air vs nitrox

[Thalassamania]

We are not disagreeing at all. I fear that I have not made the point clear enough.

The question of fatigue is not related to the energy that the body spends (or does not spend) taking up oxygen and moving it about the body. That's pretty much a constant.

There is anecdotal evidence that diving NITROX is less fatiguing. No one is suggestion that this has anything to do with the energetics of moving oxygen except for the possibility that venous side nitrogen bubbles impedes gas exchange after a dive and that reduction of gas exchange surface is what might account for the fatigue.

We are not talking about fatigue that occurs during a dive so the increased ppO2 while at pressure does not enter into the question.

 

[Thalassamania]

I forgot to add that the real reason why they administer 100% O2 to patients is because they don't have to breathe as much as we do to keep getting the needed amount of O2.

Acutally that's not the case. The reason that a patient receives O2 is, in the case of diving, to wash out nitrogen; and in the case of COPD or such, because they are not capable of getting the needed amount of O2 usualy because of reduced exchange suface.

 

[Kim]

So now lets consider breathing a regular air mix at about 100 feet. That's 3 ATMs of pressure. Multiply that times 0.21 (21% O2) and you get 0.63 ppO2. On the surface you breathe O2 at a ppO2 of 0.21 atm, so at 100 feet deep, you actually have THREE TIMES as much O2 available to your lungs as what you use on the surface.

Actually it's 4ATMs.....ppO2 - 0.84.

 

[neonstingray]

Acutally that's not the case. The reason that a patient receives O2 is, in the case of diving, to wash out nitrogen; and in the case of COPD or such, because they are not capable of getting the needed amount of O2 usualy because of reduced exchange suface.

Ok. I wasn't thinking of the first one, and the 2nd one I didn't know about. I was thinking of the cases where the person is short of breath or having difficulty breathing.

 

[neonstingray]

Actually it's 4ATMs.....ppO2 - 0.84.

Yeah Kim, you're right, sorry. I normally just think in ATM's of depth, so every 33 ft deep as 1 ATM. I forgot to add the 1 ATM you start with when referring to breathing gas.

 

[Kim]

Yeah Kim, you're right, sorry. I normally just think in ATM's of depth, so every 33 ft deep as 1 ATM. I forgot to add the 1 ATM you start with when referring to breathing gas.

I wasn't trying to be picky.....just thought we should keep it factual! With Nitrox mixes that is important to end up with the correct MOD for a given gas. eyebrow