Please Educate A Newbie on Nitrox :)

[The Kraken]

Hi all,

I was just recently Open Water certified, and have logged 5 freshwater dives so far. I am planning a couple upcoming dive trips. One of the trips I want to go on is 60-80ft saltwater, taking a tour of a reefed ship. The dive shop that handles the trip recommends the use of Nitrox for the dives, and offers certification for people (like me) that don't already have it.

I understand that Nitrox allows for longer bottom times and reduces the risk of decompression sickness, but that's all I know. Are there any other benefits to diving Nitrox, or any other risks (other than Oxygen Toxicity at depth)?

Is this something that I as a recreational diver should be certified in, or is Nitrox one of those things that I will only use once in a blue moon?

Thanks for any help.

Tim

Get the certification.

If nothing else, it helps you understand better the physics and physiology of diving.

Nitrox can extend your bottom times if you have a tank with sufficient capacity to allow you to do so. You're going to breathe what you're going to breath regarless of the composition of the breathing gas.

If you tank is of insufficient volume to allow you to take advantage of extended bottom times, then it can allow you to reduce the surface interval time for off gassing for a repetive dive.

the K

 

[muddiver]

You're talking about a theory, which is certainly based on solid arguments. But for something to be proven "safer" or proven to "reduce risk of DCS" you would need clinical studies that show a reduced incidence of DCS with recreational nitrox use. As far as I know, such a study does not yet exist.

I agree with the logic that, all other things equal, breathing a gas with lower N2 content will result in less N2 loading, and consequently SHOULD reduce the risk of DCS. But that's different that proving that using nitrox does in fact make one less likely to get DCS.

But, my post was emphasizing that if you use nitrox to increase bottom time, the theoretical additional safety margin is either diminished or lost.

Agreed.

 

[blue steal]

Heck the LDS here want $225 + $49 if you add the dives (shore), $99 for boat dives plus boat charges.

 

[Van Isle]

Roughly half my dives (~100) have been on 32%. I'll do one dive a day to 4 dives a day, all recreational. Diving nitrox is to me like diving a drysuit in cold water, or having a good light for night dives: once you start with it and actually realize the benefits, you'll wonder why you ever did without.

YMMV, just my 2psi, I don't know what I'm talking about, I'm not even certified. :cool2:

For the record I feel better after I dive nitrox, despite the claims of the single, small sample, limited scope, poorly constructed-but-oft-cited clinical study to the contrary.

 

[k ellis]

Roughly half my dives (~100) have been on 32%. I'll do one dive a day to 4 dives a day, all recreational. Diving nitrox is to me like diving a drysuit in cold water, or having a good light for night dives: once you start with it and actually realize the benefits, you'll wonder why you ever did without.

YMMV, just my 2psi, I don't know what I'm talking about, I'm not even certified. :cool2:

For the record I feel better after I dive nitrox, despite the claims of the single, small sample, limited scope, poorly constructed-but-oft-cited clinical study to the contrary.

I could not have said it better. The majority of my lake dives are 36 percent since I am a shallow lake diver most of the time...... In the ocean when I go I try to get 32 percent since it allows for my 80 - 90 foot cap I live by

 

[boulderjohn]

... the single, small sample, limited scope, poorly constructed-but-oft-cited clinical study to the contrary.

I am not sure I can think of a more poorly constructed study. It is absolutely worthless from a scientific point of view. But you are right. It is often cited.

 

[String]

I am not sure I can think of a more poorly constructed study. It is absolutely worthless from a scientific point of view. But you are right. It is often cited.

No matter how small that study its better than the alternative - an uncontrolled series of non-quantitative claims without a single shred of testing, comparison or scientific method used

A small controlled study is far better than "i think its this".

Scientific method is very clear - you propose something, you investigate it using standard defined controls, comparisons and review. IF someone is claiming nitrox makes them less tired its up to them and the group that claims it does to actually prove it. Otherwise its just hearsay. If there was actually any sort of plausible mechanism where it could do that it would help but again there isnt!

 

[lulubelle]

That sounds expensive to me, but then again, I negotiated mine with an instructor from whom I was buying dive charter spots. So basically, I paid 50 bucks plus the book. I have a background in the sciences, I'm sure that I taught myself most of the content, but that worked for me. DO NOT DO THE ONLINE CERT, most ops will not take it.

Agree that the theory you will get is well worth it.

Nitrox to me was a necessity, I dive in NC to 130 feet and bottom times on air, and DCS risk at these depths, make it almost necessary. I feel far better when diving it too. Fewer post dive headaches, less fatigue, etc.

One thing to mention, my doctor wants me to dive nitrox, especially for multi dive days. One caution though, You should check any medications you take with DAN, as a number of them can increase seizure threshold, which is a greater risk when diving Nitrox anyway. Well you actually should check any medications you take period, Nitrox or not. I recently learned that there was theoretical concern with the use of migraine meds for instance.

Good luck, have fun.

 

[Mike Boswell]

No matter how small that study its better than the alternative - an uncontrolled series of non-quantitative claims without a single shred of testing, comparison or scientific method used

A small controlled study is far better than "i think its this".

Scientific method is very clear - you propose something, you investigate it using standard defined controls, comparisons and review. IF someone is claiming nitrox makes them less tired its up to them and the group that claims it does to actually prove it. Otherwise its just hearsay. If there was actually any sort of plausible mechanism where it could do that it would help but again there isnt!

While I don't feel tired after diving and don't personally feel any difference using Nitrox, it is my understanding that there IS a theoretical basis for the claims.

The idea is that after a dive, tiny nitrogen bubbles form in the bloodstream and are trapped in the fine capillaries in the lungs and, perhaps by reducing oxygen transfer, make people feel "tired". This mechanism seems very plausible to me.

There is some credible evidence for this "bubbles-make-you-tired" phenomenon from Dr. Pyle, whose personal experiences were that deep stops and the subsequent off-gassing made him feel better after deep dives.

 

[ScubaFeenD]

Many divers who do real decompression dives, and decompress with 50% EANx or 100% O2, say they feel great at the end of dives. I suppose since technically you are off-gassing as you come up on a higher % of O2 you could at least accept the hypothesis as logical. More O2 while decompressing leads to feeling better. However, regardless of any logic, there hasnt been, so far, and evidence to support the assertion that a person "feels better" after using nitrox. However, if you personally "feel better" then who cares if what the studies say, as long as you dont use "feeling better" as a license to take part in activities that might predispose you to a DCS hit (like vigorous exercise).