Nitrox: Narcosis myth?

[tarponchik]

Fair enough. But people were diving close to the line. Seems that close to the line nitrox might give less stress and less fatigue. Do you think this is unlikely?

I've always been skeptical of such claims cause I've never felt "diver's fatigue" myself and I haven't seen any plausible scientific explanations of why the excess of N2 should make you tired. And even if for some people diving is more strenuous than for me, what's the connection with DCS? So I'm in favor of the most simple explanation: the lesser N2 accumulation, the fewer cases of DCS.

 

[RainPilot]

The majority being you and...she/he/it the @RainPilot? Or I forgot someone?

S/he is a pretty standard internet way of referring to a poster when the gender is unknown and one is trying to be polite.

Unlike you, I put my name to my postings so there really isn't much doubt about my gender.

She/he/it is just being passive aggressive and stirring. Like every other time you are involved in a thread.

There are a lot more than 3 who disagree with you, unfortunately most of them are too polite to hijack an entire thread arguing with you over your issues.

Apologies OP for the hijack, I'm out.

 

[Steve_C]

On multiple diving days in the 80-90 ft range, on nitrox on ride NDL on dive 1 and on dive 2

I haven't seen any plausible scientific explanations of why the excess of N2 should make you tired. And even if for some people diving is more strenuous than for me, what's the connection with DCS? So I'm in favor of the most simple explanation: the lesser N2 accumulation, the fewer cases of DCS.

Lesser N2 fewer DCS is data since Wookie's sample is large.

However, that is separate from the "Fatigue" issue. When I was younger a couple beers during the day had no noticable effect (at least to my perception). But now I find that if I have a beer or two earlier in the day, say at lunch, it tends to make me feel more tired in the afternoon so I generally avoid it. N2 has an effect on the nervous system. Why could it not have a similar affect on some people and they call that "after dive fatigue". Does not prove anything one way or another but does suggest a possible mechanism

 

[cneal]

When I was younger a couple beers during the day had no noticable effect (at least to my perception). But now I find that if I have a beer or two earlier in the day, say at lunch, it tends to make me feel more tired in the afternoon so I generally avoid it.

I have the same problem, but just blame lack of practice.

 

[tarponchik]

On multiple diving days in the 80-90 ft range, on nitrox on ride NDL on dive 1 and on dive 2


Lesser N2 fewer DCS is data since Wookie's sample is large.

However, that is separate from the "Fatigue" issue. When I was younger a couple beers during the day had no noticable effect (at least to my perception). But now I find that if I have a beer or two earlier in the day, say at lunch, it tends to make me feel more tired in the afternoon so I generally avoid it. N2 has an effect on the nervous system. Why could it not have a similar affect on some people and they call that "after dive fatigue". Does not prove anything one way or another but does suggest a possible mechanism

In Wookie's case, if I remember correctly, he is operating a short-run liveaboard. Folks go out for something like 2-3 days of diving and, quite likely, they feel pressure to max out for their money and I am not surprised they dive like there's no tomorrow. On longer trips the mood can be more relaxed, "tomorrow we'll dive another day."

You may be right about fatigue being more mental than physical, but still what's the connection with DCS?

 

[Steve_C]

As you know it is not easy sorting out cause, effect, and correlation. A can be a factor in B, A can be a factor in C so we can see B and C correlated but that does not mean that either B or C have any sort of causal relationship with each other. Also humans vary greatly. Heck we do not all even have the same number of bones, the vessels in our brains are not all the same, we are sensitive to different chemicals, we have different DNA etc etc etc.

 

[Bob DBF]

You may be right about fatigue being more mental than physical, but still what's the connection with DCS?

The last study I saw found there was no decrease in fatigue, however they noticed that divers on Nitrox consistently felt better after the dive. They attributed the feeling better to having less sub clinical DCS. Since the study was about fatigue the feeling better after the dive was just note on the findings.

It seems fatigue has a different scientific meaning than the meaning regular people use.



Bob

 

[Steve_C]

It seems fatigue has a different scientific meaning than the meaning regular people use.
Bob

Good observation. If I feel less tired then I feel better. Perhaps they mean fatigue in the sense of measurably less muscle capability or some such. Whatever it means, I will have another tank of feel better next dive.

 

[ajduplessis]

Eh, no? Nitrogen is used to try to counterbalance HPNS, which is due to helium as far as I understand it, since hydreliox is used against it.

I doubt saturation divers add nitrogen to their breathing mixes to counterbalance the effects of HPNS. HPNS is triggered by rapid descent rates utilising trimix/heliox mixes beyond 150-200m. Descent rate is the key to managing HPNS, not nitrogen.

Nitrogen is a serious consideration in calulating trimix/deco gasses on deep dives to prevent ICD during switches......

 

[Patoux01]

I doubt saturation divers add nitrogen to their breathing mixes to counterbalance the effects of HPNS.

High Pressure Neurological Syndrome | DIVER magazine
And a few others seem to disagree with you. I don't have access to "proper" resources at the moment, so I simply picked one of the first google hits which presents it.