Nitrox!

[boulderjohn]

In Richard Pyle's article about deep stops he tells about fish collecting in deep waters of Hawaii. Most of the time, his catch was either dead or distressed upon surfacing, and he usually needed a nap after diving. One dive he had an issue which caused him to stop for a couple of minutes during his ascent. His catch was in perfect health after surfacing and he felt great. After more research he found this to be the case every dive.

Pyle's article is not talking about simply feeling tired--he is talking about the possibility of subclinical DCS. This is the origin of his deep stop system for decompression ascents (the Pyle Stop), not merely an ascent at a safe rate. He has since had second thoughts about it. He was a part of a presentation team at the DAN 2008 Technical Diving conference which cast strong doubt on the value of deep stops. I heard (but did not see first hand) that he has recently said that after a life time of diving, the only diving related concept named for him--the Pyle Stop--does not work.

I've always been amazed at how many divers say that nitrox makes you less fatigued, despite the fact that every course book tells them it's a placebo.

I have not read every text on Nitrox, but the ones I have read and the one I use when I teach do not say it is a placebo effect. They say that the fatigue benefit is unproven. There is a big difference. Saying it is a placebo is saying that it has been proven, and nothing has been proven.

I have seen several posts over the years in Scuba Board that refer to the only attempt I know to measure the effect, a test which showed no benefit. That test was absolutely absurd. I don't remember the details exactly, but it was something on the order of taking divers to something like 60 feet for 30 minutes for two dives and comparing the levels of fatigue. No one gets tired under those circumstances. Put people on a liveaboard doing 4-5 real dives a day for a week and check the difference, and you might have a real basis to compare.

As an instructor, I tell people that the effect is unproven through experimentation, but many people report that they do feel less fatigued when diving over time with nitrox. That is all we know, and all we can say for sure.

 

[Puffer Fish]

In Richard Pyle's article about deep stops he tells about fish collecting in deep waters of Hawaii. Most of the time, his catch was either dead or distressed upon surfacing, and he usually needed a nap after diving. One dive he had an issue which caused him to stop for a couple of minutes during his ascent. His catch was in perfect health after surfacing and he felt great. After more research he found this to be the case every dive.
I've always been amazed at how many divers say that nitrox makes you less fatigued, despite the fact that every course book tells them it's a placebo.

I don't doubt that experience is true.. fish are effected by the same effects we are. But at best, that describes a single set of conditions. To enlarge that to include every person, in every situation is not science.

A good example of very recent times is ulcers.. which for hundreds of years were caused by nerves and diet...it was obvious that was the cause...there were thousands of proven examples of how this caused ulcers.. well, until someone found out a bacteria was causing most of the cases.

Unless one has hard information on the blood chemistry of someone that says they feel better using nitrox from both conditions...at best we can say is that it may be a placibo effect.

However, one obvious quick answer is that bubble generation varies tremenously from person to person... it could be that slow to you, may be way to fast for someone else...I would be willing to bet that there are some people out that, that no matter how slow they went, would show some signs of the issue you just pointed out...and with Nitrox, they would feel better.

 

[wve]

Some recent work has shown that breathing higher O2 can cause a drop in blood sugar levels...resulting in the potential in some people to pass out.

Do you have a reference for that? I'd be interested in reading that article, especially since this is an unexpected finding.

When we have patients on high levels of oxygen in the hospital, we do not typically worry about them becoming hypoglycemic. If they do, there are usually other reasons.

 

[halocline]

I read about half of this thread, so please forgive me if I post something that's already been said. It is an intuitive assumption that diving with nitrox in recreational settings can be "safer" in terms of lower N2 loading, much like it's an intuitive assumption that using a more conservative computer adds a "safety" factor. By "safety" in both instances, I'm referring to likelihood of DCS. Obviously there are other safety factors in diving, like drowning.

However, until there are statistical studies that prove a link between use of nitrox and lowered incidence of DCS, all the comments made about it's "safety" are assumptions and should be treated as such when trying to evaluate your own personal risk tolerance. To my knowledge, there are no such studies yet. Many people have opinions, and there certainly are reasonable, logical ideas about it's use. But anyone who says "it's safer to use nitrox" is simply not stating a fact.

Dive tables (and computer logarithms) were developed on theories but not put into accepted use until they were subjected to extensive clinical tests with statistical indicators.

There are other good reasons to use nitrox.

 

[ScubaSteve]

To me, the real benefit to diving Nitrox is you don't feel so doggone tired!!!!

As many others have corrected this already, my response will be short. I DO believe that people feel less tired after diving Nitrox. I do. However, I also believe that this is nothing more than a placebo effect (as mentioned by others). And anybody that offers this as a real and proven reason to dive Nitrox is simply being irresponsible. I am giving you the benefit of the doubt here because I am not sure that that was what you were actually doing.

 

[Reg Braithwaite]

As many others have corrected this already, my response will be short. I DO believe that people feel less tired after diving Nitrox. I do. However, I also believe that this is nothing more than a placebo effect (as mentioned by others). And anybody that offers this as a real and proven reason to dive Nitrox is simply being irresponsible. I am giving you the benefit of the doubt here because I am not sure that that was what you were actually doing.

I believe that I feel less tired after diving Nitrox, however I do not believe it is the Placebo Effect, I think it is the increased N2 gradient as I ascend from depth which suppresses the size and number of bubbles, which in turn reduces my body's immue system reaction and thus suppresses sub-clinical DCS symptoms such as perceived fatigue and muscle soreness.

But I agree with you that the plural of "anecdote" is not "data."

 

[underwatersquid]

I would like to try Nitrox sometime soon.

 

[joker31]

Nitox is not 'safer' than air. If diver A uses air and diver B uses Nitrox for the exact same dive, then then diver B is less likely to get DCS, but diver A is less likely to get O2 tox. (assuming absorption rates and everything are the same for the diver).

Nitrox and air each have their pros and cons. Remember most divers are limited by the amout of as in ther tank. Not how long the dive tables say you can stay down. Divers are usually long out of air (or Nitrox) before they hit that max time.

Some say there is less post dive fatigue.. Not sure 100% or not, but since a lot of places have free nitrox upgrades might as well start using it.
Thats my take on it....

 

[Doc]

but since a lot of places have free nitrox upgrades might as well start using it.

The first one's always free. :evilbunny:

I would like to try Nitrox sometime soon.

You must quit capitalizing nitrox. The industry :cyborg: has already done that on it.

 

[wve]

Remember most divers are limited by the amout of as in ther tank. Not how long the dive tables say you can stay down. Divers are usually long out of air (or Nitrox) before they hit that max time.

If you are only talking about one dive at a time, then most divers probably are limited by the amount of gas in their tanks, not by nitrogen loading.

However, when considering multiple dives per day on consecutive days, nitrogen can become a limiting factor. In such circumstances, Nitrox can help to mitigate this.

Of course, using Nitrox to gain more bottom time over multiple dives on multiple days can offset any arguable safety benefits one might have gained.