That won't help, sorry. It is still a good course to take, and can be very useful with NDLs,
Too shallow to get narced?
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Nitrox doesn't help avoid narcosis. Although Nitrox contains more oxygen and less nitrogen than air, the oxygen is narcotic, too, just like the nitrogen. Most of the oxygen is bound to hemoglobin and metabolized. The gas that ultimately diffuses into your tissues and contributes to narcosis is still nitrogen. The only way that you can reduce the narcotic effect of your breathing gas, other than to not dive so deep, is to breathe a gas that is less narcotic than nitrogen and oxygen, and that gas would be helium.
On the flip side, if you don't consider O2 narcotic and he was breathing 36% at 80', EAD would be 58'.
I'm no expert in dive physiology, but my high level understanding was that since O2 can be metabolized it's not a significant contributor to narcosis.
While Oxygen may or may not give a narcotic effect (at least compared to nitrogen), Nitrox is probably not going to make a big difference in terms of gas narcosis. It's still great to have to decrease the nitrogen loading giving you a longer NDL, but I wouldn't count on it when it comes to narcosis.
The more I read, listen and learn about scuba, the more convinced I am that the real problem underwater is CO2. And CO2 retention is directly affected by gas density and work of breathing (WOB). CO2 also has the nasty habit of making you hyperventilate, and the increased WOB at depth that exacerbates the shallow and inefficient ventilation - leading to more CO2 retention. Also, CO2 makes you more panicky and less coordinated, which can lead to a lot of wasteful movements and more CO2 production. Yes, it's a vicious cycle. This is also why helium is so efficient at decreasing narcosis - not only does it lower the concentration of narcotic gas, it also decreases the gas density and makes ventilation easier.
I this is one of the reasons why nerves and experience influence narcosis so much, because nerves affect our breathing. The more experienced, relaxed and comfortable you are, the less you are likely to be affected by CO2 retention. As an added bonus, the experience lets you handle the effects of narcosis better, because the dive takes less mental capacity and you're more likely to do the right things when it hits - slow down, deep breaths, etc. I know I've had very different experiences from dive to dive in the depth range of 20m to 30m, from feeling perfectly fine to feeling narced out of my mind. My worst experience underwater was a bad "dark narc" at 30m, which I attribute to being a little nervous + a very tight weight belt restricting my breathing...
So, my advice would be:
- If you feel nervous, uneasy, maybe do a shallower dive, or be ready to ascend if necessary
- Remember to stop, breathe, think, act - slow and steady. When panick hits it can go downhill fast.
- Be careful with gas density (My training agency sets the limit at 30m for air/nitrox)
The more I read, listen and learn about scuba, the more convinced I am that the real problem underwater is CO2. And CO2 retention is directly affected by gas density and work of breathing (WOB). CO2 also has the nasty habit of making you hyperventilate, and the increased WOB at depth that exacerbates the shallow and inefficient ventilation - leading to more CO2 retention. Also, CO2 makes you more panicky and less coordinated, which can lead to a lot of wasteful movements and more CO2 production. Yes, it's a vicious cycle. This is also why helium is so efficient at decreasing narcosis - not only does it lower the concentration of narcotic gas, it also decreases the gas density and makes ventilation easier.
I this is one of the reasons why nerves and experience influence narcosis so much, because nerves affect our breathing. The more experienced, relaxed and comfortable you are, the less you are likely to be affected by CO2 retention. As an added bonus, the experience lets you handle the effects of narcosis better, because the dive takes less mental capacity and you're more likely to do the right things when it hits - slow down, deep breaths, etc. I know I've had very different experiences from dive to dive in the depth range of 20m to 30m, from feeling perfectly fine to feeling narced out of my mind. My worst experience underwater was a bad "dark narc" at 30m, which I attribute to being a little nervous + a very tight weight belt restricting my breathing...
So, my advice would be:
- If you feel nervous, uneasy, maybe do a shallower dive, or be ready to ascend if necessary
- Remember to stop, breathe, think, act - slow and steady. When panick hits it can go downhill fast.
- Be careful with gas density (My training agency sets the limit at 30m for air/nitrox)
The Chairman
Chairman of the Board
You rarely ever "feel" narcosis. Your two biggest clues, walking and talking, are absent underwater.
Negative, Ghost Rider. O2 is just as narcotic as N2. You'll be able to mitigate N2 becoming a deco problem a bit, but it will have no effect on narcosis. He2 can alleviate most narcosis, but it has a few other issues.
I have dove with an instructor one time who suffered from narcosis, and we hadn't been deeper than 85 ft, He knew what was happening so was able to control the situation, He was just as supprised as me and said.."It happens"
OP
freeflowigb
Registered
Apparently I was under the wrong impression that reducing nitrogen content would fix the narcosis issue to an extent. I am glad to know it won’t before I tried that. Again SB saves me money, time and useless effort.
Might as well keep my diving shallower and work on my general fitness underwater in terms of breathing and not overexerting, and when the time is right I will venture deep again, better armed with knowledge and stuff - I did not even have an SMB with me, a torch and a cutting tool.
But man was it an exciting experience. I liked diving with sharks, but this was a whole different story - there is the real man made object that at some point people walked on, talked and made friends, and now it is resting in what it was supposed to conquer. Otherworldly.
Might as well keep my diving shallower and work on my general fitness underwater in terms of breathing and not overexerting, and when the time is right I will venture deep again, better armed with knowledge and stuff - I did not even have an SMB with me, a torch and a cutting tool.
But man was it an exciting experience. I liked diving with sharks, but this was a whole different story - there is the real man made object that at some point people walked on, talked and made friends, and now it is resting in what it was supposed to conquer. Otherworldly.
Also since we're on the topic of NN how does everyone feel about the Mount-Milner studies?
Edit from TDM issue 2:
THE MOUNT-MILNER TEST
In 1965 a research project was conducted by professional diver Tom
Mount and psychiatrist Dr. Gilbert Milner to determine the effects
of anticipated behavior modeling in diving students with respect
to narcosis. Three control groups of four students with equal male/
female ratios were trained in identical dive classes except:
Group One was taught that a diver will get narcosis at 130 fsw (39.4
m), and much emphasis was placed on the high probability of narcosis
impairment with severe symptoms.
Group Two was taught of the existence of narcosis, the symptoms and
depths of occurrence cited as beginning at 100 fsw (30.3 m), but were
not as intimidated with narcosis manifestations.
Group Three was well educated on narcosis with three full hours of
lecture on symptoms, risk, danger and known research. They were
told that divers with strong will power as postulated by Miles (1961)
could mentally prepare themselves and greatly
reduce the effects.
Prior to the open water deep dives all students were given two dives
to 30 fsw (9.1 m) and two dives to 100 fsw (30.3 m) to develop good
breathing techniques.
Before the actual dives for testing purposes, the students were
taken on a 50 fsw (15.2 m) dive where the tests were performed so
a mental/dexterity familiarity could be achieved with the format of
the test problems. Changes were then made in the test so they could
not be performed from memory. The tests consisted of handwriting
evaluations, pegboard testing, math, and ball bearing placement in a
long-necked narrow bottle etc.
In the initial test depth of 130 fsw (39.4 m), divers in Group One
had minor-to-above-average narcosis problems while Group Two and
three divers had little effect on test scores.
At the 180 fsw (54.6 m) test depth, two Group One divers dropped
from the exercise due to severe narcosis problems and were removed
from the dive. All Group Two divers were affected although still
functioning at about 50% test levels. Group Three divers had minor
impairment.
At the 200 fsw (60.6 m) test depth, all divers in Group One and two from
Group Two were dropped due to severe narcosis and apprehension.
Group Three divers actually showed slight improvement in test scores.
At the 240 fsw (72.7 m) test depth, one diver was dropped from Group
Two and one from Group Three due to severe narcosis. The remaining
Group Two diver and three Group Three divers showed levels of
impairment but again scores and performance showed improvement
over the previous depth level. One diver, a female from Group Three,
registered her highest scores on all tests at the 240 fsw (72.7 m) level.
Concurrent testing of experienced deep divers showed seven out of
ten divers with no decrease in performance or scores at the 200 fsw
(60.6 m) test level. The three divers with decreased performance
finished the testing (two with perfect scores) but required additional
time than was usual. At 240 fsw (72.7 m), five out of ten performed
all tests with no decreased performance. One diver had problems
with the ball bearing test but perfect scores on the pegboard, math
and handwriting. The other two showed up to 42% deficits and had
problems completing the tests.
The obvious conclusions include a subjective validation to both
“adaptation” and the negative influence of “modeling” behavior in
those groups of divers pre-conditioned that narcosis was inevitable
and severe. The Group Three divers with little prior diving experience
were satisfactorily still performing at the 200 fsw (60.6 m) level and
three divers continued to perform (with one showing improvement
still) at the 240 fsw (72.7 m) test level.
If we teach our children that all dogs will bite, we can safely assume
that when presented with a specimen even as lowly as a toy poodle
(which should probably be shot on sight anyway), we can expect a high
fear index. Likewise, if we teach our dive students that narcosis is a
finite, unyielding biophysical wall, then we can logically expect such
conditioning to impair their performance beyond a more realistically
educated diver lacking pre-conceived phobias and suggestions.
Education is the key to performance and safety
Edit from TDM issue 2:
THE MOUNT-MILNER TEST
In 1965 a research project was conducted by professional diver Tom
Mount and psychiatrist Dr. Gilbert Milner to determine the effects
of anticipated behavior modeling in diving students with respect
to narcosis. Three control groups of four students with equal male/
female ratios were trained in identical dive classes except:
Group One was taught that a diver will get narcosis at 130 fsw (39.4
m), and much emphasis was placed on the high probability of narcosis
impairment with severe symptoms.
Group Two was taught of the existence of narcosis, the symptoms and
depths of occurrence cited as beginning at 100 fsw (30.3 m), but were
not as intimidated with narcosis manifestations.
Group Three was well educated on narcosis with three full hours of
lecture on symptoms, risk, danger and known research. They were
told that divers with strong will power as postulated by Miles (1961)
could mentally prepare themselves and greatly
reduce the effects.
Prior to the open water deep dives all students were given two dives
to 30 fsw (9.1 m) and two dives to 100 fsw (30.3 m) to develop good
breathing techniques.
Before the actual dives for testing purposes, the students were
taken on a 50 fsw (15.2 m) dive where the tests were performed so
a mental/dexterity familiarity could be achieved with the format of
the test problems. Changes were then made in the test so they could
not be performed from memory. The tests consisted of handwriting
evaluations, pegboard testing, math, and ball bearing placement in a
long-necked narrow bottle etc.
In the initial test depth of 130 fsw (39.4 m), divers in Group One
had minor-to-above-average narcosis problems while Group Two and
three divers had little effect on test scores.
At the 180 fsw (54.6 m) test depth, two Group One divers dropped
from the exercise due to severe narcosis problems and were removed
from the dive. All Group Two divers were affected although still
functioning at about 50% test levels. Group Three divers had minor
impairment.
At the 200 fsw (60.6 m) test depth, all divers in Group One and two from
Group Two were dropped due to severe narcosis and apprehension.
Group Three divers actually showed slight improvement in test scores.
At the 240 fsw (72.7 m) test depth, one diver was dropped from Group
Two and one from Group Three due to severe narcosis. The remaining
Group Two diver and three Group Three divers showed levels of
impairment but again scores and performance showed improvement
over the previous depth level. One diver, a female from Group Three,
registered her highest scores on all tests at the 240 fsw (72.7 m) level.
Concurrent testing of experienced deep divers showed seven out of
ten divers with no decrease in performance or scores at the 200 fsw
(60.6 m) test level. The three divers with decreased performance
finished the testing (two with perfect scores) but required additional
time than was usual. At 240 fsw (72.7 m), five out of ten performed
all tests with no decreased performance. One diver had problems
with the ball bearing test but perfect scores on the pegboard, math
and handwriting. The other two showed up to 42% deficits and had
problems completing the tests.
The obvious conclusions include a subjective validation to both
“adaptation” and the negative influence of “modeling” behavior in
those groups of divers pre-conditioned that narcosis was inevitable
and severe. The Group Three divers with little prior diving experience
were satisfactorily still performing at the 200 fsw (60.6 m) level and
three divers continued to perform (with one showing improvement
still) at the 240 fsw (72.7 m) test level.
If we teach our children that all dogs will bite, we can safely assume
that when presented with a specimen even as lowly as a toy poodle
(which should probably be shot on sight anyway), we can expect a high
fear index. Likewise, if we teach our dive students that narcosis is a
finite, unyielding biophysical wall, then we can logically expect such
conditioning to impair their performance beyond a more realistically
educated diver lacking pre-conceived phobias and suggestions.
Education is the key to performance and safety
L13
Contributor
My understanding was that the latest dive science suggests that O2 probably isn't narcotic. See this post by @Dr Simon Mitchell :
Equivalent Air Depth question
Okay so I have a question. I’m currently working towards my ADCI card. (commercial diver card). On the commercial side we use Bimix so HeO2. Why on the TECH or REC side do we use TRIMIX? Wouldn’t it be easier and actually safer to take nitrogen out of the picture? I understand by using...
L13
Contributor
Don't give up on this too soon. see my prior post.
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