NITROX for any and all dives?

[tursiops]

I've been told that diving nitrox will lessen the dry mouth you get when diving on air.

This is likely backwards. Originally, plain old air fills had a certain amount of filtration, which removed some moisture. Then Nitrox came along and more filtration was desirable to avoid any chance of petroleum products in the tank; that extra filtration mean even less moisture in the Nitrox, so you got "dry mouth." Now, pretty much all the air fills are double-filtered as well as the Nitrox, so there should not be any difference. That is, dry mouth from both.

 

[Dish]

I found this interesting...

Measurement of fatigue following 18 msw dry chamber dives breathing air or enriched air nitrox
"Since the early days of compressed gas diving, air has been the principle gas employed due to its ready availability. Using EANx, bottom time can be significantly increased compared to diving at the same depth with air, without additional decompression penalty. It is extremely common for divers to claim less fatigue following a dive breathing EANx than they would expect for a similar air dive. In this study following simulated dives controlled for depth, bottom time, decompression rate, temperature, and physical exertion, subjects blinded to breathing gas reported no subjective difference in fatigue (visual analogue scale) breathing air or EANx. In addition there was no difference in fatigue as assessed by the MFI-20 or in the psychometric tests for attention and concentration."

That said, I prefer to dive NITROX for the reason Wookie and others have pointed out. Plus this study:
Enriched Air Nitrox Breathing Reduces Venous Gas Bubbles after Simulated SCUBA Diving: A Double-Blind Cross-Over Randomized Trial is reason enough for me.

 

[kelemvor]

That's my thinking. In a nutshell: More nitrogen cannot be better for me than less nitrogen. I haven't noticed any effect on fatigue during those multiple days of multiple dives, but then again, I can't say I have done a comparison with the exact same sequence of dives on air.

Still, when some smartarse huffs "Air is for tires," I want to smack them.

Air is for squares.

I don't think they put regular air into tires anymore. Well, maybe some people do. Some people breathe air when scuba diving as well .

 

[kelemvor]

When it comes to gas consumption

The only time I've personally seen that claim is from new divers who don't really understand nitrox. Do some people really believe it impacts gas consumption?

 

[kelemvor]

I found this interesting...

Measurement of fatigue following 18 msw dry chamber dives breathing air or enriched air nitrox
"Since the early days of compressed gas diving, air has been the principle gas employed due to its ready availability. Using EANx, bottom time can be significantly increased compared to diving at the same depth with air, without additional decompression penalty. It is extremely common for divers to claim less fatigue following a dive breathing EANx than they would expect for a similar air dive. In this study following simulated dives controlled for depth, bottom time, decompression rate, temperature, and physical exertion, subjects blinded to breathing gas reported no subjective difference in fatigue (visual analogue scale) breathing air or EANx. In addition there was no difference in fatigue as assessed by the MFI-20 or in the psychometric tests for attention and concentration."

That said, I prefer to dive NITROX for the reason Wookie and others have pointed out. Plus this study:
Enriched Air Nitrox Breathing Reduces Venous Gas Bubbles after Simulated SCUBA Diving: A Double-Blind Cross-Over Randomized Trial is reason enough for me.

That's the flawed study I was talking about earlier. Here's the first big flaw:

All simulated dives were performed in the hyperbaric chamber at the Hyperbaric Medicine Unit, Royal Adelaide Hospital.

The people being studied were not exercising at all, exactly the opposite of what you have on a recreational scuba dive. Although it may be somewhat similar to what a very experienced cave diver with a Sheck Exley award does a recreational dive.

They need to do something along the lines of giving nitrox to divers at some busy resort. They should do it free and not tell the divers, perhaps gaining permission with some kind of waiver. Then they should do some sort of survey that includes questions about fatigue. Obviously they'll have to give nitrox to some, while not giving it to others in order to have something to compare to.

In this situation, using a dry chamber really invalidates the results.

There are other flaws in that study (only 12 subjects for example), but that one is my biggest complaint.

 

[boulderjohn]

The study was also flawed in that the dives compared were such simple short, shallow dives that no one would feel any fatigue regardless of what was breathed.

What you need to do is put people on a liveaboard for a week and see what happens.

 

[Saniflush]

What you need to do is put people on a liveaboard for a week and see what happens.

DIBBBS!

 

[leadduck]

I'll have to wing this one on memory as this tablet is a pos in finding information. When I find it I'll repost a link, which I should have done the last time.

The study, which was after the chamber study, I saw, found there was no decrease in fatigue, however they noticed that divers on Nitrox consistently felt better after the dive. The study 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.

The study was double blind with the divers in the water diving. I believe there were two tank dives every other day.

Bob

I guess the chamber study you mean is this one of 2003: Measurement of fatigue following 18 msw dry chamber dives breathing air or enriched air nitrox. - PubMed - NCBI
and the later one of 2008 is: Measurement of Fatigue following 18 msw Open Water Dives Breathing Air or EAN36.
Both don't support Nitrox having an influence on fatigue. In the second study, the divers' DHS survey responses were a little better for Nitrox than for Air.

 

[tursiops]

Measurement of fatigue following 18 msw dry chamber dives breathing air or enriched air nitrox
"Since the early days of compressed gas diving, air has been the principle gas employed due to its ready availability. Using EANx, bottom time can be significantly increased compared to diving at the same depth with air, without additional decompression penalty. It is extremely common for divers to claim less fatigue following a dive breathing EANx than they would expect for a similar air dive. In this study following simulated dives controlled for depth, bottom time, decompression rate, temperature, and physical exertion, subjects blinded to breathing gas reported no subjective difference in fatigue (visual analogue scale) breathing air or EANx. In addition there was no difference in fatigue as assessed by the MFI-20 or in the psychometric tests for attention and concentration."

Continuing to quote from the same article:
"It is possible that anecdotal reports of “sub-clinical” fatigue following recreational diving originate from dives that produce higher than typical decompression stress; we are not aware of any systematic study of this phenomenon."
the question remains open. Part of the problem is the definition of "fatigue," which appears to in be rather narrow in the linked study, and not the same as "feeling less tired."

 

[Wookie]

Still, when some smartarse huffs "Air is for tires," I want to smack them.

Well, nitrox is NOT for putting in your tires. Oxygen and rubber do not go well together.