Please Educate A Newbie on Nitrox :)

[TSandM]

String has a good point, though; if less nitrogen absorption means less fatigue, then you should feel better after shallow dives than you do after deeper ones.

I am a "Nitrox makes me feel better" person, but I have to admit that, simultaneously with taking Nitrox, I also changed my ascent procedures, and that may have more to do with the change in my fatigue level post-dive. I WILL say that, from very uncomfortable personal experience, I totally believe in fatigue as a symptom of subclinical DCS.

 

[halocline]

I don't notice any difference in fatigue using nitrox, but I did substantially lower my post dive fatigue by extending my safety stop and taking a full minute or more to surface from the stop. I do this on air and nitrox. If, as many people suspect, the fatigue is due to elevated N2 when surfacing, there should be absolutely no difference between using nitrox or extended shallow stops to reduce N2 level when surfacing, as long as the resulting level upon surfacing is the same.

 

[String]

The idea is that after a dive, tiny nitrogen bubbles form in the bloodstream and are trapped in the fine capillaries in the lungs and, perhaps by reducing oxygen transfer, make people feel "tired". This mechanism seems very plausible to me.

Sub-clinical DCS. Thats got nothing at all to do with the gas though, thats a direct correlation between nitrogen loading an elimination. Again, for the less tired on nitrox claims to be true you'd have to also claim someone feels more tired dive to a certain depth on air for 30 mins than they do for 20 mins and so on.

The sub-clinical bubble formation has a mechanism but its not gas choice that might effect that, its slow controlled ascents, proper safety stops and sensible profiles to reduce bubble formation. Nothing to do with gas. Bubbles especially their potential immune system response (which is known to cause fatigue) make sense hence sensible profiles i can see a mechanism at least where they can reduce fatigue. Im doing 500+ dives a year currently and couldnt tell you if i was on nitrox or air if i didnt know in advance - i notice no difference at all. However, on a guided dive where im up and down a lot, chasing people, strange profiles, some saw tooth i do seem to be more tired than on a dive where ive done a proper staged ascent and extended stops without lots of ups and downs. Again though, could be placebo.

 

[Herk_Man]

Orrrrr, there's more oxygen. It doesn't have to be all about the nitrogen.

 

[Bogie]

I use Nitrox all the time. It can give me very short surface intervals and I think it gives me more energy after the dive. Also, the energy you save not waiting so long between dives is good and it helps me not being on the boat so long to avoid sea sickness.

I would get certified. Knowledge is good.

 

[Peter Guy]

While somewhat off topic, String wrote

No matter how small that study its better than the alternative - an uncontrolled series of non-quantitative claims without a single shred of testing, comparison or scientific method used

A small controlled study is far better than "i think its this".

Scientific method is very clear - you propose something, you investigate it using standard defined controls, comparisons and review. IF someone is claiming nitrox makes them less tired its up to them and the group that claims it does to actually prove it. Otherwise its just hearsay. If there was actually any sort of plausible mechanism where it could do that it would help but again there isnt!

While the "plural of anecdote is not data" it is also true that "anecdotes" do provide real information. Years ago I was responsible for running numerous real world pricing tests for my company and they were done as controlled as possible, but they were real world which means they weren't "perfect." I discussed this with a friend who was a statistician (he ran bio-stat studies and taught stat at a major university) and asked him about how I should interpret the results. His response, and one which I believe applies here to the "anecdotal responses", was that "Until you have better information, go with the results you have -- even if they are just random they are still the best results you have."

There are enough "random anecdotal responses" that EAN usage, especially in multiple-dive/multiple-day diving, results in less fatigue to support his statement -- until we have better information, go with the results we have.

String, as someone else wrote, there IS at least a theoretical basis for the better feeling which relates to the possibility (probability?) of a reduced inflammatory response by the body to the fewer N2 bubbles. So the anecdotal responses are in line with a theoretical mechanism.

 

[gsk3]

I discussed this with a friend who was a statistician (he ran bio-stat studies and taught stat at a major university) and asked him about how I should interpret the results. His response, and one which I believe applies here to the "anecdotal responses", was that "Until you have better information, go with the results you have -- even if they are just random they are still the best results you have."

He was probably a Bayesian :shocked2:

 

[James R]

Nitrox topic well covered already.

If you're referring to diving the Texas Clipper, I would strongly suggest you at least gain AOW certification prior to going out there. I was just there a few weeks ago and my avg depth for repetitive dives was 94' with a max of 116fsw. Additionally currents there can be anything from none to quite strong. Personally, I wouldn't suggest a newly certified diver dive this wreck at all.

 

[Mike Boswell]

String has a good point, though; if less nitrogen absorption means less fatigue, then you should feel better after shallow dives than you do after deeper ones. .....

Sub-clinical DCS. Thats got nothing at all to do with the gas though, thats a direct correlation between nitrogen loading an elimination. Again, for the less tired on nitrox claims to be true you'd have to also claim someone feels more tired dive to a certain depth on air for 30 mins than they do for 20 mins and so on. ..... /QUOTE]


Perhaps there is a threshold? If short shallow dives produce no effects, and very deep (a la Pyle) dives do, then perhaps there is a minimum level of bubbling required to cause the effect.

And perhaps there is much individual variation caused by lung size and efficiency, capillary size, immune response, etc.

Please explain the "nothing to do with the gas" idea. Does not More O2/Less N2 = Fewer N2 bubbles?

 

[ScubaFeenD]

While somewhat off topic, String wrote
While the "plural of anecdote is not data" it is also true that "anecdotes" do provide real information. Years ago I was responsible for running numerous real world pricing tests for my company and they were done as controlled as possible, but they were real world which means they weren't "perfect." I discussed this with a friend who was a statistician (he ran bio-stat studies and taught stat at a major university) and asked him about how I should interpret the results. His response, and one which I believe applies here to the "anecdotal responses", was that "Until you have better information, go with the results you have -- even if they are just random they are still the best results you have."

There are enough "random anecdotal responses" that EAN usage, especially in multiple-dive/multiple-day diving, results in less fatigue to support his statement -- until we have better information, go with the results we have.

String, as someone else wrote, there IS at least a theoretical basis for the better feeling which relates to the possibility (probability?) of a reduced inflammatory response by the body to the fewer N2 bubbles. So the anecdotal responses are in line with a theoretical mechanism.

There is too much bias in the reporting for me to accept is as data. BUT who cares if there is data to support it. If people "feel" better and arent having increased DCS cases then let them feel better. There are so many reasons to use nitrox beyond "feeling" better it shouldnt matter if someone "feels" better or not.