170 ft bounce dive in the Caribbean on air but had no signs of narcosis.

 

[MXGratefulDiver]

Its not just based on depth. The only time I have ever been narc'd was when very foolishly diving on a cold dark 110 ft wreck in Lake Ontario with a bad hangover from a night of partying and little sleep. I had been on that same wreck twenty times previously with never a problem but that day I was completely out of it and semi panicked as it was my first experience with being narc'd.

In contrast I once (also foolishly) went down to a 170 ft bounce dive in the Caribbean on air but had no signs of narcosis.

Physiologically, you were just as narc'd each time ... the difference was in your perception of your condition. As long as everything's going as expected, you can manage your dive just fine with no noticeable (to you) sign of impairment. But you are still impaired, and that impairment will still affect your ability to recognize a problem, your ability to decide what to do about it, and your ability to react once you've made that decision.

People who claim they aren't narc'd on those deep dives are deceiving themselves. They're narc'd ... they just don't notice it. Often, however, their buddy does ...

... Bob (Grateful Diver)

 

[certified in 1976]

Physiologically, you were just as narc'd each time ... the difference was in your perception of your condition. As long as everything's going as expected, you can manage your dive just fine with no noticeable (to you) sign of impairment. But you are still impaired, and that impairment will still affect your ability to recognize a problem, your ability to decide what to do about it, and your ability to react once you've made that decision.

People who claim they aren't narc'd on those deep dives are deceiving themselves. They're narc'd ... they just don't notice it. Often, however, their buddy does ...

... Bob (Grateful Diver)

Also possible I could have still been drunk from the night before. At any rate it was the worst dive of my life and I`ve never got drunk the night before diving since. Did some dumb stuff in my younger years.

 

[rhwestfall]

My tech instructor talks of a dive one year where he was setting the mooring line for the season. The wreck was an old sailing ship, with an intact crow's nest on a fallen mast, and in the 130-150' range. Pre-dive he had talked with the other diver bout checking out 'nest while on the dive. When the dive was over, he said to his partner, "We didn't check out the 'nest". His buddy replied, "You were sitting on the mast right next to it coiling the mooring line before sending the float to the surface"....

Yep, needed a little He on that one..

 

[DevonDiver]

From my experience:

30-40m (100-130ft): Some slight mental 'dullness'. Less vibrant thinking and slightly decreased situational awareness of periphery stimulus. Loss of situational awareness and 'joining-the-dots' only apparent once the same familiar sites have been dived using trimix. Few, if any, skills degraded. Able to problem solve and anticipate problems. Easy to follow the dive plan, operate equipment and monitor other divers.

40-60m (130-190ft): Decreased problem-solving ability. Some confusion if the unforeseen happens. More easily disorientated. Less information goes from the eyes to the brain. Navigational confusion on unfamiliar sites. Emotional state can be exaggerated, but kept under control. Need to consciously focus to achieve less ingrained tasks. Ingrained skills and procedures unaffected, but feel the need to double-check any assumptions and monitor gauges more deliberately. Difficulty doing mental calculations (i.e.gas consumption predictions). Some self-discipline needed in decision making to retain prudent risk management.

60-90m (190-290ft): Significant loss of awareness and perception of the environment. Tunnel vision on immediate task at hand, but dive plans followed successfully if sufficient concentration and a high degree of self-discipline is maintained consistently. Non-routine tasks completed only through extreme focus. Thought processing feels like pushing your hand through thick syrup; noticeably sluggish and slow intellectual capacity. Navigation extremely difficult. Significant post-dive amnesia on the deeper end of this depth range difficult to remember any clear details from the dive; all observations (wreck identification dives) needed to be written on a slate at depth, or they would be lost from the memory upon surfacing. Strong exaggeration of emotions - experienced total euphoria on one particularly picturesque descent. No noticeable impact on physical coordination or dexterity.

Here's my article on the subject: Nitrogen Narcosis - Perceptions of Susceptibility