PERCEPTIONS vs FACT ????

[deco_martini]

Title: Measurement of fatigue following 18 msw dry chamber dives breathing air or enriched air nitrox. Authors: Harris, RJ; Doolette, DJ; Wilkinson, DC; Williams, DJ

Issue Date: 2003

Publisher: Undersea and Hyperbaric Medical Society, Inc.

Citation: Undersea Hyperb Med. 2003 Winter;30(4):285-91.

Abstract: 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.

Description: Undersea & Hyperbaric Medicine : Journal of the Undersea and Hyperbaric Medical Society, Inc.

URI: Rubicon Research Repository: Item 123456789/3975

Appears in Collections:Undersea and Hyperbaric Medicine Journal

That's the classic work, the problem is that it only addresses fatigue on a single 18m dry dive.

The other thing being a typical diver does very little exertion underwater.

Yes, there is a large placebo effect with nitrox since people who dive on it are almost always told "you will feel better" before they dive on it. Most people who claim they feel "so much better" after diving 1 or 2 martini dives on nitrox I usually write off like that.

The only time I have felt like I have seen a huge benefit on anything other than my bottom time was on a 4-5 dive a day regimen every day for a solid week.

 

[PNW Dive Girl]

I feel better when I'm diving on nitrox. I don't feel as tired, even after a two-tank dive. If it's all just in my mind - I don't really care.

I'm with you here.

I very rarely do one dive in a day. Vis has got to be to the point where I can't see my gauges.

 

[Thalassamania]

The issue is how do you dive EAN, if you use it to get more no-D bottom time, and take it about the no-D limit, I would not expect you to feel any different than if you took air to its no-D limit. But if your dives are limited by air consumption, or if you dive EAN on air tables, the effect may be very real, anecdotal data says it is but there are no trials that address precisely this question.

 

[Al Mialkovsky]

The issue is how do you dive EAN, if you use it to get more no-D bottom time, and take it about the no-D limit, I would not expect you to feel any different than if you took air to its no-D limit. But if your dives are limited by air consumption, or if you dive EAN on air tables, the effect may be very real, anecdotal data says it is but there are no trials that address precisely this question.

Very true, while doing checkouts on Nitrox I alway felt very refreshed after a long day of diving. While on vacation I dove nitrox close to limits and felt as tired as though I had dove on air.

But darn it, staying down is what it's about

 

[drbill]

I'm not Nitrox certified so I can't really tell you, but Wiilldd1 hit on my reason... $12-16 per tank vs free air. My wallet feels MUCH better after I dive on air.

 

[sunnyboy]

I used to dive nitrox using the "dive nitrox as air" guidelines, and felt more refreshed after dives. Of course, the lighter wallet may have helped - less to lug around. ;-)

Finally I bit the bullet and moved the gas blending station to my back, where it can do the most good. I usually dive a constant PO2 of 1.3 except on very shallow dives. Plus, you can manually switch to 100% above 20fsw or even after the dive if you want.

-S

 

[lamont]

The issue is how do you dive EAN, if you use it to get more no-D bottom time, and take it about the no-D limit, I would not expect you to feel any different than if you took air to its no-D limit. But if your dives are limited by air consumption, or if you dive EAN on air tables, the effect may be very real, anecdotal data says it is but there are no trials that address precisely this question.

I've gotten a "fatigue hit" on air with a maxdepth of 80 for 10-15 mins and a lot of time spent above 40 fsw and 1-1-1 deco. I've felt fine on square dives to 80 with bottom times >30 minutes and 1-1-1-1-1 deco on 32% and 30/30. The 30/30 dives feel "better" than the 32% as well. The latter might be placebo, but the former symptoms with fatigue, chills and feverishness I doubt is placebo...

There is something nasty about air that goes well beyond gas loading...

 

[Kim]

I just did a 6 day liveaboard - 3 or 4 dives a day. I used 32% on every dive except one day when we just did two dives. I felt a CLEAR difference. All my dives were air profiles (with everyone else in my group using plain air)

One girl had been diving air for three days and did her course for Nitrox. She'd been getting slight headaches at the end of the dives. That stopped immediately she switched to 32%.

To really answer this question IMO someone needs to double blind it over much more than a single dive. Make it 4 dives a day over 6 days (like a liveaboard), and then come back and try and say it's a "placebo"!

 

[Walter]

I agree, that's exactly the type of test we need. I'll be happy to administer the test if you can get us funding.

 

[Kim]

I agree, that's exactly the type of test we need. I'll be happy to administer the test if you can get us funding.

You live in Florida so I'd have thought it would be easy enough to arrange there no?

Can't Thass get some university or other interested in such a test? Or maybe Gene Hobbs.....

I'll ask him on DMX.

Seems strange nobody did it yet.