Is this nitrogen narcosis?

[IncreaseMyT]

Ive never went into deco on a dive, the closest I have came to running out my bottom time was 4 minutes.

I am super hangry after a day of diving, and I can eat a ton. I think what you're describing is pretty normal, but I am not a doctor.

Also I don't tend to eat much on the boat, so when I get off the boat and eat a big meal, insulin is going to spike because its been low most of the day, and you're gonna be sleepy.

 

[EFX]

Uh-oh.

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[Storker]

What I suspect MIGHT be a myth, and which apparently the experts in that DAN article also doubt, is that nitrox causes less fatigue for the SAME amount of N2 loading

I've read a few threads about nitrox here on SB, but this is the first time I've ever heard about that claim.

 

[doctormike]

I've read a few threads about nitrox here on SB, but this is the first time I've ever heard about that claim.

I'm pretty sure that most recreational divers who enthusiastically post that they feel better when diving Nitrox don't switch to air tables, right? They just dive nitrox and set their computers to their mix.

So that's implying that they have less fatigue with the same amount of N2 loading, right? Longer NDLs, than on air, but essentially the same N2 load.

 

[RyanT]

@doctormike, here's a link to the pdf

https://s3.amazonaws.com/academia.e...=Persistence_of_critical_flicker_fusion_f.pdf

I agree, the ideal additional control would be divers on trimix. In this study, they provide some evidence of why their assay should be related to narcosis and the divers were their own controls. So yes, it's possible the impairment could have come from sources other than narcosis, but regardless, the results are interesting!

 

[doctormike]

@doctormike, here's a link to the pdf

https://s3.amazonaws.com/academia.edu.documents/45046189/Persistence_of_critical_flicker_fusion_f20160424-18989-1yzxmtp.pdf?AWSAccessKeyId=AKIAIWOWYYGZ2Y53UL3A&Expires=1556422826&Signature=DuP+HhX9RSSdeMkkzGK2naK74lk=&response-content-disposition=inline; filename=Persistence_of_critical_flicker_fusion_f.pdf

I agree, the ideal additional control would be divers on trimix. In this study, they provide some evidence of why their assay should be related to narcosis and the divers were their own controls. So yes, it's possible the impairment could have come from sources other than narcosis, but regardless, the results are interesting!

Absolutely, especially given the fact that narcosis is thought to have a real, molecular pathophysiological cause.

That's something that you might be able to directly measure in an animal study (the neurotransmitters), and be able to easily compare cohorts of nitrox and trimix subjects, both with animals (neurotransmitter assay) and divers (CFFF).

It's a fascinating paper! Thanks for sharing it... I hadn't heard of the CFFF test before reading that.

 

[Seaweed Doc]

I'm too tired from morning dives and perhaps too lazy to look up literature, but could a perceived effect of nitrox be due to high oxygen rather than low N?

I seem to recall that breathing oxygen "cures" headaches. I imagine it would also reduce lactic acid buildup during exercise. Perhaps myoglobin in muscles would end up being more oxygenated post nitrox dive?

Of course, a study looking at just air vs. nitrox and, say, arithmetic pre and post tests (or whatever psych test is administered) couldn't differentiate between lower N or higher O. I guess trimix is needed..

 

[Bob DBF]

I'm pretty sure that most recreational divers who enthusiastically post that they feel better when diving Nitrox don't switch to air tables, right? They just dive nitrox and set their computers to their mix.

So that's implying that they have less fatigue with the same amount of N2 loading, right? Longer NDLs, than on air, but essentially the same N2 load.

Pretty much the only time I dive Nitrox is when I lobster dive out here on the West Coast, 3 days 12 to 15 dives, usually shallow. The dives are constrained by gas rather than NDL, whether air or Nitrox, so I would have less N2 exposure with Nitrox.

I have not noticed any difference when just diving a couple of tanks, but with multiple dives over days to me there is noticeable difference between air and Nitrox.


Bob

 

[Storker]

I'm pretty sure that most recreational divers who enthusiastically post that they feel better when diving Nitrox don't switch to air tables, right? They just dive nitrox and set their computers to their mix.

So that's implying that they have less fatigue with the same amount of N2 loading, right? Longer NDLs, than on air, but essentially the same N2 load.

You're basing your conclusion on a huge and untested assumption there.

NDL isn't the only thing which can limit bottom time, particularly on OC single tank. Gas may just as well limit bottom time. Also, a diver who switches from air to EAN32 may very well go from being saturation limited to being gas limited.

 

[doctormike]

You're basing your conclusion on a huge and untested assumption there.

NDL isn't the only thing which can limit bottom time, particularly on OC single tank. A diver who switches from air to EAN32 may very well go from being saturation limited to being gas limited.

Wait, what?

There are a million posts here where people claim to be less tired with nitrox, right? Most of them don't add they dive air tables.

I said that just switching to nitrox alone wouldn't necessarily change your N2 loading, if you want THAT effect then you need to dive nitrox on air tables. If you just switch to nitrox and dive nitrox tables (i.e. same amount of N2 loading), there isn't much literature support for that alone (controlling for different N2 loading) reducing fatigue. And then I said that Pollack and Harris seemed to agree with that in 2014.

Then you said that you had never heard anyone make that claim.

So I was surprised to hear that.

Sure, a given nitrox diver might become gas limited before he reaches his NDLs, wheras on air he was NDL limited, so in some cases you could find a cohort of people who switched to nitrox, dove nitrox tables, and then had less N2 loading.

But I don't see what that has to do with the fact that it's a pretty common position to say that all other things being equal, nitrox doesn't make you less tired. I mean, you may disagree with that, many people do, given their own experiences. But it's hardly a unique or uncommon conclusion.