Nitrox Certification?

[Atticus]

Thanks Atticus. The issue on O2 metabolism arose regarding the narcotic effect of oxygen. String, made a point that we only metabolize 4% of oxygen. Mstudley pointed out that it was basic human physiology (of the 21% of oxygen in air, we exhale 16% ergo consume 4%).

It's not part of the original thread but do you have any info on this?

I have a couple of rebreather texts that I can point you to. Probably the easiest thing to get ahold of is the book Mastering Rebreathers. I don't think it quite deserves the title "mastering", but it does have info metabolizing oxygen.

As to the narcotic affect, all I can add is that there is a lot of debate about it. I will offer from personal experience that I feel a little narc affect when I come off Trimix and go onto ean50 at 70 fsw. The ppN2 is very low, but I still feel slightly buzzed. To my senses this about equal to what I feel on air at that depth.

~Merlin

 

[BarryNL]

I'm not sure. Regardless of depth the FO2 stays the same while the PO2 changes but I don't know whether or not what you metabolize stays the same or changes. If I had to guess I'd say yes, you metabolize more O2 at greater depth hence the need for things like hypoxic trimix and such....

Not really. Your body only does one of two things with the oxygen you breathe in. The first is convert it to energy (and water and CO2); the second is breathe it back out again. So, unless you are producing more energy you body will not be "using" up any more O2 molecules (well, they are actually split into O atoms first IIRC). This means as the gas gets more dense (higher ppO2) you will be metabolizing a lower proportion of the O2 you breathe in.