Does nitrox make you feel good?

[fisherdvm]

I have a theory, please rebuff me if you have recently taken biochemistry.

Perhaps dive boats emit more carbon monoxide than we realized. As CO has high affinity for hemoglobin, the higher oxygen concentration might displace the CO molecules, thus making us feeling mentally and physically better.

It might be more complicated than the simple oxygen-hemoglobin dissociation curve...

Right now, at 15 to 10, it is hard for me to dismiss this as the "placebo" effect.

We really need to do a double blind study on this matter.

 

[String]

Blind study is impossible as there are no quantitative means to measure what "feel better" actually is.

If CO was an issue air divers would have headaches and other affects especially at depth if CO still bound to Haemoglobin.

It also wouldnt be an issue on all boats and shore dives.

The slightly increased % of O2 in back gas mixes have relatively little/no affect to dissociation curves as well. Im far too lazy to drag out my biochemistry texts from the other room to put actual figures on it though.

Suffice to say im certain in my own mind this theory ISNT true.

 

[fisherdvm]

String, you are too boring.

We need more theories, otherwise I'd have to conclude that 2/5 of our diving community are wackos......

What I said is double blind study... Meaning that you have no idea what's in your tank, and the admistrator of the research has no idea who got what tank. It does not mean that we use blind divers.

My gut feeling, just like you have said, is there is no difference.... But we need to explain why we respond so happily to the nitrox brand.

 

[Walter]

Blind study is impossible as there are no quantitative means to measure what "feel better" actually is.

Actually, it's not impossible and one double blind study was conducted. The results showed no difference. Some people do feel better after diving with nitrox, but it's not the nitrox that makes them feel better, it's their mind that does the trick.

 

[String]

I know exactly what a blind, double blind and other types of study are (i should do after doing a biochemistry degree).

The issue isnt blind/non blind its that its very hard borderline impossible to define "feel better" in criteria that are easily measurable.

There maybe the issue nitrox affects different people differently, there maybe an affect, there maybe no effect. We have a statistically insignificant sample size here which cant be used for anything. Online forum the problem as well is a self-selecting sample which causes bias issues. And as lots of trials have shown, placebo affect is so powerful it can easily swamp and meaningful data in a study.

So many other factors could also mask any small if it exists affect.

For example i feel tired after dives whether i use air or nitrox. However i think the reason is theyre usually done after 3-4 hours sleep, 5am starts followed by 250 mile round trip in the car and a typical day lasts 16 hours for 2 x 45 min dives.

 

[CBulla]

Know what I notice? Not the lack of being physically tired but the lack of mentally tired an hour or so post dive. Well, that and the headache.. I thought it was my clearing, etc., that gave me a headache during/post dives... that hasn't happened since I started diving nitrox only. I dove 1 can of air in a lake on a play dive and I had a headache afterwards. In my head or not, I don't have the same post dive effects.

 

[String]

Getting regular headaches after diving imho should mean a visit to a diving medic before continuing with dives. Its not normal and could be a something such as a PFO.

Or just CO2 retention/poorly adjusted regulator.

 

[rockjock3]

Blind study is impossible as there are no quantitative means to measure what "feel better" actually is.

If CO was an issue air divers would have headaches and other affects especially at depth if CO still bound to Haemoglobin.

It also wouldnt be an issue on all boats and shore dives.

The slightly increased % of O2 in back gas mixes have relatively little/no affect to dissociation curves as well. Im far too lazy to drag out my biochemistry texts from the other room to put actual figures on it though.

Suffice to say im certain in my own mind this theory ISNT true.

Blind studies are never impossible. The results from a blind study might, however, be just as subjective as individual experience though.

On that note. I am trying to locate the study (found it once before) that was done in Europe, I believe. They did this study with 30-40 people and doing many dives over several days they would tell each person what gas they were breathing, let them dive and then evaluate how they felt. The results were split. They had an equal number of people saying they felt better after diving nitrox (when they were actually on air) and people saying they felt better after diving nitrox (when they were actually on nitrox).

As far as scientific studies on actual gas absorbtion and release rates as well as certain physiological changes diving on different gases, I have not heard of any.

As far as my own personal experience. I went into diving nitrox with an open mind and not truly knowing if it would make me feel better or not. Well, I don't feel any different either way. I have even dove it on some of my long shore dives (90 minutes at 30-40 feet) just to see if extended time on it would have any effect and I don't feel any different after those dives either.

 

[String]

Maybe i wasnt clear, wasnt saying blind study was impossible but rather setting specific criteria for measuring the results, ie "feel good" isnt really easy to quantify scientifically.

 

[ScubaMilo]

Not really. The blood is already saturated long before that.

You utilise typically 4% Oxygen per breath. Higher O2 content just means you breathe it out. The whole point of nitrox is not to increase O2 content, it reduces nitrogen/inert contents - it just so happens that O2 replaces it.

Under pressure with even higher PPO2s then blood will definately be saturated to the extent the extra O2 content in nitrox will make no difference.

So lets take take your theroy to the next level.
You've stated it's not the elevated level of o2 making you feel better.
So then could it be the decreased on gassing of nitrogen.
Which in turn means your body is not working as hard internally to off gas the nitrogen after a nitrox dive compared to after a dive of the same profile on air.
Therefore the fatigue may be due to less work not more o2.
Just a thought what do you guys think.
Milo