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

[tursiops]

I've already expressed my honest doubts in the existence of such "post-dive lethargy" a.k.a. fatigue.

LOL. Your doubt is irrelevant to the reality.

 

[MaxBottomtime]

Nobody has said using nitrox does not increase safety margins. The rate of DCS is already so low using air that nitrox can only lower the risk a minute amount. Setting your computer for air while breathing nitrox is not going to lower the risk of DCS by any measurable amount. It's like driving 64mph on the freeway rather than 65 mph.

 

[jhnmdahl]

15 Insane Things That Correlate With Each Other

These are some neat examples and I enjoyed reading them, but they are limited to 10 data points for each measured phenomenon. Make it 30 data points, or hundreds, or thousands, and now it starts to become statistically more relevant.

For example, it would be interesting for a group of regular divers to dive 50 dives each on Nitrox and 50 dives on air, interspersed and double-blind, and log how they felt afterward. Without something like this, it's difficult to say that it's statistically certain to a specific degree. Nevertheless, if I feel better after a handful of dives on Nitrox than I do after diving air, I probably won't require much more proof to prefer Nitrox for a couple extra bucks per tank.

John

 

[Storker]

I've already expressed my honest doubts in the existence of such "post-dive lethargy" a.k.a. fatigue.

I'm not very surprised to read that.

You continue to support my opinion about your worldview, BTW.

 

[Storker]

These are some neat examples and I enjoyed reading them, but they are limited to 10 data points for each measured phenomenon. Make it 30 data points, or hundreds, or thousands, and now it starts to become statistically more relevant.

I think you miss the whole point of the site.

 

[DevonDiver]

I've already expressed my honest doubts in the existence of such "post-dive lethargy" a.k.a. fatigue.

So, DCS is binary? Bent or not bent.

Or are you denying that fatigue is a DCS symptom in all aspects?

Post-dive vitality has long been monitored as a personal benchmark for decompression success by those active towards the higher limits of challenging diving.

And yet, as a no-stop recreational diver of barely intermediate experience, doing mediocre (at best) dives that are firmly within the statistical and algorithmic median... you seem to have very strong opinions against the validity of post-dive fatigue.

Where and how, might I ask, did you formulate those opinions?

It just get curioser and curioser with every post.

What's curious is your ability to ignore a simple and direct question.

 

[jhnmdahl]

I think you miss the whole point of the site.

Ha! Perhaps. Doing the math often takes the fun out of arguing.

 

[Basking Ridge Diver]

Ha! Perhaps. Doing the math often takes the fun out of arguing.

Spurious Correlation - "A false presumption that two variables are correlated when in reality they are not. Spurious correlation is often a result of a third factor that is not apparent at the time of examination. Spurious comes from the Latin word spurious, which means illegitimate or false."

Nothing to do with the math...

 

[DevonDiver]

And for the record I still have not stated anything about bubble mechanics. [...] EAN can increase no decompression limits but somehow does not provide safety margin against decompression injury. It does both by reducing the partial pressure of nitrogen and subsequently it's absorption. Which is Henry's law. That is all I have stated is fact.

As I've mentioned, and you've ignored, Henry's Law alone does not predict or explain decompression sickness.

To discuss DCS and inert gas diffusion IS to discuss bubble mechanics.

Whether we're considering the formulation of M-values, dissolved versus free gas, the direct physical impact of bubbles or the less understood issues of blood/brain chemistry... the FORMATION of bubbles and/or the occurrence of DCS is not explained or predicted by Henry's Law.

You are discussing the diffusion of inert gas in and out of the body. In a hyper-simplistic understanding, Henry's Law must seem very poignant to that. It is, of course, but it's only the first issue...of many... between gaining super-saturation and DCS presentation.

Henry's Law is undisputed. There are no universal 'Laws' pertaining to, explaining or predicting DCS. Thus... no 'facts'. Not yet.

All I've attempted to do is illuminate that DCS is far more complicated and less understood than relative diffusion of inert gas from one medium to another.

As this debate is in the 'Basic Scuba' (??) area... I didn't want casual readers to walk away thinking that certain current concepts were inalienable scientific facts.

 

[dmaziuk]

For example, it would be interesting for a group of regular divers to dive 50 dives each on Nitrox and 50 dives on air, interspersed and double-blind, and log how they felt afterward.

Yeah... I've seen it mentioned somewhere that you could get away with as few as 100 (?) divers: test and control groups of 50 each. Now, you'd probably need a fair amount of saturation to get nice significant bubbles, so we're talking long and/or deep. Of course with those aggressive-ish profiles you want a chamber ready, just in case, and to be on the safe side you must not have more divers in the water than can fit in your chamber.

Now, how long do you guesstimate the study will take?