Nitrox for "safety margin"

[Gene_Hobbs]

Originally Posted by String

Ive not come across any research that's shown this to be the case so basically ARE there any studies out there showing a statistically significant reduction in the incidences of DCS from using Nitrox on air tables?

Not really, but these might be worth a read:

Logan. 1961. An evaluation of the equivalent air depth theory. US Naval Experimental Diving Unit Technical Report NEDU-RR-01-61.
RRR ID: 3835

Berghage and McCraken. Equivalent air depth: fact or fiction. Undersea Biomed Res. 1979 Dec;6(4):379-84.
RRR ID: 2835

also listed here.

[wibble32]

Not a comment on DCI, however I have dived on Air for a week, 2-3 dives a day and been knackered, yawning for england. Then 1 week of 4 dives a day on air profiles breathing Nitrox 32 result ermm wide awake. So I am happy that it improves my alertness, which I guess means that not being dopey decison making is quicker. I like that.

[Scuby]

Originally Posted by String

Im not debating the fact that its less nitrogen so in theory at least less of a risk. What i am wondering (and have failed to find) is if this is actually enough of a difference to have any real world measurable effect or is it like some other things something that looks sane on paper but in the real world the effect is so small its masked by other factors and statistically insignificant.

You're asking too much. You want direct evidence based on actual dives. That is a rubbish way of doing research, far too many uncontrolled variables, etc. What you really want is a load of people of known and tested fitness / "all other variables" controlled to do loads of dives a lot of times to get statistically significant numbers of bends to prove it. That will never happen, and doesn't need to. Medical research is often done with animals etc, because they're known to be close enough to humans (in various aspects) to be good enough for testing. From the animal tests (and increasingly computer models) they extrapolate out to humans. Diving seemed to use goats a lot (as I understand it), and from that people developed deco theories (not all of them, but some). From this we can see that less nitrogen = less risk.

Think it's just one of those things you'll have to trust (or give up diving)

David

[Bantam]

Originally Posted by Scuby

You're asking too much. You want direct evidence based on actual dives. That is a rubbish way of doing research, far too many uncontrolled variables, etc. What you really want is a load of people of known and tested fitness / "all other variables" controlled to do loads of dives a lot of times to get statistically significant numbers of bends to prove it. That will never happen, and doesn't need to. Medical research is often done with animals etc, because they're known to be close enough to humans (in various aspects) to be good enough for testing. From the animal tests (and increasingly computer models) they extrapolate out to humans. Diving seemed to use goats a lot (as I understand it), and from that people developed deco theories (not all of them, but some). From this we can see that less nitrogen = less risk.

Think it's just one of those things you'll have to trust (or give up diving)

David

I think you have your research - it's just not collated - and that the majority of us who dive Nitrox and especially those with Air tables.

Us - us who dive nitrox - we are the data.

All you'd need to do is put together a simple online form and get people to fill it in to get some sort of idea. I know that's what the DDRC are currently up to.

[Scuby]

Originally Posted by Bantam

All you'd need to do is put together a simple online form and get people to fill it in to get some sort of idea. I know that's what the DDRC are currently up to.

Yeah i've seen (and filled in) the DDRC forms a while ago - they strapped a computer to my twins for a week in Scapa to see what I was up to.

While I appreciate the effort, i'm still not convinced that it's anything like enough to prove what String is hoping to find. For that sort of evidence you need a much much more controlled group, the same dives repeated by large numbers of people on the same mixes, etc.

Will be all useful stuff to contribute to the volume of evidence around deco though.

David

[Bantam]

Originally Posted by Scuby

Yeah i've seen (and filled in) the DDRC forms a while ago - they strapped a computer to my twins for a week in Scapa to see what I was up to.

While I appreciate the effort, i'm still not convinced that it's anything like enough to prove what String is hoping to find. For that sort of evidence you need a much much more controlled group, the same dives repeated by large numbers of people on the same mixes, etc.

Will be all useful stuff to contribute to the volume of evidence around deco though.

David

I agree - but the biggest problem is that everyone's uptake of Nitrogen and Oxygen is different, and what will bend one person will not bend another.

So the evidence will never exist truly because it's so variable.

As with it all - it's 100% best guess. Nothing truly knows.

Well, yet anyway

[Ali]

Since I tested positive for PFO I have dived EAN 40%.
Up until then I had 6 episodes of post dive Migraine with Aura. That was diving mainly air, and they didn't need to be too a demanding dive to cause them. On one occasion I did 1 dive 1hr and a max of 18m using air, 40mins post dive the light were flashing away.

Since testing positive I dive EAN 40% max depth 25m, regularly dive for an hour per dive and do 2 dives with a 1-30 to 2hr SI. Dive computer set to air.
I have had no Migraines post dive since diving Nitrox with my computer set to air!


So I think it works for me

Shit, hope I haven't tempted fate by posting this.

Ali