Tissue stress associated with bubble formation; potential benefits of diving enriched air

[packrat12]

No, you missed the point again. The point here is that breathing EAN not to prevent DCS during recreational diving but just for the heck of breathing EAN doesn't make sense.

I've seen 3 arguments here for breathing EAN just for the heck of it:

1. Because it is available. This argument is irrational, so is not worth discussing. As for the price, my estimate is that diving NITROX adds on average about 5% to you diving cost (for example, $150 on our Aggressor trip, etc). This makes it certainly non-negligible in mathematical sense; whether this is negligible or not in economic sense is up to you to decide.
2. Because it feels good. I disagree with this one based on my personal experience. I suspect that, most likely, the believers fell into the trap of small numbers statistics. They got tired once diving on air for some unrelated reasons, then felt good next time diving on NITROX and came to wrong conclusion. However, it is entirely possible that there are indeed 2 kinds of people who respond differently to EAN. If this is so, this can be proved in a double-blind trial. Fatigue can be actually measured, not just felt, so there should be no problems running such trial.
3. N2 bubbles formed during recreational (rec) diving, even w/o DCS symptoms, are still harmful and result in tissue stress. So breathing NITROX reduces this effect. Well, if this is so, there should be some stats on negative effect of rec scuba diving on human health by now. Also, tissue stress has its markers that can be measured but no such data exist so far for rec divers.

tarponchik - What you are really saying is that there is no disadvantage to nitrox other than cost. Advantages are arguable. One of my advantages, I hate switching back and forth. Much easier for me just to deal with nitrox. I will get some advantages as I go deeper as a bonus.

As for cost, I have spent $3000 + on the trip, airfare, lost time at work, parking, driving, tips, food etc - I do not think $150 is going to break my bank. If all we are doing is 30' dives, I would probably not spend that kind of money on that trip anyway, let alone nitrox. Now I have nitrox and just do not worry about it no matter what diving profiles I have. As for pulmonary, recreational divers have a hard time getting to that risk level. It can be done on a live aboard or many repetitive days of diving but I think the overall advantages outweigh the issues for each individual dive.

 

[Storker]

I am not ignoring your references; it is just that these are not direct references to scientific research.

Uh... OK...

"There's no longer such thing as fact"
- Kellyanne Conway

 

[DevonDiver]

I am not ignoring your references; it is just that these are not direct references to scientific research.

You missed these?. . . .

Moreover, one of your references states that "It is well proven in multiple studies that all divers develop small bubbles in their body after diving, but these micro-bubbles (also known as "silent bubbles") are insufficiently large to cause us significant, immediate harm", which is exactly my point.

What's your point?

You understand the gist of SUB-CLINICAL issues?

If there was significant and immediate harm, it'd hardly be a sub-clinical issue would it?

Licking asbestos or mercury might not cause significant and immediate harm... But it's not clever, is it?

Also, I haven't seen any references that such bubbles can trigger immune response.

Your lack of diligence in reading the materials given to you is not an excuse for willful ignorance.

Honestly, I'm gonna call 'troll', if you're forcing the debate to be this inane...

 

[Lorenzoid]

Some quotes and links/references that may be considered pertinent to the debate in the following articles:

Subclinical DCS, Decompression Stress and Post-Dive Fatigue

Mildly Bent - Decompression Stress and Micro-Bubbles

Am I correct that these articles present what one would call hypotheses? If I understand correctly, the authors are proposing a reasoned explanation for something, but none of this has yet been confirmed by research studies. The studies they cite all seem to focus on peripheral bits that fit the hypothesis, but no direct link has been found yet, am I correct?

Edit: Andy posted the previous reply while I was typing. I have no idea if those articles answer my question.

 

[Diver-Drex]

@tarponchik - I fully agree that breathing EAN just because is not a sound practice. Strange that this started with you posting that you asked for EAN "just because" the group was using it without indicating any dive planning. I suspect your real gripe with that situation is that the decision to dive on EAN may have been a good one based on the plan. The group's inability to execute that plan is why the EAN did not serve its intended purpose. The group, not EAN was the issue.

As to whether or not someone feels better I will not argue, it's subjective.

I have argued neither of the first two points. I have stated that EAN works specifically because the reduced nitrogen content results in less nitrogen being absorbed by tissues. This is a fact. A diver can use that fact to increase NDL. Or you can continue to dive air profiles and use EAN to account for other contributing DCS factors, i.e. thermal stress, poor hydration, physical exertion, rapid ascent, etc.

BTY, I do not agree with doing this while using a single dive computer. With one computer set to air and a second set to the actual breathing gas as a means to add conservatism while still tracking the actual exposure, sure that's one way to do.

The line between harmless bubbles and DCS is blurry and can move dive to dive for the same person. That is the point of EAN for added safety. That is the point of all safety and redundant gear, it's there when things don't go as planned. Alternate second stages, cutting tools, dsmb,
seat belts... It's not a matter of harmless or harmful bubbles, it's less absorbed inert gas to potentially form any bubbles. This is again fact.

I'm honestly not certain what point you're trying to make. Are you trying to say that in normal recreational diving the risk of tissue damage from breathing EAN is greater than the risk of tissue damage from bubble formation? You haven't presented anything to support this.

 

[DevonDiver]

Am I correct that these articles present what one would call hypotheses? . . . no direct link has been found yet, am I correct?

I posted those (my) articles only as a shortcut to quickly linking all of the reports, studies and articles I referenced.

My articles are irrelevant.. as you say, they're unproven hypothesis meant to draw varied research strands together for the sake of stimulating discussions only.

HOWEVER the referenced links directly answered some questions about micro-emboli and varied short and long term issues they cause.

Thats exactly why I said this, when I posted those links. . .

Some quotes and links/references that may be considered pertinent to the debate in the following articles:

A point to raise. . .

The line between harmless bubbles and DCS is blurry and can move dive to dive for the same person.

People assume that micro-emboli are harmless below some varying radius and/or of some vague pressure needed to exert sufficient force to cause a myriad of physical manifestations. . .

I think that's a very short-sighted assumption to make.

The absence of being airlifted to a chamber in pain doesnt mean you've not been harmed.

There is evidence of health issues arising from (currrently) sub-clinical DCS, or decompression stress. The lack of proof does not nullify that evidence. . . it merely indicates insufficient progression of research in a highly complex field, retarded by limited funding and a more pressing agenda to eliminate the "immediate" consequences of improper decompression.

. . . , it's less absorbed inert gas to potentially form any bubbles. This is again fact.

Unwise to use the 'F-word' in relation to decompression science. LOL

 

[Diver-Drex]

To summarize this thread...

tarponchik - Nitrox use for anything other than extending bottom time is pointless. It's not effective at reducing bubbles and those bubbles are harmless anyway, or at least no one has proven that they do any damage.

DevonDiver - All bubbles may cause damage, we're not sure yet.

Me - Breathe EAN when it is called for and don't push NDLs so you have a little extra margin of safety no matter who is right.

 

[MaxBottomtime]

Me - Nitrox allows for greater available bottom time or shorter surface intervals. The risk of DCS and any other harmful maladies while diving air is already so low in recreational diving that any reduction of nitrogen is negligible. Arguing with someone who believes they feel better after diving nitrox is like telling a religious zealot that his beliefs are not based on any fact. You can't change their mind. They will continue to have faith in spite of no evidence.

 

[Lorenzoid]

Thanks, Andy. That's what I thought.

 

[Diver-Drex]

Unwise to use the 'F-word' in relation to decompression science. LOL

If there is less nitrogen absorbed there is less available to come out. There are a lot of unknowns here, that's not one of them.