A little help with Nitrox, please...

[roni]

I will combine my reply here to answer Dandy and Don.

First call me old fashion, but I believe in being careful, I had been diving for quit a long time, and naturally being Trimix ITT I am very found of deep diving. I never had a DCS incident, and I never had a student in a course that had one. I believe that the chance for DCS are there, there are to many contributing factors that can increases your chance of having a DCS hit. Therefore, I believe deeply in diving base on conservative planning. When I dive to 400+ feet I do not use accelerated decompression, I believe that if I want to go this depth I should have the patient for the deco time. I would say that this days the only way I will do a deep or cave dive is on a CCRs, and naturally I am diving in warm water.

I do agree that drinking/ dehydration is common problem in CM, but this is the realty in any tropical destination. I worked in Egypt, T&C Belize, and NC, the first 3 location are very much vacation destinations. People are coming for one week or so of yearly vacation, they are looking to have fun, they are going out, partying and drinking. Most popular dive destination are very hot, and most vacationers do not drink sufficient amount of water. In additional most vacation divers doing 10 to 14 dives a year and are out of shape. So, there is great numbers of contributing factors here. If you will go to any of the local chamber in any of this destination you will find that they are quit busy...

I promote Nitrox heavily, and I teach quit a few students. I do NOT promote Nitrox for extended dive time, but for safety and fatigue.
The two of you sound like active divers, with the case of Dandy you sound like you doing "deep" dives, and I been living 12 years in NC, so I am very familiar with NC and VA dives (Don I did not check your old posting so I do not have any idea what type of diving you do, so do not take offence).
The two of you are not the typical diver.

On a side note, we have an Oxygen Generator (I believe one of only two in existence in the dive industry), so we produce our own O2.

Dandy I hope to see you next week, the $100 nitrox upgrade is a standard item for us, naturally you need to dive with us.

 

[glbirch]

I am not aware of any research on the subject, but as I teach 10 to 20 nitrox student a month, I can tell you that majority of them say that they feel less tired.

In regards to explanation of why you feel less tired; any time you going diving your tissue is loading up with Nitrogen, in the end of a normal dive the size of the nitrogen bubble is to small to cause a DCS. However, the nitrogen loading in the tissue is not part of our normal physics, and your buddy immune system is becoming active in a attempt to combat the nitrogen. This is what cause the fating in the end of day of diving, after all, diving is definitely not an aerobics activity. When you dive Nitrox the Nitrogen loading in the tissue is less, and the body spend less reduce in fighting.

Interesting theory, but I don't think I buy it. N2 is inert, and something we are exposed to all the time. I can't see it causing an immune system reaction. I might believe that the higher O2 in the mix helps flush fatigue poisons or something. Of course I'm not a doctor, nor do I play one on television, so I could just be right off base.

 

[Scuba_Vixen]

Interesting theory, but I don't think I buy it. N2 is inert, and something we are exposed to all the time. I can't see it causing an immune system reaction. I might believe that the higher O2 in the mix helps flush fatigue poisons or something. Of course I'm not a doctor, nor do I play one on television, so I could just be right off base.

I don't exactly buy that theory either, but empirically speaking:

A lot of mix divers that have switched to 50/50 heliox for the 70' bottle, (or even 50/25/25), all report feeling very much better post dive than they did on Ean50.

Nitrogen, at anything much greater than .79ata, is just nasty sh*t. Any time you have a reasonable way to avoid it, you'll be better off for having done so.

Darlene

 

[Don Burke]

I promote Nitrox heavily, and I teach quit a few students. I do NOT promote Nitrox for extended dive time, but for safety and fatigue.
The two of you sound like active divers, with the case of Dandy you sound like you doing "deep" dives, and I been living 12 years in NC, so I am very familiar with NC and VA dives (Don I did not check your old posting so I do not have any idea what type of diving you do, so do not take offence).
The two of you are not the typical diver.

Perhaps we aren't typical of resort divers, but there are quite a few divers who don't know off the top of their heads what weight they need to dive with no exposure protection. Is a resort diver the "typical diver"? Possibly, but I doubt it.

If you send pretty much any diver out with a couple of big tanks, he will run into the no-stop limits on air, normally on the second dive. For diving in the mid-Atlantic, longer bottom times the are reason for diving nitrox. I doubt this region is unique.

On a side note, we have an Oxygen Generator (I believe one of only two in existence in the dive industry), so we produce our own O2.

There are plenty of membrane plants out there. Do you mean you have a cryo plant? That would be something to see.

 

[DandyDon]

On a side note, we have an Oxygen Generator (I believe one of only two in existence in the dive industry), so we produce our own O2.

Dandy I hope to see you next week, the $100 nitrox upgrade is a standard item for us, naturally you need to dive with us.

Actually, I think that a lot of stateside dealers use O2 generators, but I am impressed that you have one there. I generally expect "welders" oxygen in the Caribbean.

I'm delighted to hear that you offer $100 a week Nx deals. With that, I totally agree - dive Nx for all dives to recreational limits for better overall safety and possibly "that Nitrox feel good feeling."

I will be in contact with you by PM to work that out. Thanks a lot.

 

[TheStroke]

Interesting theory, but I don't think I buy it. N2 is inert, and something we are exposed to all the time. I can't see it causing an immune system reaction. I might believe that the higher O2 in the mix helps flush fatigue poisons or something. Of course I'm not a doctor, nor do I play one on television, so I could just be right off base.

Three plus years ago i went on my first major LOB, 5 dives a day for six days, over the past few years have done similar trips and been basically knackered come 9pm. earlier this year i took a nitrox course then went on a similar LOB, same number of dives, just as, if not, more stressfull (certainly colder) than my trip three years ago and stayed on nitrox all week and was still sat up at 11pm every night and up early everyday.

So three years older, no fitter, but feeling better after diving, cant prove it was the trox but it certainly looks that way

 

[lost dog]

So three years older, no fitter, but feeling better after diving, cant prove it was the trox but it certainly looks that way

I'm relatively new to nitrox, but now use it largely because I believe it to be safer for all depths I generally dive.

I think I feel less fatigue using nitrox, but am sure this is mostly a placebo effect.

A quick google search uncovered the following two studies:

This study apparently demonstrated NO reduction in fatigue using various nitrogen / oxygen mixes in a double-blind study:
http://www.hboevidence.com/Diving_Medicine/Harris.htm.

This double-blind firefighter study suggests that the perceived exertion levels using air with higher oxygen levels is lower than when using normal air: http://www.usfa.fema.gov/downloads/pdf/tr_98bw.pdf

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