First Nitrox Dives

[Nemrod]

If GOD came down here and told you it made no difference on scubaboard the urban legend would continue. Maybe we need a study to study the study to study the study?

DandyDon, I like your avatar, I guess it answers the thread, "where to put my PadI merit badges"---lol. Nice sword too, almost big enough to be my carry knife.

N

 

[tridacna]

anyone have a link to these studies? were they done for just one dive or multiple dives? I personally don't notice any difference after a single dive, but a huge difference doing 4 dives in a day on nitrox vs air.

http://archive.rubicon-foundation.org/3975

 

[Thalassamania]

Many divers report less fatigue following diving breathing oxygen rich N2-O2 mixtures compared with breathing air. In this double blinded, randomized controlled study 11 divers breathed either air or Enriched Air Nitrox 36% (oxygen 36%, nitrogen 64%) during an 18 msw (281 kPa(a)) dry chamber dive for a bottom time of 40 minutes. Two periods of exercise were performed during the dive. Divers were assessed before and after each dive using the Multidimensional Fatigue Inventory-20, a visual analogue scale, Digit Span Tests, Stroop Tests, and Divers Health Survey (DHS). Diving to 18m produced no measurable difference in fatigue, attention levels, ability to concentrate or DHS scores, following dives using either breathing gas.

This study indicates that for a single, dry chamber exposure to 18msw there is no difference between air and NITROX. While this may be indicitive, it in fact says nothing about wet dives, dives with different ascent rates, dives to 17 or 19 msw (or other depths), repetitive dives, decompression dives, longer dives, shorter dives, etc.

 

[Charlie59]

Okay, now, are we supposed to use the nitrox while driving? Do people who feel better after diving nitrox just have a placebo experience?

Man, maybe if I drove with it and not dove with it I'd see the difference.

This diving (or is it driving) stuff is so confusing.

 

[Charlie59]

One other question, do I need to wear my mask while driving with nitrox to see the effect?

 

[Thalassamania]

By and large I use NITROX in place of air, when depth appropriate, on air tables (or an air computer). I take my margin in the extra risk reduction rather than in longer bottom time or shorter surface intervals. On one dive I notice little or no difference but on a multi-dive, multi-day series of dives I feel that I have much less fatigue.

 

[vladimir]

Double blind studies have been done and show NO evidence of reduced fatigue after using nitrox. I'm over 40 and I don't feel any difference after using nitrox. Placebo effects can be very powerful to the believer....that is certainly proven in every scientific study!

Is it? From the Skeptic's Dictionary, http://skepdic.com/placebo.html:

the powerful placebo challenged

The powerful effect of the placebo is not in doubt. It should be, however, according to Danish researchers Asbjørn Hróbjartsson and Peter C. Götzsche. Their meta-study of 114 studies involving placebos found "little evidence in general that placebos had powerful clinical effects...[and]...compared with no treatment, placebo had no significant effect on binary outcomes, regardless of whether these outcomes were subjective or objective. For the trials with continuous outcomes, placebo had a beneficial effect, but the effect decreased with increasing sample size, indicating a possible bias related to the effects of small trials ("Is the Placebo Powerless? An Analysis of Clinical Trials Comparing Placebo with No Treatment," The New England Journal of Medicine, May 24, 2001 (Vol. 344, No. 21)."

According to Dr. Hróbjartsson, professor of medical philosophy and research methodology at University of Copenhagen, "The high levels of placebo effect which have been repeatedly reported in many articles, in our mind are the result of flawed research methodology."* This claim flies in the face of more than fifty years of research. At the very least, we can expect to see more rigorously designed research projects trying to disprove Hróbjartsson and Götzsche.

 

[Saskia]

If it's a placebo effect, well, that's wonderful now isn't it? Who cares if it's real or not, if it's there for you, woohoo! that's all i can say ...

 

[tridacna]

If it's a placebo effect, well, that's wonderful now isn't it? Who cares if it's real or not, if it's there for you, woohoo! that's all i can say ...

I'll tell you who does. There are a whole bunch of LDSs that convince people that the reason that they should use nitrox is because of the "feel good" thing. I've heard and seen it often. That's crap.

I dive nitrox whenver I can. It's great. For feeling good after diving? Spend a few days a week in the gym exercising and you'll feel much better before, during and after diving!

 

[tridacna]

This study indicates that for a single, dry chamber exposure to 18msw there is no difference between air and NITROX. While this may be indicitive, it in fact says nothing about wet dives, dives with different ascent rates, dives to 17 or 19 msw (or other depths), repetitive dives, decompression dives, longer dives, shorter dives, etc.

http://breathing.com/oxy-water.htm

I guess we could just use this stuff and extend our bottom times too.

You know that a multivariate analysis incorporating all of the variables you mentioned could never be performed. It's too expensive unless it was sponsored by the Society of Nitrox Divers (SNIDE) or Rodales (if they were paid enough). There has never been anything published (nor will there be) showing Febrile Improvement Bouyancy Statistics (FIBS) indicating post-diving improved fatigue (SPIF) correlation based on nitrox use.

Let's face it, if you feel better - great. But please no assumptions about the elevated O2 content of your mix causing you to feel better. It's purely subjective.