Why Nitrox

[Walter]

My understanding of the 'feelgood' effect of nitrox is that it's more related to not getting subclinical dcs so easily -

I've heard that as well, but it's pure speculation. It doesn't seem to be supported by the facts. Fatigue is not a common symptom of DCS. If you'll read the article I linked to, you'll see:

The case of “fatigue” associated with diving is a good example to examine. Fatigue was initially reported as being associated with decompression sickness (DCS) in a large series of cases in Navy divers. In this series it was reported to occur only one time in approximately 1000 cases of DCS. Never was it reported as the predominant symptom of DCS. Nonetheless it has since then become a “poster child” for amorphous and subjective symptomatology associated with DCS.

 

[espenskogen]

I've heard that as well, but it's pure speculation. It doesn't seem to be supported by the facts. Fatigue is not a common symptom of DCS. If you'll read the article I linked to, you'll see:

Well, I can attest to that it's not the primary symptom. Joint pain etc tend to be the wakeup call in most cases. However, for subclinical DCI, fatigue is a common symptom, and if you speak to a few sufferers of DCI, I'm sure they will all attest to feeling pretty worn out as a result. I've had a hit myself, and I can attest to that after the primary symptoms (paralysis) was taken care of, I still felt like going to sleep for about a year.

I've spoken to several other divers ranging from skin bends to the more serious symptoms, and fatigue is a common denominator. But be that as it may - As an experiment, try to do a dive within the NDL limit - Say 60 ft for 20 minutes, and then shoot to the surface like a scud missile. I'm pretty sure you'd feel something similar to flu symptoms for the next few hours.

Now get on the 100% O2, and I think you'll find the flu symptoms vanishes after about 15 minutes.

E

 

[cummings66]

Probably not enough to make a difference, tho - I'm still betting on placebo effect.

Here's my theory that partially supports some.

The human creature is an amazing machine, we can will ourselves into altered states of being, i.e. look at what those who practice yoga can do for an example. Ever notice some people get a cold and life goes on, others make you think it's their last day on Earth.

I believe that those who believe Nitrox helps them feel better after a dive do indeed feel better after a dive, but only because they made their body believe that in the first place. For those like myself who do not believe in it I suspect there will be no difference because I feel good after a dive anyhow because I believe it's fun and restful.

It's all a state of mind IMO and IME.

 

[espenskogen]

Okay, here is a simplistic approach to why Nitrox may make one feel better. How does this sound...?

The body operates with the use of oxygen in the blood. Loading up on nitrogen blood gases will reduce the amount of oxygen available, therefore the body cannot operate as efficiently, therefore one will feel fatigue. Enriched air with higher oxygen levels will decrease the amount of nitrogen blood gasses, thereby increasing possible oxygen levels, and the body feels better...?

Probably not enough to make a difference, tho - I'm still betting on placebo effect.

Not quite - Nitrogen saturation does not reduce the amount of oxygen available. This has simply to do with the way gasses dissolve in tissue under pressure. blod oxygen levels are dictated by haemoglobin. Also remember that the fraction of gasses remain the same - Just the pressure increases.

The fatigue is put down to an immune response to microbubbles in tissue. When it's in the blood, it isn't so much of an issue, because it will be carried to the lungs, where it will be filtered out in the capilaries - Unless you've got a PFO or a shunt, in which case the blood bubbles can lead to a more serious DCS hit. The microbubbles in the blood is effectively what happens when we do our shallow, long stops after a deep dive - High gradient between the saturated tissue's PPN2, and the gas we breathe.

George Irvine has a good explanation about this on the WKPP web pages - I've provided a link to this earlier in the thread.

E

 

[espenskogen]

Here's my theory that partially supports some.

The human creature is an amazing machine, we can will ourselves into altered states of being, i.e. look at what those who practice yoga can do for an example. Ever notice some people get a cold and life goes on, others make you think it's their last day on Earth.

I believe that those who believe Nitrox helps them feel better after a dive do indeed feel better after a dive, but only because they made their body believe that in the first place. For those like myself who do not believe in it I suspect there will be no difference because I feel good after a dive anyhow because I believe it's fun and restful.

It's all a state of mind IMO and IME.

Personally, I think this is a bit like the people arguing that the world is flat, or that Darwin's theory of evolution is a load of crap, and that God Almighty himself put us here in an instant cataclysmic event. My personal opinion of the evidence at hand is that reduced N2 during diving does a world of good for you. Anybody arguing otherwise has IMHO either not read the evidence, or refuse to accept the science behind it.

But hey - Nobody's twisting your arm - So good diving - On whichever gas you choose

 

[Walter]

My personal opinion of the evidence at hand is that reduced N2 during diving does a world of good for you. Anybody arguing otherwise has IMHO either not read the evidence, or refuse to accept the science behind it.

But hey - Nobody's twisting your arm - So good diving - On whichever gas you choose

Has anyone disputed that reduced N2 is a good thing? There's just no evidence that it actually makes you feel better.

 

[wedivebc]

- As an experiment, try to do a dive within the NDL limit - Say 60 ft for 20 minutes, and then shoot to the surface like a scud missile. I'm pretty sure you'd feel something similar to flu symptoms for the next few hours.

Shooting to the surface is NOT within the NDL limits by any tables I am aware of. I certainly hope you are not actually advising someone to do anything as dangerous as this
All tables are designed to operate within a certain ascent rate. The PADI tables for instance are designed to work with 60ft/min of ascent. If you ascend faster than that you are outside the limits of the tables and the results could be very serios.

 

[MoonWrasse]

Has anyone disputed that reduced N2 is a good thing? There's just no evidence that it actually makes you feel better.

Except for being narcd or nitrous oxide, I agree with you

 

[cummings66]

I think Walter is right, nobody has tried to claim diving on Nitrox isn't good for what it can do. It's more along the lines of there is no proof it does anything to make you feel better.

I believe you feel better because you want to feel better so badly that your body obeys and you do. Same reason people can firewalk, go into a trance, etc. It's your mind controlling the body and that's all, IMO.

 

[wedivebc]

I think Walter and others would agree that micobubbles contribute to the feeling of fatigue we sometimes feel after a dive. Although I have never read any studies on the subject until now I have always believed that nitrox allows you to feel better after a dive in the same way that deep stops and very slow ascents from the last 20ft make me feel better than just following NDL limits of outdated tables
It all depends how you use it